mod_dav.c   [plain text]

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * DAV extension module for Apache 2.0.*
 *
 * This module is repository-independent. It depends on hooks provided by a
 * repository implementation.
 *
 * APACHE ISSUES:
 *   - within a DAV hierarchy, if an unknown method is used and we default
 *     to Apache's implementation, it sends back an OPTIONS with the wrong
 *     set of methods -- there is NO HOOK for us.
 *     therefore: we need to manually handle the HTTP_METHOD_NOT_ALLOWED
 *       and HTTP_NOT_IMPLEMENTED responses (not ap_send_error_response).
 *   - process_mkcol_body() had to dup code from ap_setup_client_block().
 *   - it would be nice to get status lines from Apache for arbitrary
 *     status codes
 *   - it would be nice to be able to extend Apache's set of response
 *     codes so that it doesn't return 500 when an unknown code is placed
 *     into r->status.
 *   - http_vhost functions should apply "const" to their params
 *
 * DESIGN NOTES:
 *   - For PROPFIND, we batch up the entire response in memory before
 *     sending it. We may want to reorganize around sending the information
 *     as we suck it in from the propdb. Alternatively, we should at least
 *     generate a total Content-Length if we're going to buffer in memory
 *     so that we can keep the connection open.
 */

#include "apr_strings.h"
#include "apr_lib.h"            /* for apr_is* */

#define APR_WANT_STRFUNC
#include "apr_want.h"

#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_main.h"
#include "http_protocol.h"
#include "http_request.h"
#include "util_script.h"

#include "mod_dav.h"


/* ### what is the best way to set this? */
#define DAV_DEFAULT_PROVIDER    "filesystem"

/* used to denote that mod_dav will be handling this request */
#define DAV_HANDLER_NAME "dav-handler"

enum {
    DAV_ENABLED_UNSET = 0,
    DAV_ENABLED_OFF,
    DAV_ENABLED_ON
};

/* per-dir configuration */
typedef struct {
    const char *provider_name;
    const dav_provider *provider;
    const char *dir;
    int locktimeout;
    int allow_depthinfinity;

} dav_dir_conf;

/* per-server configuration */
typedef struct {
    int unused;

} dav_server_conf;

#define DAV_INHERIT_VALUE(parent, child, field) \
                ((child)->field ? (child)->field : (parent)->field)


/* forward-declare for use in configuration lookup */
extern module DAV_DECLARE_DATA dav_module;

/* DAV methods */
enum {
    DAV_M_BIND = 0,
    DAV_M_SEARCH,
    DAV_M_LAST
};
static int dav_methods[DAV_M_LAST];


static int dav_init_handler(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp,
                             server_rec *s)
{
    /* DBG0("dav_init_handler"); */

    /* Register DAV methods */
    dav_methods[DAV_M_BIND] = ap_method_register(p, "BIND");
    dav_methods[DAV_M_SEARCH] = ap_method_register(p, "SEARCH");

    ap_add_version_component(p, "DAV/2");

    return OK;
}

static void *dav_create_server_config(apr_pool_t *p, server_rec *s)
{
    dav_server_conf *newconf;

    newconf = (dav_server_conf *)apr_pcalloc(p, sizeof(*newconf));

    /* ### this isn't used at the moment... */

    return newconf;
}

static void *dav_merge_server_config(apr_pool_t *p, void *base, void *overrides)
{
#if 0
    dav_server_conf *child = overrides;
#endif
    dav_server_conf *newconf;

    newconf = (dav_server_conf *)apr_pcalloc(p, sizeof(*newconf));

    /* ### nothing to merge right now... */

    return newconf;
}

static void *dav_create_dir_config(apr_pool_t *p, char *dir)
{
    /* NOTE: dir==NULL creates the default per-dir config */

    dav_dir_conf *conf;

    conf = (dav_dir_conf *)apr_pcalloc(p, sizeof(*conf));

    /* clean up the directory to remove any trailing slash */
    if (dir != NULL) {
        char *d;
        apr_size_t l;

        d = apr_pstrdup(p, dir);
        l = strlen(d);
        if (l > 1 && d[l - 1] == '/')
            d[l - 1] = '\0';
        conf->dir = d;
    }

    return conf;
}

static void *dav_merge_dir_config(apr_pool_t *p, void *base, void *overrides)
{
    dav_dir_conf *parent = base;
    dav_dir_conf *child = overrides;
    dav_dir_conf *newconf = (dav_dir_conf *)apr_pcalloc(p, sizeof(*newconf));

    /* DBG3("dav_merge_dir_config: new=%08lx  base=%08lx  overrides=%08lx",
       (long)newconf, (long)base, (long)overrides); */

    newconf->provider_name = DAV_INHERIT_VALUE(parent, child, provider_name);
    newconf->provider = DAV_INHERIT_VALUE(parent, child, provider);
    if (parent->provider_name != NULL) {
        if (child->provider_name == NULL) {
            ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL,
                         "\"DAV Off\" cannot be used to turn off a subtree "
                         "of a DAV-enabled location.");
        }
        else if (strcasecmp(child->provider_name,
                            parent->provider_name) != 0) {
            ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL,
                         "A subtree cannot specify a different DAV provider "
                         "than its parent.");
        }
    }

    newconf->locktimeout = DAV_INHERIT_VALUE(parent, child, locktimeout);
    newconf->dir = DAV_INHERIT_VALUE(parent, child, dir);
    newconf->allow_depthinfinity = DAV_INHERIT_VALUE(parent, child,
                                                     allow_depthinfinity);

    return newconf;
}

static const dav_provider *dav_get_provider(request_rec *r)
{
    dav_dir_conf *conf;

    conf = ap_get_module_config(r->per_dir_config, &dav_module);
    /* assert: conf->provider_name != NULL
       (otherwise, DAV is disabled, and we wouldn't be here) */

    /* assert: conf->provider != NULL
       (checked when conf->provider_name is set) */
    return conf->provider;
}

DAV_DECLARE(const dav_hooks_locks *) dav_get_lock_hooks(request_rec *r)
{
    return dav_get_provider(r)->locks;
}

DAV_DECLARE(const dav_hooks_propdb *) dav_get_propdb_hooks(request_rec *r)
{
    return dav_get_provider(r)->propdb;
}

DAV_DECLARE(const dav_hooks_vsn *) dav_get_vsn_hooks(request_rec *r)
{
    return dav_get_provider(r)->vsn;
}

DAV_DECLARE(const dav_hooks_binding *) dav_get_binding_hooks(request_rec *r)
{
    return dav_get_provider(r)->binding;
}

DAV_DECLARE(const dav_hooks_search *) dav_get_search_hooks(request_rec *r)
{
    return dav_get_provider(r)->search;
}

/*
 * Command handler for the DAV directive, which is TAKE1.
 */
static const char *dav_cmd_dav(cmd_parms *cmd, void *config, const char *arg1)
{
    dav_dir_conf *conf = (dav_dir_conf *)config;

    if (strcasecmp(arg1, "on") == 0) {
        conf->provider_name = DAV_DEFAULT_PROVIDER;
    }
    else if (strcasecmp(arg1, "off") == 0) {
        conf->provider_name = NULL;
        conf->provider = NULL;
    }
    else {
        conf->provider_name = apr_pstrdup(cmd->pool, arg1);
    }

    if (conf->provider_name != NULL) {
        /* lookup and cache the actual provider now */
        conf->provider = dav_lookup_provider(conf->provider_name);

        if (conf->provider == NULL) {
            /* by the time they use it, the provider should be loaded and
               registered with us. */
            return apr_psprintf(cmd->pool,
                                "Unknown DAV provider: %s",
                                conf->provider_name);
        }
    }

    return NULL;
}

/*
 * Command handler for the DAVDepthInfinity directive, which is FLAG.
 */
static const char *dav_cmd_davdepthinfinity(cmd_parms *cmd, void *config,
                                            int arg)
{
    dav_dir_conf *conf = (dav_dir_conf *)config;

    if (arg)
        conf->allow_depthinfinity = DAV_ENABLED_ON;
    else
        conf->allow_depthinfinity = DAV_ENABLED_OFF;
    return NULL;
}

/*
 * Command handler for DAVMinTimeout directive, which is TAKE1
 */
static const char *dav_cmd_davmintimeout(cmd_parms *cmd, void *config,
                                         const char *arg1)
{
    dav_dir_conf *conf = (dav_dir_conf *)config;

    conf->locktimeout = atoi(arg1);
    if (conf->locktimeout < 0)
        return "DAVMinTimeout requires a non-negative integer.";

    return NULL;
}

/*
** dav_error_response()
**
** Send a nice response back to the user. In most cases, Apache doesn't
** allow us to provide details in the body about what happened. This
** function allows us to completely specify the response body.
**
** ### this function is not logging any errors! (e.g. the body)
*/
static int dav_error_response(request_rec *r, int status, const char *body)
{
    r->status = status;

    /* ### I really don't think this is needed; gotta test */
    r->status_line = ap_get_status_line(status);

    ap_set_content_type(r, "text/html; charset=ISO-8859-1");

    /* begin the response now... */
    ap_rvputs(r,
              DAV_RESPONSE_BODY_1,
              r->status_line,
              DAV_RESPONSE_BODY_2,
              &r->status_line[4],
              DAV_RESPONSE_BODY_3,
              body,
              DAV_RESPONSE_BODY_4,
              ap_psignature("<hr />\n", r),
              DAV_RESPONSE_BODY_5,
              NULL);

    /* the response has been sent. */
    /*
     * ### Use of DONE obviates logging..!
     */
    return DONE;
}


/*
 * Send a "standardized" error response based on the error's namespace & tag
 */
static int dav_error_response_tag(request_rec *r,
                                  dav_error *err)
{
    r->status = err->status;

    /* ### I really don't think this is needed; gotta test */
    r->status_line = ap_get_status_line(err->status);

    ap_set_content_type(r, DAV_XML_CONTENT_TYPE);

    ap_rputs(DAV_XML_HEADER DEBUG_CR
             "<D:error xmlns:D=\"DAV:\"", r);

    if (err->desc != NULL) {
        /* ### should move this namespace somewhere (with the others!) */
        ap_rputs(" xmlns:m=\"http://apache.org/dav/xmlns\"", r);
    }

    if (err->namespace != NULL) {
        ap_rprintf(r,
                   " xmlns:C=\"%s\">" DEBUG_CR
                   "<C:%s/>" DEBUG_CR,
                   err->namespace, err->tagname);
    }
    else {
        ap_rprintf(r,
                   ">" DEBUG_CR
                   "<D:%s/>" DEBUG_CR, err->tagname);
    }

    /* here's our mod_dav specific tag: */
    if (err->desc != NULL) {
        ap_rprintf(r,
                   "<m:human-readable errcode=\"%d\">" DEBUG_CR
                   "%s" DEBUG_CR
                   "</m:human-readable>" DEBUG_CR,
                   err->error_id,
                   apr_xml_quote_string(r->pool, err->desc, 0));
    }

    ap_rputs("</D:error>" DEBUG_CR, r);

    /* the response has been sent. */
    /*
     * ### Use of DONE obviates logging..!
     */
    return DONE;
}


/*
 * Apache's URI escaping does not replace '&' since that is a valid character
 * in a URI (to form a query section). We must explicitly handle it so that
 * we can embed the URI into an XML document.
 */
static const char *dav_xml_escape_uri(apr_pool_t *p, const char *uri)
{
    const char *e_uri = ap_escape_uri(p, uri);

    /* check the easy case... */
    if (ap_strchr_c(e_uri, '&') == NULL)
        return e_uri;

    /* there was a '&', so more work is needed... sigh. */

    /*
     * Note: this is a teeny bit of overkill since we know there are no
     * '<' or '>' characters, but who cares.
     */
    return apr_xml_quote_string(p, e_uri, 0);
}


/* Write a complete RESPONSE object out as a <DAV:repsonse> xml
   element.  Data is sent into brigade BB, which is auto-flushed into
   OUTPUT filter stack.  Use POOL for any temporary allocations.

   [Presumably the <multistatus> tag has already been written;  this
   routine is shared by dav_send_multistatus and dav_stream_response.]
*/
static void dav_send_one_response(dav_response *response,
                                  apr_bucket_brigade *bb,
                                  ap_filter_t *output,
                                  apr_pool_t *pool)
{
    apr_text *t = NULL;

    if (response->propresult.xmlns == NULL) {
      ap_fputs(output, bb, "<D:response>");
    }
    else {
      ap_fputs(output, bb, "<D:response");
      for (t = response->propresult.xmlns; t; t = t->next) {
        ap_fputs(output, bb, t->text);
      }
      ap_fputc(output, bb, '>');
    }

    ap_fputstrs(output, bb,
                DEBUG_CR "<D:href>",
                dav_xml_escape_uri(pool, response->href),
                "</D:href>" DEBUG_CR,
                NULL);

    if (response->propresult.propstats == NULL) {
      /* use the Status-Line text from Apache.  Note, this will
       * default to 500 Internal Server Error if first->status
       * is not a known (or valid) status code.
       */
      ap_fputstrs(output, bb,
                  "<D:status>HTTP/1.1 ",
                  ap_get_status_line(response->status),
                  "</D:status>" DEBUG_CR,
                  NULL);
    }
    else {
      /* assume this includes <propstat> and is quoted properly */
      for (t = response->propresult.propstats; t; t = t->next) {
        ap_fputs(output, bb, t->text);
      }
    }

    if (response->desc != NULL) {
      /*
       * We supply the description, so we know it doesn't have to
       * have any escaping/encoding applied to it.
       */
      ap_fputstrs(output, bb,
                  "<D:responsedescription>",
                  response->desc,
                  "</D:responsedescription>" DEBUG_CR,
                  NULL);
    }

    ap_fputs(output, bb, "</D:response>" DEBUG_CR);
}


/* Factorized helper function: prep request_rec R for a multistatus
   response and write <multistatus> tag into BB, destined for
   R->output_filters.  Use xml NAMESPACES in initial tag, if
   non-NULL. */
static void dav_begin_multistatus(apr_bucket_brigade *bb,
                                  request_rec *r, int status,
                                  apr_array_header_t *namespaces)
{
    /* Set the correct status and Content-Type */
    r->status = status;
    ap_set_content_type(r, DAV_XML_CONTENT_TYPE);

    /* Send the headers and actual multistatus response now... */
    ap_fputs(r->output_filters, bb, DAV_XML_HEADER DEBUG_CR
             "<D:multistatus xmlns:D=\"DAV:\"");

    if (namespaces != NULL) {
       int i;

       for (i = namespaces->nelts; i--; ) {
           ap_fprintf(r->output_filters, bb, " xmlns:ns%d=\"%s\"", i,
                      APR_XML_GET_URI_ITEM(namespaces, i));
       }
    }

    ap_fputs(r->output_filters, bb, ">" DEBUG_CR);
}

/* Finish a multistatus response started by dav_begin_multistatus: */
static apr_status_t dav_finish_multistatus(request_rec *r,
                                           apr_bucket_brigade *bb)
{
    apr_bucket *b;

    ap_fputs(r->output_filters, bb, "</D:multistatus>" DEBUG_CR);

    /* indicate the end of the response body */
    b = apr_bucket_eos_create(r->connection->bucket_alloc);
    APR_BRIGADE_INSERT_TAIL(bb, b);

    /* deliver whatever might be remaining in the brigade */
    return ap_pass_brigade(r->output_filters, bb);
}

static void dav_send_multistatus(request_rec *r, int status,
                                 dav_response *first,
                                 apr_array_header_t *namespaces)
{
    apr_pool_t *subpool;
    apr_bucket_brigade *bb = apr_brigade_create(r->pool,
                                                r->connection->bucket_alloc);

    dav_begin_multistatus(bb, r, status, namespaces);

    apr_pool_create(&subpool, r->pool);

    for (; first != NULL; first = first->next) {
      apr_pool_clear(subpool);
      dav_send_one_response(first, bb, r->output_filters, subpool);
    }
    apr_pool_destroy(subpool);

    dav_finish_multistatus(r, bb);
}

/*
 * dav_log_err()
 *
 * Write error information to the log.
 */
static void dav_log_err(request_rec *r, dav_error *err, int level)
{
    dav_error *errscan;

    /* Log the errors */
    /* ### should have a directive to log the first or all */
    for (errscan = err; errscan != NULL; errscan = errscan->prev) {
        if (errscan->desc == NULL)
            continue;

        if (errscan->save_errno != 0) {
            errno = errscan->save_errno;
            ap_log_rerror(APLOG_MARK, level, errno, r, "%s  [%d, #%d]",
                          errscan->desc, errscan->status, errscan->error_id);
        }
        else {
            ap_log_rerror(APLOG_MARK, level, 0, r,
                          "%s  [%d, #%d]",
                          errscan->desc, errscan->status, errscan->error_id);
        }
    }
}

/*
 * dav_handle_err()
 *
 * Handle the standard error processing. <err> must be non-NULL.
 *
 * <response> is set by the following:
 *   - dav_validate_request()
 *   - dav_add_lock()
 *   - repos_hooks->remove_resource
 *   - repos_hooks->move_resource
 *   - repos_hooks->copy_resource
 *   - vsn_hooks->update
 */
static int dav_handle_err(request_rec *r, dav_error *err,
                          dav_response *response)
{
    /* log the errors */
    dav_log_err(r, err, APLOG_ERR);

    if (response == NULL) {
        dav_error *stackerr = err;

        /* our error messages are safe; tell Apache this */
        apr_table_setn(r->notes, "verbose-error-to", "*");

        /* Didn't get a multistatus response passed in, but we still
           might be able to generate a standard <D:error> response.
           Search the error stack for an errortag. */
        while (stackerr != NULL && stackerr->tagname == NULL)
            stackerr = stackerr->prev;

        if (stackerr != NULL && stackerr->tagname != NULL)
            return dav_error_response_tag(r, stackerr);

        return err->status;
    }

    /* send the multistatus and tell Apache the request/response is DONE. */
    dav_send_multistatus(r, err->status, response, NULL);
    return DONE;
}

/* handy function for return values of methods that (may) create things */
static int dav_created(request_rec *r, const char *locn, const char *what,
                       int replaced)
{
    const char *body;

    if (locn == NULL) {
        locn = r->uri;
    }

    /* did the target resource already exist? */
    if (replaced) {
        /* Apache will supply a default message */
        return HTTP_NO_CONTENT;
    }

    /* Per HTTP/1.1, S10.2.2: add a Location header to contain the
     * URI that was created. */

    /* Convert locn to an absolute URI, and return in Location header */
    apr_table_setn(r->headers_out, "Location", ap_construct_url(r->pool, locn, r));

    /* ### insert an ETag header? see HTTP/1.1 S10.2.2 */

    /* Apache doesn't allow us to set a variable body for HTTP_CREATED, so
     * we must manufacture the entire response. */
    body = apr_psprintf(r->pool, "%s %s has been created.",
                        what, ap_escape_html(r->pool, locn));
    return dav_error_response(r, HTTP_CREATED, body);
}

/* ### move to dav_util? */
DAV_DECLARE(int) dav_get_depth(request_rec *r, int def_depth)
{
    const char *depth = apr_table_get(r->headers_in, "Depth");

    if (depth == NULL) {
        return def_depth;
    }

    if (strcasecmp(depth, "infinity") == 0) {
        return DAV_INFINITY;
    }
    else if (strcmp(depth, "0") == 0) {
        return 0;
    }
    else if (strcmp(depth, "1") == 0) {
        return 1;
    }

    /* The caller will return an HTTP_BAD_REQUEST. This will augment the
     * default message that Apache provides. */
    ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                  "An invalid Depth header was specified.");
    return -1;
}

static int dav_get_overwrite(request_rec *r)
{
    const char *overwrite = apr_table_get(r->headers_in, "Overwrite");

    if (overwrite == NULL) {
        return 1; /* default is "T" */
    }

    if ((*overwrite == 'F' || *overwrite == 'f') && overwrite[1] == '\0') {
        return 0;
    }

    if ((*overwrite == 'T' || *overwrite == 't') && overwrite[1] == '\0') {
        return 1;
    }

    /* The caller will return an HTTP_BAD_REQUEST. This will augment the
     * default message that Apache provides. */
    ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                  "An invalid Overwrite header was specified.");
    return -1;
}

/* resolve a request URI to a resource descriptor.
 *
 * If label_allowed != 0, then allow the request target to be altered by
 * a Label: header.
 *
 * If use_checked_in is true, then the repository provider should return
 * the resource identified by the DAV:checked-in property of the resource
 * identified by the Request-URI.
 */
static dav_error *dav_get_resource(request_rec *r, int label_allowed,
                                   int use_checked_in, dav_resource **res_p)
{
    dav_dir_conf *conf;
    const char *label = NULL;
    dav_error *err;

    /* if the request target can be overridden, get any target selector */
    if (label_allowed) {
        label = apr_table_get(r->headers_in, "label");
    }

    conf = ap_get_module_config(r->per_dir_config, &dav_module);
    /* assert: conf->provider != NULL */

    /* resolve the resource */
    err = (*conf->provider->repos->get_resource)(r, conf->dir,
                                                 label, use_checked_in,
                                                 res_p);
    if (err != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             "Could not fetch resource information.", err);
        return err;
    }

    /* Note: this shouldn't happen, but just be sure... */
    if (*res_p == NULL) {
        /* ### maybe use HTTP_INTERNAL_SERVER_ERROR */
        return dav_new_error(r->pool, HTTP_NOT_FOUND, 0,
                             apr_psprintf(r->pool,
                                          "The provider did not define a "
                                          "resource for %s.",
                                          ap_escape_html(r->pool, r->uri)));
    }

    /* ### hmm. this doesn't feel like the right place or thing to do */
    /* if there were any input headers requiring a Vary header in the response,
     * add it now */
    dav_add_vary_header(r, r, *res_p);

    return NULL;
}

static dav_error * dav_open_lockdb(request_rec *r, int ro, dav_lockdb **lockdb)
{
    const dav_hooks_locks *hooks = DAV_GET_HOOKS_LOCKS(r);

    if (hooks == NULL) {
        *lockdb = NULL;
        return NULL;
    }

    /* open the thing lazily */
    return (*hooks->open_lockdb)(r, ro, 0, lockdb);
}

/**
 * @return  1 if valid content-range,
 *          0 if no content-range,
 *         -1 if malformed content-range
 */
static int dav_parse_range(request_rec *r,
                           apr_off_t *range_start, apr_off_t *range_end)
{
    const char *range_c;
    char *range;
    char *dash;
    char *slash;
    char *errp;

    range_c = apr_table_get(r->headers_in, "content-range");
    if (range_c == NULL)
        return 0;

    range = apr_pstrdup(r->pool, range_c);
    if (strncasecmp(range, "bytes ", 6) != 0
        || (dash = ap_strchr(range, '-')) == NULL
        || (slash = ap_strchr(range, '/')) == NULL) {
        /* malformed header */
        return -1;
    }

    *dash++ = *slash++ = '\0';

    /* detect invalid ranges */
    if (apr_strtoff(range_start, range + 6, &errp, 10)
        || *errp || *range_start < 0) {
        return -1;
    }
    if (apr_strtoff(range_end, dash, &errp, 10)
        || *errp || *range_end < 0 || *range_end < *range_start) {
        return -1;
    }

    if (*slash != '*') {
        apr_off_t dummy;

        if (apr_strtoff(&dummy, slash, &errp, 10)
            || *errp || dummy <= *range_end) {
            return -1;
        }
    }

    /* we now have a valid range */
    return 1;
}

/* handle the GET method */
static int dav_method_get(request_rec *r)
{
    dav_resource *resource;
    dav_error *err;
    int status;

    /* This method should only be called when the resource is not
     * visible to Apache. We will fetch the resource from the repository,
     * then create a subrequest for Apache to handle.
     */
    err = dav_get_resource(r, 1 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    /* set up the HTTP headers for the response */
    if ((err = (*resource->hooks->set_headers)(r, resource)) != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             "Unable to set up HTTP headers.",
                             err);
        return dav_handle_err(r, err, NULL);
    }

    /* Handle conditional requests */
    status = ap_meets_conditions(r);
    if (status) {
      return status;
    }

    if (r->header_only) {
        return DONE;
    }

    /* okay... time to deliver the content */
    if ((err = (*resource->hooks->deliver)(resource,
                                           r->output_filters)) != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             "Unable to deliver content.",
                             err);
        return dav_handle_err(r, err, NULL);
    }

    return DONE;
}

/* validate resource/locks on POST, then pass to the default handler */
static int dav_method_post(request_rec *r)
{
    dav_resource *resource;
    dav_error *err;

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    /* Note: depth == 0. Implies no need for a multistatus response. */
    if ((err = dav_validate_request(r, resource, 0, NULL, NULL,
                                    DAV_VALIDATE_RESOURCE, NULL)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, NULL);
    }

    return DECLINED;
}

/* handle the PUT method */
static int dav_method_put(request_rec *r)
{
    dav_resource *resource;
    int resource_state;
    dav_auto_version_info av_info;
    const dav_hooks_locks *locks_hooks = DAV_GET_HOOKS_LOCKS(r);
    const char *body;
    dav_error *err;
    dav_error *err2;
    dav_stream_mode mode;
    dav_stream *stream;
    dav_response *multi_response;
    int has_range;
    apr_off_t range_start;
    apr_off_t range_end;

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    /* If not a file or collection resource, PUT not allowed */
    if (resource->type != DAV_RESOURCE_TYPE_REGULAR
        && resource->type != DAV_RESOURCE_TYPE_WORKING) {
        body = apr_psprintf(r->pool,
                            "Cannot create resource %s with PUT.",
                            ap_escape_html(r->pool, r->uri));
        return dav_error_response(r, HTTP_CONFLICT, body);
    }

    /* Cannot PUT a collection */
    if (resource->collection) {
        return dav_error_response(r, HTTP_CONFLICT,
                                  "Cannot PUT to a collection.");

    }

    resource_state = dav_get_resource_state(r, resource);

    /*
     * Note: depth == 0 normally requires no multistatus response. However,
     * if we pass DAV_VALIDATE_PARENT, then we could get an error on a URI
     * other than the Request-URI, thereby requiring a multistatus.
     *
     * If the resource does not exist (DAV_RESOURCE_NULL), then we must
     * check the resource *and* its parent. If the resource exists or is
     * a locknull resource, then we check only the resource.
     */
    if ((err = dav_validate_request(r, resource, 0, NULL, &multi_response,
                                    resource_state == DAV_RESOURCE_NULL ?
                                    DAV_VALIDATE_PARENT :
                                    DAV_VALIDATE_RESOURCE, NULL)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, multi_response);
    }

    has_range = dav_parse_range(r, &range_start, &range_end);
    if (has_range < 0) {
        /* RFC 2616 14.16: If we receive an invalid Content-Range we must
         * not use the content.
         */
        body = apr_psprintf(r->pool,
                            "Malformed Content-Range header for PUT %s.",
                            ap_escape_html(r->pool, r->uri));
        return dav_error_response(r, HTTP_BAD_REQUEST, body);
    } else if (has_range) {
        mode = DAV_MODE_WRITE_SEEKABLE;
    }
    else {
        mode = DAV_MODE_WRITE_TRUNC;
    }

    /* make sure the resource can be modified (if versioning repository) */
    if ((err = dav_auto_checkout(r, resource,
                                 0 /* not parent_only */,
                                 &av_info)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, NULL);
    }

    /* Create the new file in the repository */
    if ((err = (*resource->hooks->open_stream)(resource, mode,
                                               &stream)) != NULL) {
        /* ### assuming FORBIDDEN is probably not quite right... */
        err = dav_push_error(r->pool, HTTP_FORBIDDEN, 0,
                             apr_psprintf(r->pool,
                                          "Unable to PUT new contents for %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
    }

    if (err == NULL && has_range) {
        /* a range was provided. seek to the start */
        err = (*resource->hooks->seek_stream)(stream, range_start);
    }

    if (err == NULL) {
        apr_bucket_brigade *bb;
        apr_bucket *b;
        int seen_eos = 0;

        bb = apr_brigade_create(r->pool, r->connection->bucket_alloc);

        do {
            apr_status_t rc;

            rc = ap_get_brigade(r->input_filters, bb, AP_MODE_READBYTES,
                                APR_BLOCK_READ, DAV_READ_BLOCKSIZE);

            if (rc != APR_SUCCESS) {
                err = dav_new_error(r->pool, HTTP_INTERNAL_SERVER_ERROR, 0,
                                    "Could not get next bucket brigade");
                break;
            }

            for (b = APR_BRIGADE_FIRST(bb);
                 b != APR_BRIGADE_SENTINEL(bb);
                 b = APR_BUCKET_NEXT(b))
            {
                const char *data;
                apr_size_t len;

                if (APR_BUCKET_IS_EOS(b)) {
                    seen_eos = 1;
                    break;
                }

                if (APR_BUCKET_IS_METADATA(b)) {
                    continue;
                }

                rc = apr_bucket_read(b, &data, &len, APR_BLOCK_READ);
                if (rc != APR_SUCCESS) {
                    err = dav_new_error(r->pool, HTTP_BAD_REQUEST, 0,
                                        "An error occurred while reading "
                                        "the request body.");
                    break;
                }

                if (err == NULL) {
                    /* write whatever we read, until we see an error */
                    err = (*resource->hooks->write_stream)(stream, data, len);
                }
            }

            apr_brigade_cleanup(bb);
        } while (!seen_eos);

        apr_brigade_destroy(bb);

        err2 = (*resource->hooks->close_stream)(stream,
                                                err == NULL /* commit */);
        if (err2 != NULL && err == NULL) {
            /* no error during the write, but we hit one at close. use it. */
            err = err2;
        }
    }

    /*
     * Ensure that we think the resource exists now.
     * ### eek. if an error occurred during the write and we did not commit,
     * ### then the resource might NOT exist (e.g. dav_fs_repos.c)
     */
    if (err == NULL) {
        resource->exists = 1;
    }

    /* restore modifiability of resources back to what they were */
    err2 = dav_auto_checkin(r, resource, err != NULL /* undo if error */,
                            0 /*unlock*/, &av_info);

    /* check for errors now */
    if (err != NULL) {
        return dav_handle_err(r, err, NULL);
    }

    if (err2 != NULL) {
        /* just log a warning */
        err2 = dav_push_error(r->pool, err2->status, 0,
                              "The PUT was successful, but there "
                              "was a problem automatically checking in "
                              "the resource or its parent collection.",
                              err2);
        dav_log_err(r, err2, APLOG_WARNING);
    }

    /* ### place the Content-Type and Content-Language into the propdb */

    if (locks_hooks != NULL) {
        dav_lockdb *lockdb;

        if ((err = (*locks_hooks->open_lockdb)(r, 0, 0, &lockdb)) != NULL) {
            /* The file creation was successful, but the locking failed. */
            err = dav_push_error(r->pool, err->status, 0,
                                 "The file was PUT successfully, but there "
                                 "was a problem opening the lock database "
                                 "which prevents inheriting locks from the "
                                 "parent resources.",
                                 err);
            return dav_handle_err(r, err, NULL);
        }

        /* notify lock system that we have created/replaced a resource */
        err = dav_notify_created(r, lockdb, resource, resource_state, 0);

        (*locks_hooks->close_lockdb)(lockdb);

        if (err != NULL) {
            /* The file creation was successful, but the locking failed. */
            err = dav_push_error(r->pool, err->status, 0,
                                 "The file was PUT successfully, but there "
                                 "was a problem updating its lock "
                                 "information.",
                                 err);
            return dav_handle_err(r, err, NULL);
        }
    }

    /* NOTE: WebDAV spec, S8.7.1 states properties should be unaffected */

    /* return an appropriate response (HTTP_CREATED or HTTP_NO_CONTENT) */
    return dav_created(r, NULL, "Resource", resource_state == DAV_RESOURCE_EXISTS);
}


/* Use POOL to temporarily construct a dav_response object (from WRES
   STATUS, and PROPSTATS) and stream it via WRES's ctx->brigade. */
static void dav_stream_response(dav_walk_resource *wres,
                                int status,
                                dav_get_props_result *propstats,
                                apr_pool_t *pool)
{
    dav_response resp = { 0 };
    dav_walker_ctx *ctx = wres->walk_ctx;

    resp.href = wres->resource->uri;
    resp.status = status;
    if (propstats) {
        resp.propresult = *propstats;
    }

    dav_send_one_response(&resp, ctx->bb, ctx->r->output_filters, pool);
}


/* ### move this to dav_util? */
DAV_DECLARE(void) dav_add_response(dav_walk_resource *wres,
                                   int status, dav_get_props_result *propstats)
{
    dav_response *resp;

    /* just drop some data into an dav_response */
    resp = apr_pcalloc(wres->pool, sizeof(*resp));
    resp->href = apr_pstrdup(wres->pool, wres->resource->uri);
    resp->status = status;
    if (propstats) {
        resp->propresult = *propstats;
    }

    resp->next = wres->response;
    wres->response = resp;
}


/* handle the DELETE method */
static int dav_method_delete(request_rec *r)
{
    dav_resource *resource;
    dav_auto_version_info av_info;
    dav_error *err;
    dav_error *err2;
    dav_response *multi_response;
    int result;
    int depth;

    /* We don't use the request body right now, so torch it. */
    if ((result = ap_discard_request_body(r)) != OK) {
        return result;
    }

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);
    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    /* 2518 says that depth must be infinity only for collections.
     * For non-collections, depth is ignored, unless it is an illegal value (1).
     */
    depth = dav_get_depth(r, DAV_INFINITY);

    if (resource->collection && depth != DAV_INFINITY) {
        /* This supplies additional information for the default message. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "Depth must be \"infinity\" for DELETE of a collection.");
        return HTTP_BAD_REQUEST;
    }

    if (!resource->collection && depth == 1) {
        /* This supplies additional information for the default message. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "Depth of \"1\" is not allowed for DELETE.");
        return HTTP_BAD_REQUEST;
    }

    /*
    ** If any resources fail the lock/If: conditions, then we must fail
    ** the delete. Each of the failing resources will be listed within
    ** a DAV:multistatus body, wrapped into a 424 response.
    **
    ** Note that a failure on the resource itself does not generate a
    ** multistatus response -- only internal members/collections.
    */
    if ((err = dav_validate_request(r, resource, depth, NULL,
                                    &multi_response,
                                    DAV_VALIDATE_PARENT
                                    | DAV_VALIDATE_USE_424, NULL)) != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not DELETE %s due to a failed "
                                          "precondition (e.g. locks).",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, multi_response);
    }

    /* ### RFC 2518 s. 8.10.5 says to remove _all_ locks, not just those
     *     locked by the token(s) in the if_header.
     */
    if ((result = dav_unlock(r, resource, NULL)) != OK) {
        return result;
    }

    /* if versioned resource, make sure parent is checked out */
    if ((err = dav_auto_checkout(r, resource, 1 /* parent_only */,
                                 &av_info)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, NULL);
    }

    /* try to remove the resource */
    err = (*resource->hooks->remove_resource)(resource, &multi_response);

    /* restore writability of parent back to what it was */
    err2 = dav_auto_checkin(r, NULL, err != NULL /* undo if error */,
                            0 /*unlock*/, &av_info);

    /* check for errors now */
    if (err != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not DELETE %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, multi_response);
    }
    if (err2 != NULL) {
        /* just log a warning */
        err = dav_push_error(r->pool, err2->status, 0,
                             "The DELETE was successful, but there "
                             "was a problem automatically checking in "
                             "the parent collection.",
                             err2);
        dav_log_err(r, err, APLOG_WARNING);
    }

    /* ### HTTP_NO_CONTENT if no body, HTTP_OK if there is a body (some day) */

    /* Apache will supply a default error for this. */
    return HTTP_NO_CONTENT;
}

/* generate DAV:supported-method-set OPTIONS response */
static dav_error *dav_gen_supported_methods(request_rec *r,
                                            const apr_xml_elem *elem,
                                            const apr_table_t *methods,
                                            apr_text_header *body)
{
    const apr_array_header_t *arr;
    const apr_table_entry_t *elts;
    apr_xml_elem *child;
    apr_xml_attr *attr;
    char *s;
    int i;

    apr_text_append(r->pool, body, "<D:supported-method-set>" DEBUG_CR);

    if (elem->first_child == NULL) {
        /* show all supported methods */
        arr = apr_table_elts(methods);
        elts = (const apr_table_entry_t *)arr->elts;

        for (i = 0; i < arr->nelts; ++i) {
            if (elts[i].key == NULL)
                continue;

            s = apr_psprintf(r->pool,
                             "<D:supported-method D:name=\"%s\"/>"
                             DEBUG_CR,
                             elts[i].key);
            apr_text_append(r->pool, body, s);
        }
    }
    else {
        /* check for support of specific methods */
        for (child = elem->first_child; child != NULL; child = child->next) {
            if (child->ns == APR_XML_NS_DAV_ID
                && strcmp(child->name, "supported-method") == 0) {
                const char *name = NULL;

                /* go through attributes to find method name */
                for (attr = child->attr; attr != NULL; attr = attr->next) {
                    if (attr->ns == APR_XML_NS_DAV_ID
                        && strcmp(attr->name, "name") == 0)
                            name = attr->value;
                }

                if (name == NULL) {
                    return dav_new_error(r->pool, HTTP_BAD_REQUEST, 0,
                                         "A DAV:supported-method element "
                                         "does not have a \"name\" attribute");
                }

                /* see if method is supported */
                if (apr_table_get(methods, name) != NULL) {
                    s = apr_psprintf(r->pool,
                                     "<D:supported-method D:name=\"%s\"/>"
                                     DEBUG_CR,
                                     name);
                    apr_text_append(r->pool, body, s);
                }
            }
        }
    }

    apr_text_append(r->pool, body, "</D:supported-method-set>" DEBUG_CR);
    return NULL;
}

/* generate DAV:supported-live-property-set OPTIONS response */
static dav_error *dav_gen_supported_live_props(request_rec *r,
                                               const dav_resource *resource,
                                               const apr_xml_elem *elem,
                                               apr_text_header *body)
{
    dav_lockdb *lockdb;
    dav_propdb *propdb;
    apr_xml_elem *child;
    apr_xml_attr *attr;
    dav_error *err;

    /* open lock database, to report on supported lock properties */
    /* ### should open read-only */
    if ((err = dav_open_lockdb(r, 0, &lockdb)) != NULL) {
        return dav_push_error(r->pool, err->status, 0,
                              "The lock database could not be opened, "
                              "preventing the reporting of supported lock "
                              "properties.",
                              err);
    }

    /* open the property database (readonly) for the resource */
    if ((err = dav_open_propdb(r, lockdb, resource, 1, NULL,
                               &propdb)) != NULL) {
        if (lockdb != NULL)
            (*lockdb->hooks->close_lockdb)(lockdb);

        return dav_push_error(r->pool, err->status, 0,
                              "The property database could not be opened, "
                              "preventing report of supported properties.",
                              err);
    }

    apr_text_append(r->pool, body, "<D:supported-live-property-set>" DEBUG_CR);

    if (elem->first_child == NULL) {
        /* show all supported live properties */
        dav_get_props_result props = dav_get_allprops(propdb, DAV_PROP_INSERT_SUPPORTED);
        body->last->next = props.propstats;
        while (body->last->next != NULL)
            body->last = body->last->next;
    }
    else {
        /* check for support of specific live property */
        for (child = elem->first_child; child != NULL; child = child->next) {
            if (child->ns == APR_XML_NS_DAV_ID
                && strcmp(child->name, "supported-live-property") == 0) {
                const char *name = NULL;
                const char *nmspace = NULL;

                /* go through attributes to find name and namespace */
                for (attr = child->attr; attr != NULL; attr = attr->next) {
                    if (attr->ns == APR_XML_NS_DAV_ID) {
                        if (strcmp(attr->name, "name") == 0)
                            name = attr->value;
                        else if (strcmp(attr->name, "namespace") == 0)
                            nmspace = attr->value;
                    }
                }

                if (name == NULL) {
                    err = dav_new_error(r->pool, HTTP_BAD_REQUEST, 0,
                                        "A DAV:supported-live-property "
                                        "element does not have a \"name\" "
                                        "attribute");
                    break;
                }

                /* default namespace to DAV: */
                if (nmspace == NULL)
                    nmspace = "DAV:";

                /* check for support of property */
                dav_get_liveprop_supported(propdb, nmspace, name, body);
            }
        }
    }

    apr_text_append(r->pool, body, "</D:supported-live-property-set>" DEBUG_CR);

    dav_close_propdb(propdb);

    if (lockdb != NULL)
        (*lockdb->hooks->close_lockdb)(lockdb);

    return err;
}

/* generate DAV:supported-report-set OPTIONS response */
static dav_error *dav_gen_supported_reports(request_rec *r,
                                            const dav_resource *resource,
                                            const apr_xml_elem *elem,
                                            const dav_hooks_vsn *vsn_hooks,
                                            apr_text_header *body)
{
    apr_xml_elem *child;
    apr_xml_attr *attr;
    dav_error *err;
    char *s;

    apr_text_append(r->pool, body, "<D:supported-report-set>" DEBUG_CR);

    if (vsn_hooks != NULL) {
        const dav_report_elem *reports;
        const dav_report_elem *rp;

        if ((err = (*vsn_hooks->avail_reports)(resource, &reports)) != NULL) {
            return dav_push_error(r->pool, err->status, 0,
                                  "DAV:supported-report-set could not be "
                                  "determined due to a problem fetching the "
                                  "available reports for this resource.",
                                  err);
        }

        if (reports != NULL) {
            if (elem->first_child == NULL) {
                /* show all supported reports */
                for (rp = reports; rp->nmspace != NULL; ++rp) {
                    /* Note: we presume reports->namespace is
                     * properly XML/URL quoted */
                    s = apr_psprintf(r->pool,
                                     "<D:supported-report D:name=\"%s\" "
                                     "D:namespace=\"%s\"/>" DEBUG_CR,
                                     rp->name, rp->nmspace);
                    apr_text_append(r->pool, body, s);
                }
            }
            else {
                /* check for support of specific report */
                for (child = elem->first_child; child != NULL; child = child->next) {
                    if (child->ns == APR_XML_NS_DAV_ID
                        && strcmp(child->name, "supported-report") == 0) {
                        const char *name = NULL;
                        const char *nmspace = NULL;

                        /* go through attributes to find name and namespace */
                        for (attr = child->attr; attr != NULL; attr = attr->next) {
                            if (attr->ns == APR_XML_NS_DAV_ID) {
                                if (strcmp(attr->name, "name") == 0)
                                    name = attr->value;
                                else if (strcmp(attr->name, "namespace") == 0)
                                    nmspace = attr->value;
                            }
                        }

                        if (name == NULL) {
                            return dav_new_error(r->pool, HTTP_BAD_REQUEST, 0,
                                                 "A DAV:supported-report element "
                                                 "does not have a \"name\" attribute");
                        }

                        /* default namespace to DAV: */
                        if (nmspace == NULL)
                            nmspace = "DAV:";

                        for (rp = reports; rp->nmspace != NULL; ++rp) {
                            if (strcmp(name, rp->name) == 0
                                && strcmp(nmspace, rp->nmspace) == 0) {
                                /* Note: we presume reports->nmspace is
                                 * properly XML/URL quoted
                                 */
                                s = apr_psprintf(r->pool,
                                                 "<D:supported-report "
                                                 "D:name=\"%s\" "
                                                 "D:namespace=\"%s\"/>"
                                                 DEBUG_CR,
                                                 rp->name, rp->nmspace);
                                apr_text_append(r->pool, body, s);
                                break;
                            }
                        }
                    }
                }
            }
        }
    }

    apr_text_append(r->pool, body, "</D:supported-report-set>" DEBUG_CR);
    return NULL;
}


/* handle the SEARCH method */
static int dav_method_search(request_rec *r)
{
    const dav_hooks_search *search_hooks = DAV_GET_HOOKS_SEARCH(r);
    dav_resource *resource;
    dav_error *err;
    dav_response *multi_status;

    /* If no search provider, decline the request */
    if (search_hooks == NULL)
        return DECLINED;

    /* This method should only be called when the resource is not
     * visible to Apache. We will fetch the resource from the repository,
     * then create a subrequest for Apache to handle.
     */
    err = dav_get_resource(r, 1 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    /* set up the HTTP headers for the response */
    if ((err = (*resource->hooks->set_headers)(r, resource)) != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             "Unable to set up HTTP headers.",
                             err);
        return dav_handle_err(r, err, NULL);
    }

    if (r->header_only) {
        return DONE;
    }

    /* okay... time to search the content */
    /* Let's validate XML and process walk function
     * in the hook function
     */
    if ((err = (*search_hooks->search_resource)(r, &multi_status)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, NULL);
    }

    /* We have results in multi_status */
    /* Should I pass namespace?? */
    dav_send_multistatus(r, HTTP_MULTI_STATUS, multi_status, NULL);

    return DONE;
}


/* handle the OPTIONS method */
static int dav_method_options(request_rec *r)
{
    const dav_hooks_locks *locks_hooks = DAV_GET_HOOKS_LOCKS(r);
    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
    const dav_hooks_binding *binding_hooks = DAV_GET_HOOKS_BINDING(r);
    const dav_hooks_search *search_hooks = DAV_GET_HOOKS_SEARCH(r);
    dav_resource *resource;
    const char *dav_level;
    char *allow;
    char *s;
    const apr_array_header_t *arr;
    const apr_table_entry_t *elts;
    apr_table_t *methods = apr_table_make(r->pool, 12);
    apr_text_header vsn_options = { 0 };
    apr_text_header body = { 0 };
    apr_text *t;
    int text_size;
    int result;
    int i;
    apr_array_header_t *uri_ary;
    apr_xml_doc *doc;
    const apr_xml_elem *elem;
    dav_error *err;

    /* resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    /* parse any request body */
    if ((result = ap_xml_parse_input(r, &doc)) != OK) {
        return result;
    }
    /* note: doc == NULL if no request body */

    if (doc && !dav_validate_root(doc, "options")) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The \"options\" element was not found.");
        return HTTP_BAD_REQUEST;
    }

    /* determine which providers are available */
    dav_level = "1";

    if (locks_hooks != NULL) {
        dav_level = "1,2";
    }

    if (binding_hooks != NULL)
        dav_level = apr_pstrcat(r->pool, dav_level, ",bindings", NULL);

    /* ###
     * MSFT Web Folders chokes if length of DAV header value > 63 characters!
     * To workaround that, we use separate DAV headers for versioning and
     * live prop provider namespace URIs.
     * ###
     */
    apr_table_setn(r->headers_out, "DAV", dav_level);

    /*
     * If there is a versioning provider, generate DAV headers
     * for versioning options.
     */
    if (vsn_hooks != NULL) {
        (*vsn_hooks->get_vsn_options)(r->pool, &vsn_options);

        for (t = vsn_options.first; t != NULL; t = t->next)
            apr_table_addn(r->headers_out, "DAV", t->text);
    }

    /*
     * Gather property set URIs from all the liveprop providers,
     * and generate a separate DAV header for each URI, to avoid
     * problems with long header lengths.
     */
    uri_ary = apr_array_make(r->pool, 5, sizeof(const char *));
    dav_run_gather_propsets(uri_ary);
    for (i = 0; i < uri_ary->nelts; ++i) {
        if (((char **)uri_ary->elts)[i] != NULL)
            apr_table_addn(r->headers_out, "DAV", ((char **)uri_ary->elts)[i]);
    }

    /* this tells MSFT products to skip looking for FrontPage extensions */
    apr_table_setn(r->headers_out, "MS-Author-Via", "DAV");

    /*
     * Determine which methods are allowed on the resource.
     * Three cases:  resource is null (3), is lock-null (7.4), or exists.
     *
     * All cases support OPTIONS, and if there is a lock provider, LOCK.
     * (Lock-) null resources also support MKCOL and PUT.
     * Lock-null supports PROPFIND and UNLOCK.
     * Existing resources support lots of stuff.
     */

    apr_table_addn(methods, "OPTIONS", "");

    /* ### take into account resource type */
    switch (dav_get_resource_state(r, resource))
    {
    case DAV_RESOURCE_EXISTS:
        /* resource exists */
        apr_table_addn(methods, "GET", "");
        apr_table_addn(methods, "HEAD", "");
        apr_table_addn(methods, "POST", "");
        apr_table_addn(methods, "DELETE", "");
        apr_table_addn(methods, "TRACE", "");
        apr_table_addn(methods, "PROPFIND", "");
        apr_table_addn(methods, "PROPPATCH", "");
        apr_table_addn(methods, "COPY", "");
        apr_table_addn(methods, "MOVE", "");

        if (!resource->collection)
            apr_table_addn(methods, "PUT", "");

        if (locks_hooks != NULL) {
            apr_table_addn(methods, "LOCK", "");
            apr_table_addn(methods, "UNLOCK", "");
        }

        break;

    case DAV_RESOURCE_LOCK_NULL:
        /* resource is lock-null. */
        apr_table_addn(methods, "MKCOL", "");
        apr_table_addn(methods, "PROPFIND", "");
        apr_table_addn(methods, "PUT", "");

        if (locks_hooks != NULL) {
            apr_table_addn(methods, "LOCK", "");
            apr_table_addn(methods, "UNLOCK", "");
        }

        break;

    case DAV_RESOURCE_NULL:
        /* resource is null. */
        apr_table_addn(methods, "MKCOL", "");
        apr_table_addn(methods, "PUT", "");

        if (locks_hooks != NULL)
            apr_table_addn(methods, "LOCK", "");

        break;

    default:
        /* ### internal error! */
        break;
    }

    /* If there is a versioning provider, add versioning methods */
    if (vsn_hooks != NULL) {
        if (!resource->exists) {
            if ((*vsn_hooks->versionable)(resource))
                apr_table_addn(methods, "VERSION-CONTROL", "");

            if (vsn_hooks->can_be_workspace != NULL
                && (*vsn_hooks->can_be_workspace)(resource))
                apr_table_addn(methods, "MKWORKSPACE", "");

            if (vsn_hooks->can_be_activity != NULL
                && (*vsn_hooks->can_be_activity)(resource))
                apr_table_addn(methods, "MKACTIVITY", "");
        }
        else if (!resource->versioned) {
            if ((*vsn_hooks->versionable)(resource))
                apr_table_addn(methods, "VERSION-CONTROL", "");
        }
        else if (resource->working) {
            apr_table_addn(methods, "CHECKIN", "");

            /* ### we might not support this DeltaV option */
            apr_table_addn(methods, "UNCHECKOUT", "");
        }
        else if (vsn_hooks->add_label != NULL) {
            apr_table_addn(methods, "CHECKOUT", "");
            apr_table_addn(methods, "LABEL", "");
        }
        else {
            apr_table_addn(methods, "CHECKOUT", "");
        }
    }

    /* If there is a bindings provider, see if resource is bindable */
    if (binding_hooks != NULL
        && (*binding_hooks->is_bindable)(resource)) {
        apr_table_addn(methods, "BIND", "");
    }

    /* If there is a search provider, set SEARCH in option */
    if (search_hooks != NULL) {
        apr_table_addn(methods, "SEARCH", "");
    }

    /* Generate the Allow header */
    arr = apr_table_elts(methods);
    elts = (const apr_table_entry_t *)arr->elts;
    text_size = 0;

    /* first, compute total length */
    for (i = 0; i < arr->nelts; ++i) {
        if (elts[i].key == NULL)
            continue;

        /* add 1 for comma or null */
        text_size += strlen(elts[i].key) + 1;
    }

    s = allow = apr_palloc(r->pool, text_size);

    for (i = 0; i < arr->nelts; ++i) {
        if (elts[i].key == NULL)
            continue;

        if (s != allow)
            *s++ = ',';

        strcpy(s, elts[i].key);
        s += strlen(s);
    }

    apr_table_setn(r->headers_out, "Allow", allow);


    /* If there is search set_option_head function, set head */
    /* DASL: <DAV:basicsearch>
     * DASL: <http://foo.bar.com/syntax1>
     * DASL: <http://akuma.com/syntax2>
     */
    if (search_hooks != NULL
        && *search_hooks->set_option_head != NULL) {
        if ((err = (*search_hooks->set_option_head)(r)) != NULL) {
            return dav_handle_err(r, err, NULL);
        }
    }

    /* if there was no request body, then there is no response body */
    if (doc == NULL) {
        ap_set_content_length(r, 0);

        /* ### this sends a Content-Type. the default OPTIONS does not. */

        /* ### the default (ap_send_http_options) returns OK, but I believe
         * ### that is because it is the default handler and nothing else
         * ### will run after the thing. */
        return DONE;
    }

    /* handle each options request */
    for (elem = doc->root->first_child; elem != NULL; elem = elem->next) {
        /* check for something we recognize first */
        int core_option = 0;
        dav_error *err = NULL;

        if (elem->ns == APR_XML_NS_DAV_ID) {
            if (strcmp(elem->name, "supported-method-set") == 0) {
                err = dav_gen_supported_methods(r, elem, methods, &body);
                core_option = 1;
            }
            else if (strcmp(elem->name, "supported-live-property-set") == 0) {
                err = dav_gen_supported_live_props(r, resource, elem, &body);
                core_option = 1;
            }
            else if (strcmp(elem->name, "supported-report-set") == 0) {
                err = dav_gen_supported_reports(r, resource, elem, vsn_hooks, &body);
                core_option = 1;
            }
        }

        if (err != NULL)
            return dav_handle_err(r, err, NULL);

        /* if unrecognized option, pass to versioning provider */
        if (!core_option && vsn_hooks != NULL) {
            if ((err = (*vsn_hooks->get_option)(resource, elem, &body))
                != NULL) {
                return dav_handle_err(r, err, NULL);
            }
        }
    }

    /* send the options response */
    r->status = HTTP_OK;
    ap_set_content_type(r, DAV_XML_CONTENT_TYPE);

    /* send the headers and response body */
    ap_rputs(DAV_XML_HEADER DEBUG_CR
             "<D:options-response xmlns:D=\"DAV:\">" DEBUG_CR, r);

    for (t = body.first; t != NULL; t = t->next)
        ap_rputs(t->text, r);

    ap_rputs("</D:options-response>" DEBUG_CR, r);

    /* we've sent everything necessary to the client. */
    return DONE;
}

static void dav_cache_badprops(dav_walker_ctx *ctx)
{
    const apr_xml_elem *elem;
    apr_text_header hdr = { 0 };

    /* just return if we built the thing already */
    if (ctx->propstat_404 != NULL) {
        return;
    }

    apr_text_append(ctx->w.pool, &hdr,
                    "<D:propstat>" DEBUG_CR
                    "<D:prop>" DEBUG_CR);

    elem = dav_find_child(ctx->doc->root, "prop");
    for (elem = elem->first_child; elem; elem = elem->next) {
        apr_text_append(ctx->w.pool, &hdr,
                        apr_xml_empty_elem(ctx->w.pool, elem));
    }

    apr_text_append(ctx->w.pool, &hdr,
                    "</D:prop>" DEBUG_CR
                    "<D:status>HTTP/1.1 404 Not Found</D:status>" DEBUG_CR
                    "</D:propstat>" DEBUG_CR);

    ctx->propstat_404 = hdr.first;
}

static dav_error * dav_propfind_walker(dav_walk_resource *wres, int calltype)
{
    dav_walker_ctx *ctx = wres->walk_ctx;
    dav_error *err;
    dav_propdb *propdb;
    dav_get_props_result propstats = { 0 };

    /*
    ** Note: ctx->doc can only be NULL for DAV_PROPFIND_IS_ALLPROP. Since
    ** dav_get_allprops() does not need to do namespace translation,
    ** we're okay.
    **
    ** Note: we cast to lose the "const". The propdb won't try to change
    ** the resource, however, since we are opening readonly.
    */
    err = dav_open_propdb(ctx->r, ctx->w.lockdb, wres->resource, 1,
                          ctx->doc ? ctx->doc->namespaces : NULL, &propdb);
    if (err != NULL) {
        /* ### do something with err! */

        if (ctx->propfind_type == DAV_PROPFIND_IS_PROP) {
            dav_get_props_result badprops = { 0 };

            /* some props were expected on this collection/resource */
            dav_cache_badprops(ctx);
            badprops.propstats = ctx->propstat_404;
            dav_stream_response(wres, 0, &badprops, ctx->scratchpool);
        }
        else {
            /* no props on this collection/resource */
            dav_stream_response(wres, HTTP_OK, NULL, ctx->scratchpool);
        }

        apr_pool_clear(ctx->scratchpool);
        return NULL;
    }
    /* ### what to do about closing the propdb on server failure? */

    if (ctx->propfind_type == DAV_PROPFIND_IS_PROP) {
        propstats = dav_get_props(propdb, ctx->doc);
    }
    else {
        dav_prop_insert what = ctx->propfind_type == DAV_PROPFIND_IS_ALLPROP
                                 ? DAV_PROP_INSERT_VALUE
                                 : DAV_PROP_INSERT_NAME;
        propstats = dav_get_allprops(propdb, what);
    }
    dav_close_propdb(propdb);

    dav_stream_response(wres, 0, &propstats, ctx->scratchpool);

    /* at this point, ctx->scratchpool has been used to stream a
       single response.  this function fully controls the pool, and
       thus has the right to clear it for the next iteration of this
       callback. */
    apr_pool_clear(ctx->scratchpool);

    return NULL;
}

/* handle the PROPFIND method */
static int dav_method_propfind(request_rec *r)
{
    dav_resource *resource;
    int depth;
    dav_error *err;
    int result;
    apr_xml_doc *doc;
    const apr_xml_elem *child;
    dav_walker_ctx ctx = { { 0 } };
    dav_response *multi_status;

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 1 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    if (dav_get_resource_state(r, resource) == DAV_RESOURCE_NULL) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    if ((depth = dav_get_depth(r, DAV_INFINITY)) < 0) {
        /* dav_get_depth() supplies additional information for the
         * default message. */
        return HTTP_BAD_REQUEST;
    }

    if (depth == DAV_INFINITY && resource->collection) {
        dav_dir_conf *conf;
        conf = (dav_dir_conf *)ap_get_module_config(r->per_dir_config,
                                                    &dav_module);
        /* default is to DISALLOW these requests */
        if (conf->allow_depthinfinity != DAV_ENABLED_ON) {
            return dav_error_response(r, HTTP_FORBIDDEN,
                                      apr_psprintf(r->pool,
                                                   "PROPFIND requests with a "
                                                   "Depth of \"infinity\" are "
                                                   "not allowed for %s.",
                                                   ap_escape_html(r->pool,
                                                                  r->uri)));
        }
    }

    if ((result = ap_xml_parse_input(r, &doc)) != OK) {
        return result;
    }
    /* note: doc == NULL if no request body */

    if (doc && !dav_validate_root(doc, "propfind")) {
        /* This supplies additional information for the default message. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The \"propfind\" element was not found.");
        return HTTP_BAD_REQUEST;
    }

    /* ### validate that only one of these three elements is present */

    if (doc == NULL
        || (child = dav_find_child(doc->root, "allprop")) != NULL) {
        /* note: no request body implies allprop */
        ctx.propfind_type = DAV_PROPFIND_IS_ALLPROP;
    }
    else if ((child = dav_find_child(doc->root, "propname")) != NULL) {
        ctx.propfind_type = DAV_PROPFIND_IS_PROPNAME;
    }
    else if ((child = dav_find_child(doc->root, "prop")) != NULL) {
        ctx.propfind_type = DAV_PROPFIND_IS_PROP;
    }
    else {
        /* "propfind" element must have one of the above three children */

        /* This supplies additional information for the default message. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The \"propfind\" element does not contain one of "
                      "the required child elements (the specific command).");
        return HTTP_BAD_REQUEST;
    }

    ctx.w.walk_type = DAV_WALKTYPE_NORMAL | DAV_WALKTYPE_AUTH;
    ctx.w.func = dav_propfind_walker;
    ctx.w.walk_ctx = &ctx;
    ctx.w.pool = r->pool;
    ctx.w.root = resource;

    ctx.doc = doc;
    ctx.r = r;
    ctx.bb = apr_brigade_create(r->pool, r->connection->bucket_alloc);
    apr_pool_create(&ctx.scratchpool, r->pool);

    /* ### should open read-only */
    if ((err = dav_open_lockdb(r, 0, &ctx.w.lockdb)) != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             "The lock database could not be opened, "
                             "preventing access to the various lock "
                             "properties for the PROPFIND.",
                             err);
        return dav_handle_err(r, err, NULL);
    }
    if (ctx.w.lockdb != NULL) {
        /* if we have a lock database, then we can walk locknull resources */
        ctx.w.walk_type |= DAV_WALKTYPE_LOCKNULL;
    }

    /* send <multistatus> tag, with all doc->namespaces attached.  */

    /* NOTE: we *cannot* leave out the doc's namespaces from the
       initial <multistatus> tag.  if a 404 was generated for an HREF,
       then we need to spit out the doc's namespaces for use by the
       404. Note that <response> elements will override these ns0,
       ns1, etc, but NOT within the <response> scope for the
       badprops. */
    dav_begin_multistatus(ctx.bb, r, HTTP_MULTI_STATUS,
                          doc ? doc->namespaces : NULL);

    /* Have the provider walk the resource. */
    err = (*resource->hooks->walk)(&ctx.w, depth, &multi_status);

    if (ctx.w.lockdb != NULL) {
        (*ctx.w.lockdb->hooks->close_lockdb)(ctx.w.lockdb);
    }

    if (err != NULL) {
        /* If an error occurred during the resource walk, there's
           basically nothing we can do but abort the connection and
           log an error.  This is one of the limitations of HTTP; it
           needs to "know" the entire status of the response before
           generating it, which is just impossible in these streamy
           response situations. */
        err = dav_push_error(r->pool, err->status, 0,
                             "Provider encountered an error while streaming"
                             " a multistatus PROPFIND response.", err);
        dav_log_err(r, err, APLOG_ERR);
        r->connection->aborted = 1;
        return DONE;
    }

    dav_finish_multistatus(r, ctx.bb);

    /* the response has been sent. */
    return DONE;
}

static apr_text * dav_failed_proppatch(apr_pool_t *p,
                                      apr_array_header_t *prop_ctx)
{
    apr_text_header hdr = { 0 };
    int i = prop_ctx->nelts;
    dav_prop_ctx *ctx = (dav_prop_ctx *)prop_ctx->elts;
    dav_error *err424_set = NULL;
    dav_error *err424_delete = NULL;
    const char *s;

    /* ### might be nice to sort by status code and description */

    for ( ; i-- > 0; ++ctx ) {
        apr_text_append(p, &hdr,
                        "<D:propstat>" DEBUG_CR
                        "<D:prop>");
        apr_text_append(p, &hdr, apr_xml_empty_elem(p, ctx->prop));
        apr_text_append(p, &hdr, "</D:prop>" DEBUG_CR);

        if (ctx->err == NULL) {
            /* nothing was assigned here yet, so make it a 424 */

            if (ctx->operation == DAV_PROP_OP_SET) {
                if (err424_set == NULL)
                    err424_set = dav_new_error(p, HTTP_FAILED_DEPENDENCY, 0,
                                               "Attempted DAV:set operation "
                                               "could not be completed due "
                                               "to other errors.");
                ctx->err = err424_set;
            }
            else if (ctx->operation == DAV_PROP_OP_DELETE) {
                if (err424_delete == NULL)
                    err424_delete = dav_new_error(p, HTTP_FAILED_DEPENDENCY, 0,
                                                  "Attempted DAV:remove "
                                                  "operation could not be "
                                                  "completed due to other "
                                                  "errors.");
                ctx->err = err424_delete;
            }
        }

        s = apr_psprintf(p,
                         "<D:status>"
                         "HTTP/1.1 %d (status)"
                         "</D:status>" DEBUG_CR,
                         ctx->err->status);
        apr_text_append(p, &hdr, s);

        /* ### we should use compute_desc if necessary... */
        if (ctx->err->desc != NULL) {
            apr_text_append(p, &hdr, "<D:responsedescription>" DEBUG_CR);
            apr_text_append(p, &hdr, ctx->err->desc);
            apr_text_append(p, &hdr, "</D:responsedescription>" DEBUG_CR);
        }

        apr_text_append(p, &hdr, "</D:propstat>" DEBUG_CR);
    }

    return hdr.first;
}

static apr_text * dav_success_proppatch(apr_pool_t *p, apr_array_header_t *prop_ctx)
{
    apr_text_header hdr = { 0 };
    int i = prop_ctx->nelts;
    dav_prop_ctx *ctx = (dav_prop_ctx *)prop_ctx->elts;

    /*
     * ### we probably need to revise the way we assemble the response...
     * ### this code assumes everything will return status==200.
     */

    apr_text_append(p, &hdr,
                    "<D:propstat>" DEBUG_CR
                    "<D:prop>" DEBUG_CR);

    for ( ; i-- > 0; ++ctx ) {
        apr_text_append(p, &hdr, apr_xml_empty_elem(p, ctx->prop));
    }

    apr_text_append(p, &hdr,
                   "</D:prop>" DEBUG_CR
                   "<D:status>HTTP/1.1 200 OK</D:status>" DEBUG_CR
                   "</D:propstat>" DEBUG_CR);

    return hdr.first;
}

static void dav_prop_log_errors(dav_prop_ctx *ctx)
{
    dav_log_err(ctx->r, ctx->err, APLOG_ERR);
}

/*
 * Call <func> for each context. This can stop when an error occurs, or
 * simply iterate through the whole list.
 *
 * Returns 1 if an error occurs (and the iteration is aborted). Returns 0
 * if all elements are processed.
 *
 * If <reverse> is true (non-zero), then the list is traversed in
 * reverse order.
 */
static int dav_process_ctx_list(void (*func)(dav_prop_ctx *ctx),
                                apr_array_header_t *ctx_list, int stop_on_error,
                                int reverse)
{
    int i = ctx_list->nelts;
    dav_prop_ctx *ctx = (dav_prop_ctx *)ctx_list->elts;

    if (reverse)
        ctx += i;

    while (i--) {
        if (reverse)
            --ctx;

        (*func)(ctx);
        if (stop_on_error && DAV_PROP_CTX_HAS_ERR(*ctx)) {
            return 1;
        }

        if (!reverse)
            ++ctx;
    }

    return 0;
}

/* handle the PROPPATCH method */
static int dav_method_proppatch(request_rec *r)
{
    dav_error *err;
    dav_resource *resource;
    int result;
    apr_xml_doc *doc;
    apr_xml_elem *child;
    dav_propdb *propdb;
    int failure = 0;
    dav_response resp = { 0 };
    apr_text *propstat_text;
    apr_array_header_t *ctx_list;
    dav_prop_ctx *ctx;
    dav_auto_version_info av_info;

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);
    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    if ((result = ap_xml_parse_input(r, &doc)) != OK) {
        return result;
    }
    /* note: doc == NULL if no request body */

    if (doc == NULL || !dav_validate_root(doc, "propertyupdate")) {
        /* This supplies additional information for the default message. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The request body does not contain "
                      "a \"propertyupdate\" element.");
        return HTTP_BAD_REQUEST;
    }

    /* Check If-Headers and existing locks */
    /* Note: depth == 0. Implies no need for a multistatus response. */
    if ((err = dav_validate_request(r, resource, 0, NULL, NULL,
                                    DAV_VALIDATE_RESOURCE, NULL)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, NULL);
    }

    /* make sure the resource can be modified (if versioning repository) */
    if ((err = dav_auto_checkout(r, resource,
                                 0 /* not parent_only */,
                                 &av_info)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, NULL);
    }

    if ((err = dav_open_propdb(r, NULL, resource, 0, doc->namespaces,
                               &propdb)) != NULL) {
        /* undo any auto-checkout */
        dav_auto_checkin(r, resource, 1 /*undo*/, 0 /*unlock*/, &av_info);

        err = dav_push_error(r->pool, HTTP_INTERNAL_SERVER_ERROR, 0,
                             apr_psprintf(r->pool,
                                          "Could not open the property "
                                          "database for %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, NULL);
    }
    /* ### what to do about closing the propdb on server failure? */

    /* ### validate "live" properties */

    /* set up an array to hold property operation contexts */
    ctx_list = apr_array_make(r->pool, 10, sizeof(dav_prop_ctx));

    /* do a first pass to ensure that all "remove" properties exist */
    for (child = doc->root->first_child; child; child = child->next) {
        int is_remove;
        apr_xml_elem *prop_group;
        apr_xml_elem *one_prop;

        /* Ignore children that are not set/remove */
        if (child->ns != APR_XML_NS_DAV_ID
            || (!(is_remove = strcmp(child->name, "remove") == 0)
                && strcmp(child->name, "set") != 0)) {
            continue;
        }

        /* make sure that a "prop" child exists for set/remove */
        if ((prop_group = dav_find_child(child, "prop")) == NULL) {
            dav_close_propdb(propdb);

            /* undo any auto-checkout */
            dav_auto_checkin(r, resource, 1 /*undo*/, 0 /*unlock*/, &av_info);

            /* This supplies additional information for the default message. */
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "A \"prop\" element is missing inside "
                          "the propertyupdate command.");
            return HTTP_BAD_REQUEST;
        }

        for (one_prop = prop_group->first_child; one_prop;
             one_prop = one_prop->next) {

            ctx = (dav_prop_ctx *)apr_array_push(ctx_list);
            ctx->propdb = propdb;
            ctx->operation = is_remove ? DAV_PROP_OP_DELETE : DAV_PROP_OP_SET;
            ctx->prop = one_prop;

            ctx->r = r;         /* for later use by dav_prop_log_errors() */

            dav_prop_validate(ctx);

            if ( DAV_PROP_CTX_HAS_ERR(*ctx) ) {
                failure = 1;
            }
        }
    }

    /* ### should test that we found at least one set/remove */

    /* execute all of the operations */
    if (!failure && dav_process_ctx_list(dav_prop_exec, ctx_list, 1, 0)) {
        failure = 1;
    }

    /* generate a failure/success response */
    if (failure) {
        (void)dav_process_ctx_list(dav_prop_rollback, ctx_list, 0, 1);
        propstat_text = dav_failed_proppatch(r->pool, ctx_list);
    }
    else {
        (void)dav_process_ctx_list(dav_prop_commit, ctx_list, 0, 0);
        propstat_text = dav_success_proppatch(r->pool, ctx_list);
    }

    /* make sure this gets closed! */
    dav_close_propdb(propdb);

    /* complete any auto-versioning */
    dav_auto_checkin(r, resource, failure, 0 /*unlock*/, &av_info);

    /* log any errors that occurred */
    (void)dav_process_ctx_list(dav_prop_log_errors, ctx_list, 0, 0);

    resp.href = resource->uri;

    /* ### should probably use something new to pass along this text... */
    resp.propresult.propstats = propstat_text;

    dav_send_multistatus(r, HTTP_MULTI_STATUS, &resp, doc->namespaces);

    /* the response has been sent. */
    return DONE;
}

static int process_mkcol_body(request_rec *r)
{
    /* This is snarfed from ap_setup_client_block(). We could get pretty
     * close to this behavior by passing REQUEST_NO_BODY, but we need to
     * return HTTP_UNSUPPORTED_MEDIA_TYPE (while ap_setup_client_block
     * returns HTTP_REQUEST_ENTITY_TOO_LARGE). */

    const char *tenc = apr_table_get(r->headers_in, "Transfer-Encoding");
    const char *lenp = apr_table_get(r->headers_in, "Content-Length");

    /* make sure to set the Apache request fields properly. */
    r->read_body = REQUEST_NO_BODY;
    r->read_chunked = 0;
    r->remaining = 0;

    if (tenc) {
        if (strcasecmp(tenc, "chunked")) {
            /* Use this instead of Apache's default error string */
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "Unknown Transfer-Encoding %s", tenc);
            return HTTP_NOT_IMPLEMENTED;
        }

        r->read_chunked = 1;
    }
    else if (lenp) {
        const char *pos = lenp;

        while (apr_isdigit(*pos) || apr_isspace(*pos)) {
            ++pos;
        }

        if (*pos != '\0') {
            /* This supplies additional information for the default message. */
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "Invalid Content-Length %s", lenp);
            return HTTP_BAD_REQUEST;
        }

        r->remaining = apr_atoi64(lenp);
    }

    if (r->read_chunked || r->remaining > 0) {
        /* ### log something? */

        /* Apache will supply a default error for this. */
        return HTTP_UNSUPPORTED_MEDIA_TYPE;
    }

    /*
     * Get rid of the body. this will call ap_setup_client_block(), but
     * our copy above has already verified its work.
     */
    return ap_discard_request_body(r);
}

/* handle the MKCOL method */
static int dav_method_mkcol(request_rec *r)
{
    dav_resource *resource;
    int resource_state;
    dav_auto_version_info av_info;
    const dav_hooks_locks *locks_hooks = DAV_GET_HOOKS_LOCKS(r);
    dav_error *err;
    dav_error *err2;
    int result;
    dav_dir_conf *conf;
    dav_response *multi_status;

    /* handle the request body */
    /* ### this may move lower once we start processing bodies */
    if ((result = process_mkcol_body(r)) != OK) {
        return result;
    }

    conf = (dav_dir_conf *)ap_get_module_config(r->per_dir_config,
                                                &dav_module);

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    if (resource->exists) {
        /* oops. something was already there! */

        /* Apache will supply a default error for this. */
        /* ### we should provide a specific error message! */
        return HTTP_METHOD_NOT_ALLOWED;
    }

    resource_state = dav_get_resource_state(r, resource);

    /*
     * Check If-Headers and existing locks.
     *
     * Note: depth == 0 normally requires no multistatus response. However,
     * if we pass DAV_VALIDATE_PARENT, then we could get an error on a URI
     * other than the Request-URI, thereby requiring a multistatus.
     *
     * If the resource does not exist (DAV_RESOURCE_NULL), then we must
     * check the resource *and* its parent. If the resource exists or is
     * a locknull resource, then we check only the resource.
     */
    if ((err = dav_validate_request(r, resource, 0, NULL, &multi_status,
                                    resource_state == DAV_RESOURCE_NULL ?
                                    DAV_VALIDATE_PARENT :
                                    DAV_VALIDATE_RESOURCE, NULL)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, multi_status);
    }

    /* if versioned resource, make sure parent is checked out */
    if ((err = dav_auto_checkout(r, resource, 1 /* parent_only */,
                                 &av_info)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, NULL);
    }

    /* try to create the collection */
    resource->collection = 1;
    err = (*resource->hooks->create_collection)(resource);

    /* restore modifiability of parent back to what it was */
    err2 = dav_auto_checkin(r, NULL, err != NULL /* undo if error */,
                            0 /*unlock*/, &av_info);

    /* check for errors now */
    if (err != NULL) {
        return dav_handle_err(r, err, NULL);
    }
    if (err2 != NULL) {
        /* just log a warning */
        err = dav_push_error(r->pool, err2->status, 0,
                             "The MKCOL was successful, but there "
                             "was a problem automatically checking in "
                             "the parent collection.",
                             err2);
        dav_log_err(r, err, APLOG_WARNING);
    }

    if (locks_hooks != NULL) {
        dav_lockdb *lockdb;

        if ((err = (*locks_hooks->open_lockdb)(r, 0, 0, &lockdb)) != NULL) {
            /* The directory creation was successful, but the locking failed. */
            err = dav_push_error(r->pool, err->status, 0,
                                 "The MKCOL was successful, but there "
                                 "was a problem opening the lock database "
                                 "which prevents inheriting locks from the "
                                 "parent resources.",
                                 err);
            return dav_handle_err(r, err, NULL);
        }

        /* notify lock system that we have created/replaced a resource */
        err = dav_notify_created(r, lockdb, resource, resource_state, 0);

        (*locks_hooks->close_lockdb)(lockdb);

        if (err != NULL) {
            /* The dir creation was successful, but the locking failed. */
            err = dav_push_error(r->pool, err->status, 0,
                                 "The MKCOL was successful, but there "
                                 "was a problem updating its lock "
                                 "information.",
                                 err);
            return dav_handle_err(r, err, NULL);
        }
    }

    /* return an appropriate response (HTTP_CREATED) */
    return dav_created(r, NULL, "Collection", 0);
}

/* handle the COPY and MOVE methods */
static int dav_method_copymove(request_rec *r, int is_move)
{
    dav_resource *resource;
    dav_resource *resnew;
    dav_auto_version_info src_av_info = { 0 };
    dav_auto_version_info dst_av_info = { 0 };
    const char *body;
    const char *dest;
    dav_error *err;
    dav_error *err2;
    dav_error *err3;
    dav_response *multi_response;
    dav_lookup_result lookup;
    int is_dir;
    int overwrite;
    int depth;
    int result;
    dav_lockdb *lockdb;
    int replace_dest;
    int resnew_state;

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, !is_move /* label_allowed */,
                           0 /* use_checked_in */, &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    /* If not a file or collection resource, COPY/MOVE not allowed */
    /* ### allow COPY/MOVE of DeltaV resource types */
    if (resource->type != DAV_RESOURCE_TYPE_REGULAR) {
        body = apr_psprintf(r->pool,
                            "Cannot COPY/MOVE resource %s.",
                            ap_escape_html(r->pool, r->uri));
        return dav_error_response(r, HTTP_METHOD_NOT_ALLOWED, body);
    }

    /* get the destination URI */
    dest = apr_table_get(r->headers_in, "Destination");
    if (dest == NULL) {
        /* Look in headers provided by Netscape's Roaming Profiles */
        const char *nscp_host = apr_table_get(r->headers_in, "Host");
        const char *nscp_path = apr_table_get(r->headers_in, "New-uri");

        if (nscp_host != NULL && nscp_path != NULL)
            dest = apr_psprintf(r->pool, "http://%s%s", nscp_host, nscp_path);
    }
    if (dest == NULL) {
        /* This supplies additional information for the default message. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The request is missing a Destination header.");
        return HTTP_BAD_REQUEST;
    }

    lookup = dav_lookup_uri(dest, r, 1 /* must_be_absolute */);
    if (lookup.rnew == NULL) {
        if (lookup.err.status == HTTP_BAD_REQUEST) {
            /* This supplies additional information for the default message. */
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "%s", lookup.err.desc);
            return HTTP_BAD_REQUEST;
        }

        /* ### this assumes that dav_lookup_uri() only generates a status
         * ### that Apache can provide a status line for!! */

        return dav_error_response(r, lookup.err.status, lookup.err.desc);
    }
    if (lookup.rnew->status != HTTP_OK) {
        const char *auth = apr_table_get(lookup.rnew->err_headers_out,
                                        "WWW-Authenticate");
        if (lookup.rnew->status == HTTP_UNAUTHORIZED && auth != NULL) {
            /* propagate the WWW-Authorization header up from the
             * subreq so the client sees it. */
            apr_table_set(r->err_headers_out, "WWW-Authenticate",
                          apr_pstrdup(r->pool, auth));
        }

        /* ### how best to report this... */
        return dav_error_response(r, lookup.rnew->status,
                                  "Destination URI had an error.");
    }

    if (dav_get_provider(lookup.rnew) == NULL) {
        return dav_error_response(r, HTTP_METHOD_NOT_ALLOWED,
                                  "DAV not enabled for Destination URI.");
    }

    /* Resolve destination resource */
    err = dav_get_resource(lookup.rnew, 0 /* label_allowed */,
                           0 /* use_checked_in */, &resnew);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    /* are the two resources handled by the same repository? */
    if (resource->hooks != resnew->hooks) {
        /* ### this message exposes some backend config, but screw it... */
        return dav_error_response(r, HTTP_BAD_GATEWAY,
                                  "Destination URI is handled by a "
                                  "different repository than the source URI. "
                                  "MOVE or COPY between repositories is "
                                  "not possible.");
    }

    /* get and parse the overwrite header value */
    if ((overwrite = dav_get_overwrite(r)) < 0) {
        /* dav_get_overwrite() supplies additional information for the
         * default message. */
        return HTTP_BAD_REQUEST;
    }

    /* quick failure test: if dest exists and overwrite is false. */
    if (resnew->exists && !overwrite) {
        /* Supply some text for the error response body. */
        return dav_error_response(r, HTTP_PRECONDITION_FAILED,
                                  "Destination is not empty and "
                                  "Overwrite is not \"T\"");
    }

    /* are the source and destination the same? */
    if ((*resource->hooks->is_same_resource)(resource, resnew)) {
        /* Supply some text for the error response body. */
        return dav_error_response(r, HTTP_FORBIDDEN,
                                  "Source and Destination URIs are the same.");

    }

    is_dir = resource->collection;

    /* get and parse the Depth header value. "0" and "infinity" are legal. */
    if ((depth = dav_get_depth(r, DAV_INFINITY)) < 0) {
        /* dav_get_depth() supplies additional information for the
         * default message. */
        return HTTP_BAD_REQUEST;
    }
    if (depth == 1) {
        /* This supplies additional information for the default message. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "Depth must be \"0\" or \"infinity\" for COPY or MOVE.");
        return HTTP_BAD_REQUEST;
    }
    if (is_move && is_dir && depth != DAV_INFINITY) {
        /* This supplies additional information for the default message. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "Depth must be \"infinity\" when moving a collection.");
        return HTTP_BAD_REQUEST;
    }

    /*
     * Check If-Headers and existing locks for each resource in the source
     * if we are performing a MOVE. We will return a 424 response with a
     * DAV:multistatus body. The multistatus responses will contain the
     * information about any resource that fails the validation.
     *
     * We check the parent resource, too, since this is a MOVE. Moving the
     * resource effectively removes it from the parent collection, so we
     * must ensure that we have met the appropriate conditions.
     *
     * If a problem occurs with the Request-URI itself, then a plain error
     * (rather than a multistatus) will be returned.
     */
    if (is_move
        && (err = dav_validate_request(r, resource, depth, NULL,
                                       &multi_response,
                                       DAV_VALIDATE_PARENT
                                       | DAV_VALIDATE_USE_424,
                                       NULL)) != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not MOVE %s due to a failed "
                                          "precondition on the source "
                                          "(e.g. locks).",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, multi_response);
    }

    /*
     * Check If-Headers and existing locks for destination. Note that we
     * use depth==infinity since the target (hierarchy) will be deleted
     * before the move/copy is completed.
     *
     * Note that we are overwriting the target, which implies a DELETE, so
     * we are subject to the error/response rules as a DELETE. Namely, we
     * will return a 424 error if any of the validations fail.
     * (see dav_method_delete() for more information)
     */
    if ((err = dav_validate_request(lookup.rnew, resnew, DAV_INFINITY, NULL,
                                    &multi_response,
                                    DAV_VALIDATE_PARENT
                                    | DAV_VALIDATE_USE_424, NULL)) != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not MOVE/COPY %s due to a "
                                          "failed precondition on the "
                                          "destination (e.g. locks).",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, multi_response);
    }

    if (is_dir
        && depth == DAV_INFINITY
        && (*resource->hooks->is_parent_resource)(resource, resnew)) {
        /* Supply some text for the error response body. */
        return dav_error_response(r, HTTP_FORBIDDEN,
                                  "Source collection contains the "
                                  "Destination.");

    }
    if (is_dir
        && (*resnew->hooks->is_parent_resource)(resnew, resource)) {
        /* The destination must exist (since it contains the source), and
         * a condition above implies Overwrite==T. Obviously, we cannot
         * delete the Destination before the MOVE/COPY, as that would
         * delete the Source.
         */

        /* Supply some text for the error response body. */
        return dav_error_response(r, HTTP_FORBIDDEN,
                                  "Destination collection contains the Source "
                                  "and Overwrite has been specified.");
    }

    /* ### for now, we don't need anything in the body */
    if ((result = ap_discard_request_body(r)) != OK) {
        return result;
    }

    if ((err = dav_open_lockdb(r, 0, &lockdb)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, NULL);
    }

    /* remove any locks from the old resources */
    /*
     * ### this is Yet Another Traversal. if we do a rename(), then we
     * ### really don't have to do this in some cases since the inode
     * ### values will remain constant across the move. but we can't
     * ### know that fact from outside the provider :-(
     *
     * ### note that we now have a problem atomicity in the move/copy
     * ### since a failure after this would have removed locks (technically,
     * ### this is okay to do, but really...)
     */
    if (is_move && lockdb != NULL) {
        /* ### this is wrong! it blasts direct locks on parent resources */
        /* ### pass lockdb! */
        (void)dav_unlock(r, resource, NULL);
    }

    /* if this is a move, then the source parent collection will be modified */
    if (is_move) {
        if ((err = dav_auto_checkout(r, resource, 1 /* parent_only */,
                                     &src_av_info)) != NULL) {
            if (lockdb != NULL)
                (*lockdb->hooks->close_lockdb)(lockdb);

            /* ### add a higher-level description? */
            return dav_handle_err(r, err, NULL);
        }
    }

    /*
     * Remember the initial state of the destination, so the lock system
     * can be notified as to how it changed.
     */
    resnew_state = dav_get_resource_state(lookup.rnew, resnew);

    /* In a MOVE operation, the destination is replaced by the source.
     * In a COPY operation, if the destination exists, is under version
     * control, and is the same resource type as the source,
     * then it should not be replaced, but modified to be a copy of
     * the source.
     */
    if (!resnew->exists)
        replace_dest = 0;
    else if (is_move || !resource->versioned)
        replace_dest = 1;
    else if (resource->type != resnew->type)
        replace_dest = 1;
    else if ((resource->collection == 0) != (resnew->collection == 0))
        replace_dest = 1;
    else
        replace_dest = 0;

    /* If the destination must be created or replaced,
     * make sure the parent collection is writable
     */
    if (!resnew->exists || replace_dest) {
        if ((err = dav_auto_checkout(r, resnew, 1 /*parent_only*/,
                                     &dst_av_info)) != NULL) {
            /* could not make destination writable:
             * if move, restore state of source parent
             */
            if (is_move) {
                (void)dav_auto_checkin(r, NULL, 1 /* undo */,
                                       0 /*unlock*/, &src_av_info);
            }

            if (lockdb != NULL)
                (*lockdb->hooks->close_lockdb)(lockdb);

            /* ### add a higher-level description? */
            return dav_handle_err(r, err, NULL);
        }
    }

    /* If source and destination parents are the same, then
     * use the same resource object, so status updates to one are reflected
     * in the other, when doing auto-versioning. Otherwise,
     * we may try to checkin the parent twice.
     */
    if (src_av_info.parent_resource != NULL
        && dst_av_info.parent_resource != NULL
        && (*src_av_info.parent_resource->hooks->is_same_resource)
            (src_av_info.parent_resource, dst_av_info.parent_resource)) {

        dst_av_info.parent_resource = src_av_info.parent_resource;
    }

    /* If destination is being replaced, remove it first
     * (we know Ovewrite must be TRUE). Then try to copy/move the resource.
     */
    if (replace_dest)
        err = (*resnew->hooks->remove_resource)(resnew, &multi_response);

    if (err == NULL) {
        if (is_move)
            err = (*resource->hooks->move_resource)(resource, resnew,
                                                    &multi_response);
        else
            err = (*resource->hooks->copy_resource)(resource, resnew, depth,
                                                    &multi_response);
    }

    /* perform any auto-versioning cleanup */
    err2 = dav_auto_checkin(r, NULL, err != NULL /* undo if error */,
                            0 /*unlock*/, &dst_av_info);

    if (is_move) {
        err3 = dav_auto_checkin(r, NULL, err != NULL /* undo if error */,
                                0 /*unlock*/, &src_av_info);
    }
    else
        err3 = NULL;

    /* check for error from remove/copy/move operations */
    if (err != NULL) {
        if (lockdb != NULL)
            (*lockdb->hooks->close_lockdb)(lockdb);

        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not MOVE/COPY %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, multi_response);
    }

    /* check for errors from auto-versioning */
    if (err2 != NULL) {
        /* just log a warning */
        err = dav_push_error(r->pool, err2->status, 0,
                             "The MOVE/COPY was successful, but there was a "
                             "problem automatically checking in the "
                             "source parent collection.",
                             err2);
        dav_log_err(r, err, APLOG_WARNING);
    }
    if (err3 != NULL) {
        /* just log a warning */
        err = dav_push_error(r->pool, err3->status, 0,
                             "The MOVE/COPY was successful, but there was a "
                             "problem automatically checking in the "
                             "destination or its parent collection.",
                             err3);
        dav_log_err(r, err, APLOG_WARNING);
    }

    /* propagate any indirect locks at the target */
    if (lockdb != NULL) {

        /* notify lock system that we have created/replaced a resource */
        err = dav_notify_created(r, lockdb, resnew, resnew_state, depth);

        (*lockdb->hooks->close_lockdb)(lockdb);

        if (err != NULL) {
            /* The move/copy was successful, but the locking failed. */
            err = dav_push_error(r->pool, err->status, 0,
                                 "The MOVE/COPY was successful, but there "
                                 "was a problem updating the lock "
                                 "information.",
                                 err);
            return dav_handle_err(r, err, NULL);
        }
    }

    /* return an appropriate response (HTTP_CREATED or HTTP_NO_CONTENT) */
    return dav_created(r, lookup.rnew->uri, "Destination",
                       resnew_state == DAV_RESOURCE_EXISTS);
}

/* dav_method_lock:  Handler to implement the DAV LOCK method
 *    Returns appropriate HTTP_* response.
 */
static int dav_method_lock(request_rec *r)
{
    dav_error *err;
    dav_resource *resource;
    const dav_hooks_locks *locks_hooks;
    int result;
    int depth;
    int new_lock_request = 0;
    apr_xml_doc *doc;
    dav_lock *lock;
    dav_response *multi_response = NULL;
    dav_lockdb *lockdb;
    int resource_state;

    /* If no locks provider, decline the request */
    locks_hooks = DAV_GET_HOOKS_LOCKS(r);
    if (locks_hooks == NULL)
        return DECLINED;

    if ((result = ap_xml_parse_input(r, &doc)) != OK)
        return result;

    depth = dav_get_depth(r, DAV_INFINITY);
    if (depth != 0 && depth != DAV_INFINITY) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "Depth must be 0 or \"infinity\" for LOCK.");
        return HTTP_BAD_REQUEST;
    }

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    /*
     * Open writable. Unless an error occurs, we'll be
     * writing into the database.
     */
    if ((err = (*locks_hooks->open_lockdb)(r, 0, 0, &lockdb)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, NULL);
    }

    if (doc != NULL) {
        if ((err = dav_lock_parse_lockinfo(r, resource, lockdb, doc,
                                               &lock)) != NULL) {
            /* ### add a higher-level description to err? */
            goto error;
        }
        new_lock_request = 1;

        lock->auth_user = apr_pstrdup(r->pool, r->user);
    }

    resource_state = dav_get_resource_state(r, resource);

    /*
     * Check If-Headers and existing locks.
     *
     * If this will create a locknull resource, then the LOCK will affect
     * the parent collection (much like a PUT/MKCOL). For that case, we must
     * validate the parent resource's conditions.
     */
    if ((err = dav_validate_request(r, resource, depth, NULL, &multi_response,
                                    (resource_state == DAV_RESOURCE_NULL
                                     ? DAV_VALIDATE_PARENT
                                     : DAV_VALIDATE_RESOURCE)
                                    | (new_lock_request ? lock->scope : 0)
                                    | DAV_VALIDATE_ADD_LD,
                                    lockdb)) != OK) {
        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not LOCK %s due to a failed "
                                          "precondition (e.g. other locks).",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        goto error;
    }

    if (new_lock_request == 0) {
        dav_locktoken_list *ltl;

        /*
         * Refresh request
         * ### Assumption:  We can renew multiple locks on the same resource
         * ### at once. First harvest all the positive lock-tokens given in
         * ### the If header. Then modify the lock entries for this resource
         * ### with the new Timeout val.
         */

        if ((err = dav_get_locktoken_list(r, &ltl)) != NULL) {
            err = dav_push_error(r->pool, err->status, 0,
                                 apr_psprintf(r->pool,
                                              "The lock refresh for %s failed "
                                              "because no lock tokens were "
                                              "specified in an \"If:\" "
                                              "header.",
                                              ap_escape_html(r->pool, r->uri)),
                                 err);
            goto error;
        }

        if ((err = (*locks_hooks->refresh_locks)(lockdb, resource, ltl,
                                                 dav_get_timeout(r),
                                                 &lock)) != NULL) {
            /* ### add a higher-level description to err? */
            goto error;
        }
    } else {
        /* New lock request */
        char *locktoken_txt;
        dav_dir_conf *conf;

        conf = (dav_dir_conf *)ap_get_module_config(r->per_dir_config,
                                                    &dav_module);

        /* apply lower bound (if any) from DAVMinTimeout directive */
        if (lock->timeout != DAV_TIMEOUT_INFINITE
            && lock->timeout < time(NULL) + conf->locktimeout)
            lock->timeout = time(NULL) + conf->locktimeout;

        err = dav_add_lock(r, resource, lockdb, lock, &multi_response);
        if (err != NULL) {
            /* ### add a higher-level description to err? */
            goto error;
        }

        locktoken_txt = apr_pstrcat(r->pool, "<",
                                    (*locks_hooks->format_locktoken)(r->pool,
                                        lock->locktoken),
                                    ">", NULL);

        apr_table_set(r->headers_out, "Lock-Token", locktoken_txt);
    }

    (*locks_hooks->close_lockdb)(lockdb);

    r->status = HTTP_OK;
    ap_set_content_type(r, DAV_XML_CONTENT_TYPE);

    ap_rputs(DAV_XML_HEADER DEBUG_CR "<D:prop xmlns:D=\"DAV:\">" DEBUG_CR, r);
    if (lock == NULL)
        ap_rputs("<D:lockdiscovery/>" DEBUG_CR, r);
    else {
        ap_rprintf(r,
                   "<D:lockdiscovery>" DEBUG_CR
                   "%s" DEBUG_CR
                   "</D:lockdiscovery>" DEBUG_CR,
                   dav_lock_get_activelock(r, lock, NULL));
    }
    ap_rputs("</D:prop>", r);

    /* the response has been sent. */
    return DONE;

  error:
    (*locks_hooks->close_lockdb)(lockdb);
    return dav_handle_err(r, err, multi_response);
}

/* dav_method_unlock:  Handler to implement the DAV UNLOCK method
 *    Returns appropriate HTTP_* response.
 */
static int dav_method_unlock(request_rec *r)
{
    dav_error *err;
    dav_resource *resource;
    const dav_hooks_locks *locks_hooks;
    int result;
    const char *const_locktoken_txt;
    char *locktoken_txt;
    dav_locktoken *locktoken = NULL;
    int resource_state;
    dav_response *multi_response;

    /* If no locks provider, decline the request */
    locks_hooks = DAV_GET_HOOKS_LOCKS(r);
    if (locks_hooks == NULL)
        return DECLINED;

    if ((const_locktoken_txt = apr_table_get(r->headers_in,
                                             "Lock-Token")) == NULL) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "Unlock failed (%s):  "
                      "No Lock-Token specified in header", r->filename);
        return HTTP_BAD_REQUEST;
    }

    locktoken_txt = apr_pstrdup(r->pool, const_locktoken_txt);
    if (locktoken_txt[0] != '<') {
        /* ### should provide more specifics... */
        return HTTP_BAD_REQUEST;
    }
    locktoken_txt++;

    if (locktoken_txt[strlen(locktoken_txt) - 1] != '>') {
        /* ### should provide more specifics... */
        return HTTP_BAD_REQUEST;
    }
    locktoken_txt[strlen(locktoken_txt) - 1] = '\0';

    if ((err = (*locks_hooks->parse_locktoken)(r->pool, locktoken_txt,
                                               &locktoken)) != NULL) {
        err = dav_push_error(r->pool, HTTP_BAD_REQUEST, 0,
                             apr_psprintf(r->pool,
                                          "The UNLOCK on %s failed -- an "
                                          "invalid lock token was specified "
                                          "in the \"If:\" header.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, NULL);
    }

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    resource_state = dav_get_resource_state(r, resource);

    /*
     * Check If-Headers and existing locks.
     *
     * Note: depth == 0 normally requires no multistatus response. However,
     * if we pass DAV_VALIDATE_PARENT, then we could get an error on a URI
     * other than the Request-URI, thereby requiring a multistatus.
     *
     * If the resource is a locknull resource, then the UNLOCK will affect
     * the parent collection (much like a delete). For that case, we must
     * validate the parent resource's conditions.
     */
    if ((err = dav_validate_request(r, resource, 0, locktoken,
                                    &multi_response,
                                    resource_state == DAV_RESOURCE_LOCK_NULL
                                    ? DAV_VALIDATE_PARENT
                                    : DAV_VALIDATE_RESOURCE, NULL)) != NULL) {
        /* ### add a higher-level description? */
        return dav_handle_err(r, err, multi_response);
    }

    /* ### RFC 2518 s. 8.11: If this resource is locked by locktoken,
     *     _all_ resources locked by locktoken are released.  It does not say
     *     resource has to be the root of an infinte lock.  Thus, an UNLOCK
     *     on any part of an infinte lock will remove the lock on all resources.
     *
     *     For us, if r->filename represents an indirect lock (part of an infinity lock),
     *     we must actually perform an UNLOCK on the direct lock for this resource.
     */
    if ((result = dav_unlock(r, resource, locktoken)) != OK) {
        return result;
    }

    return HTTP_NO_CONTENT;
}

static int dav_method_vsn_control(request_rec *r)
{
    dav_resource *resource;
    int resource_state;
    dav_auto_version_info av_info;
    const dav_hooks_locks *locks_hooks = DAV_GET_HOOKS_LOCKS(r);
    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
    dav_error *err;
    apr_xml_doc *doc;
    const char *target = NULL;
    int result;

    /* if no versioning provider, decline the request */
    if (vsn_hooks == NULL)
        return DECLINED;

    /* ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    /* remember the pre-creation resource state */
    resource_state = dav_get_resource_state(r, resource);

    /* parse the request body (may be a version-control element) */
    if ((result = ap_xml_parse_input(r, &doc)) != OK) {
        return result;
    }
    /* note: doc == NULL if no request body */

    if (doc != NULL) {
        const apr_xml_elem *child;
        apr_size_t tsize;

        if (!dav_validate_root(doc, "version-control")) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "The request body does not contain "
                          "a \"version-control\" element.");
            return HTTP_BAD_REQUEST;
        }

        /* get the version URI */
        if ((child = dav_find_child(doc->root, "version")) == NULL) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "The \"version-control\" element does not contain "
                          "a \"version\" element.");
            return HTTP_BAD_REQUEST;
        }

        if ((child = dav_find_child(child, "href")) == NULL) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "The \"version\" element does not contain "
                          "an \"href\" element.");
            return HTTP_BAD_REQUEST;
        }

        /* get version URI */
        apr_xml_to_text(r->pool, child, APR_XML_X2T_INNER, NULL, NULL,
                        &target, &tsize);
        if (tsize == 0) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "An \"href\" element does not contain a URI.");
            return HTTP_BAD_REQUEST;
        }
    }

    /* Check request preconditions */

    /* ### need a general mechanism for reporting precondition violations
     * ### (should be returning XML document for 403/409 responses)
     */

    /* if not versioning existing resource, must specify version to select */
    if (!resource->exists && target == NULL) {
        err = dav_new_error(r->pool, HTTP_CONFLICT, 0,
                            "<DAV:initial-version-required/>");
        return dav_handle_err(r, err, NULL);
    }
    else if (resource->exists) {
        /* cannot add resource to existing version history */
        if (target != NULL) {
            err = dav_new_error(r->pool, HTTP_CONFLICT, 0,
                                "<DAV:cannot-add-to-existing-history/>");
            return dav_handle_err(r, err, NULL);
        }

        /* resource must be unversioned and versionable, or version selector */
        if (resource->type != DAV_RESOURCE_TYPE_REGULAR
            || (!resource->versioned && !(vsn_hooks->versionable)(resource))) {
            err = dav_new_error(r->pool, HTTP_CONFLICT, 0,
                                "<DAV:must-be-versionable/>");
            return dav_handle_err(r, err, NULL);
        }

        /* the DeltaV spec says if resource is a version selector,
         * then VERSION-CONTROL is a no-op
         */
        if (resource->versioned) {
            /* set the Cache-Control header, per the spec */
            apr_table_setn(r->headers_out, "Cache-Control", "no-cache");

            /* no body */
            ap_set_content_length(r, 0);

            return DONE;
        }
    }

    /* Check If-Headers and existing locks */
    /* Note: depth == 0. Implies no need for a multistatus response. */
    if ((err = dav_validate_request(r, resource, 0, NULL, NULL,
                                    resource_state == DAV_RESOURCE_NULL ?
                                    DAV_VALIDATE_PARENT :
                                    DAV_VALIDATE_RESOURCE, NULL)) != NULL) {
        return dav_handle_err(r, err, NULL);
    }

    /* if in versioned collection, make sure parent is checked out */
    if ((err = dav_auto_checkout(r, resource, 1 /* parent_only */,
                                 &av_info)) != NULL) {
        return dav_handle_err(r, err, NULL);
    }

    /* attempt to version-control the resource */
    if ((err = (*vsn_hooks->vsn_control)(resource, target)) != NULL) {
        dav_auto_checkin(r, resource, 1 /*undo*/, 0 /*unlock*/, &av_info);
        err = dav_push_error(r->pool, HTTP_CONFLICT, 0,
                             apr_psprintf(r->pool,
                                          "Could not VERSION-CONTROL resource %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, NULL);
    }

    /* revert writability of parent directory */
    err = dav_auto_checkin(r, resource, 0 /*undo*/, 0 /*unlock*/, &av_info);
    if (err != NULL) {
        /* just log a warning */
        err = dav_push_error(r->pool, err->status, 0,
                             "The VERSION-CONTROL was successful, but there "
                             "was a problem automatically checking in "
                             "the parent collection.",
                             err);
        dav_log_err(r, err, APLOG_WARNING);
    }

    /* if the resource is lockable, let lock system know of new resource */
    if (locks_hooks != NULL
        && (*locks_hooks->get_supportedlock)(resource) != NULL) {
        dav_lockdb *lockdb;

        if ((err = (*locks_hooks->open_lockdb)(r, 0, 0, &lockdb)) != NULL) {
            /* The resource creation was successful, but the locking failed. */
            err = dav_push_error(r->pool, err->status, 0,
                                 "The VERSION-CONTROL was successful, but there "
                                 "was a problem opening the lock database "
                                 "which prevents inheriting locks from the "
                                 "parent resources.",
                                 err);
            return dav_handle_err(r, err, NULL);
        }

        /* notify lock system that we have created/replaced a resource */
        err = dav_notify_created(r, lockdb, resource, resource_state, 0);

        (*locks_hooks->close_lockdb)(lockdb);

        if (err != NULL) {
            /* The dir creation was successful, but the locking failed. */
            err = dav_push_error(r->pool, err->status, 0,
                                 "The VERSION-CONTROL was successful, but there "
                                 "was a problem updating its lock "
                                 "information.",
                                 err);
            return dav_handle_err(r, err, NULL);
        }
    }

    /* set the Cache-Control header, per the spec */
    apr_table_setn(r->headers_out, "Cache-Control", "no-cache");

    /* return an appropriate response (HTTP_CREATED) */
    return dav_created(r, resource->uri, "Version selector", 0 /*replaced*/);
}

/* handle the CHECKOUT method */
static int dav_method_checkout(request_rec *r)
{
    dav_resource *resource;
    dav_resource *working_resource;
    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
    dav_error *err;
    int result;
    apr_xml_doc *doc;
    int apply_to_vsn = 0;
    int is_unreserved = 0;
    int is_fork_ok = 0;
    int create_activity = 0;
    apr_array_header_t *activities = NULL;

    /* If no versioning provider, decline the request */
    if (vsn_hooks == NULL)
        return DECLINED;

    if ((result = ap_xml_parse_input(r, &doc)) != OK)
        return result;

    if (doc != NULL) {
        const apr_xml_elem *aset;

        if (!dav_validate_root(doc, "checkout")) {
            /* This supplies additional information for the default msg. */
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "The request body, if present, must be a "
                          "DAV:checkout element.");
            return HTTP_BAD_REQUEST;
        }

        if (dav_find_child(doc->root, "apply-to-version") != NULL) {
            if (apr_table_get(r->headers_in, "label") != NULL) {
                /* ### we want generic 403/409 XML reporting here */
                /* ### DAV:must-not-have-label-and-apply-to-version */
                return dav_error_response(r, HTTP_CONFLICT,
                                          "DAV:apply-to-version cannot be "
                                          "used in conjunction with a "
                                          "Label header.");
            }
            apply_to_vsn = 1;
        }

        is_unreserved = dav_find_child(doc->root, "unreserved") != NULL;
        is_fork_ok = dav_find_child(doc->root, "fork-ok") != NULL;

        if ((aset = dav_find_child(doc->root, "activity-set")) != NULL) {
            if (dav_find_child(aset, "new") != NULL) {
                create_activity = 1;
            }
            else {
                const apr_xml_elem *child = aset->first_child;

                activities = apr_array_make(r->pool, 1, sizeof(const char *));

                for (; child != NULL; child = child->next) {
                    if (child->ns == APR_XML_NS_DAV_ID
                        && strcmp(child->name, "href") == 0) {
                        const char *href;

                        href = dav_xml_get_cdata(child, r->pool,
                                                 1 /* strip_white */);
                        *(const char **)apr_array_push(activities) = href;
                    }
                }

                if (activities->nelts == 0) {
                    /* no href's is a DTD violation:
                       <!ELEMENT activity-set (href+ | new)>
                    */

                    /* This supplies additional info for the default msg. */
                    ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                                  "Within the DAV:activity-set element, the "
                                  "DAV:new element must be used, or at least "
                                  "one DAV:href must be specified.");
                    return HTTP_BAD_REQUEST;
                }
            }
        }
    }

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 1 /*label_allowed*/, apply_to_vsn, &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    /* Check the state of the resource: must be a file or collection,
     * must be versioned, and must not already be checked out.
     */
    if (resource->type != DAV_RESOURCE_TYPE_REGULAR
        && resource->type != DAV_RESOURCE_TYPE_VERSION) {
        return dav_error_response(r, HTTP_CONFLICT,
                                  "Cannot checkout this type of resource.");
    }

    if (!resource->versioned) {
        return dav_error_response(r, HTTP_CONFLICT,
                                  "Cannot checkout unversioned resource.");
    }

    if (resource->working) {
        return dav_error_response(r, HTTP_CONFLICT,
                                  "The resource is already checked out to the workspace.");
    }

    /* ### do lock checks, once behavior is defined */

    /* Do the checkout */
    if ((err = (*vsn_hooks->checkout)(resource, 0 /*auto_checkout*/,
                                      is_unreserved, is_fork_ok,
                                      create_activity, activities,
                                      &working_resource)) != NULL) {
        err = dav_push_error(r->pool, HTTP_CONFLICT, 0,
                             apr_psprintf(r->pool,
                                          "Could not CHECKOUT resource %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, NULL);
    }

    /* set the Cache-Control header, per the spec */
    apr_table_setn(r->headers_out, "Cache-Control", "no-cache");

    /* if no working resource created, return OK,
     * else return CREATED with working resource URL in Location header
     */
    if (working_resource == NULL) {
        /* no body */
        ap_set_content_length(r, 0);
        return DONE;
    }

    return dav_created(r, working_resource->uri, "Checked-out resource", 0);
}

/* handle the UNCHECKOUT method */
static int dav_method_uncheckout(request_rec *r)
{
    dav_resource *resource;
    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
    dav_error *err;
    int result;

    /* If no versioning provider, decline the request */
    if (vsn_hooks == NULL)
        return DECLINED;

    if ((result = ap_discard_request_body(r)) != OK) {
        return result;
    }

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    /* Check the state of the resource: must be a file or collection,
     * must be versioned, and must be checked out.
     */
    if (resource->type != DAV_RESOURCE_TYPE_REGULAR) {
        return dav_error_response(r, HTTP_CONFLICT,
                                  "Cannot uncheckout this type of resource.");
    }

    if (!resource->versioned) {
        return dav_error_response(r, HTTP_CONFLICT,
                                  "Cannot uncheckout unversioned resource.");
    }

    if (!resource->working) {
        return dav_error_response(r, HTTP_CONFLICT,
                                  "The resource is not checked out to the workspace.");
    }

    /* ### do lock checks, once behavior is defined */

    /* Do the uncheckout */
    if ((err = (*vsn_hooks->uncheckout)(resource)) != NULL) {
        err = dav_push_error(r->pool, HTTP_CONFLICT, 0,
                             apr_psprintf(r->pool,
                                          "Could not UNCHECKOUT resource %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, NULL);
    }

    /* no body */
    ap_set_content_length(r, 0);

    return DONE;
}

/* handle the CHECKIN method */
static int dav_method_checkin(request_rec *r)
{
    dav_resource *resource;
    dav_resource *new_version;
    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
    dav_error *err;
    int result;
    apr_xml_doc *doc;
    int keep_checked_out = 0;

    /* If no versioning provider, decline the request */
    if (vsn_hooks == NULL)
        return DECLINED;

    if ((result = ap_xml_parse_input(r, &doc)) != OK)
        return result;

    if (doc != NULL) {
        if (!dav_validate_root(doc, "checkin")) {
            /* This supplies additional information for the default msg. */
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "The request body, if present, must be a "
                          "DAV:checkin element.");
            return HTTP_BAD_REQUEST;
        }

        keep_checked_out = dav_find_child(doc->root, "keep-checked-out") != NULL;
    }

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    /* Check the state of the resource: must be a file or collection,
     * must be versioned, and must be checked out.
     */
    if (resource->type != DAV_RESOURCE_TYPE_REGULAR) {
        return dav_error_response(r, HTTP_CONFLICT,
                                  "Cannot checkin this type of resource.");
    }

    if (!resource->versioned) {
        return dav_error_response(r, HTTP_CONFLICT,
                                  "Cannot checkin unversioned resource.");
    }

    if (!resource->working) {
        return dav_error_response(r, HTTP_CONFLICT,
                                  "The resource is not checked out.");
    }

    /* ### do lock checks, once behavior is defined */

    /* Do the checkin */
    if ((err = (*vsn_hooks->checkin)(resource, keep_checked_out, &new_version))
        != NULL) {
        err = dav_push_error(r->pool, HTTP_CONFLICT, 0,
                             apr_psprintf(r->pool,
                                          "Could not CHECKIN resource %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, NULL);
    }

    return dav_created(r, new_version->uri, "Version", 0);
}

static int dav_method_update(request_rec *r)
{
    dav_resource *resource;
    dav_resource *version = NULL;
    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
    apr_xml_doc *doc;
    apr_xml_elem *child;
    int is_label = 0;
    int depth;
    int result;
    apr_size_t tsize;
    const char *target;
    dav_response *multi_response;
    dav_error *err;
    dav_lookup_result lookup;

    /* If no versioning provider, or UPDATE not supported,
     * decline the request */
    if (vsn_hooks == NULL || vsn_hooks->update == NULL)
        return DECLINED;

    if ((depth = dav_get_depth(r, 0)) < 0) {
        /* dav_get_depth() supplies additional information for the
         * default message. */
        return HTTP_BAD_REQUEST;
    }

    /* parse the request body */
    if ((result = ap_xml_parse_input(r, &doc)) != OK) {
        return result;
    }

    if (doc == NULL || !dav_validate_root(doc, "update")) {
        /* This supplies additional information for the default message. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The request body does not contain "
                      "an \"update\" element.");
        return HTTP_BAD_REQUEST;
    }

    /* check for label-name or version element, but not both */
    if ((child = dav_find_child(doc->root, "label-name")) != NULL)
        is_label = 1;
    else if ((child = dav_find_child(doc->root, "version")) != NULL) {
        /* get the href element */
        if ((child = dav_find_child(child, "href")) == NULL) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "The version element does not contain "
                          "an \"href\" element.");
            return HTTP_BAD_REQUEST;
        }
    }
    else {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The \"update\" element does not contain "
                      "a \"label-name\" or \"version\" element.");
        return HTTP_BAD_REQUEST;
    }

    /* a depth greater than zero is only allowed for a label */
    if (!is_label && depth != 0) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "Depth must be zero for UPDATE with a version");
        return HTTP_BAD_REQUEST;
    }

    /* get the target value (a label or a version URI) */
    apr_xml_to_text(r->pool, child, APR_XML_X2T_INNER, NULL, NULL,
                    &target, &tsize);
    if (tsize == 0) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "A \"label-name\" or \"href\" element does not contain "
                      "any content.");
        return HTTP_BAD_REQUEST;
    }

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    /* ### need a general mechanism for reporting precondition violations
     * ### (should be returning XML document for 403/409 responses)
     */
    if (resource->type != DAV_RESOURCE_TYPE_REGULAR
        || !resource->versioned || resource->working) {
        return dav_error_response(r, HTTP_CONFLICT,
                                  "<DAV:must-be-checked-in-version-controlled-resource>");
    }

    /* if target is a version, resolve the version resource */
    /* ### dav_lookup_uri only allows absolute URIs; is that OK? */
    if (!is_label) {
        lookup = dav_lookup_uri(target, r, 0 /* must_be_absolute */);
        if (lookup.rnew == NULL) {
            if (lookup.err.status == HTTP_BAD_REQUEST) {
                /* This supplies additional information for the default message. */
                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                              "%s", lookup.err.desc);
                return HTTP_BAD_REQUEST;
            }

            /* ### this assumes that dav_lookup_uri() only generates a status
             * ### that Apache can provide a status line for!! */

            return dav_error_response(r, lookup.err.status, lookup.err.desc);
        }
        if (lookup.rnew->status != HTTP_OK) {
            /* ### how best to report this... */
            return dav_error_response(r, lookup.rnew->status,
                                      "Version URI had an error.");
        }

        /* resolve version resource */
        err = dav_get_resource(lookup.rnew, 0 /* label_allowed */,
                               0 /* use_checked_in */, &version);
        if (err != NULL)
            return dav_handle_err(r, err, NULL);

        /* NULL out target, since we're using a version resource */
        target = NULL;
    }

    /* do the UPDATE operation */
    err = (*vsn_hooks->update)(resource, version, target, depth, &multi_response);

    if (err != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not UPDATE %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, multi_response);
    }

    /* set the Cache-Control header, per the spec */
    apr_table_setn(r->headers_out, "Cache-Control", "no-cache");

    /* no body */
    ap_set_content_length(r, 0);

    return DONE;
}

/* context maintained during LABEL treewalk */
typedef struct dav_label_walker_ctx
{
    /* input: */
    dav_walk_params w;

    /* label being manipulated */
    const char *label;

    /* label operation */
    int label_op;
#define DAV_LABEL_ADD           1
#define DAV_LABEL_SET           2
#define DAV_LABEL_REMOVE        3

    /* version provider hooks */
    const dav_hooks_vsn *vsn_hooks;

} dav_label_walker_ctx;

static dav_error * dav_label_walker(dav_walk_resource *wres, int calltype)
{
    dav_label_walker_ctx *ctx = wres->walk_ctx;
    dav_error *err = NULL;

    /* Check the state of the resource: must be a version or
     * non-checkedout version selector
     */
    /* ### need a general mechanism for reporting precondition violations
     * ### (should be returning XML document for 403/409 responses)
     */
    if (wres->resource->type != DAV_RESOURCE_TYPE_VERSION &&
        (wres->resource->type != DAV_RESOURCE_TYPE_REGULAR
         || !wres->resource->versioned)) {
        err = dav_new_error(ctx->w.pool, HTTP_CONFLICT, 0,
                            "<DAV:must-be-version-or-version-selector/>");
    }
    else if (wres->resource->working) {
        err = dav_new_error(ctx->w.pool, HTTP_CONFLICT, 0,
                            "<DAV:must-not-be-checked-out/>");
    }
    else {
        /* do the label operation */
        if (ctx->label_op == DAV_LABEL_REMOVE)
            err = (*ctx->vsn_hooks->remove_label)(wres->resource, ctx->label);
        else
            err = (*ctx->vsn_hooks->add_label)(wres->resource, ctx->label,
                                               ctx->label_op == DAV_LABEL_SET);
    }

    if (err != NULL) {
        /* ### need utility routine to add response with description? */
        dav_add_response(wres, err->status, NULL);
        wres->response->desc = err->desc;
    }

    return NULL;
}

static int dav_method_label(request_rec *r)
{
    dav_resource *resource;
    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
    apr_xml_doc *doc;
    apr_xml_elem *child;
    int depth;
    int result;
    apr_size_t tsize;
    dav_error *err;
    dav_label_walker_ctx ctx = { { 0 } };
    dav_response *multi_status;

    /* If no versioning provider, or the provider doesn't support
     * labels, decline the request */
    if (vsn_hooks == NULL || vsn_hooks->add_label == NULL)
        return DECLINED;

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 1 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);
    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    if ((depth = dav_get_depth(r, 0)) < 0) {
        /* dav_get_depth() supplies additional information for the
         * default message. */
        return HTTP_BAD_REQUEST;
    }

    /* parse the request body */
    if ((result = ap_xml_parse_input(r, &doc)) != OK) {
        return result;
    }

    if (doc == NULL || !dav_validate_root(doc, "label")) {
        /* This supplies additional information for the default message. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The request body does not contain "
                      "a \"label\" element.");
        return HTTP_BAD_REQUEST;
    }

    /* check for add, set, or remove element */
    if ((child = dav_find_child(doc->root, "add")) != NULL) {
        ctx.label_op = DAV_LABEL_ADD;
    }
    else if ((child = dav_find_child(doc->root, "set")) != NULL) {
        ctx.label_op = DAV_LABEL_SET;
    }
    else if ((child = dav_find_child(doc->root, "remove")) != NULL) {
        ctx.label_op = DAV_LABEL_REMOVE;
    }
    else {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The \"label\" element does not contain "
                      "an \"add\", \"set\", or \"remove\" element.");
        return HTTP_BAD_REQUEST;
    }

    /* get the label string */
    if ((child = dav_find_child(child, "label-name")) == NULL) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The label command element does not contain "
                      "a \"label-name\" element.");
        return HTTP_BAD_REQUEST;
    }

    apr_xml_to_text(r->pool, child, APR_XML_X2T_INNER, NULL, NULL,
                    &ctx.label, &tsize);
    if (tsize == 0) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "A \"label-name\" element does not contain "
                      "a label name.");
        return HTTP_BAD_REQUEST;
    }

    /* do the label operation walk */
    ctx.w.walk_type = DAV_WALKTYPE_NORMAL;
    ctx.w.func = dav_label_walker;
    ctx.w.walk_ctx = &ctx;
    ctx.w.pool = r->pool;
    ctx.w.root = resource;
    ctx.vsn_hooks = vsn_hooks;

    err = (*resource->hooks->walk)(&ctx.w, depth, &multi_status);

    if (err != NULL) {
        /* some sort of error occurred which terminated the walk */
        err = dav_push_error(r->pool, err->status, 0,
                             "The LABEL operation was terminated prematurely.",
                             err);
        return dav_handle_err(r, err, multi_status);
    }

    if (multi_status != NULL) {
        /* One or more resources had errors. If depth was zero, convert
         * response to simple error, else make sure there is an
         * overall error to pass to dav_handle_err()
         */
        if (depth == 0) {
            err = dav_new_error(r->pool, multi_status->status, 0, multi_status->desc);
            multi_status = NULL;
        }
        else {
            err = dav_new_error(r->pool, HTTP_MULTI_STATUS, 0,
                                "Errors occurred during the LABEL operation.");
        }

        return dav_handle_err(r, err, multi_status);
    }

    /* set the Cache-Control header, per the spec */
    apr_table_setn(r->headers_out, "Cache-Control", "no-cache");

    /* no body */
    ap_set_content_length(r, 0);

    return DONE;
}

static int dav_method_report(request_rec *r)
{
    dav_resource *resource;
    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
    int result;
    int label_allowed;
    apr_xml_doc *doc;
    dav_error *err;

    /* If no versioning provider, decline the request */
    if (vsn_hooks == NULL)
        return DECLINED;

    if ((result = ap_xml_parse_input(r, &doc)) != OK)
        return result;
    if (doc == NULL) {
        /* This supplies additional information for the default msg. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The request body must specify a report.");
        return HTTP_BAD_REQUEST;
    }

    /* Ask repository module to resolve the resource.
     * First determine whether a Target-Selector header is allowed
     * for this report.
     */
    label_allowed = (*vsn_hooks->report_label_header_allowed)(doc);
    err = dav_get_resource(r, label_allowed, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    /* set up defaults for the report response */
    r->status = HTTP_OK;
    ap_set_content_type(r, DAV_XML_CONTENT_TYPE);

    /* run report hook */
    if ((err = (*vsn_hooks->deliver_report)(r, resource, doc,
                                            r->output_filters)) != NULL) {
        if (! r->sent_bodyct)
          /* No data has been sent to client yet;  throw normal error. */
          return dav_handle_err(r, err, NULL);

        /* If an error occurred during the report delivery, there's
           basically nothing we can do but abort the connection and
           log an error.  This is one of the limitations of HTTP; it
           needs to "know" the entire status of the response before
           generating it, which is just impossible in these streamy
           response situations. */
        err = dav_push_error(r->pool, err->status, 0,
                             "Provider encountered an error while streaming"
                             " a REPORT response.", err);
        dav_log_err(r, err, APLOG_ERR);
        r->connection->aborted = 1;
        return DONE;
    }

    return DONE;
}

static int dav_method_make_workspace(request_rec *r)
{
    dav_resource *resource;
    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
    dav_error *err;
    apr_xml_doc *doc;
    int result;

    /* if no versioning provider, or the provider does not support workspaces,
     * decline the request
     */
    if (vsn_hooks == NULL || vsn_hooks->make_workspace == NULL)
        return DECLINED;

    /* ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    /* parse the request body (must be a mkworkspace element) */
    if ((result = ap_xml_parse_input(r, &doc)) != OK) {
        return result;
    }

    if (doc == NULL
        || !dav_validate_root(doc, "mkworkspace")) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The request body does not contain "
                      "a \"mkworkspace\" element.");
        return HTTP_BAD_REQUEST;
    }

    /* Check request preconditions */

    /* ### need a general mechanism for reporting precondition violations
     * ### (should be returning XML document for 403/409 responses)
     */

    /* resource must not already exist */
    if (resource->exists) {
        err = dav_new_error(r->pool, HTTP_CONFLICT, 0,
                            "<DAV:resource-must-be-null/>");
        return dav_handle_err(r, err, NULL);
    }

    /* ### what about locking? */

    /* attempt to create the workspace */
    if ((err = (*vsn_hooks->make_workspace)(resource, doc)) != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not create workspace %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, NULL);
    }

    /* set the Cache-Control header, per the spec */
    apr_table_setn(r->headers_out, "Cache-Control", "no-cache");

    /* return an appropriate response (HTTP_CREATED) */
    return dav_created(r, resource->uri, "Workspace", 0 /*replaced*/);
}

static int dav_method_make_activity(request_rec *r)
{
    dav_resource *resource;
    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
    dav_error *err;
    int result;

    /* if no versioning provider, or the provider does not support activities,
     * decline the request
     */
    if (vsn_hooks == NULL || vsn_hooks->make_activity == NULL)
        return DECLINED;

    /* ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    /* MKACTIVITY does not have a defined request body. */
    if ((result = ap_discard_request_body(r)) != OK) {
        return result;
    }

    /* Check request preconditions */

    /* ### need a general mechanism for reporting precondition violations
     * ### (should be returning XML document for 403/409 responses)
     */

    /* resource must not already exist */
    if (resource->exists) {
        err = dav_new_error(r->pool, HTTP_CONFLICT, 0,
                            "<DAV:resource-must-be-null/>");
        return dav_handle_err(r, err, NULL);
    }

    /* the provider must say whether the resource can be created as
       an activity, i.e. whether the location is ok.  */
    if (vsn_hooks->can_be_activity != NULL
        && !(*vsn_hooks->can_be_activity)(resource)) {
      err = dav_new_error(r->pool, HTTP_FORBIDDEN, 0,
                          "<DAV:activity-location-ok/>");
      return dav_handle_err(r, err, NULL);
    }

    /* ### what about locking? */

    /* attempt to create the activity */
    if ((err = (*vsn_hooks->make_activity)(resource)) != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not create activity %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, NULL);
    }

    /* set the Cache-Control header, per the spec */
    apr_table_setn(r->headers_out, "Cache-Control", "no-cache");

    /* return an appropriate response (HTTP_CREATED) */
    return dav_created(r, resource->uri, "Activity", 0 /*replaced*/);
}

static int dav_method_baseline_control(request_rec *r)
{
    /* ### */
    return HTTP_METHOD_NOT_ALLOWED;
}

static int dav_method_merge(request_rec *r)
{
    dav_resource *resource;
    dav_resource *source_resource;
    const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
    dav_error *err;
    int result;
    apr_xml_doc *doc;
    apr_xml_elem *source_elem;
    apr_xml_elem *href_elem;
    apr_xml_elem *prop_elem;
    const char *source;
    int no_auto_merge;
    int no_checkout;
    dav_lookup_result lookup;

    /* If no versioning provider, decline the request */
    if (vsn_hooks == NULL)
        return DECLINED;

    if ((result = ap_xml_parse_input(r, &doc)) != OK)
        return result;

    if (doc == NULL || !dav_validate_root(doc, "merge")) {
        /* This supplies additional information for the default msg. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The request body must be present and must be a "
                      "DAV:merge element.");
        return HTTP_BAD_REQUEST;
    }

    if ((source_elem = dav_find_child(doc->root, "source")) == NULL) {
        /* This supplies additional information for the default msg. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The DAV:merge element must contain a DAV:source "
                      "element.");
        return HTTP_BAD_REQUEST;
    }
    if ((href_elem = dav_find_child(source_elem, "href")) == NULL) {
        /* This supplies additional information for the default msg. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The DAV:source element must contain a DAV:href "
                      "element.");
        return HTTP_BAD_REQUEST;
    }
    source = dav_xml_get_cdata(href_elem, r->pool, 1 /* strip_white */);

    /* get a subrequest for the source, so that we can get a dav_resource
       for that source. */
    lookup = dav_lookup_uri(source, r, 0 /* must_be_absolute */);
    if (lookup.rnew == NULL) {
        if (lookup.err.status == HTTP_BAD_REQUEST) {
            /* This supplies additional information for the default message. */
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "%s", lookup.err.desc);
            return HTTP_BAD_REQUEST;
        }

        /* ### this assumes that dav_lookup_uri() only generates a status
         * ### that Apache can provide a status line for!! */

        return dav_error_response(r, lookup.err.status, lookup.err.desc);
    }
    if (lookup.rnew->status != HTTP_OK) {
        /* ### how best to report this... */
        return dav_error_response(r, lookup.rnew->status,
                                  "Merge source URI had an error.");
    }
    err = dav_get_resource(lookup.rnew, 0 /* label_allowed */,
                           0 /* use_checked_in */, &source_resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    no_auto_merge = dav_find_child(doc->root, "no-auto-merge") != NULL;
    no_checkout = dav_find_child(doc->root, "no-checkout") != NULL;

    prop_elem = dav_find_child(doc->root, "prop");

    /* ### check RFC. I believe the DAV:merge element may contain any
       ### element also allowed within DAV:checkout. need to extract them
       ### here, and pass them along.
       ### if so, then refactor the CHECKOUT method handling so we can reuse
       ### the code. maybe create a structure to hold CHECKOUT parameters
       ### which can be passed to the checkout() and merge() hooks. */

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);
    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    /* ### check the source and target resources flags/types */

    /* ### do lock checks, once behavior is defined */

    /* set the Cache-Control header, per the spec */
    /* ### correct? */
    apr_table_setn(r->headers_out, "Cache-Control", "no-cache");

    /* Initialize these values for a standard MERGE response. If the MERGE
       is going to do something different (i.e. an error), then it must
       return a dav_error, and we'll reset these values properly. */
    r->status = HTTP_OK;
    ap_set_content_type(r, "text/xml");

    /* ### should we do any preliminary response generation? probably not,
       ### because we may have an error, thus demanding something else in
       ### the response body. */

    /* Do the merge, including any response generation. */
    if ((err = (*vsn_hooks->merge)(resource, source_resource,
                                   no_auto_merge, no_checkout,
                                   prop_elem,
                                   r->output_filters)) != NULL) {
        /* ### is err->status the right error here? */
        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not MERGE resource \"%s\" "
                                          "into \"%s\".",
                                          ap_escape_html(r->pool, source),
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, NULL);
    }

    /* the response was fully generated by the merge() hook. */
    /* ### urk. does this prevent logging? need to check... */
    return DONE;
}

static int dav_method_bind(request_rec *r)
{
    dav_resource *resource;
    dav_resource *binding;
    dav_auto_version_info av_info;
    const dav_hooks_binding *binding_hooks = DAV_GET_HOOKS_BINDING(r);
    const char *dest;
    dav_error *err;
    dav_error *err2;
    dav_response *multi_response = NULL;
    dav_lookup_result lookup;
    int overwrite;

    /* If no bindings provider, decline the request */
    if (binding_hooks == NULL)
        return DECLINED;

    /* Ask repository module to resolve the resource */
    err = dav_get_resource(r, 0 /* label_allowed */, 0 /* use_checked_in */,
                           &resource);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    if (!resource->exists) {
        /* Apache will supply a default error for this. */
        return HTTP_NOT_FOUND;
    }

    /* get the destination URI */
    dest = apr_table_get(r->headers_in, "Destination");
    if (dest == NULL) {
        /* This supplies additional information for the default message. */
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "The request is missing a Destination header.");
        return HTTP_BAD_REQUEST;
    }

    lookup = dav_lookup_uri(dest, r, 0 /* must_be_absolute */);
    if (lookup.rnew == NULL) {
        if (lookup.err.status == HTTP_BAD_REQUEST) {
            /* This supplies additional information for the default message. */
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "%s", lookup.err.desc);
            return HTTP_BAD_REQUEST;
        }
        else if (lookup.err.status == HTTP_BAD_GATEWAY) {
            /* ### Bindings protocol draft 02 says to return 507
             * ### (Cross Server Binding Forbidden); Apache already defines 507
             * ### as HTTP_INSUFFICIENT_STORAGE. So, for now, we'll return
             * ### HTTP_FORBIDDEN
             */
             return dav_error_response(r, HTTP_FORBIDDEN,
                                       "Cross server bindings are not "
                                       "allowed by this server.");
        }

        /* ### this assumes that dav_lookup_uri() only generates a status
         * ### that Apache can provide a status line for!! */

        return dav_error_response(r, lookup.err.status, lookup.err.desc);
    }
    if (lookup.rnew->status != HTTP_OK) {
        /* ### how best to report this... */
        return dav_error_response(r, lookup.rnew->status,
                                  "Destination URI had an error.");
    }

    /* resolve binding resource */
    err = dav_get_resource(lookup.rnew, 0 /* label_allowed */,
                           0 /* use_checked_in */, &binding);
    if (err != NULL)
        return dav_handle_err(r, err, NULL);

    /* are the two resources handled by the same repository? */
    if (resource->hooks != binding->hooks) {
        /* ### this message exposes some backend config, but screw it... */
        return dav_error_response(r, HTTP_BAD_GATEWAY,
                                  "Destination URI is handled by a "
                                  "different repository than the source URI. "
                                  "BIND between repositories is not possible.");
    }

    /* get and parse the overwrite header value */
    if ((overwrite = dav_get_overwrite(r)) < 0) {
        /* dav_get_overwrite() supplies additional information for the
         * default message. */
        return HTTP_BAD_REQUEST;
    }

    /* quick failure test: if dest exists and overwrite is false. */
    if (binding->exists && !overwrite) {
        return dav_error_response(r, HTTP_PRECONDITION_FAILED,
                                  "Destination is not empty and "
                                  "Overwrite is not \"T\"");
    }

    /* are the source and destination the same? */
    if ((*resource->hooks->is_same_resource)(resource, binding)) {
        return dav_error_response(r, HTTP_FORBIDDEN,
                                  "Source and Destination URIs are the same.");
    }

    /*
     * Check If-Headers and existing locks for destination. Note that we
     * use depth==infinity since the target (hierarchy) will be deleted
     * before the move/copy is completed.
     *
     * Note that we are overwriting the target, which implies a DELETE, so
     * we are subject to the error/response rules as a DELETE. Namely, we
     * will return a 424 error if any of the validations fail.
     * (see dav_method_delete() for more information)
     */
    if ((err = dav_validate_request(lookup.rnew, binding, DAV_INFINITY, NULL,
                                    &multi_response,
                                    DAV_VALIDATE_PARENT
                                    | DAV_VALIDATE_USE_424, NULL)) != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not BIND %s due to a "
                                          "failed precondition on the "
                                          "destination (e.g. locks).",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, multi_response);
    }

    /* guard against creating circular bindings */
    if (resource->collection
        && (*resource->hooks->is_parent_resource)(resource, binding)) {
        return dav_error_response(r, HTTP_FORBIDDEN,
                                  "Source collection contains the Destination.");
    }
    if (resource->collection
        && (*resource->hooks->is_parent_resource)(binding, resource)) {
        /* The destination must exist (since it contains the source), and
         * a condition above implies Overwrite==T. Obviously, we cannot
         * delete the Destination before the BIND, as that would
         * delete the Source.
         */

        return dav_error_response(r, HTTP_FORBIDDEN,
                                  "Destination collection contains the Source and "
                                  "Overwrite has been specified.");
    }

    /* prepare the destination collection for modification */
    if ((err = dav_auto_checkout(r, binding, 1 /* parent_only */,
                                 &av_info)) != NULL) {
        /* could not make destination writable */
        return dav_handle_err(r, err, NULL);
    }

    /* If target exists, remove it first (we know Ovewrite must be TRUE).
     * Then try to bind to the resource.
     */
    if (binding->exists)
        err = (*resource->hooks->remove_resource)(binding, &multi_response);

    if (err == NULL) {
        err = (*binding_hooks->bind_resource)(resource, binding);
    }

    /* restore parent collection states */
    err2 = dav_auto_checkin(r, NULL,
                            err != NULL /* undo if error */,
                            0 /* unlock */, &av_info);

    /* check for error from remove/bind operations */
    if (err != NULL) {
        err = dav_push_error(r->pool, err->status, 0,
                             apr_psprintf(r->pool,
                                          "Could not BIND %s.",
                                          ap_escape_html(r->pool, r->uri)),
                             err);
        return dav_handle_err(r, err, multi_response);
    }

    /* check for errors from reverting writability */
    if (err2 != NULL) {
        /* just log a warning */
        err = dav_push_error(r->pool, err2->status, 0,
                             "The BIND was successful, but there was a "
                             "problem automatically checking in the "
                             "source parent collection.",
                             err2);
        dav_log_err(r, err, APLOG_WARNING);
    }

    /* return an appropriate response (HTTP_CREATED) */
    /* ### spec doesn't say what happens when destination was replaced */
    return dav_created(r, lookup.rnew->uri, "Binding", 0);
}


/*
 * Response handler for DAV resources
 */
static int dav_handler(request_rec *r)
{
    if (strcmp(r->handler, DAV_HANDLER_NAME) != 0)
        return DECLINED;

    /* Reject requests with an unescaped hash character, as these may
     * be more destructive than the user intended. */
    if (r->parsed_uri.fragment != NULL) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                     "buggy client used un-escaped hash in Request-URI");
        return dav_error_response(r, HTTP_BAD_REQUEST,
                                  "The request was invalid: the URI included "
                                  "an un-escaped hash character");
    }

    /* ### do we need to do anything with r->proxyreq ?? */

    /*
     * ### anything else to do here? could another module and/or
     * ### config option "take over" the handler here? i.e. how do
     * ### we lock down this hierarchy so that we are the ultimate
     * ### arbiter? (or do we simply depend on the administrator
     * ### to avoid conflicting configurations?)
     */

    /*
     * Set up the methods mask, since that's one of the reasons this handler
     * gets called, and lower-level things may need the info.
     *
     * First, set the mask to the methods we handle directly.  Since by
     * definition we own our managed space, we unconditionally set
     * the r->allowed field rather than ORing our values with anything
     * any other module may have put in there.
     *
     * These are the HTTP-defined methods that we handle directly.
     */
    r->allowed = 0
        | (AP_METHOD_BIT << M_GET)
        | (AP_METHOD_BIT << M_PUT)
        | (AP_METHOD_BIT << M_DELETE)
        | (AP_METHOD_BIT << M_OPTIONS)
        | (AP_METHOD_BIT << M_INVALID);

    /*
     * These are the DAV methods we handle.
     */
    r->allowed |= 0
        | (AP_METHOD_BIT << M_COPY)
        | (AP_METHOD_BIT << M_LOCK)
        | (AP_METHOD_BIT << M_UNLOCK)
        | (AP_METHOD_BIT << M_MKCOL)
        | (AP_METHOD_BIT << M_MOVE)
        | (AP_METHOD_BIT << M_PROPFIND)
        | (AP_METHOD_BIT << M_PROPPATCH);

    /*
     * These are methods that we don't handle directly, but let the
     * server's default handler do for us as our agent.
     */
    r->allowed |= 0
        | (AP_METHOD_BIT << M_POST);

    /* ### hrm. if we return HTTP_METHOD_NOT_ALLOWED, then an Allow header
     * ### is sent; it will need the other allowed states; since the default
     * ### handler is not called on error, then it doesn't add the other
     * ### allowed states, so we must
     */

    /* ### we might need to refine this for just where we return the error.
     * ### also, there is the issue with other methods (see ISSUES)
     */

    /* dispatch the appropriate method handler */
    if (r->method_number == M_GET) {
        return dav_method_get(r);
    }

    if (r->method_number == M_PUT) {
        return dav_method_put(r);
    }

    if (r->method_number == M_POST) {
        return dav_method_post(r);
    }

    if (r->method_number == M_DELETE) {
        return dav_method_delete(r);
    }

    if (r->method_number == M_OPTIONS) {
        return dav_method_options(r);
    }

    if (r->method_number == M_PROPFIND) {
        return dav_method_propfind(r);
    }

    if (r->method_number == M_PROPPATCH) {
        return dav_method_proppatch(r);
    }

    if (r->method_number == M_MKCOL) {
        return dav_method_mkcol(r);
    }

    if (r->method_number == M_COPY) {
        return dav_method_copymove(r, DAV_DO_COPY);
    }

    if (r->method_number == M_MOVE) {
        return dav_method_copymove(r, DAV_DO_MOVE);
    }

    if (r->method_number == M_LOCK) {
        return dav_method_lock(r);
    }

    if (r->method_number == M_UNLOCK) {
        return dav_method_unlock(r);
    }

    if (r->method_number == M_VERSION_CONTROL) {
        return dav_method_vsn_control(r);
    }

    if (r->method_number == M_CHECKOUT) {
        return dav_method_checkout(r);
    }

    if (r->method_number == M_UNCHECKOUT) {
        return dav_method_uncheckout(r);
    }

    if (r->method_number == M_CHECKIN) {
        return dav_method_checkin(r);
    }

    if (r->method_number == M_UPDATE) {
        return dav_method_update(r);
    }

    if (r->method_number == M_LABEL) {
        return dav_method_label(r);
    }

    if (r->method_number == M_REPORT) {
        return dav_method_report(r);
    }

    if (r->method_number == M_MKWORKSPACE) {
        return dav_method_make_workspace(r);
    }

    if (r->method_number == M_MKACTIVITY) {
        return dav_method_make_activity(r);
    }

    if (r->method_number == M_BASELINE_CONTROL) {
        return dav_method_baseline_control(r);
    }

    if (r->method_number == M_MERGE) {
        return dav_method_merge(r);
    }

    /* BIND method */
    if (r->method_number == dav_methods[DAV_M_BIND]) {
        return dav_method_bind(r);
    }

    /* DASL method */
    if (r->method_number == dav_methods[DAV_M_SEARCH]) {
        return dav_method_search(r);
    }

    /* ### add'l methods for Advanced Collections, ACLs */

    return DECLINED;
}

static int dav_fixups(request_rec *r)
{
    dav_dir_conf *conf;

    /* quickly ignore any HTTP/0.9 requests which aren't subreqs. */
    if (r->assbackwards && !r->main) {
        return DECLINED;
    }

    conf = (dav_dir_conf *)ap_get_module_config(r->per_dir_config,
                                                &dav_module);

    /* if DAV is not enabled, then we've got nothing to do */
    if (conf->provider == NULL) {
        return DECLINED;
    }

    /* We are going to handle almost every request. In certain cases,
       the provider maps to the filesystem (thus, handle_get is
       FALSE), and core Apache will handle it. a For that case, we
       just return right away.  */
    if (r->method_number == M_GET) {
        /*
         * ### need some work to pull Content-Type and Content-Language
         * ### from the property database.
         */

        /*
         * If the repository hasn't indicated that it will handle the
         * GET method, then just punt.
         *
         * ### this isn't quite right... taking over the response can break
         * ### things like mod_negotiation. need to look into this some more.
         */
        if (!conf->provider->repos->handle_get) {
            return DECLINED;
        }
    }

    /* ### this is wrong.  We should only be setting the r->handler for the
     * requests that mod_dav knows about.  If we set the handler for M_POST
     * requests, then CGI scripts that use POST will return the source for the
     * script.  However, mod_dav DOES handle POST, so something else needs
     * to be fixed.
     */
    if (r->method_number != M_POST) {

        /* We are going to be handling the response for this resource. */
        r->handler = DAV_HANDLER_NAME;
        return OK;
    }

    return DECLINED;
}

static void register_hooks(apr_pool_t *p)
{
    ap_hook_handler(dav_handler, NULL, NULL, APR_HOOK_MIDDLE);
    ap_hook_post_config(dav_init_handler, NULL, NULL, APR_HOOK_MIDDLE);
    ap_hook_fixups(dav_fixups, NULL, NULL, APR_HOOK_MIDDLE);

    dav_hook_find_liveprop(dav_core_find_liveprop, NULL, NULL, APR_HOOK_LAST);
    dav_hook_insert_all_liveprops(dav_core_insert_all_liveprops,
                                  NULL, NULL, APR_HOOK_MIDDLE);

    dav_core_register_uris(p);
}

/*---------------------------------------------------------------------------
 *
 * Configuration info for the module
 */

static const command_rec dav_cmds[] =
{
    /* per directory/location */
    AP_INIT_TAKE1("DAV", dav_cmd_dav, NULL, ACCESS_CONF,
                  "specify the DAV provider for a directory or location"),

    /* per directory/location, or per server */
    AP_INIT_TAKE1("DAVMinTimeout", dav_cmd_davmintimeout, NULL,
                  ACCESS_CONF|RSRC_CONF,
                  "specify minimum allowed timeout"),

    /* per directory/location, or per server */
    AP_INIT_FLAG("DAVDepthInfinity", dav_cmd_davdepthinfinity, NULL,
                 ACCESS_CONF|RSRC_CONF,
                 "allow Depth infinity PROPFIND requests"),

    { NULL }
};

module DAV_DECLARE_DATA dav_module =
{
    STANDARD20_MODULE_STUFF,
    dav_create_dir_config,      /* dir config creater */
    dav_merge_dir_config,       /* dir merger --- default is to override */
    dav_create_server_config,   /* server config */
    dav_merge_server_config,    /* merge server config */
    dav_cmds,                   /* command table */
    register_hooks,             /* register hooks */
};

APR_HOOK_STRUCT(
    APR_HOOK_LINK(gather_propsets)
    APR_HOOK_LINK(find_liveprop)
    APR_HOOK_LINK(insert_all_liveprops)
    )

APR_IMPLEMENT_EXTERNAL_HOOK_VOID(dav, DAV, gather_propsets,
                                 (apr_array_header_t *uris),
                                 (uris))

APR_IMPLEMENT_EXTERNAL_HOOK_RUN_FIRST(dav, DAV, int, find_liveprop,
                                      (const dav_resource *resource,
                                       const char *ns_uri, const char *name,
                                       const dav_hooks_liveprop **hooks),
                                      (resource, ns_uri, name, hooks), 0)

APR_IMPLEMENT_EXTERNAL_HOOK_VOID(dav, DAV, insert_all_liveprops,
                                 (request_rec *r, const dav_resource *resource,
                                  dav_prop_insert what, apr_text_header *phdr),
                                 (r, resource, what, phdr))