/* * Copyright (c) 1988, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * Portions Copyright (c) 1993 by Digital Equipment Corporation. * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies, and that * the name of Digital Equipment Corporation not be used in advertising or * publicity pertaining to distribution of the document or software without * specific, written prior permission. * * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS * SOFTWARE. */ /* * Portions Copyright (c) 1996-1999 by Internet Software Consortium. * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS * SOFTWARE. */ #if defined(LIBC_SCCS) && !defined(lint) static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; static const char rcsid[] = "$Id: res_query.c,v 1.1 2006/03/01 19:01:38 majka Exp $"; #endif /* LIBC_SCCS and not lint */ #ifndef __APPLE__ #include "port_before.h" #endif #include #include #include #include #include #include #include #include #include #include #include #include #include "res_private.h" #include #include #include #include #include #include #include #ifndef __APPLE__ #include "port_after.h" #endif /* interrupt mechanism is implemented in res_send.c */ __private_extern__ int interrupt_pipe_enabled; __private_extern__ pthread_key_t interrupt_pipe_key; /* Options. Leave them on. */ #define DEBUG #if PACKETSZ > 1024 #define MAXPACKET PACKETSZ #else #define MAXPACKET 1024 #endif #define BILLION 1000000000 /* length of a reverse DNS IPv6 address query name, e.g. "9.4.a.f.c.e.e.f.e.e.1.5.4.1.4.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.e.f.ip6.arpa" */ #define IPv6_REVERSE_LEN 72 /* index of the trailing char that must be "8", "9", "A", "a", "b", or "B" */ #define IPv6_REVERSE_LINK_LOCAL_TRAILING_CHAR 58 /* index of low-order nibble of embedded scope id */ #define IPv6_REVERSE_LINK_LOCAL_SCOPE_ID_LOW 48 const static uint8_t hexval[128] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 0 - 15 */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 16 - 31 */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 32 - 47 */ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, /* 48 - 63 */ 0, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 64 - 79 */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 80 - 95 */ 0, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 96 - 111 */ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 /* 112 - 127 */ }; struct res_query_context { u_char *answer; size_t anslen; size_t ansmaxlen; uint16_t lastanstype; uint32_t ifnum; uint32_t res_flags; DNSServiceFlags flags; DNSServiceErrorType error; }; static void res_query_callback(DNSServiceRef sdRef, DNSServiceFlags flags, uint32_t ifIndex, DNSServiceErrorType errorCode, const char *fullname, uint16_t rrtype, uint16_t rrclass, uint16_t rdlen, const void *rdata, uint32_t ttl, void *ctx) { struct res_query_context *context; int n; size_t buflen; u_char *dnlist[2], *cp; HEADER *ans; struct in6_addr a6; context = (struct res_query_context *)ctx; context->flags = flags; context->error = errorCode; if (errorCode != kDNSServiceErr_NoError) { if (context->res_flags & RES_DEBUG) printf(";; res_query_mDNSResponder callback [%s %hu %hu]: error %u\n", fullname, rrtype, rrclass, errorCode); return; } buflen = context->ansmaxlen - context->anslen; if (buflen < NS_HFIXEDSZ) { if (context->res_flags & RES_DEBUG) printf(";; res_query_mDNSResponder callback [%s %hu %hu]: malformed reply\n", fullname, rrtype, rrclass); return; } dnlist[0] = context->answer + NS_HFIXEDSZ; dnlist[1] = NULL; cp = context->answer + context->anslen; n = dn_comp((char *)fullname, cp, buflen, dnlist, &dnlist[1]); if (n < 0) { if (context->res_flags & RES_DEBUG) printf(";; res_query_mDNSResponder callback [%s %hu %hu]: name mismatch\n", fullname, rrtype, rrclass); return; } /* * Check that there is enough space in the buffer for the resource name (n), * the resource record data (rdlen) and the resource record header (10). */ if (buflen < n + rdlen + 10) { if (context->res_flags & RES_DEBUG) printf(";; res_query_mDNSResponder callback [%s %hu %hu]: insufficient buffer space for reply\n", fullname, rrtype, rrclass); return; } if (context->res_flags & RES_DEBUG) printf(";; res_query_mDNSResponder callback for %s %hu %hu\n", fullname, rrtype, rrclass); cp += n; buflen -= n; putshort(rrtype, cp); cp += sizeof(uint16_t); putshort(rrclass, cp); cp += sizeof(uint16_t); putlong(ttl, cp); cp += sizeof(uint32_t); putshort(rdlen, cp); cp += sizeof(uint16_t); memcpy(cp, rdata, rdlen); cp += rdlen; ans = (HEADER *)context->answer; ans->ancount = htons(ntohs(ans->ancount) + 1); context->anslen = (size_t)(cp - context->answer); context->lastanstype = rrtype; /* * Save the interface number for the first AAAA record for link-local addresses. * It's used by getaddrinfo to set the scope id. */ if ((context->ifnum == 0) && (rrtype == ns_t_aaaa)) { memset(&a6, 0, sizeof(struct in6_addr)); memcpy(&a6, rdata, sizeof(struct in6_addr)); if (IN6_IS_ADDR_LINKLOCAL(&a6)) context->ifnum = ifIndex; } } static void h_errno_for_dnssd_err(DNSServiceErrorType dnssd_err, int *h_errno_err) { switch (dnssd_err) { case kDNSServiceErr_NoError: *h_errno_err = NETDB_SUCCESS; break; case kDNSServiceErr_Unknown: *h_errno_err = NO_RECOVERY; break; case kDNSServiceErr_NoSuchRecord: *h_errno_err = NO_DATA; break; case kDNSServiceErr_NoSuchName: *h_errno_err = HOST_NOT_FOUND; break; case kDNSServiceErr_NoMemory: default: *h_errno_err = NETDB_INTERNAL; break; } } static int _is_rev_link_local(const char *name) { int len, i; if (name == NULL) return 0; len = strlen(name); if (len == 0) return 0; /* check for trailing '.' */ if (name[len - 1] == '.') len--; if (len != IPv6_REVERSE_LEN) return 0; i = IPv6_REVERSE_LINK_LOCAL_TRAILING_CHAR; if ((name[i] != '8') && (name[i] != '9') && (name[i] != 'A') && (name[i] != 'a') && (name[i] != 'B') && (name[i] != 'b')) return 0; i = IPv6_REVERSE_LINK_LOCAL_TRAILING_CHAR + 1; if (strncasecmp(name + i, ".e.f.ip6.arpa", 13)) return 0; for (i = 0; i < IPv6_REVERSE_LINK_LOCAL_TRAILING_CHAR; i += 2) { if (name[i] < '0') return 0; if ((name[i] > '9') && (name[i] < 'A')) return 0; if ((name[i] > 'F') && (name[i] < 'a')) return 0; if (name[i] > 'f') return 0; if (name[i + 1] != '.') return 0; } return 1; } int res_query_mDNSResponder(res_state statp, const char *name, int class, int type, u_char *answer, int anslen, struct sockaddr *from, uint32_t *fromlen) { DNSServiceRef sdRef; DNSServiceErrorType result; struct res_query_context context; int i, kq, n, wait, cancelled, notify_token, status; struct kevent mevent, ievent, event; struct timeval ctv; struct timespec now, finish, timeout; HEADER *ans; uint32_t iface; uint16_t nibble; char *qname, *notify_name; int *interrupt_pipe; uint64_t exit_requested; interrupt_pipe = NULL; result = 0; kq = -1; ans = (HEADER *)answer; cancelled = 0; ans->rcode = 0; memset(&context, 0, sizeof(struct res_query_context)); /* Build a dummy DNS header with question for the answer */ context.res_flags = statp->options; context.answer = answer; context.ansmaxlen = anslen; context.anslen = res_nmkquery(statp, ns_o_query, name, class, type, NULL, 0, NULL, answer, anslen); if (context.anslen <= 0) return 0; /* Mark DNS packet as a response */ ans->qr = 1; ans->qr = htons(ans->qr); /* Pull out Scope ID in link-local reverse queries */ qname = (char *)name; iface = 0; if (_is_rev_link_local(name)) { /* _is_rev_link_local rejects chars > 127 so it's safe to index into hexval */ i = IPv6_REVERSE_LINK_LOCAL_SCOPE_ID_LOW; nibble = hexval[(uint32_t)name[i]]; iface = nibble; i += 2; nibble = hexval[(uint32_t)name[i]]; iface += (nibble << 4); i += 2; nibble = hexval[(uint32_t)name[i]]; iface += (nibble << 8); i += 2; nibble = hexval[(uint32_t)name[i]]; iface += (nibble << 12); if (iface != 0) { qname = strdup(name); if (qname == NULL) { h_errno = NO_RECOVERY; errno = ENOMEM; return -1; } i = IPv6_REVERSE_LINK_LOCAL_SCOPE_ID_LOW; qname[i] = '0'; qname[i + 2] = '0'; qname[i + 4] = '0'; qname[i + 6] = '0'; } } if (statp->options & RES_DEBUG) printf(";; res_query_mDNSResponder\n"); result = DNSServiceQueryRecord(&sdRef, kDNSServiceFlagsReturnIntermediates, iface, qname, type, class, res_query_callback, &context); if (iface != 0) free(qname); if (result != 0) return 0; /* Use a kqueue to wait for a response from mDNSResponder */ kq = kqueue(); /* determine the maximum time to wait for a result */ gettimeofday(&ctv, NULL); /* N.B. statp->retrans is actually the total timeount in seconds */ timeout.tv_sec = statp->retrans; timeout.tv_nsec = 0; finish.tv_sec = ctv.tv_sec + statp->retrans; finish.tv_nsec = ctv.tv_usec * 1000; /* add mdns reply FD to kqueue */ EV_SET(&mevent, DNSServiceRefSockFD(sdRef), EVFILT_READ, EV_ADD, 0, 0, 0); n = kevent(kq, &mevent, 1, NULL, 0, NULL); if (n != 0) return 0; /* add interrupt pipe to kqueue if interrupt is enabled */ if (interrupt_pipe_enabled != 0) { interrupt_pipe = pthread_getspecific(interrupt_pipe_key); if (interrupt_pipe != NULL) { if (interrupt_pipe[0] >= 0) { EV_SET(&ievent, interrupt_pipe[0], EVFILT_READ, EV_ADD, 0, 0, (void *)name); /* allow this to fail silently (should never happen, but it would only break interrupts */ n = kevent(kq, &ievent, 1, NULL, 0, NULL); } } } /* * Get notification token * we use a self-notification token to allow a caller * to signal the thread doing this DNS query to quit. */ notify_name = NULL; notify_token = -1; asprintf(¬ify_name, "self.thread.%lu", (unsigned long)pthread_self()); if (notify_name != NULL) { status = notify_register_plain(notify_name, ¬ify_token); free(notify_name); } wait = 1; while (wait == 1) { memset(&event, 0, sizeof(struct kevent)); n = kevent(kq, NULL, 0, &event, 1, &timeout); if (notify_token != -1) { exit_requested = 0; status = notify_get_state(notify_token, &exit_requested); if (exit_requested == ThreadStateExitRequested) { /* interrupted */ if (statp->options & RES_DEBUG) printf(";; cancelled\n"); cancelled = 1; break; } } if (n < 0) { if (errno == EINTR) goto keep_waiting; h_errno = NO_RECOVERY; wait = 0; } else if ((n == 0) && (ans->ancount == 0)) { h_errno = TRY_AGAIN; wait = 0; } else if (event.udata == (void *)name) { /* interrupted */ if (statp->options & RES_DEBUG) printf(";; cancelled\n"); cancelled = 1; break; } else { result = DNSServiceProcessResult(sdRef); if ((result != 0) || (context.error != 0)) { if (result == 0) result = context.error; h_errno_for_dnssd_err(result, &h_errno); wait = 0; } if ((ans->ancount > 0) && ((context.flags & kDNSServiceFlagsMoreComing) == 0) && ((context.lastanstype != ns_t_cname) || (type == ns_t_cname))) wait = 0; } keep_waiting: if (wait == 1) { /* calculate remaining timeout */ gettimeofday(&ctv, NULL); now.tv_sec = ctv.tv_sec; now.tv_nsec = ctv.tv_usec * 1000; timeout.tv_sec = finish.tv_sec - now.tv_sec; if (finish.tv_nsec >= now.tv_nsec) { timeout.tv_nsec = finish.tv_nsec - now.tv_nsec; } else { timeout.tv_nsec = BILLION - now.tv_nsec + finish.tv_nsec; timeout.tv_sec--; } } } if (notify_token != -1) notify_cancel(notify_token); DNSServiceRefDeallocate(sdRef); close(kq); if ((ans->ancount == 0) || (cancelled == 1)) context.anslen = -1; if ((from != NULL) && (fromlen != NULL) && (context.ifnum != 0)) { ((struct sockaddr_in6 *)from)->sin6_len = sizeof(struct sockaddr_in6); ((struct sockaddr_in6 *)from)->sin6_family = AF_INET6; ((struct sockaddr_in6 *)from)->sin6_addr.__u6_addr.__u6_addr8[15] = 1; ((struct sockaddr_in6 *)from)->sin6_scope_id = context.ifnum; *fromlen = sizeof(struct sockaddr_in6); } return context.anslen; } static int res_soa_minimum(const u_char *msg, int len) { ns_msg handle; const u_char *eom; uint32_t i; int32_t b; int min, soa_min; eom = msg + len; handle._msg = msg; handle._eom = eom; if (msg + NS_INT16SZ > eom) return -1; NS_GET16(handle._id, msg); if (msg + NS_INT16SZ > eom) return -1; NS_GET16(handle._flags, msg); for (i = 0; i < ns_s_max; i++) { if (msg + NS_INT16SZ > eom) return -1; NS_GET16(handle._counts[i], msg); } if (handle._counts[ns_s_ns] == 0) return -1; /* Skip forward to nameserver section */ for (i = 0; i < ns_s_ns; i++) { if (handle._counts[i] == 0) handle._sections[i] = NULL; else { b = ns_skiprr(msg, eom, (ns_sect)i, handle._counts[i]); if (b < 0) return -1; handle._sections[i] = msg; msg += b; } } min = -1; for (i = 0; i < handle._counts[ns_s_ns]; i++) { b = ns_skiprr(msg, eom, ns_s_ns, 1); if (b < 0) return -1; memcpy(&soa_min, msg + b - sizeof(int32_t), sizeof(int32_t)); soa_min = ntohl(soa_min); if ((i == 0) || (soa_min < min)) min = soa_min; msg += b; } return min; } /* * Formulate a normal query, send, and await answer. * Returned answer is placed in supplied buffer "answer". * Perform preliminary check of answer, returning success only * if no error is indicated and the answer count is nonzero. * Return the size of the response on success, -1 on error. * Error number is left in H_ERRNO. * * Caller must parse answer and determine whether it answers the question. */ __private_extern__ int res_nquery_soa_min(res_state statp, const char *name, int class, int type, u_char *answer, int anslen, struct sockaddr *from, int *fromlen, int *min) { u_char buf[MAXPACKET]; HEADER *hp = (HEADER *) answer; int n; u_int oflags; if (min != NULL) *min = -1; oflags = statp->_flags; again: __h_errno_set(statp, 0); hp->rcode = ns_r_noerror; /* default */ #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_query(%s, %d, %d)\n", name, class, type); #endif n = res_nmkquery(statp, ns_o_query, name, class, type, NULL, 0, NULL, buf, sizeof(buf)); #ifdef RES_USE_EDNS0 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0) n = res_nopt(statp, n, buf, sizeof(buf), anslen); #endif if (n <= 0) { #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_query: mkquery failed\n"); #endif __h_errno_set(statp, NO_RECOVERY); return (n); } n = res_nsend_2(statp, buf, n, answer, anslen, from, fromlen); if (n < 0) { #ifdef RES_USE_EDNS0 /* if the query choked with EDNS0, retry without EDNS0 */ if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0 && ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { statp->_flags |= RES_F_EDNS0ERR; if (statp->options & RES_DEBUG) printf(";; res_nquery: retry without EDNS0\n"); goto again; } #endif #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_query: send error\n"); #endif __h_errno_set(statp, TRY_AGAIN); return (n); } if ((hp->rcode == ns_r_nxdomain) || ((hp->rcode == ns_r_noerror) && (ntohs(hp->ancount) == 0))) { if (min != NULL) { *min = res_soa_minimum(answer, anslen); if (statp->options & RES_DEBUG) printf(";; res_nquery: SOA minimum TTL = %d\n", *min); } } if (hp->rcode != ns_r_noerror || ntohs(hp->ancount) == 0) { #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; rcode = %d, ancount=%d\n", hp->rcode, ntohs(hp->ancount)); #endif switch (hp->rcode) { case ns_r_nxdomain: __h_errno_set(statp, HOST_NOT_FOUND); break; case ns_r_servfail: __h_errno_set(statp, TRY_AGAIN); break; case ns_r_noerror: __h_errno_set(statp, NO_DATA); break; case ns_r_formerr: case ns_r_notimpl: case ns_r_refused: default: __h_errno_set(statp, NO_RECOVERY); break; } return (-1); } return (n); } int res_nquery_2(res_state statp, const char *name, int class, int type, u_char *answer, int anslen, struct sockaddr *from, int *fromlen) { int unused = 0; return res_nquery_soa_min(statp, name, class, type, answer, anslen, from, fromlen, &unused); } int res_nquery(res_state statp, const char *name, int class, int type, u_char *answer, int anslen) { struct sockaddr_storage f; int l; l = sizeof(struct sockaddr_storage); return res_nquery_2(statp, name, class, type, answer, anslen, (struct sockaddr *)&f, &l); } /* * Perform a call on res_query on the concatenation of name and domain, * removing a trailing dot from name if domain is NULL. */ int res_nquerydomain_2(res_state statp, const char *name, const char *domain, int class, int type, u_char *answer, int anslen, struct sockaddr *from, int *fromlen) { char nbuf[NS_MAXDNAME]; const char *longname = nbuf; int n, d; #ifdef DEBUG if (statp->options & RES_DEBUG) printf(";; res_nquerydomain(%s, %s, %d, %d)\n", name, domain?domain:"", class, type); #endif if (domain == NULL) { /* * Check for trailing '.'; * copy without '.' if present. */ n = strlen(name); if (n >= NS_MAXDNAME) { __h_errno_set(statp, NO_RECOVERY); return (-1); } n--; if (n >= 0 && name[n] == '.') { strncpy(nbuf, name, n); nbuf[n] = '\0'; } else { longname = name; } } else { n = strlen(name); d = strlen(domain); if (n + d + 1 >= NS_MAXDNAME) { __h_errno_set(statp, NO_RECOVERY); return (-1); } sprintf(nbuf, "%s.%s", name, domain); } return (res_nquery_2(statp, longname, class, type, answer, anslen, from, fromlen)); } int res_nquerydomain(res_state statp, const char *name, const char *domain, int class, int type, u_char *answer, int anslen) { struct sockaddr_storage f; int l; l = sizeof(struct sockaddr_storage); return res_nquerydomain_2(statp, name, domain, class, type, answer, anslen, (struct sockaddr *)&f, &l); } /* * Formulate a normal query, send, and retrieve answer in supplied buffer. * Return the size of the response on success, -1 on error. * If enabled, implement search rules until answer or unrecoverable failure * is detected. Error code, if any, is left in H_ERRNO. */ int res_nsearch_2(res_state statp, const char *name, int class, int type, u_char *answer, int anslen, struct sockaddr *from, int *fromlen) { const char *cp, * const *domain; HEADER *hp = (HEADER *) answer; char tmp[NS_MAXDNAME]; u_int dots; int trailing_dot, ret, saved_herrno; int got_nodata = 0, got_servfail = 0, root_on_list = 0; int tried_as_is = 0; int searched = 0; errno = 0; __h_errno_set(statp, HOST_NOT_FOUND); /* True if we never query. */ dots = 0; for (cp = name; *cp != '\0'; cp++) dots += (*cp == '.'); trailing_dot = 0; if (cp > name && *--cp == '.') trailing_dot++; /* If there aren't any dots, it could be a user-level alias. */ if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) return (res_nquery(statp, cp, class, type, answer, anslen)); /* * If there are enough dots in the name, let's just give it a * try 'as is'. The threshold can be set with the "ndots" option. * Also, query 'as is', if there is a trailing dot in the name. */ saved_herrno = -1; if (dots >= statp->ndots || trailing_dot) { ret = res_nquerydomain_2(statp, name, NULL, class, type, answer, anslen, from, fromlen); if (ret > 0 || trailing_dot) return (ret); saved_herrno = h_errno; tried_as_is++; } /* * We do at least one level of search if * - there is no dot and RES_DEFNAME is set, or * - there is at least one dot, there is no trailing dot, * and RES_DNSRCH is set. */ if ((!dots && (statp->options & RES_DEFNAMES) != 0) || (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) { int done = 0; for (domain = (const char * const *)statp->dnsrch; *domain && !done; domain++) { searched = 1; if (domain[0][0] == '\0' || (domain[0][0] == '.' && domain[0][1] == '\0')) root_on_list++; ret = res_nquerydomain_2(statp, name, *domain, class, type, answer, anslen, from, fromlen); if (ret > 0) return (ret); /* * If no server present, give up. * If name isn't found in this domain, * keep trying higher domains in the search list * (if that's enabled). * On a NO_DATA error, keep trying, otherwise * a wildcard entry of another type could keep us * from finding this entry higher in the domain. * If we get some other error (negative answer or * server failure), then stop searching up, * but try the input name below in case it's * fully-qualified. */ if (errno == ECONNREFUSED) { __h_errno_set(statp, TRY_AGAIN); return (-1); } switch (statp->res_h_errno) { case NO_DATA: got_nodata++; /* FALLTHROUGH */ case HOST_NOT_FOUND: /* keep trying */ break; case TRY_AGAIN: if (hp->rcode == ns_r_refused) { /* try next search element, if any */ got_servfail++; break; } /* FALLTHROUGH */ default: /* anything else implies that we're done */ done++; } /* if we got here for some reason other than DNSRCH, * we only wanted one iteration of the loop, so stop. */ if ((statp->options & RES_DNSRCH) == 0) done++; } } /* * If the query has not already been tried as is then try it * unless RES_NOTLDQUERY is set and there were no dots. */ if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0) && !(tried_as_is || root_on_list)) { ret = res_nquerydomain_2(statp, name, NULL, class, type, answer, anslen, from, fromlen); if (ret > 0) return (ret); } /* if we got here, we didn't satisfy the search. * if we did an initial full query, return that query's H_ERRNO * (note that we wouldn't be here if that query had succeeded). * else if we ever got a nodata, send that back as the reason. * else send back meaningless H_ERRNO, that being the one from * the last DNSRCH we did. */ if (saved_herrno != -1) __h_errno_set(statp, saved_herrno); else if (got_nodata) __h_errno_set(statp, NO_DATA); else if (got_servfail) __h_errno_set(statp, TRY_AGAIN); return (-1); } int __res_nsearch_list_2(res_state statp, const char *name, int class, int type, u_char *answer, int anslen, struct sockaddr *from, int *fromlen, int nsearch, char **search) { const char *cp, *domain; HEADER *hp = (HEADER *) answer; char tmp[NS_MAXDNAME]; u_int dots; int trailing_dot, ret, saved_herrno, i; int got_nodata = 0, got_servfail = 0, root_on_list = 0; int tried_as_is = 0; int searched = 0; errno = 0; __h_errno_set(statp, HOST_NOT_FOUND); /* True if we never query. */ dots = 0; for (cp = name; *cp != '\0'; cp++) dots += (*cp == '.'); trailing_dot = 0; if (cp > name && *--cp == '.') trailing_dot++; /* If there aren't any dots, it could be a user-level alias. */ if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp)) != NULL) return (res_nquery(statp, cp, class, type, answer, anslen)); /* * If there are enough dots in the name, let's just give it a * try 'as is'. The threshold can be set with the "ndots" option. * Also, query 'as is', if there is a trailing dot in the name. */ saved_herrno = -1; if (dots >= statp->ndots || trailing_dot) { ret = res_nquerydomain(statp, name, NULL, class, type, answer, anslen); if (ret > 0 || trailing_dot) return ret; saved_herrno = h_errno; tried_as_is++; } /* * We do at least one level of search if * - there is no dot and RES_DEFNAME is set, or * - there is at least one dot, there is no trailing dot, * and RES_DNSRCH is set. */ if ((!dots && (statp->options & RES_DEFNAMES) != 0) || (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) { int done = 0; for (i = 0; i < nsearch; i++) { domain = search[i]; searched = 1; if (domain[0] == '\0' || (domain[0] == '.' && domain[1] == '\0')) root_on_list++; ret = res_nquerydomain_2(statp, name, domain, class, type, answer, anslen, from, fromlen); if (ret > 0) return ret; /* * If no server present, give up. * If name isn't found in this domain, * keep trying higher domains in the search list * (if that's enabled). * On a NO_DATA error, keep trying, otherwise * a wildcard entry of another type could keep us * from finding this entry higher in the domain. * If we get some other error (negative answer or * server failure), then stop searching up, * but try the input name below in case it's * fully-qualified. */ if (errno == ECONNREFUSED) { __h_errno_set(statp, TRY_AGAIN); return -1; } switch (statp->res_h_errno) { case NO_DATA: got_nodata++; /* FALLTHROUGH */ case HOST_NOT_FOUND: /* keep trying */ break; case TRY_AGAIN: if (hp->rcode == ns_r_refused) { /* try next search element, if any */ got_servfail++; break; } /* FALLTHROUGH */ default: /* anything else implies that we're done */ done++; } /* * if we got here for some reason other than DNSRCH, * we only wanted one iteration of the loop, so stop. */ if ((statp->options & RES_DNSRCH) == 0) done++; } } /* * If the query has not already been tried as is then try it * unless RES_NOTLDQUERY is set and there were no dots. */ if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0) && !(tried_as_is || root_on_list)) { ret = res_nquerydomain_2(statp, name, NULL, class, type, answer, anslen, from, fromlen); if (ret > 0) return ret; } /* * we got here, we didn't satisfy the search. * if we did an initial full query, return that query's H_ERRNO * (note that we wouldn't be here if that query had succeeded). * else if we ever got a nodata, send that back as the reason. * else send back meaningless H_ERRNO, that being the one from * the last DNSRCH we did. */ if (saved_herrno != -1) __h_errno_set(statp, saved_herrno); else if (got_nodata) __h_errno_set(statp, NO_DATA); else if (got_servfail) __h_errno_set(statp, TRY_AGAIN); return -1; } int res_nsearch(res_state statp, const char *name, int class, int type, u_char *answer, int anslen) { struct sockaddr_storage f; int l; l = sizeof(struct sockaddr_storage); return res_nsearch_2(statp, name, class, type, answer, anslen, (struct sockaddr *)&f, &l); } const char * res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { char *file, *cp1, *cp2; char buf[BUFSIZ]; FILE *fp; if (statp->options & RES_NOALIASES) return (NULL); file = getenv("HOSTALIASES"); if (file == NULL || (fp = fopen(file, "r")) == NULL) return (NULL); setbuf(fp, NULL); buf[sizeof(buf) - 1] = '\0'; while (fgets(buf, sizeof(buf), fp)) { for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) ; if (!*cp1) break; *cp1 = '\0'; if (ns_samename(buf, name) == 1) { while (isspace((unsigned char)*++cp1)) ; if (!*cp1) break; for (cp2 = cp1 + 1; *cp2 && !isspace((unsigned char)*cp2); ++cp2) ; *cp2 = '\0'; strncpy(dst, cp1, siz - 1); dst[siz - 1] = '\0'; fclose(fp); return (dst); } } fclose(fp); return (NULL); }