Searcher.c   [plain text]


/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2002-2003 Apple Computer, Inc. All rights reserved.
 *
 * Licensed 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.
 */

#include <stdio.h>                      // For printf()
#include <string.h>                     // For strcpy()

#include <Events.h>                     // For WaitNextEvent()
#include <CodeFragments.h>              // For SIOkUnresolvedCFragSymbolAddress

#include <SIOUX.h>                      // For SIOUXHandleOneEvent()

#include <OpenTransport.h>
#include <OpenTptInternet.h>

#include "dns_sd.h"

#define ns_c_in 1
#define ns_t_a 1

typedef union { UInt8 b[2]; UInt16 NotAnInteger; } mDNSOpaque16;
static UInt16 mDNSVal16(mDNSOpaque16 x) { return((UInt16)(x.b[0]<<8 | x.b[1])); }
static mDNSOpaque16 mDNSOpaque16fromIntVal(UInt16 v)
{ mDNSOpaque16 x; x.b[0] = (UInt8)(v >> 8); x.b[1] = (UInt8)(v & 0xFF); return(x); }

typedef struct
{
    OTLIFO serviceinfolist;
    Boolean headerPrinted;
    Boolean lostRecords;
} SearcherServices;

typedef struct
{
    SearcherServices *services;
    char name[kDNSServiceMaxDomainName];
    char type[kDNSServiceMaxDomainName];
    char domn[kDNSServiceMaxDomainName];
    char host[kDNSServiceMaxDomainName];
    char text[kDNSServiceMaxDomainName];
    InetHost address;
    mDNSOpaque16 notAnIntPort;
    DNSServiceRef sdRef;
    Boolean add;
    Boolean dom;
    OTLink link;
} linkedServiceInfo;

static SearcherServices services;

// PrintServiceInfo prints the service information to standard out
// A real application might want to do something else with the information
static void PrintServiceInfo(SearcherServices *services)
{
    OTLink *link = OTReverseList(OTLIFOStealList(&services->serviceinfolist));

    while (link)
    {
        linkedServiceInfo *s = OTGetLinkObject(link, linkedServiceInfo, link);

        if (!services->headerPrinted)
        {
            printf("%-55s Type             Domain         Target Host     IP Address      Port Info\n", "Name");
            services->headerPrinted = true;
        }

        if (s->dom)
        {
            if (s->add) printf("%-55s available for browsing\n", s->domn);
            else printf("%-55s no longer available for browsing\n", s->domn);
        }
        else
        {
            char ip[16];
            unsigned char *p = (unsigned char *)&s->address;
            sprintf(ip, "%d.%d.%d.%d", p[0], p[1], p[2], p[3]);
            printf("%-55s %-16s %-14s ", s->name, s->type, s->domn);
            if (s->add) printf("%-15s %-15s %5d %s\n", s->host, ip, mDNSVal16(s->notAnIntPort), s->text);
            else printf("Removed\n");
        }

        link = link->fNext;
        OTFreeMem(s);
    }
}

static void FoundInstanceAddress(DNSServiceRef sdRef, DNSServiceFlags flags, uint32_t interfaceIndex, DNSServiceErrorType errorCode,
                                 const char *fullname, uint16_t rrtype, uint16_t rrclass, uint16_t rdlen, const void *rdata, uint32_t ttl, void *context)
{
    linkedServiceInfo *info = (linkedServiceInfo *)context;
    SearcherServices *services = info->services;
    (void)sdRef;            // Unused
    (void)interfaceIndex;   // Unused
    (void)fullname;         // Unused
    (void)ttl;              // Unused
    if (errorCode == kDNSServiceErr_NoError)
        if (flags & kDNSServiceFlagsAdd)
            if (rrclass == ns_c_in && rrtype == ns_t_a && rdlen == sizeof(info->address))
            {
                memcpy(&info->address, rdata, sizeof(info->address));
                DNSServiceRefDeallocate(info->sdRef);
                OTLIFOEnqueue(&services->serviceinfolist, &info->link);
            }
}

static void FoundInstanceInfo(DNSServiceRef sdRef, DNSServiceFlags flags, uint32_t interfaceIndex,
                              DNSServiceErrorType errorCode, const char *fullname, const char *hosttarget, uint16_t notAnIntPort,
                              uint16_t txtLen, const unsigned char *txtRecord, void *context)
{
    linkedServiceInfo *info = (linkedServiceInfo *)context;
    SearcherServices *services = info->services;
    (void)sdRef;            // Unused
    (void)flags;            // Unused
    (void)interfaceIndex;   // Unused
    (void)errorCode;        // Unused
    (void)fullname;         // Unused
    strcpy(info->host, hosttarget);
    if (txtLen == 0) info->text[0] = 0;
    else
    {
        strncpy(info->text, (char *)txtRecord+1, txtRecord[0]);
        info->text[txtRecord[0]] = 0;
    }
    info->notAnIntPort.NotAnInteger = notAnIntPort;
    DNSServiceRefDeallocate(info->sdRef);
    DNSServiceQueryRecord(&info->sdRef, 0, 0, info->host, ns_t_a, ns_c_in, FoundInstanceAddress, info);
}

// When a new named instance of a service is found, FoundInstance() is called.
// In this sample code we turn around and immediately to a DNSServiceResolve() to resolve that service name
// to find its target host, port, and txtinfo, but a normal browing application would just display the name.
// Resolving every single thing you find can be quite hard on the network, so you shouldn't do this
// in a real application. Defer resolving until the client has picked which instance from the
// long list of services is the one they want to use, and then resolve only that one.
static void FoundInstance(DNSServiceRef client, DNSServiceFlags flags, uint32_t interface, DNSServiceErrorType errorCode,
                          const char *replyName, const char *replyType, const char *replyDomain, void *context)
{
#pragma unused(client, interface, errorCode)
    SearcherServices *services = (SearcherServices *)context;
    linkedServiceInfo *info;

    if (!services) { DebugStr("\pFoundInstance: services is NULL"); return; }

    info = (linkedServiceInfo *)OTAllocMem(sizeof(linkedServiceInfo));
    if (!info) { services->lostRecords = true; return; }

    info->services = services;
    strcpy(info->name, replyName);
    strcpy(info->type, replyType);
    strcpy(info->domn, replyDomain);
    info->text[0] = 0;
    info->add = (flags & kDNSServiceFlagsAdd) ? true : false;
    info->dom = false;

    if (!info->add) // If TTL == 0 we're deleting a service,
        OTLIFOEnqueue(&services->serviceinfolist, &info->link);
    else                                // else we're adding a new service
        DNSServiceResolve(&info->sdRef, 0, 0, info->name, info->type, info->domn, FoundInstanceInfo, info);
}

// YieldSomeTime() just cooperatively yields some time to other processes running on classic Mac OS
static Boolean YieldSomeTime(UInt32 milliseconds)
{
    extern Boolean SIOUXQuitting;
    EventRecord e;
    WaitNextEvent(everyEvent, &e, milliseconds / 17, NULL);
    SIOUXHandleOneEvent(&e);
    return(SIOUXQuitting);
}

int main()
{
    OSStatus err;
    void *tempmem;
    DNSServiceRef sdRef;
    DNSServiceErrorType dse;

    SIOUXSettings.asktosaveonclose = false;
    SIOUXSettings.userwindowtitle  = "\pMulticast DNS Searcher";
    SIOUXSettings.rows             = 40;
    SIOUXSettings.columns          = 160;

    printf("DNS-SD Search Client\n\n");
    printf("This software reports errors using MacsBug breaks,\n");
    printf("so if you don't have MacsBug installed your Mac may crash.\n\n");
    printf("******************************************************************************\n\n");

    if (DNSServiceBrowse == (void*)kUnresolvedCFragSymbolAddress)
    {
        printf("Before you can use mDNS/DNS-SD clients, you need to place the \n");
        printf("\"Multicast DNS & DNS-SD\" Extension in the Extensions Folder and restart\n");
        return(-1);
    }

    err = InitOpenTransport();
    if (err) { printf("InitOpenTransport failed %d", err); return(err); }

    // Make sure OT has a large enough memory pool for us to draw from at OTNotifier (interrupt) time
    tempmem = OTAllocMem(0x10000);
    if (tempmem) OTFreeMem(tempmem);
    else printf("**** Warning: OTAllocMem couldn't pre-allocate 64K for us.\n");

    services.serviceinfolist.fHead = NULL;
    services.headerPrinted         = false;
    services.lostRecords           = false;

    printf("Sending mDNS service lookup queries and waiting for responses...\n\n");
    dse = DNSServiceBrowse(&sdRef, 0, 0, "_http._tcp", "", FoundInstance, &services);
    if (dse == kDNSServiceErr_NoError)
    {
        while (!YieldSomeTime(35))
        {
            if (services.serviceinfolist.fHead)
                PrintServiceInfo(&services);

            if (services.lostRecords)
            {
                services.lostRecords = false;
                printf("**** Warning: Out of memory: Records have been missed.\n");
            }
        }
    }

    DNSServiceRefDeallocate(sdRef);
    CloseOpenTransport();
    return(0);
}