mDNSPosix/Client.c

   1 /* -*- Mode: C; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2002-2004 Apple Computer, Inc. All rights reserved.
   4  *
   5  * Licensed under the Apache License, Version 2.0 (the "License");
   6  * you may not use this file except in compliance with the License.
   7  * You may obtain a copy of the License at
   8  *
   9  *     http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software
  12  * distributed under the License is distributed on an "AS IS" BASIS,
  13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  * See the License for the specific language governing permissions and
  15  * limitations under the License.
  16  */
  17
  18 #include <assert.h>
  19 #include <signal.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <stdlib.h>
  24 #include <sys/socket.h>
  25
  26 #include "mDNSEmbeddedAPI.h" // Defines the interface to the mDNS core code
  27 #include "mDNSPosix.h"    // Defines the specific types needed to run mDNS on this platform
  28 #include "ExampleClientApp.h"
  29
  30 // Globals
  31 mDNSexport mDNS mDNSStorage;       // mDNS core uses this to store its globals
  32 static mDNS_PlatformSupport PlatformStorage;  // Stores this platform's globals
  33 #define RR_CACHE_SIZE 500
  34 static CacheEntity gRRCache[RR_CACHE_SIZE];
  35
  36 mDNSexport const char ProgramName[] = "mDNSClientPosix";
  37
  38 static const char *gProgramName = ProgramName;
  39
  40 static void BrowseCallback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
  41 // A callback from the core mDNS code that indicates that we've received a
  42 // response to our query.  Note that this code runs on the main thread
  43 // (in fact, there is only one thread!), so we can safely printf the results.
  44 {
  45     domainlabel name;
  46     domainname type;
  47     domainname domain;
  48     char nameC  [MAX_DOMAIN_LABEL+1];           // Unescaped name: up to 63 bytes plus C-string terminating NULL.
  49     char typeC  [MAX_ESCAPED_DOMAIN_NAME];
  50     char domainC[MAX_ESCAPED_DOMAIN_NAME];
  51     const char *state;
  52
  53     (void)m;        // Unused
  54     (void)question; // Unused
  55
  56     assert(answer->rrtype == kDNSType_PTR);
  57
  58     DeconstructServiceName(&answer->rdata->u.name, &name, &type, &domain);
  59
  60     ConvertDomainLabelToCString_unescaped(&name, nameC);
  61     ConvertDomainNameToCString(&type, typeC);
  62     ConvertDomainNameToCString(&domain, domainC);
  63
  64     // If the TTL has hit 0, the service is no longer available.
  65     if (!AddRecord) {
  66         state = "Lost ";
  67     } else {
  68         state = "Found";
  69     }
  70     fprintf(stderr, "*** %s name = '%s', type = '%s', domain = '%s'\n", state, nameC, typeC, domainC);
  71 }
  72
  73 static mDNSBool CheckThatServiceTypeIsUsable(const char *serviceType, mDNSBool printExplanation)
  74 // Checks that serviceType is a reasonable service type
  75 // label and, if it isn't and printExplanation is true, prints
  76 // an explanation of why not.
  77 {
  78     mDNSBool result;
  79
  80     result = mDNStrue;
  81     if (result && strlen(serviceType) > 63) {
  82         if (printExplanation) {
  83             fprintf(stderr,
  84                     "%s: Service type specified by -t is too long (must be 63 characters or less)\n",
  85                     gProgramName);
  86         }
  87         result = mDNSfalse;
  88     }
  89     if (result && serviceType[0] == 0) {
  90         if (printExplanation) {
  91             fprintf(stderr,
  92                     "%s: Service type specified by -t can't be empty\n",
  93                     gProgramName);
  94         }
  95         result = mDNSfalse;
  96     }
  97     return result;
  98 }
  99
 100 static const char kDefaultServiceType[] = "_afpovertcp._tcp";
 101 static const char kDefaultDomain[]      = "local.";
 102
 103 static void PrintUsage()
 104 {
 105     fprintf(stderr,
 106             "Usage: %s [-v level] [-t type] [-d domain]\n",
 107             gProgramName);
 108     fprintf(stderr, "          -v verbose mode, level is a number from 0 to 2\n");
 109     fprintf(stderr, "             0 = no debugging info (default)\n");
 110     fprintf(stderr, "             1 = standard debugging info\n");
 111     fprintf(stderr, "             2 = intense debugging info\n");
 112     fprintf(stderr, "          -t uses 'type' as the service type (default is '%s')\n", kDefaultServiceType);
 113     fprintf(stderr, "          -d uses 'domain' as the domain to browse (default is '%s')\n", kDefaultDomain);
 114 }
 115
 116 static const char *gServiceType      = kDefaultServiceType;
 117 static const char *gServiceDomain    = kDefaultDomain;
 118
 119 static void ParseArguments(int argc, char **argv)
 120 // Parses our command line arguments into the global variables
 121 // listed above.
 122 {
 123     int ch;
 124
 125     // Set gProgramName to the last path component of argv[0]
 126
 127     gProgramName = strrchr(argv[0], '/');
 128     if (gProgramName == NULL) {
 129         gProgramName = argv[0];
 130     } else {
 131         gProgramName += 1;
 132     }
 133
 134     // Parse command line options using getopt.
 135
 136     do {
 137         ch = getopt(argc, argv, "v:t:d:");
 138         if (ch != -1) {
 139             switch (ch) {
 140             case 'v':
 141                 gMDNSPlatformPosixVerboseLevel = atoi(optarg);
 142                 if (gMDNSPlatformPosixVerboseLevel < 0 || gMDNSPlatformPosixVerboseLevel > 2) {
 143                     fprintf(stderr,
 144                             "%s: Verbose mode must be in the range 0..2\n",
 145                             gProgramName);
 146                     exit(1);
 147                 }
 148                 break;
 149             case 't':
 150                 gServiceType = optarg;
 151                 if ( !CheckThatServiceTypeIsUsable(gServiceType, mDNStrue) ) {
 152                     exit(1);
 153                 }
 154                 break;
 155             case 'd':
 156                 gServiceDomain = optarg;
 157                 break;
 158             case '?':
 159             default:
 160                 PrintUsage();
 161                 exit(1);
 162                 break;
 163             }
 164         }
 165     } while (ch != -1);
 166
 167     // Check for any left over command line arguments.
 168
 169     if (optind != argc) {
 170         fprintf(stderr, "%s: Unexpected argument '%s'\n", gProgramName, argv[optind]);
 171         exit(1);
 172     }
 173 }
 174
 175 int main(int argc, char **argv)
 176 // The program's main entry point.  The program does a trivial
 177 // mDNS query, looking for all AFP servers in the local domain.
 178 {
 179     int result;
 180     mStatus status;
 181     DNSQuestion question;
 182     domainname type;
 183     domainname domain;
 184
 185     // Parse our command line arguments.  This won't come back if there's an error.
 186     ParseArguments(argc, argv);
 187
 188     // Initialise the mDNS core.
 189     status = mDNS_Init(&mDNSStorage, &PlatformStorage,
 190                        gRRCache, RR_CACHE_SIZE,
 191                        mDNS_Init_DontAdvertiseLocalAddresses,
 192                        mDNS_Init_NoInitCallback, mDNS_Init_NoInitCallbackContext);
 193     if (status == mStatus_NoError) {
 194
 195         // Construct and start the query.
 196
 197         MakeDomainNameFromDNSNameString(&type, gServiceType);
 198         MakeDomainNameFromDNSNameString(&domain, gServiceDomain);
 199
 200         status = mDNS_StartBrowse(&mDNSStorage, &question, &type, &domain, mDNSInterface_Any, 0, mDNSfalse, mDNSfalse, BrowseCallback, NULL);
 201
 202         // Run the platform main event loop until the user types ^C.
 203         // The BrowseCallback routine is responsible for printing
 204         // any results that we find.
 205
 206         if (status == mStatus_NoError) {
 207             fprintf(stderr, "Hit ^C when you're bored waiting for responses.\n");
 208             ExampleClientEventLoop(&mDNSStorage);
 209             mDNS_StopQuery(&mDNSStorage, &question);
 210             mDNS_Close(&mDNSStorage);
 211         }
 212     }
 213
 214     if (status == mStatus_NoError) {
 215         result = 0;
 216     } else {
 217         result = 2;
 218     }
 219     if ( (result != 0) || (gMDNSPlatformPosixVerboseLevel > 0) ) {
 220         fprintf(stderr, "%s: Finished with status %d, result %d\n", gProgramName, (int)status, result);
 221     }
 222
 223     return 0;
 224 }