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
  25 #include "mDNSEmbeddedAPI.h" // Defines the interface to the mDNS core code
  26 #include "mDNSPosix.h"    // Defines the specific types needed to run mDNS on this platform
  27 #include "ExampleClientApp.h"
  28
  29 // Globals
  30 static mDNS mDNSStorage;       // mDNS core uses this to store its globals
  31 static mDNS_PlatformSupport PlatformStorage;  // Stores this platform's globals
  32 #define RR_CACHE_SIZE 500
  33 static CacheEntity gRRCache[RR_CACHE_SIZE];
  34
  35 mDNSexport const char ProgramName[] = "mDNSClientPosix";
  36
  37 static const char *gProgramName = ProgramName;
  38
  39 static void BrowseCallback(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
  40 // A callback from the core mDNS code that indicates that we've received a
  41 // response to our query.  Note that this code runs on the main thread
  42 // (in fact, there is only one thread!), so we can safely printf the results.
  43 {
  44     domainlabel name;
  45     domainname type;
  46     domainname domain;
  47     char nameC  [MAX_DOMAIN_LABEL+1];           // Unescaped name: up to 63 bytes plus C-string terminating NULL.
  48     char typeC  [MAX_ESCAPED_DOMAIN_NAME];
  49     char domainC[MAX_ESCAPED_DOMAIN_NAME];
  50     const char *state;
  51
  52     (void)m;        // Unused
  53     (void)question; // Unused
  54
  55     assert(answer->rrtype == kDNSType_PTR);
  56
  57     DeconstructServiceName(&answer->rdata->u.name, &name, &type, &domain);
  58
  59     ConvertDomainLabelToCString_unescaped(&name, nameC);
  60     ConvertDomainNameToCString(&type, typeC);
  61     ConvertDomainNameToCString(&domain, domainC);
  62
  63     // If the TTL has hit 0, the service is no longer available.
  64     if (!AddRecord) {
  65         state = "Lost ";
  66     } else {
  67         state = "Found";
  68     }
  69     fprintf(stderr, "*** %s name = '%s', type = '%s', domain = '%s'\n", state, nameC, typeC, domainC);
  70 }
  71
  72 static mDNSBool CheckThatServiceTypeIsUsable(const char *serviceType, mDNSBool printExplanation)
  73 // Checks that serviceType is a reasonable service type
  74 // label and, if it isn't and printExplanation is true, prints
  75 // an explanation of why not.
  76 {
  77     mDNSBool result;
  78
  79     result = mDNStrue;
  80     if (result && strlen(serviceType) > 63) {
  81         if (printExplanation) {
  82             fprintf(stderr,
  83                     "%s: Service type specified by -t is too long (must be 63 characters or less)\n",
  84                     gProgramName);
  85         }
  86         result = mDNSfalse;
  87     }
  88     if (result && serviceType[0] == 0) {
  89         if (printExplanation) {
  90             fprintf(stderr,
  91                     "%s: Service type specified by -t can't be empty\n",
  92                     gProgramName);
  93         }
  94         result = mDNSfalse;
  95     }
  96     return result;
  97 }
  98
  99 static const char kDefaultServiceType[] = "_afpovertcp._tcp";
 100 static const char kDefaultDomain[]      = "local.";
 101
 102 static void PrintUsage()
 103 {
 104     fprintf(stderr,
 105             "Usage: %s [-v level] [-t type] [-d domain]\n",
 106             gProgramName);
 107     fprintf(stderr, "          -v verbose mode, level is a number from 0 to 2\n");
 108     fprintf(stderr, "             0 = no debugging info (default)\n");
 109     fprintf(stderr, "             1 = standard debugging info\n");
 110     fprintf(stderr, "             2 = intense debugging info\n");
 111     fprintf(stderr, "          -t uses 'type' as the service type (default is '%s')\n", kDefaultServiceType);
 112     fprintf(stderr, "          -d uses 'domain' as the domain to browse (default is '%s')\n", kDefaultDomain);
 113 }
 114
 115 static const char *gServiceType      = kDefaultServiceType;
 116 static const char *gServiceDomain    = kDefaultDomain;
 117
 118 static void ParseArguments(int argc, char **argv)
 119 // Parses our command line arguments into the global variables
 120 // listed above.
 121 {
 122     int ch;
 123
 124     // Set gProgramName to the last path component of argv[0]
 125
 126     gProgramName = strrchr(argv[0], '/');
 127     if (gProgramName == NULL) {
 128         gProgramName = argv[0];
 129     } else {
 130         gProgramName += 1;
 131     }
 132
 133     // Parse command line options using getopt.
 134
 135     do {
 136         ch = getopt(argc, argv, "v:t:d:");
 137         if (ch != -1) {
 138             switch (ch) {
 139             case 'v':
 140                 gMDNSPlatformPosixVerboseLevel = atoi(optarg);
 141                 if (gMDNSPlatformPosixVerboseLevel < 0 || gMDNSPlatformPosixVerboseLevel > 2) {
 142                     fprintf(stderr,
 143                             "%s: Verbose mode must be in the range 0..2\n",
 144                             gProgramName);
 145                     exit(1);
 146                 }
 147                 break;
 148             case 't':
 149                 gServiceType = optarg;
 150                 if ( !CheckThatServiceTypeIsUsable(gServiceType, mDNStrue) ) {
 151                     exit(1);
 152                 }
 153                 break;
 154             case 'd':
 155                 gServiceDomain = optarg;
 156                 break;
 157             case '?':
 158             default:
 159                 PrintUsage();
 160                 exit(1);
 161                 break;
 162             }
 163         }
 164     } while (ch != -1);
 165
 166     // Check for any left over command line arguments.
 167
 168     if (optind != argc) {
 169         fprintf(stderr, "%s: Unexpected argument '%s'\n", gProgramName, argv[optind]);
 170         exit(1);
 171     }
 172 }
 173
 174 int main(int argc, char **argv)
 175 // The program's main entry point.  The program does a trivial
 176 // mDNS query, looking for all AFP servers in the local domain.
 177 {
 178     int result;
 179     mStatus status;
 180     DNSQuestion question;
 181     domainname type;
 182     domainname domain;
 183
 184     // Parse our command line arguments.  This won't come back if there's an error.
 185     ParseArguments(argc, argv);
 186
 187     // Initialise the mDNS core.
 188     status = mDNS_Init(&mDNSStorage, &PlatformStorage,
 189                        gRRCache, RR_CACHE_SIZE,
 190                        mDNS_Init_DontAdvertiseLocalAddresses,
 191                        mDNS_Init_NoInitCallback, mDNS_Init_NoInitCallbackContext);
 192     if (status == mStatus_NoError) {
 193
 194         // Construct and start the query.
 195
 196         MakeDomainNameFromDNSNameString(&type, gServiceType);
 197         MakeDomainNameFromDNSNameString(&domain, gServiceDomain);
 198
 199         status = mDNS_StartBrowse(&mDNSStorage, &question, &type, &domain, mDNSNULL, mDNSInterface_Any, 0, mDNSfalse, mDNSfalse, BrowseCallback, NULL);
 200
 201         // Run the platform main event loop until the user types ^C.
 202         // The BrowseCallback routine is responsible for printing
 203         // any results that we find.
 204
 205         if (status == mStatus_NoError) {
 206             fprintf(stderr, "Hit ^C when you're bored waiting for responses.\n");
 207             ExampleClientEventLoop(&mDNSStorage);
 208             mDNS_StopQuery(&mDNSStorage, &question);
 209             mDNS_Close(&mDNSStorage);
 210         }
 211     }
 212
 213     if (status == mStatus_NoError) {
 214         result = 0;
 215     } else {
 216         result = 2;
 217     }
 218     if ( (result != 0) || (gMDNSPlatformPosixVerboseLevel > 0) ) {
 219         fprintf(stderr, "%s: Finished with status %d, result %d\n", gProgramName, (int)status, result);
 220     }
 221
 222     return 0;
 223 }