mdns_dns_sd.c

   1 /*
   2  * Embedded dns-sd client. This file is part of Shairport.
   3  * Copyright (c) Paul Lietar 2013
   4  * All rights reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person
   7  * obtaining a copy of this software and associated documentation
   8  * files (the "Software"), to deal in the Software without
   9  * restriction, including without limitation the rights to use,
  10  * copy, modify, merge, publish, distribute, sublicense, and/or
  11  * sell copies of the Software, and to permit persons to whom the
  12  * Software is furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be
  15  * included in all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  19  * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  20  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  21  * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  22  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  * OTHER DEALINGS IN THE SOFTWARE.
  25  */
  26
  27 #include "common.h"
  28 #include "mdns.h"
  29 #include <arpa/inet.h>
  30 #include <dns_sd.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33
  34 static DNSServiceRef service;
  35
  36 static int mdns_dns_sd_register(char *ap1name, __attribute__((unused)) char *ap2name, int port,
  37                                 __attribute__((unused)) char **txt_records,
  38                                 __attribute__((unused)) char **secondary_txt_records) {
  39   char *recordwithoutmetadata[] = {MDNS_RECORD_WITHOUT_METADATA, NULL};
  40 #ifdef CONFIG_METADATA
  41   char *recordwithmetadata[] = {MDNS_RECORD_WITH_METADATA, NULL};
  42 #endif
  43   char **record;
  44 #ifdef CONFIG_METADATA
  45   if (config.metadata_enabled)
  46     record = recordwithmetadata;
  47   else
  48 #endif
  49     record = recordwithoutmetadata;
  50
  51   uint16_t length = 0;
  52   char **field;
  53
  54   // Concatenate string contained i record into buf.
  55
  56   for (field = record; *field; field++) {
  57     length += strlen(*field) + 1; // One byte for length each time
  58   }
  59
  60   char *buf = malloc(length * sizeof(char));
  61   if (buf == NULL) {
  62     warn("dns_sd: buffer record allocation failed");
  63     return -1;
  64   }
  65
  66   char *p = buf;
  67
  68   for (field = record; *field; field++) {
  69     char *newp = stpcpy(p + 1, *field);
  70     *p = newp - p - 1;
  71     p = newp;
  72   }
  73
  74   DNSServiceErrorType error;
  75   error = DNSServiceRegister(&service, 0, kDNSServiceInterfaceIndexAny, ap1name, config.regtype, "",
  76                              NULL, htons((uint16_t)port), length, buf, NULL, NULL);
  77
  78   free(buf);
  79
  80   if (error == kDNSServiceErr_NoError)
  81     return 0;
  82   else {
  83     warn("dns-sd: DNSServiceRegister error %d", error);
  84     return -1;
  85   }
  86 }
  87
  88 static void mdns_dns_sd_unregister(void) {
  89   if (service) {
  90     DNSServiceRefDeallocate(service);
  91     service = NULL;
  92   }
  93 }
  94
  95 mdns_backend mdns_dns_sd = {.name = "dns-sd",
  96                             .mdns_register = mdns_dns_sd_register,
  97                             .mdns_unregister = mdns_dns_sd_unregister,
  98                             .mdns_dacp_monitor_start = NULL,
  99                             .mdns_dacp_monitor_set_id = NULL,
 100                             .mdns_dacp_monitor_stop = NULL};