mdns.c

   1 /*
   2  * mDNS registration handler. This file is part of Shairport.
   3  * Copyright (c) James Laird 2013
   4  * Modifications, updates and additions (c) Mike Brady 2014 -- 2020
   5  * All rights reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person
   8  * obtaining a copy of this software and associated documentation
   9  * files (the "Software"), to deal in the Software without
  10  * restriction, including without limitation the rights to use,
  11  * copy, modify, merge, publish, distribute, sublicense, and/or
  12  * sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be
  16  * included in all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  19  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  20  * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  21  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  22  * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  23  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  24  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  25  * OTHER DEALINGS IN THE SOFTWARE.
  26  */
  27
  28 #include "mdns.h"
  29 #include "common.h"
  30 #include "config.h"
  31 #include <memory.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35
  36 #ifdef CONFIG_AVAHI
  37 extern mdns_backend mdns_avahi;
  38 #endif
  39 #ifdef CONFIG_DNS_SD
  40 extern mdns_backend mdns_dns_sd;
  41 #endif
  42 #ifdef CONFIG_TINYSVCMDNS
  43 extern mdns_backend mdns_tinysvcmdns;
  44 #endif
  45
  46 #ifdef CONFIG_EXTERNAL_MDNS
  47 extern mdns_backend mdns_external_avahi;
  48 extern mdns_backend mdns_external_dns_sd;
  49 #endif
  50
  51 static mdns_backend *mdns_backends[] = {
  52 #ifdef CONFIG_AVAHI
  53     &mdns_avahi,
  54 #endif
  55 #ifdef CONFIG_DNS_SD
  56     &mdns_dns_sd,
  57 #endif
  58 #ifdef CONFIG_TINYSVCMDNS
  59     &mdns_tinysvcmdns,
  60 #endif
  61 #ifdef CONFIG_EXTERNAL_MDNS
  62     &mdns_external_avahi,
  63     &mdns_external_dns_sd,
  64 #endif
  65     NULL};
  66
  67 void mdns_register(char **txt_records, char **secondary_txt_records) {
  68   char *ap1_service_name = alloca(strlen(config.service_name) + 14);
  69   char *p = ap1_service_name;
  70   int i;
  71   for (i = 0; i < 6; i++) {
  72     snprintf(p, 3, "%02X", config.ap1_prefix[i]);
  73     p += 2;
  74   }
  75   *p++ = '@';
  76   strcpy(p, config.service_name);
  77
  78   mdns_backend **b = NULL;
  79
  80   if (config.mdns_name != NULL) {
  81     for (b = mdns_backends; *b; b++) {
  82       if (strcmp((*b)->name, config.mdns_name) != 0) // Not the one we are looking for
  83         continue;
  84       int error = (*b)->mdns_register(ap1_service_name, config.service_name, config.port,
  85                                       txt_records, secondary_txt_records);
  86       if (error >= 0) {
  87         config.mdns = *b;
  88       }
  89       break;
  90     }
  91
  92     if (*b == NULL)
  93       warn("%s mDNS backend not found");
  94   } else {
  95     // default -- pick the first back end
  96     for (b = mdns_backends; *b; b++) {
  97       int error = (*b)->mdns_register(ap1_service_name, config.service_name, config.port,
  98                                       txt_records, secondary_txt_records);
  99       if (error >= 0) {
 100         config.mdns = *b;
 101         break;
 102       }
 103     }
 104   }
 105
 106   if (config.mdns == NULL)
 107     die("Could not establish mDNS advertisement!");
 108
 109   mdns_dacp_monitor_start(); // create a dacp monitor thread
 110 }
 111
 112 void mdns_update(char **txt_records, char **secondary_txt_records) {
 113   if ((config.mdns) && (config.mdns->mdns_update)) {
 114     config.mdns->mdns_update(txt_records, secondary_txt_records);
 115   } else
 116     debug(1, "Can't mdns_update -- no mdns_update registered.");
 117 }
 118
 119 void mdns_unregister(void) {
 120   mdns_dacp_monitor_stop();
 121   if (config.mdns) {
 122     config.mdns->mdns_unregister();
 123   }
 124 }
 125
 126 void mdns_dacp_monitor_start(void) {
 127   if ((config.mdns) && (config.mdns->mdns_dacp_monitor_start)) {
 128     config.mdns->mdns_dacp_monitor_start();
 129   } else
 130     debug(3, "Can't start a DACP monitor -- no mdns_dacp_monitor start registered.");
 131 }
 132
 133 void mdns_dacp_monitor_stop() {
 134   if ((config.mdns) && (config.mdns->mdns_dacp_monitor_stop)) {
 135     config.mdns->mdns_dacp_monitor_stop();
 136   } else
 137     debug(3, "Can't stop a DACP monitor -- no mdns_dacp_monitor_stop registered.");
 138 }
 139
 140 void mdns_dacp_monitor_set_id(const char *dacp_id) {
 141   if ((config.mdns) && (config.mdns->mdns_dacp_monitor_set_id)) {
 142     config.mdns->mdns_dacp_monitor_set_id(dacp_id);
 143   } else
 144     debug(3, "Can't set dacp_id -- no mdns_dacp_set_id registered.");
 145 }
 146
 147 void mdns_ls_backends(void) {
 148   mdns_backend **b = NULL;
 149   printf("Available mDNS backends: \n");
 150   for (b = mdns_backends; *b; b++) {
 151     printf("    %s\n", (*b)->name);
 152   }
 153 }