mdns.c

/*
 * mDNS registration handler. This file is part of Shairport.
 * Copyright (c) James Laird 2013
 * All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#include "mdns.h"
#include "common.h"
#include "config.h"
#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifdef CONFIG_AVAHI
extern mdns_backend mdns_avahi;
extern mdns_backend mdns_external_avahi;
#endif
#ifdef CONFIG_HAVE_DNS_SD_H
extern mdns_backend mdns_dns_sd;
extern mdns_backend mdns_external_dns_sd;
#endif
#ifdef CONFIG_TINYSVCMDNS
extern mdns_backend mdns_tinysvcmdns;
#endif

static mdns_backend *mdns_backends[] = {
#ifdef CONFIG_AVAHI
    &mdns_avahi,
    &mdns_external_avahi,
#endif
#ifdef CONFIG_HAVE_DNS_SD_H
    &mdns_dns_sd,
    &mdns_external_dns_sd,
#endif
#ifdef CONFIG_TINYSVCMDNS
    &mdns_tinysvcmdns,
#endif
    NULL};

void mdns_register(void) {
  char *mdns_service_name = alloca(strlen(config.service_name) + 14);
  char *p = mdns_service_name;
  int i;
  for (i = 0; i < 6; i++) {
    snprintf(p, 3, "%02X", config.hw_addr[i]);
    p += 2;
  }
  *p++ = '@';
  strcpy(p, config.service_name);

  mdns_backend **b = NULL;

  if (config.mdns_name != NULL) {
    for (b = mdns_backends; *b; b++) {
      if (strcmp((*b)->name, config.mdns_name) != 0) // Not the one we are looking for
        continue;
      int error = (*b)->mdns_register(mdns_service_name, config.port);
      if (error >= 0) {
        config.mdns = *b;
      }
      break;
    }

    if (*b == NULL)
      warn("%s mDNS backend not found");
  } else {
    for (b = mdns_backends; *b; b++) {
      int error = (*b)->mdns_register(mdns_service_name, config.port);
      if (error >= 0) {
        config.mdns = *b;
        break;
      }
    }
  }

  if (config.mdns == NULL)
    die("Could not establish mDNS advertisement!");
}

void mdns_unregister(void) {
  if (config.mdns) {
    config.mdns->mdns_unregister();
  }
}

void *mdns_dacp_monitor(char *dacp_id) {
  void *reply = NULL;
  if ((dacp_id != NULL) && (*dacp_id != '\0')) {
    if ((config.mdns) && (config.mdns->mdns_dacp_monitor)) {
      reply = config.mdns->mdns_dacp_monitor(dacp_id);
      if (reply == NULL) {
        debug(1, "Error starting a DACP monitor.");
      }
    } else
      debug(3, "Can't start a DACP monitor -- none registered.");
  }
  return reply;
}

void mdns_dacp_dont_monitor(void *userdata) {
  if ((config.mdns) && (config.mdns->mdns_dacp_dont_monitor)) {
    config.mdns->mdns_dacp_dont_monitor(userdata);
  } else
    debug(3, "Can't stop a DACP monitor -- none registered.");
}
void mdns_ls_backends(void) {
  mdns_backend **b = NULL;
  printf("Available mDNS backends: \n");
  for (b = mdns_backends; *b; b++) {
    printf("    %s\n", (*b)->name);
  }
}