mdns_dns_sd.c

/*
 * Embedded dns-sd client. This file is part of Shairport.
 * Copyright (c) Paul Lietar 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 <dns_sd.h>
#include <string.h>
#include <stdlib.h>
#include "mdns.h"
#include "common.h"

static DNSServiceRef service;

static int mdns_dns_sd_register(char *apname, int port) {
    const char *recordwithoutmetadata[] = { MDNS_RECORD_WITHOUT_METADATA, NULL };
    const char **record = recordwithoutmetadata;
    	
    uint16_t length = 0;
    const char **field;

    // Concatenate string contained i record into buf.

    for (field = record; *field; field ++)
    {
        length += strlen(*field) + 1; // One byte for length each time
    } 

    char *buf = malloc(length * sizeof(char));
    if (buf == NULL)
    {
        warn("dns_sd: buffer record allocation failed");
        return -1;
    }

    char *p = buf;

    for (field = record; *field; field ++)
    {
        char * newp = stpcpy(p + 1, *field);
        *p = newp - p - 1;
        p = newp;
    }

    DNSServiceErrorType error;
    error = DNSServiceRegister(&service,
                               0,
                               kDNSServiceInterfaceIndexAny,
                               apname,
                               "_raop._tcp",
                               "",
                               NULL,
                               htons((uint16_t)port),
                               length,
                               buf,
                               NULL,
                               NULL);

    free(buf);

    if (error == kDNSServiceErr_NoError)
        return 0;
    else
    {
        warn("dns-sd: DNSServiceRegister error %d", error);
        return -1;
    }
}

static void mdns_dns_sd_unregister(void) {
    if (service)
    {
        DNSServiceRefDeallocate(service);
        service = NULL;
    }
}

mdns_backend mdns_dns_sd = {
    .name = "dns-sd",
    .mdns_register = mdns_dns_sd_register,
    .mdns_unregister = mdns_dns_sd_unregister
};