shairport.c

/*
 * Shairport, an Apple Airplay receiver
 * 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 <sys/types.h>
#include <signal.h>
#include <errno.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <memory.h>
#include <sys/wait.h>
#include <getopt.h>
#include <stdio.h>
#include <stdlib.h>
#include <popt.h>
#include <libgen.h>
#include <libconfig.h>

#include "config.h"

#ifdef HAVE_LIBPOLARSSL
#include <polarssl/md5.h>
#endif

#ifdef HAVE_LIBSSL
#include <openssl/md5.h>
#endif

#include "common.h"
#include "rtsp.h"
#include "rtp.h"
#include "mdns.h"

#include <libdaemon/dfork.h>
#include <libdaemon/dsignal.h>
#include <libdaemon/dlog.h>
#include <libdaemon/dpid.h>
#include <libdaemon/dexec.h>


static int shutting_down = 0;
static char* appName = NULL;

void shairport_shutdown() {
	if (shutting_down)
		return;
	shutting_down = 1;
	mdns_unregister();
	rtsp_shutdown_stream();
	if (config.output)
		config.output->deinit();
}

static void sig_ignore(int foo, siginfo_t *bar, void *baz) {
}
static void sig_shutdown(int foo, siginfo_t *bar, void *baz) {
	debug(1, "shutdown requested...");
	shairport_shutdown();
	daemon_log(LOG_NOTICE, "exit...");
	daemon_retval_send(255);
	daemon_pid_file_remove();
	exit(0);
}

static void sig_child(int foo, siginfo_t *bar, void *baz) {
	pid_t pid;
	while ((pid = waitpid((pid_t)-1, 0, WNOHANG)) > 0) {
		if (pid == mdns_pid && !shutting_down) {
			die("MDNS child process died unexpectedly!");
		}
	}
}

static void sig_disconnect_audio_output(int foo, siginfo_t *bar, void *baz) {
	debug(1,"disconnect audio output requested.");
    set_requested_connection_state_to_output(0);
}

static void sig_connect_audio_output(int foo, siginfo_t *bar, void *baz) {
	debug(1,"connect audio output requested.");
    set_requested_connection_state_to_output(1);
}

void print_version(void) {
  char version_string[200];
	strcpy(version_string,PACKAGE_VERSION);
#ifdef HAVE_LIBPOLARSSL
	strcat(version_string,"-polarssl");
#endif
#ifdef HAVE_LIBSSL
	strcat(version_string,"-openssl");
#endif
#ifdef CONFIG_TINYSVCMDNS
	strcat(version_string,"-tinysvcmdns");
#endif
#ifdef CONFIG_AVAHI
	strcat(version_string,"-Avahi");
#endif
#ifdef CONFIG_DNS_SD
	strcat(version_string,"-dns_sd");
#endif
#ifdef CONFIG_ALSA
	strcat(version_string,"-ALSA");
#endif
#ifdef CONFIG_SNDIO
	strcat(version_string,"-sndio");
#endif
#ifdef CONFIG_AO
	strcat(version_string,"-ao");
#endif
#ifdef CONFIG_PULSE
	strcat(version_string,"-pulse");
#endif
#ifdef HAVE_LIBSOXR
	strcat(version_string,"-soxr");
#endif
#ifdef CONFIG_METADATA
  strcat(version_string,"-metadata");
#endif
#ifdef SUPPORT_CONFIG_FILES
  strcat(version_string,"-configfile");
#endif
  printf("%s\n",version_string);
}

void usage(char *progname) {
    printf("Usage: %s [options...]\n", progname);
    printf("  or:  %s [options...] -- [audio output-specific options]\n", progname);
    printf("\n");
    printf("Options:\n");
    printf("    -h, --help              show this help\n");
    printf("    -d, --daemon            daemonise.\n");
    printf("    -V, --version           show version information\n");
    printf("    -k, --kill              kill the existing shairport daemon.\n");
    printf("    -D, --disconnectFromOutput  disconnect immediately from the output device.\n");
    printf("    -R, --reconnectToOutput  reconnect to the output device.\n");
    printf("    -c, --configfile=FILE   read configuration settings from FILE. Default is /etc/shairport-sync.conf.\n");

#ifdef COMMAND_LINE_ARGUMENT_SUPPORT
    printf("    -v, --verbose           -v print debug information; -vv more; -vvv lots\n");
    printf("    -p, --port=PORT         set RTSP listening port\n");
    printf("    -a, --name=NAME         set advertised name\n");
    printf("    -A, --AirPlayLatency=FRAMES set the latency for audio sent from an AirPlay device.\n");
    printf("                            The default value is %u frames.\n", config.AirPlayLatency);
    printf("    -i, --iTunesLatency=FRAMES set the latency for audio sent from iTunes 10 or later.\n");
    printf("                            The default value is %u frames.\n", config.iTunesLatency);
    printf("    -L, --latency=FRAMES    set the latency for audio sent from an unknown device\n");
    printf("                            or from an old version of iTunes. Default is %d frames.\n",config.latency);
    printf("    --forkedDaapdLatency=FRAMES set the latency for audio sent from forked-daapd.\n");
    printf("    -S, --stuffing=MODE set how to adjust current latency to match desired latency \n");
    printf("                            \"basic\" (default) inserts or deletes audio frames from packet frames with low processor overhead.\n");
    printf("                            \"soxr\" uses libsoxr to minimally resample packet frames -- moderate processor overhead.\n");
    printf("                            \"soxr\" option only available if built with soxr support.\n");
    printf("    -B, --on-start=PROGRAM  run PROGRAM when playback is about to begin.\n");
    printf("    -E, --on-stop=PROGRAM   run PROGRAM when playback has ended.\n");
    printf("                            For -B and -E options, specify the full path to the program, e.g. /usr/bin/logger.\n");
    printf("                            Executable scripts work, but must have #!/bin/sh (or whatever) in the headline.\n");
    printf("    -w, --wait-cmd          wait until the -B or -E programs finish before continuing\n");
    printf("    -o, --output=BACKEND    select audio output method\n");
    printf("    -m, --mdns=BACKEND      force the use of BACKEND to advertize the service\n");
    printf("                            if no mdns provider is specified,\n");
    printf("                            shairport tries them all until one works.\n");
    printf("    -r, --resync=THRESHOLD  resync if error exceeds this number of frames. Set to 0 to stop resyncing.\n");
    printf("    -t, --timeout=SECONDS   go back to idle mode from play mode after a break in communications of this many seconds (default 120). Set to 0 never to exit play mode.\n");
    printf("    --statistics            print some interesting statistics -- output to the logfile if running as a daemon.\n");
    printf("    --tolerance=TOLERANCE   allow a synchronization error of TOLERANCE frames (default 88) before trying to correct it.\n");
    printf("    --password=PASSWORD     require PASSWORD to connect. Default is not to require a password.\n");
#ifdef CONFIG_METADATA
    printf("    --metadata-pipename=PIPE send metadata to PIPE, e.g. --metadata-pipename=/tmp/shairport-sync-metadata.\n");
    printf("    --get-coverart          send cover art through the metadata pipe.\n");
#endif
#endif
#ifdef SUPPORT_CONFIG_FILES
    printf("\nGeneral options can be configured in /etc/%s.conf.\n",appName);
#endif
    printf("\n");
    mdns_ls_backends();
    printf("\n");
    audio_ls_outputs();
}

int parse_options(int argc, char **argv) {
  char    *stuffing = NULL;  /* used for picking up the stuffing option */
  
  
  

  signed char    c;            /* used for argument parsing */
  int     i = 0;        /* used for tracking options */
  poptContext optCon;   /* context for parsing command-line options */
  struct poptOption optionsTable[] = {
    { "verbose", 'v', POPT_ARG_NONE, NULL, 'v', NULL },
    { "disconnectFromOutput", 'D', POPT_ARG_NONE, NULL, 0, NULL },
    { "reconnectToOutput", 'R', POPT_ARG_NONE, NULL, 0, NULL },
    { "kill", 'k', POPT_ARG_NONE, NULL, 0, NULL },
    { "daemon", 'd', POPT_ARG_NONE, &config.daemonise, 0, NULL },
#ifdef SUPPORT_CONFIG_FILES
    { "configfile", 'c', POPT_ARG_STRING, &config.configfile, 0, NULL },
#endif
#ifdef COMMAND_LINE_ARGUMENT_SUPPORT
    { "statistics", 0, POPT_ARG_NONE, &config.statistics_requested, 0, NULL},
    { "version", 'V', POPT_ARG_NONE, NULL, 0, NULL},
    { "port", 'p', POPT_ARG_INT, &config.port, 0, NULL } ,
    { "name", 'a', POPT_ARG_STRING, &config.apname, 0, NULL } ,
    { "output", 'o', POPT_ARG_STRING, &config.output_name, 0, NULL } ,
    { "on-start", 'B', POPT_ARG_STRING, &config.cmd_start, 0, NULL } ,
    { "on-stop", 'E', POPT_ARG_STRING, &config.cmd_stop, 0, NULL } ,
    { "wait-cmd", 'w', POPT_ARG_NONE, &config.cmd_blocking, 0, NULL } ,
    { "mdns", 'm', POPT_ARG_STRING, &config.mdns_name, 0, NULL } ,
    { "latency", 'L', POPT_ARG_INT, &config.userSuppliedLatency, 0, NULL } ,
    { "AirPlayLatency", 'A', POPT_ARG_INT, &config.AirPlayLatency, 0, NULL } ,
    { "iTunesLatency", 'i', POPT_ARG_INT, &config.iTunesLatency, 0, NULL } ,
    { "forkedDaapdLatency", 0, POPT_ARG_INT, &config.ForkedDaapdLatency, 0, NULL } ,
    { "stuffing", 'S', POPT_ARG_STRING, &stuffing, 'S', NULL } ,
    { "resync", 'r', POPT_ARG_INT, &config.resyncthreshold, 0, NULL } ,
    { "timeout", 't', POPT_ARG_INT, &config.timeout, 't', NULL } ,
    { "password", 0, POPT_ARG_STRING, &config.password, 0, NULL } ,
    { "tolerance", 0, POPT_ARG_INT, &config.tolerance, 0, NULL } ,
#ifdef CONFIG_METADATA
    { "metadata-pipename", 'M', POPT_ARG_STRING, &config.metadata_pipename, 'M', NULL } ,
    { "get-coverart", 'g', POPT_ARG_NONE, &config.get_coverart, 'g', NULL } ,
#endif
    POPT_AUTOHELP
#endif
    { NULL, 0, 0, NULL, 0 }
  };

  
  int optind=argc;
  int j;
  for (j=0;j<argc;j++)
    if (strcmp(argv[j],"--")==0)
      optind=j;

  optCon = poptGetContext(NULL, optind,(const char **)argv, optionsTable, 0);
  poptSetOtherOptionHelp(optCon, "[OPTIONS]* ");

  /* Now do options processing, get portname */
 
  while ((c = poptGetNextOpt(optCon)) >= 0) {
    switch (c) {
      case 'v':
        debuglev++;
        break;
      case 't':
        if (config.timeout==0) {
          config.dont_check_timeout=1;
          config.allow_session_interruption=1;
        } else {
          config.dont_check_timeout=0;
          config.allow_session_interruption=0;
        }
        break;
#ifdef CONFIG_METADATA
      case 'M':
        config.metadata_enabled=1;
        break;
      case 'g':
        if (config.metadata_enabled==0)
          die("If you want to get cover art, you must also select the --metadata-pipename option.");
        break;
#endif
      case 'S':
        if (strcmp(stuffing,"basic")==0)           		
          config.packet_stuffing = ST_basic;
        else if (strcmp(stuffing,"soxr")==0)
#ifdef HAVE_LIBSOXR
          config.packet_stuffing = ST_soxr;
#else
          die("soxr option not available -- this version of shairport-sync was built without libsoxr support");
#endif
        else
          die("Illegal stuffing option \"%s\" -- must be \"basic\" or \"soxr\"",stuffing);
        break;
    }
  }
  if (c < -1) {
    die("%s: %s",poptBadOption(optCon, POPT_BADOPTION_NOALIAS),poptStrerror(c));
  }

#ifdef SUPPORT_CONFIG_FILES
    char configuration_file_path[4096];
    strcpy(configuration_file_path,"/etc/");
    strcat(configuration_file_path,appName);
    strcat(configuration_file_path,".conf");
    debug(2,"Looking for file \"%s\"",configuration_file_path);
    config_setting_t *setting;
    const char *str;
    int value;

    config_init(&config.cfg);
    char *cfp = configuration_file_path;
    // use the configuration file path given in the -c option, if any
    if (config.configfile)
      cfp = config.configfile;
    /* Read the file. If there is an error, report it and exit. */
    if(config_read_file(&config.cfg,cfp)) {
      /* Get the Service Name. */
      if(config_lookup_string(&config.cfg, "general.name", &str))
        config.apname=(char *)str;

      /* Get the Daemonize setting. */
      if(config_lookup_string(&config.cfg, "general.daemonize", &str)) {
        if (strcasecmp(str,"no")==0)
          config.daemonise=0;
        else if (strcasecmp(str,"yes")==0)
          config.daemonise=1;
        else
          die("Invalid daemonize option choice \"%s\". It should be \"yes\" or \"no\"");
      }

      /* Get the mdns_backend setting. */
      if(config_lookup_string(&config.cfg, "general.mdns_backend", &str))
        config.mdns_name=(char *)str;

      /* Get the output_backend setting. */
      if(config_lookup_string(&config.cfg, "general.output_backend", &str))
        config.output_name=(char *)str;

       /* Get the port setting. */
      if(config_lookup_int(&config.cfg, "general.port", &value)) {
        if ((value<0) || (value>65535))
          die("Invalid port number  \"%sd\". It should be between 0 and 65535, default is 5000",value);
        else
          config.port=value;
      }

      /* Get the password setting. */
      if(config_lookup_string(&config.cfg, "general.password", &str))
        config.password=(char *)str;

      if(config_lookup_string(&config.cfg, "general.interpolation", &str)) {
        if (strcasecmp(str,"basic")==0)
          config.packet_stuffing=ST_basic;
        else if (strcasecmp(str,"soxr")==0)
          config.packet_stuffing=ST_soxr;
        else
          die("Invalid interpolation option choice \"%s\". It should be \"basic\" or \"soxr\"");
      }

      /* Get the statistics setting. */
      if(config_lookup_string(&config.cfg, "general.statistics", &str)) {
        if (strcasecmp(str,"no")==0)
          config.statistics_requested=0;
        else if (strcasecmp(str,"yes")==0)
          config.statistics_requested=1;
        else
          die("Invalid statistics option choice \"%s\". It should be \"yes\" or \"no\"");
      }

      /* Get the drift tolerance setting. */
      if(config_lookup_int(&config.cfg, "general.drift", &value))
        config.tolerance=value;

      /* Get the resync setting. */
      if(config_lookup_int(&config.cfg, "general.resync_threshold", &value))
        config.resyncthreshold=value;

      /* Get the verbosity setting. */
      if(config_lookup_int(&config.cfg, "general.log_verbosity", &value))
        if ((value>=0) && (value<=3))
          debuglev=value;
        else
          die("Invalid log verbosity setting option choice \"%d\". It should be between 0 and 3, inclusive.",value);
          
      /* Get the ignore_volume_control setting. */
      if(config_lookup_string(&config.cfg, "general.ignore_volume_control", &str)) {
        if (strcasecmp(str,"no")==0)
          config.ignore_volume_control=0;
        else if (strcasecmp(str,"yes")==0)
          config.ignore_volume_control=1;
        else
          die("Invalid ignore_volume_control option choice \"%s\". It should be \"yes\" or \"no\"");
      }
      
      /* Get the audio backend's desired buffer size setting. */
      if(config_lookup_int(&config.cfg, "general.audio_backend_buffer_desired_length", &value)) {
        if ((value<0) || (value>66150))
          die("Invalid audio backend buffer desired length \"%sd\". It should be between 0 and 66150, default is 6615",value);
        else
          config.backend_buffer_desired_length=value;
      }
   
      /* Get the default latency. */
      if(config_lookup_int(&config.cfg, "latencies.default", &value))
        config.latency=value;

      /* Get the itunes latency. */
      if(config_lookup_int(&config.cfg, "latencies.itunes", &value))
        config.iTunesLatency=value;

      /* Get the AirPlay latency. */
      if(config_lookup_int(&config.cfg, "latencies.airplay", &value))
        config.AirPlayLatency=value;

      /* Get the forkedDaapd latency. */
      if(config_lookup_int(&config.cfg, "latencies.forkedDaapd", &value))
        config.ForkedDaapdLatency=value;

#ifdef CONFIG_METADATA
      /* Get the metadata setting. */
      if(config_lookup_string(&config.cfg, "metadata.enabled", &str)) {
        if (strcasecmp(str,"no")==0)
          config.metadata_enabled=0;
        else if (strcasecmp(str,"yes")==0)
          config.metadata_enabled=1;
        else
          die("Invalid metadata enabled option choice \"%s\". It should be \"yes\" or \"no\"");
      }
      
      if(config_lookup_string(&config.cfg, "metadata.include_cover_art", &str)) {
        if (strcasecmp(str,"no")==0)
          config.get_coverart=0;
        else if (strcasecmp(str,"yes")==0)
          config.get_coverart=1;
        else
          die("Invalid metadata include_cover_art option choice \"%s\". It should be \"yes\" or \"no\"");
      }
      
      if(config_lookup_string(&config.cfg, "metadata.pipe_name", &str)) {
        config.metadata_pipename=(char *)str;
      }
#endif

      if(config_lookup_string(&config.cfg, "sessioncontrol.run_this_before_play_begins", &str)) {
        config.cmd_start=(char *)str;
      }
      
      if(config_lookup_string(&config.cfg, "sessioncontrol.run_this_after_play_ends", &str)) {
        config.cmd_stop=(char *)str;
      }
      
      if(config_lookup_string(&config.cfg, "sessioncontrol.wait_for_completion", &str)) {
        if (strcasecmp(str,"no")==0)
          config.cmd_blocking=0;
        else if (strcasecmp(str,"yes")==0)
          config.cmd_blocking=1;
        else
          die("Invalid session control wait_for_completion option choice \"%s\". It should be \"yes\" or \"no\"");
      }
      
      if(config_lookup_string(&config.cfg, "sessioncontrol.allow_session_interruption", &str)) {
        config.dont_check_timeout=0; // this is for legacy -- only set by -t 0
        if (strcasecmp(str,"no")==0)
          config.allow_session_interruption=0;
        else if (strcasecmp(str,"yes")==0)
          config.allow_session_interruption=1;
        else
          die("Invalid session control allow_interruption option choice \"%s\". It should be \"yes\" or \"no\"");
      }

      if(config_lookup_int(&config.cfg, "sessioncontrol.session_timeout", &value)) {
        config.timeout=value;
        config.dont_check_timeout=0; // this is for legacy -- only set by -t 0
      }

    } else {
     die("Line %d of the configuration file \"%s\":\n%s",
        config_error_line(&config.cfg),config_error_file(&config.cfg),config_error_text(&config.cfg));
    }
  
#endif

  /* Print out options */
  
  debug(2,"statistics_requester status is %d.",config.statistics_requested);
  debug(2,"daemon status is %d.",config.daemonise);
  debug(2,"rtsp listening port is %d.",config.port);
  debug(2,"Shairport Sync player name is \"%s\".",config.apname);
  debug(2,"Audio Output name is \"%s\".",config.output_name);
  debug(2,"on-start action is \"%s\".",config.cmd_start);
  debug(2,"on-stop action is \"%s\".",config.cmd_stop);
  debug(2,"wait-cmd status is %d.",config.cmd_blocking);
  debug(2,"mdns backend \"%s\".",config.mdns_name);
  debug(2,"userSuppliedLatency is %d.",config.userSuppliedLatency);
  debug(2,"AirPlayLatency is %d.",config.AirPlayLatency);
  debug(2,"iTunesLatency is %d.",config.iTunesLatency);
  debug(2,"forkedDaapdLatency is %d.",config.ForkedDaapdLatency);
  debug(2,"stuffing option is \"%d\".",config.packet_stuffing);
  debug(2,"resync time is %d.",config.resyncthreshold);
  debug(2,"allow a session to be interrupted: %d.",config.allow_session_interruption);
  debug(2,"busy timeout time is %d.",config.timeout);
  debug(2,"tolerance is %d frames.",config.tolerance);
  debug(2,"password is \"%s\".",config.password);
  debug(2,"ignore_volume_contorl is %d.",config.ignore_volume_control);
  debug(2,"dac desired buffer length is %d.",config.backend_buffer_desired_length);
#ifdef CONFIG_METADATA
  debug(2,"metdata enabled is %d.",config.metadata_enabled);
  debug(2,"metadata pipename is \"%s\".",config.metadata_pipename);
  debug(2,"get-coverart is %d.",config.get_coverart);
#endif

  return optind+1;
}

void signal_setup(void) {
    // mask off all signals before creating threads.
    // this way we control which thread gets which signals.
    // for now, we don't care which thread gets the following.
    sigset_t set;
    sigfillset(&set);
    sigdelset(&set, SIGINT);
    sigdelset(&set, SIGTERM);
    sigdelset(&set, SIGHUP);
    sigdelset(&set, SIGSTOP);
    sigdelset(&set, SIGCHLD);
    sigdelset(&set, SIGUSR2);
    pthread_sigmask(SIG_BLOCK, &set, NULL);

    // setting this to SIG_IGN would prevent signalling any threads.
    struct sigaction sa;
    memset(&sa, 0, sizeof(sa));
    sa.sa_flags = SA_SIGINFO;
    sa.sa_sigaction = &sig_ignore;
    sigaction(SIGUSR1, &sa, NULL);

    sa.sa_flags = SA_SIGINFO | SA_RESTART;
    sa.sa_sigaction = &sig_shutdown;
    sigaction(SIGINT, &sa, NULL);
    sigaction(SIGTERM, &sa, NULL);

    sa.sa_sigaction = &sig_disconnect_audio_output;
    sigaction(SIGUSR2, &sa, NULL);

    sa.sa_sigaction = &sig_connect_audio_output;
    sigaction(SIGHUP, &sa, NULL);

    sa.sa_sigaction = &sig_child;
    sigaction(SIGCHLD, &sa, NULL);
}

// forked daemon lets the spawner know it's up and running OK
// should be called only once!
void shairport_startup_complete(void) {
    if (config.daemonise) {
//        daemon_ready();
    }
}

#ifdef USE_CUSTOM_PID_DIR

const char *pid_file_proc(void) {
#ifdef HAVE_ASPRINTF
   static char *fn = NULL;
   free(fn);
   asprintf(&fn,  "%s/%s.pid", PIDDIR, daemon_pid_file_ident ? daemon_pid_file_ident : "unknown");
#else
   static char fn[8192];
   snprintf(fn, sizeof(fn), "%s/%s.pid", PIDDIR, daemon_pid_file_ident ? daemon_pid_file_ident : "unknown");
#endif

   return fn;
}
#endif

void exit_function() {
#ifdef SUPPORT_CONFIG_FILES
  config_destroy(&config.cfg);
#endif  
}

int main(int argc, char **argv) {

    daemon_set_verbosity(LOG_DEBUG);
    memset(&config, 0, sizeof(config)); // also clears all strings, BTW
    atexit(exit_function);

    // set defaults
    config.statistics_requested - 0; // don't print stats in the log
    config.latency = 88200; // AirPlay. Is also reset in rtsp.c when play is about to start
    config.userSuppliedLatency = 0; // zero means none supplied
    config.iTunesLatency = 99400; // this seems to work pretty well for iTunes from Version 10 (?) upwards-- two left-ear headphones, one from the iMac jack, one from an NSLU2 running a cheap "3D Sound" USB Soundcard
    config.AirPlayLatency = 88200; // this seems to work pretty well for AirPlay -- Syncs sound and vision on AppleTV, but also used for iPhone/iPod/iPad sources
    config.ForkedDaapdLatency = 99400; // Seems to be right
    config.resyncthreshold = 441*5; // this number of frames is 50 ms
    config.timeout = 120; // this number of seconds to wait for [more] audio before switching to idle.
    config.tolerance = 88; // this number of frames of error before attempting to correct it.
    config.buffer_start_fill = 220;
    config.port = 5000;
    config.packet_stuffing = ST_basic; // simple interpolation or deletion
    char hostname[100];
    gethostname(hostname, 100);
    config.apname = malloc(20 + 100);
    snprintf(config.apname, 20 + 100, "Shairport Sync on %s", hostname);
    set_requested_connection_state_to_output(1); // we expect to be able to connect to the output device
    config.backend_buffer_desired_length = 6615; // 0.15 seconds.
    
    // this is a bit weird, but apparently necessary
    char* basec = strdup(argv[0]);
    char* bname = basename(basec);
    appName = strdup(bname);
    free(basec);
    
    /* Check if we are called with -V or --version parameter */
    if (argc >= 2 && ((strcmp(argv[1], "-V")==0) || (strcmp(argv[1], "--version")==0))) {
      print_version();
      exit(1);
    }

    /* Check if we are called with -h or --help parameter */
    if (argc >= 2 && ((strcmp(argv[1], "-h")==0) || (strcmp(argv[1], "--help")==0))) {
		  usage(argv[0]);
		  exit(1);
    }

    pid_t pid;

    /* Reset signal handlers */
    if (daemon_reset_sigs(-1) < 0) {
        daemon_log(LOG_ERR, "Failed to reset all signal handlers: %s", strerror(errno));
        return 1;
    }

    /* Unblock signals */
    if (daemon_unblock_sigs(-1) < 0) {
        daemon_log(LOG_ERR, "Failed to unblock all signals: %s", strerror(errno));
        return 1;
    }
    
    
#if USE_CUSTOM_LOCAL_STATE_DIR
    debug(1,"Locating localstatedir at \"%s\"",LOCALSTATEDIR);
    /* Point to a function to help locate where the PID file will go */
    daemon_pid_file_proc = pid_file_proc;
#endif

    /* Set indentification string for the daemon for both syslog and PID file */
    daemon_pid_file_ident = daemon_log_ident = daemon_ident_from_argv0(argv[0]);
    
    /* Check if we are called with -D or --disconnectFromOutput parameter */
    if (argc >= 2 && ((strcmp(argv[1], "-D")==0) || (strcmp(argv[1], "--disconnectFromOutput")==0))) {
      if ((pid = daemon_pid_file_is_running()) >= 0) {
        if (kill(pid,SIGUSR2)!=0) {  // try to send the signal
          daemon_log(LOG_WARNING, "Failed trying to send disconnectFromOutput command to daemon pid: %d: %s",pid, strerror(errno));
        }
      } else {
        daemon_log(LOG_WARNING, "Can't send a disconnectFromOutput request -- Failed to find daemon: %s", strerror(errno));
      }
      exit(1);
    }
      
    /* Check if we are called with -R or --reconnectToOutput parameter */
    if (argc >= 2 && ((strcmp(argv[1], "-R")==0) || (strcmp(argv[1], "--reconnectToOutput")==0))) {
      if ((pid = daemon_pid_file_is_running()) >= 0) {
        if (kill(pid,SIGHUP)!=0) {  // try to send the signal
          daemon_log(LOG_WARNING, "Failed trying to send reconnectToOutput command to daemon pid: %d: %s",pid, strerror(errno));
        }
      } else {
        daemon_log(LOG_WARNING, "Can't send a reconnectToOutput request -- Failed to find daemon: %s", strerror(errno));
      }
      exit(1);
    }
      
    /* Check if we are called with -k or --kill parameter */
    if (argc >= 2 && ((strcmp(argv[1], "-k")==0) || (strcmp(argv[1], "--kill")==0))) {
      int ret;

      /* Kill daemon with SIGTERM */
      /* Check if the new function daemon_pid_file_kill_wait() is available, if it is, use it. */
      if ((ret = daemon_pid_file_kill_wait(SIGTERM, 5)) < 0)
        daemon_log(LOG_WARNING, "Failed to kill daemon: %s", strerror(errno));
      else
        daemon_pid_file_remove();
      return ret < 0 ? 1 : 0;
    }

    /* Check that the daemon is not running twice at the same time */
    if ((pid = daemon_pid_file_is_running()) >= 0) {
        daemon_log(LOG_ERR, "Daemon already running on PID file %u", pid);
        return 1;
    }

    // parse arguments into config
    int audio_arg = parse_options(argc, argv);

    // mDNS supports maximum of 63-character names (we append 13).
    if (strlen(config.apname) > 50)
        die("Supplied name too long (max 50 characters)");
   
    /* here, daemonise with libdaemon */
    
    if (config.daemonise) {
      /* Prepare for return value passing from the initialization procedure of the daemon process */
      if (daemon_retval_init() < 0) {
          daemon_log(LOG_ERR, "Failed to create pipe.");
          return 1;
      }

      /* Do the fork */
      if ((pid = daemon_fork()) < 0) {

          /* Exit on error */
          daemon_retval_done();
          return 1;

      } else if (pid) { /* The parent */
          int ret;

          /* Wait for 20 seconds for the return value passed from the daemon process */
          if ((ret = daemon_retval_wait(20)) < 0) {
              daemon_log(LOG_ERR, "Could not receive return value from daemon process: %s", strerror(errno));
              return 255;
          }

          if (ret != 0) 
          	daemon_log(ret != 0 ? LOG_ERR : LOG_INFO, "Daemon returned %i as return value.", ret);
          return ret;

      } else { /* The daemon */

          /* Close FDs */
          if (daemon_close_all(-1) < 0) {
              daemon_log(LOG_ERR, "Failed to close all file descriptors: %s", strerror(errno));

              /* Send the error condition to the parent process */
              daemon_retval_send(1);
              goto finish;
          }
          
          /* Create the PID file */
          if (daemon_pid_file_create() < 0) {
              daemon_log(LOG_ERR, "Could not create PID file (%s).", strerror(errno));
              daemon_retval_send(2);
              goto finish;
          }
                    
          /* Send OK to parent process */
          daemon_retval_send(0);
      }
      /* end libdaemon stuff */
    }

    signal_setup();
    
    // make sure the program can create files that group and world can read
    umask(S_IWGRP | S_IWOTH);

    config.output = audio_get_output(config.output_name);
    if (!config.output) {
        audio_ls_outputs();
        die("Invalid audio output specified!");
    }
    config.output->init(argc-audio_arg, argv+audio_arg, &config.cfg);

    daemon_log(LOG_NOTICE, "startup");

    uint8_t ap_md5[16];

#ifdef HAVE_LIBSSL
    MD5_CTX ctx;
    MD5_Init(&ctx);
    MD5_Update(&ctx, config.apname, strlen(config.apname));
    MD5_Final(ap_md5, &ctx);
#endif

#ifdef HAVE_LIBPOLARSSL
     md5_context tctx;
     md5_starts(&tctx);
     md5_update(&tctx, (unsigned char *)config.apname, strlen(config.apname));
     md5_finish(&tctx, ap_md5);
#endif
    memcpy(config.hw_addr, ap_md5, sizeof(config.hw_addr));
#ifdef CONFIG_METADATA
    metadata_init() ; // create the metadata pipe if necessary
#endif

    rtsp_listen_loop();

    // should not reach this...
    shairport_shutdown();
finish:
    daemon_log(LOG_NOTICE, "Unexpected exit...");
    daemon_retval_send(255);
    daemon_pid_file_remove();
    return 1;

}