Add a command-line option to force the mDNS backend

Add this option to the system-v init script.

common.h

@@ -5,6 +5,7 @@
 #include <stdint.h>
 #include <sys/socket.h>
 #include "audio.h"
+#include "mdns.h"
 
 // struct sockaddr_in6 is bigger than struct sockaddr. derp
 #ifdef AF_INET6
@@ -23,9 +24,10 @@ typedef struct {
  int port;
  char *output_name;
  audio_output *output;
+ char *mdns_name;
+ mdns_backend *mdns;
  int buffer_start_fill;
  int daemonise;
- int mdns_internal;
  char *cmd_start, *cmd_stop;
  char *pidfile;
  char *logfile;

mdns.c

@@ -47,8 +47,6 @@ static mdns_backend *mdns_backends[] = {
  NULL
 };
 
-static mdns_backend *backend = NULL;
-
 void mdns_register(void) {
  char *mdns_apname = malloc(strlen(config.apname) + 14);
  char *p = mdns_apname;
@@ -60,26 +58,54 @@ void mdns_register(void) {
  *p++ = '@';
  strcpy(p, config.apname);
 
- backend = NULL;
- mdns_backend **s = NULL;
- for (s = mdns_backends; *s; s++)
+ mdns_backend **b = NULL;
+
+ if (config.mdns_name != NULL)
  {
- int error = (*s)->mdns_register(mdns_apname, config.port);
- if (error == 0)
+ for (b = mdns_backends; *b; b++)
  {
- backend = *s;
+ if (strcmp((*b)->name, config.mdns_name) != 0) // Not the one we are looking for
+ continue;
+ int error = (*b)->mdns_register(mdns_apname, 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_apname, config.port);
+ if (error >= 0)
+ {
+ config.mdns = *b;
+ break;
+ }
+ }
  }
 
- if (backend == NULL)
+ if (config.mdns == NULL)
  die("Could not establish mDNS advertisement!");
 }
 
 void mdns_unregister(void) {
- if (backend) {
- backend->mdns_unregister();
+ if (config.mdns) {
+ config.mdns->mdns_unregister();
  }
 }
 
+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);
+ }
+}
 

mdns.h

@@ -5,8 +5,10 @@ extern int mdns_pid;
 
 void mdns_unregister(void);
 void mdns_register(void);
+void mdns_ls_backends(void);
 
 typedef struct {
+ char *name;
  int (*mdns_register)(char *apname, int port);
  void (*mdns_unregister)(void);
 } mdns_backend;

mdns_avahi.c

@@ -141,6 +141,7 @@ static void avahi_unregister(void) {
 
 mdns_backend mdns_avahi = 
 {
+ .name = "avahi",
  .mdns_register = avahi_register,
  .mdns_unregister = avahi_unregister
 };

mdns_external.c

@@ -93,16 +93,22 @@ static int mdns_external_avahi_register(char *apname, int port) {
  };
 
  argv[0] = "avahi-publish-service";
- mdns_pid = fork_execvp(argv[0], argv);
- if (mdns_pid > 0)
+ int pid = fork_execvp(argv[0], argv);
+ if (pid >= 0)
+ {
+ mdns_pid = pid;
  return 0;
+ }
  else
  warn("Calling %s failed !", argv[0]);
 
  argv[0] = "mDNSPublish";
- mdns_pid = fork_execvp(argv[0], argv);
- if (mdns_pid > 0)
+ pid = fork_execvp(argv[0], argv);
+ if (pid >= 0)
+ {
+ mdns_pid = pid;
  return 0;
+ }
  else
  warn("Calling %s failed !", argv[0]);
 
@@ -117,9 +123,12 @@ static int mdns_external_dns_sd_register(char *apname, int port) {
  char *argv[] = {"dns-sd", "-R", apname, "_raop._tcp", ".",
  mdns_port, MDNS_RECORD, NULL};
 
- mdns_pid = fork_execvp(argv[0], argv);
- if (mdns_pid > 0)
+ int pid = fork_execvp(argv[0], argv);
+ if (pid >= 0)
+ {
+ mdns_pid = pid;
  return 0;
+ }
  else
  warn("Calling %s failed !", argv[0]);
 
@@ -133,11 +142,13 @@ static void kill_mdns_child(void) {
 }
 
 mdns_backend mdns_external_avahi = {
+ .name = "external-avahi",
  .mdns_register = mdns_external_avahi_register,
  .mdns_unregister = kill_mdns_child
 };
 
 mdns_backend mdns_external_dns_sd = {
+ .name = "external-dns-sd",
  .mdns_register = mdns_external_dns_sd_register,
  .mdns_unregister = kill_mdns_child
 };

scripts/debian/default/shairport

@@ -32,6 +32,11 @@
 #OUTPUT=ao
 #OUTPUT_OPTS=
 
+# Force the mDNS backend
+# By default, shairport will try all backends until one works.
+# Check 'shairport -h' for details
+# MDNS=avahi
+
 # Change how many frames re required to start playing
 #BUFFER_FILL=220
 

scripts/debian/init.d/shairport

@@ -35,6 +35,7 @@ DAEMON_ARGS="--daemon --pidfile $PIDFILE --log $LOGFILE"
 [ -z "$ON_START" ] || DAEMON_ARGS="$DAEMON_ARGS --on-start \"$ON_START\""
 [ -z "$ON_STOP" ] || DAEMON_ARGS="$DAEMON_ARGS --on-stop \"$ON_STOP\""
 [ -z "$OUTPUT" ] || DAEMON_ARGS="$DAEMON_ARGS --output $OUTPUT"
+[ -z "$MDNS" ] || DAEMON_ARGS="$DAEMON_ARGS --mdns $MDNS"
 [ -z "$OUTPUT_OPTS" ] || DAEMON_ARGS="$DAEMON_ARGS -- $OUTPUT_OPTS"
 
 # Exit if the package is not installed

shairport.c

@@ -93,15 +93,20 @@ void usage(char *progname) {
  printf(" written to stdout, unless a pidfile is used.\n");
  printf(" -P, --pidfile=FILE write daemon's pid to FILE on startup.\n");
  printf(" Has no effect if -d is not specified\n");
- printf(" -l, --log FILE redirect shairport's standard output to FILE\n");
- printf(" If --errror is not specified, it also redirects\n");
+ printf(" -l, --log=FILE redirect shairport's standard output to FILE\n");
+ printf(" If --error is not specified, it also redirects\n");
  printf(" error output to FILE\n");
- printf(" -e, --error FILE redirect shairport's standard error output to FILE\n");
+ printf(" -e, --error=FILE redirect shairport's standard error output to FILE\n");
  printf(" -B, --on-start=COMMAND run a shell command when playback begins\n");
  printf(" -E, --on-stop=COMMAND run a shell command when playback ends\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("\n");
+ mdns_ls_backends();
  printf("\n");
  audio_ls_outputs();
 }
@@ -111,7 +116,7 @@ int parse_options(int argc, char **argv) {
  setenv("POSIXLY_CORRECT", "", 1);
 
  static struct option long_options[] = {
- {"help", no_argument, NULL, 'h'},
+ {"help", no_argument, NULL, 'h'}, 
  {"daemon", no_argument, NULL, 'd'},
  {"pidfile", required_argument, NULL, 'P'},
  {"log", required_argument, NULL, 'l'},
@@ -121,12 +126,13 @@ int parse_options(int argc, char **argv) {
  {"output", required_argument, NULL, 'o'},
  {"on-start",required_argument, NULL, 'B'},
  {"on-stop", required_argument, NULL, 'E'},
+ {"mdns", required_argument, NULL, 'm'},
  {NULL, 0, NULL, 0}
  };
 
  int opt;
  while ((opt = getopt_long(argc, argv,
- "+hdvP:l:e:p:a:o:b:B:E:",
+ "+hdvP:l:e:p:a:o:b:B:E:m:",
  long_options, NULL)) > 0) {
  switch (opt) {
  default:
@@ -166,6 +172,9 @@ int parse_options(int argc, char **argv) {
  case 'e':
  config.errfile = optarg;
  break;
+ case 'm':
+ config.mdns_name = optarg;
+ break;
  }
  }
  return optind;