Skip to content

Commit

Permalink
Reorganize mDNS advertisement
Browse files Browse the repository at this point in the history
mDNS is now handled more or less in the same way audio is.
Multiple mDNS backends are available, shairport tries them all until one
works.

This makes it, IMHO, cleaner, and easier to add other mDNS backends in
the future, such as using tinysvcmdns or dns-sd library.
Also it will also allow to define mDNS backends as plugins, in a similar
way it is done in PR mikebrady#230.
  • Loading branch information
plietar authored and abrasive committed Oct 21, 2013
1 parent 4baca06 commit 3896909
Show file tree
Hide file tree
Showing 7 changed files with 196 additions and 52 deletions.
4 changes: 2 additions & 2 deletions Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ endif

PREFIX ?= /usr/local

SRCS := shairport.c daemon.c rtsp.c mdns.c common.c rtp.c player.c alac.c audio.c audio_dummy.c audio_pipe.c
SRCS := shairport.c daemon.c rtsp.c mdns.c mdns_external.c common.c rtp.c player.c alac.c audio.c audio_dummy.c audio_pipe.c

ifdef CONFIG_SNDIO
SRCS += audio_sndio.c
Expand All @@ -28,7 +28,7 @@ SRCS += audio_alsa.c
endif

ifdef CONFIG_AVAHI
SRCS += avahi.c
SRCS += mdns_avahi.c
endif

ifndef CONFIG_HAVE_GETOPT_H
Expand Down
7 changes: 0 additions & 7 deletions avahi.h

This file was deleted.

64 changes: 30 additions & 34 deletions mdns.c
Original file line number Diff line number Diff line change
Expand Up @@ -25,28 +25,29 @@
*/


#include <signal.h>
#include <memory.h>
#include <string.h>
#include <unistd.h>
#include "config.h"
#include "common.h"
#include "mdns.h"

#ifdef CONFIG_AVAHI
#include "avahi.h"
extern mdns_backend mdns_avahi;
#endif

int mdns_pid = 0;
extern mdns_backend mdns_external_avahi;
extern mdns_backend mdns_external_dns_sd;

void mdns_unregister(void) {
static mdns_backend *mdns_backends[] = {
#ifdef CONFIG_AVAHI
avahi_unregister();
&mdns_avahi,
#endif
&mdns_external_avahi,
&mdns_external_dns_sd,
NULL
};

if (mdns_pid)
kill(mdns_pid, SIGTERM);
mdns_pid = 0;
}
static mdns_backend *backend = NULL;

void mdns_register(void) {
char *mdns_apname = malloc(strlen(config.apname) + 14);
Expand All @@ -59,31 +60,26 @@ void mdns_register(void) {
*p++ = '@';
strcpy(p, config.apname);

#ifdef CONFIG_AVAHI
if (avahi_register(mdns_apname))
return;
warn("avahi_register failed, falling back to external programs");
#endif

if ((mdns_pid = fork()))
return;

char mdns_port[6];
sprintf(mdns_port, "%d", config.port);

char *argv[] = {
NULL, mdns_apname, "_raop._tcp", mdns_port, MDNS_RECORD, NULL
};
backend = NULL;
mdns_backend **s = NULL;
for (s = mdns_backends; *s; s++)
{
int error = (*s)->mdns_register(mdns_apname, config.port);
if (error == 0)
{
backend = *s;
break;
}
}

argv[0] = "avahi-publish-service";
execvp(argv[0], argv);
if (backend == NULL)
die("Could not establish mDNS advertisement!");
}

argv[0] = "mDNSPublish";
execvp(argv[0], argv);
void mdns_unregister(void) {
if (backend) {
backend->mdns_unregister();
}
}

char *mac_argv[] = {"dns-sd", "-R", mdns_apname, "_raop._tcp", ".",
mdns_port, MDNS_RECORD, NULL};
execvp(mac_argv[0], mac_argv);

die("Could not establish mDNS advertisement!");
}
5 changes: 5 additions & 0 deletions mdns.h
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,11 @@ extern int mdns_pid;
void mdns_unregister(void);
void mdns_register(void);

typedef struct {
int (*mdns_register)(char *apname, int port);
void (*mdns_unregister)(void);
} mdns_backend;

#define MDNS_RECORD "tp=UDP", "sm=false", "ek=1", "et=0,1", "cn=0,1", "ch=2", \
"ss=16", "sr=44100", "vn=3", "txtvers=1", \
config.password ? "pw=true" : "pw=false"
Expand Down
21 changes: 14 additions & 7 deletions avahi.c → mdns_avahi.c
Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@ static AvahiEntryGroup *group = NULL;
static AvahiThreadedPoll *tpoll = NULL;

static char *name = NULL;
static int port = 0;

static void egroup_callback(AvahiEntryGroup *g,
AvahiEntryGroupState state,
Expand Down Expand Up @@ -67,7 +68,7 @@ static void register_service(AvahiClient *c) {
"_raop._tcp",
NULL,
NULL,
config.port,
port,
MDNS_RECORD,
NULL);
if (ret < 0)
Expand Down Expand Up @@ -100,33 +101,34 @@ static void client_callback(AvahiClient *c,
}
}

int avahi_register(char *srvname) {
static int avahi_register(char *srvname, int srvport) {
debug(1, "avahi: avahi_register\n");
name = strdup(srvname);
port = srvport;

int err;
if (!(tpoll = avahi_threaded_poll_new())) {
warn("couldn't create avahi threaded tpoll!");
return 0;
return -1;
}
if (!(client = avahi_client_new(avahi_threaded_poll_get(tpoll),
0,
client_callback,
NULL,
&err))) {
warn("couldn't create avahi client: %s!", avahi_strerror(err));
return 0;
return -1;
}

if (avahi_threaded_poll_start(tpoll) < 0) {
warn("couldn't start avahi tpoll thread");
return 0;
return -1;
}

return 1;
return 0;
}

void avahi_unregister(void) {
static void avahi_unregister(void) {
debug(1, "avahi: avahi_unregister\n");
if (tpoll)
avahi_threaded_poll_stop(tpoll);
Expand All @@ -137,4 +139,9 @@ void avahi_unregister(void) {
name = NULL;
}

mdns_backend mdns_avahi =
{
.mdns_register = avahi_register,
.mdns_unregister = avahi_unregister
};

144 changes: 144 additions & 0 deletions mdns_external.c
Original file line number Diff line number Diff line change
@@ -0,0 +1,144 @@
/*
* mDNS registration handler. 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 <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include "common.h"
#include "mdns.h"

int mdns_pid = 0;

/*
* Do a fork followed by a execvp, handling execvp errors correctly.
* Return the pid of the new process upon success, or -1 if something failed.
* Check errno for error details.
*/
static int fork_execvp(const char *file, char *const argv[]) {
int execpipe[2];
int pid = 0;
if (pipe(execpipe) < 0) {
return -1;
}

if (fcntl(execpipe[1], F_SETFD, fcntl(execpipe[1], F_GETFD) | FD_CLOEXEC) < 0) {
close(execpipe[0]);
close(execpipe[1]);
return -1;
}

pid = fork();
if (pid < 0) {
close(execpipe[0]);
close(execpipe[1]);
return -1;
}
else if(pid == 0) { // Child
close(execpipe[0]); // Close the read end
execvp(file, argv);

// If we reach this point then execve has failed.
// Write erno's value into the pipe and exit.
write(execpipe[1], &errno, sizeof(errno));

_exit(-1);
return 0; // Just to make the compiler happy.
}
else { // Parent
close(execpipe[1]); // Close the write end

int childErrno;
// Block until child closes the pipe or sends errno.
if(read(execpipe[0], &childErrno, sizeof(childErrno)) == sizeof(childErrno)) { // We received errno
errno = childErrno;
return -1;
}
else { // Child closed the pipe. execvp was successful.
return pid;
}
}
}

static int mdns_external_avahi_register(char *apname, int port) {
char mdns_port[6];
sprintf(mdns_port, "%d", config.port);

char *argv[] = {
NULL, apname, "_raop._tcp", mdns_port, MDNS_RECORD, NULL
};

argv[0] = "avahi-publish-service";
mdns_pid = fork_execvp(argv[0], argv);
if (mdns_pid > 0)
return 0;
else
warn("Calling %s failed !", argv[0]);

argv[0] = "mDNSPublish";
mdns_pid = fork_execvp(argv[0], argv);
if (mdns_pid > 0)
return 0;
else
warn("Calling %s failed !", argv[0]);

// If we reach here, both execvp calls failed.
return -1;
}

static int mdns_external_dns_sd_register(char *apname, int port) {
char mdns_port[6];
sprintf(mdns_port, "%d", config.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)
return 0;
else
warn("Calling %s failed !", argv[0]);

return -1;
}

static void kill_mdns_child(void) {
if (mdns_pid)
kill(mdns_pid, SIGTERM);
mdns_pid = 0;
}

mdns_backend mdns_external_avahi = {
.mdns_register = mdns_external_avahi_register,
.mdns_unregister = kill_mdns_child
};

mdns_backend mdns_external_dns_sd = {
.mdns_register = mdns_external_dns_sd_register,
.mdns_unregister = kill_mdns_child
};

3 changes: 1 addition & 2 deletions shairport.c
Original file line number Diff line number Diff line change
Expand Up @@ -187,7 +187,7 @@ void signal_setup(void) {
// 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_flags = SA_SIGINFO | SA_RESTART;
sa.sa_sigaction = &sig_ignore;
sigaction(SIGUSR1, &sa, NULL);

Expand All @@ -198,7 +198,6 @@ void signal_setup(void) {
sa.sa_sigaction = &sig_logrotate;
sigaction(SIGHUP, &sa, NULL);

sa.sa_flags = SA_SIGINFO;
sa.sa_sigaction = &sig_child;
sigaction(SIGCHLD, &sa, NULL);
}
Expand Down

0 comments on commit 3896909

Please sign in to comment.