rewrite: add mDNS registration

Makefile

@@ -1,4 +1,4 @@
-SRCS := shairport.c rtsp.c common.c rtp.c player.c alac.c $(wildcard audio_*.c)
+SRCS := shairport.c rtsp.c mdns.c common.c rtp.c player.c alac.c $(wildcard audio_*.c)
 
 LIBS := -lcrypto -lm -lao -lpthread
 

common.h

@@ -7,6 +7,7 @@
 
 typedef struct {
     char *password;
+    char *apname;
     char hw_addr[6];
     int port;
     audio_ops *output;

mdns.c

@@ -0,0 +1,56 @@
+#include <signal.h>
+#include <memory.h>
+#include <string.h>
+#include <unistd.h>
+#include "common.h"
+
+static int mdns_pid = 0;
+
+void mdns_unregister(void) {
+    if (mdns_pid)
+        kill(mdns_pid, SIGTERM);
+    mdns_pid = 0;
+}
+
+void mdns_register(void) {
+    if (mdns_pid)
+        die("attempted to register with mDNS twice");
+
+    // XXX todo: native avahi support, if available at compile time
+
+    if ((mdns_pid = fork()))
+        return;
+    
+    char *mdns_apname = malloc(strlen(config.apname) + 14);
+    char *p = mdns_apname;
+    int i;
+    for (i=0; i<6; i++) {
+        sprintf(p, "%02X", config.hw_addr[i]);
+        p += 2;
+    }
+    *p++ = '@';
+    strcpy(p, config.apname);
+
+    char mdns_port[6];
+    sprintf(mdns_port, "%d", config.port);
+
+#define 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"
+
+    char *argv[] = {
+        NULL, mdns_apname, "_raop._tcp", mdns_port, RECORD
+    };
+
+    argv[0] = "avahi-publish-service";
+    execvp(argv[0], argv);
+
+    argv[0] = "mDNSPublish";
+    execvp(argv[0], argv);
+
+    char *mac_argv[] = {"dns-sd", "-R", mdns_apname, "_raop._tcp", ".",
+                        mdns_port, RECORD};
+    execvp(mac_argv[0], mac_argv);
+
+    die("Could not establish mDNS advertisement!\n");
+}

mdns.h

@@ -0,0 +1,7 @@
+#ifndef _MDNS_H
+#define _MDNS_H
+
+void mdns_unregister(void);
+void mdns_register(void);
+
+#endif // _MDNS_H

rtsp.c

@@ -17,6 +17,7 @@
 #include "common.h"
 #include "player.h"
 #include "rtp.h"
+#include "mdns.h"
 
 // only one thread is allowed to use the player at once.
 // it monitors the request variable (at least when interrupted)
@@ -699,6 +700,8 @@ void rtsp_listen_loop(void) {
     if (sockfd[1])
         FD_SET(sockfd[1], &fds);
 
+    mdns_register();
+
     printf("Listening for connections.\n");
 
     int acceptfd;

shairport.c

@@ -2,10 +2,12 @@
 #include <memory.h>
 #include "common.h"
 #include "rtsp.h"
+#include "mdns.h"
 
 
 static void shutdown(void) {
     printf("Shutting down...\n");
+    mdns_unregister();
     rtsp_shutdown_stream();
     config.output->deinit();
     exit(0);
@@ -23,17 +25,21 @@ int main(int argc, char **argv) {
 //    config.password = "hello";
     memcpy(config.hw_addr, "\0\x11\x22\x33\x44\x55", 6);
     config.buffer_start_fill = 220;
+    config.port = 9000;
+    config.apname = "hellothere";
 
     config.output = &audio_dummy;
     //config.output = &audio_ao;
 
     // 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, SIGSTOP);
+    sigdelset(&set, SIGCHLD);
     pthread_sigmask(SIG_BLOCK, &set, NULL);
 
     // setting this to SIG_IGN would prevent signalling any threads.
@@ -46,6 +52,7 @@ int main(int argc, char **argv) {
     sa.sa_sigaction = &sig_shutdown;
     sigaction(SIGINT, &sa, NULL);
     sigaction(SIGTERM, &sa, NULL);
+    sigaction(SIGCHLD, &sa, NULL);
 
     config.output->init(0, 0);