Add multicastsocket

src/network/multicastsocket.c

@@ -0,0 +1,71 @@
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+
+#include "multicastsocket.h"
+
+static struct ip_mreq command; /* static ?! */
+
+int setup_multicast_socket(const char *_multicast_ip, unsigned short _multicast_port, struct sockaddr_in *addr)
+{
+  int loop = 1;
+  int sock;
+
+  memset (addr, 0, sizeof (*addr));
+  addr->sin_family = AF_INET;
+  addr->sin_addr.s_addr = htonl (INADDR_ANY);
+  addr->sin_port = htons (_multicast_port);
+
+  if ( ( sock = socket(PF_INET, SOCK_DGRAM, 0)) == -1) {
+     perror ("socket()");
+     exit (EXIT_FAILURE);
+  }
+
+  /* Mehr Prozessen erlauben, denselben Port zu nutzen */
+  loop = 1;
+  if (setsockopt ( sock,
+                   SOL_SOCKET,
+                   SO_REUSEADDR,
+                   &loop, sizeof (loop)) < 0) {
+     perror ("setsockopt:SO_REUSEADDR");
+     exit (EXIT_FAILURE);
+  }
+  if(bind( sock,
+           (struct sockaddr *)addr,
+           sizeof(*addr)) < 0) {
+     perror ("bind");
+     exit (EXIT_FAILURE);
+  }
+
+  /* Broadcast auf dieser Maschine zulassen */
+  loop = 1;
+  if (setsockopt ( sock,
+                   IPPROTO_IP,
+                   IP_MULTICAST_LOOP,
+                   &loop, sizeof (loop)) < 0) {
+     perror ("setsockopt:IP_MULTICAST_LOOP");
+     exit (EXIT_FAILURE);
+  }
+
+  /* Join the broadcast group: */
+  command.imr_multiaddr.s_addr = inet_addr (_multicast_ip);
+  command.imr_interface.s_addr = htonl (INADDR_ANY);
+  if (command.imr_multiaddr.s_addr == -1) {
+     perror ("224.0.0.1 ist keine Multicast-Adresse\n");
+     exit (EXIT_FAILURE);
+  }
+  if (setsockopt ( sock,
+                   IPPROTO_IP,
+                   IP_ADD_MEMBERSHIP,
+                   &command, sizeof (command)) < 0) {
+    perror ("setsockopt:IP_ADD_MEMBERSHIP");
+  }
+  return sock;
+}