Make multicast sockets work under windows

msdn article 737550 states that "the preferred method is to call the
bind function to associate a socket with a local IP address and then
join the multicast group. Although this order of operations is not
mandatory, it is strongly recommended".
Since binding to the multicast address seems to fail, let's try binding
to INADDR_ANY and joint thereafter.

diff --git a/simgear/io/raw_socket.cxx b/simgear/io/raw_socket.cxx
index 0d9199c134b9a4d48444955b1eee74897844a4b8..971ff31f70e7129659399e6a39a3397d33a626ff 100644 (file)
--- a/simgear/io/raw_socket.cxx
+++ b/simgear/io/raw_socket.cxx
@@ -260,15 +260,31 @@ int Socket::bind ( const char* host, int port )
   int result;
   assert ( handle != -1 ) ;
   IPAddress addr ( host, port ) ;
+
+#if !defined(WINSOCK)
   if( (result = ::bind(handle,(const sockaddr*)&addr,sizeof(IPAddress))) < 0 ) {
     SG_LOG(SG_IO, SG_ALERT, "bind(" << host << ":" << port << ") failed. Errno " << errno << " (" << strerror(errno) << ")");
     return result;
   }
+#endif
 
   // 224.0.0.0 - 239.255.255.255 are multicast   
   // Usage of 239.x.x.x is recommended for local scope
   // Reference: http://tools.ietf.org/html/rfc5771
   if( ntohl(addr.getIP()) >= 0xe0000000 && ntohl(addr.getIP()) <= 0xefffffff ) {
+
+#if defined(WINSOCK)
+    struct sockaddr_in a;
+    a.sin_addr.S_un.S_addr = INADDR_ANY;
+    a.sin_family = AF_INET;
+    a.sin_port = htons(port);
+      
+    if( (result = ::bind(handle,(const sockaddr*)&a,sizeof(a))) < 0 ) {
+      SG_LOG(SG_IO, SG_ALERT, "bind(any:" << port << ") failed. Errno " << errno << " (" << strerror(errno) << ")");
+      return result;
+    }
+#endif
+
     struct ip_mreq mreq;
     mreq.imr_multiaddr.s_addr = addr.getIP();
     mreq.imr_interface.s_addr = htonl(INADDR_ANY);