avformat/udp: specify the local address for some source filtered multicast joins

We already use localaddr for the multicast joins without source filters, so we
should use them for source filters as well. This patch only fixes the
IP_ADD_SOURCE_MEMBERSHIP and the IP_BLOCK_SOURCE case.

Unless we do this, the kernel automatically selects an interface based on the
source address, and that interface might be different from the one set in
localaddr. For blocked sources this even casues EINVAL because we joined the
multicast group on a different interface.
Signed-off-by: Marton Balint <cus@passwd.hu>

libavformat/udp.c

@@ -196,6 +196,7 @@ static int udp_join_multicast_group(int sockfd, struct sockaddr *addr,struct soc
         struct ipv6_mreq mreq6;
 
         memcpy(&mreq6.ipv6mr_multiaddr, &(((struct sockaddr_in6 *)addr)->sin6_addr), sizeof(struct in6_addr));
+        //TODO: Interface index should be looked up from local_addr
         mreq6.ipv6mr_interface= 0;
         if (setsockopt(sockfd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq6, sizeof(mreq6)) < 0) {
             ff_log_net_error(NULL, AV_LOG_ERROR, "setsockopt(IPV6_ADD_MEMBERSHIP)");
@@ -228,6 +229,7 @@ static int udp_leave_multicast_group(int sockfd, struct sockaddr *addr,struct so
         struct ipv6_mreq mreq6;
 
         memcpy(&mreq6.ipv6mr_multiaddr, &(((struct sockaddr_in6 *)addr)->sin6_addr), sizeof(struct in6_addr));
+        //TODO: Interface index should be looked up from local_addr
         mreq6.ipv6mr_interface= 0;
         if (setsockopt(sockfd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6)) < 0) {
             ff_log_net_error(NULL, AV_LOG_ERROR, "setsockopt(IPV6_DROP_MEMBERSHIP)");
@@ -240,7 +242,8 @@ static int udp_leave_multicast_group(int sockfd, struct sockaddr *addr,struct so
 
 static int udp_set_multicast_sources(URLContext *h,
                                      int sockfd, struct sockaddr *addr,
-                                     int addr_len, struct sockaddr_storage *sources,
+                                     int addr_len, struct sockaddr_storage *local_addr,
+                                     struct sockaddr_storage *sources,
                                      int nb_sources, int include)
 {
 #if HAVE_STRUCT_GROUP_SOURCE_REQ && defined(MCAST_BLOCK_SOURCE) && !defined(_WIN32) && (!defined(TARGET_OS_TV) || !TARGET_OS_TV)
@@ -251,6 +254,7 @@ static int udp_set_multicast_sources(URLContext *h,
         struct group_source_req mreqs;
         int level = addr->sa_family == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
 
+        //TODO: Interface index should be looked up from local_addr
         mreqs.gsr_interface = 0;
         memcpy(&mreqs.gsr_group, addr, addr_len);
         memcpy(&mreqs.gsr_source, &sources[i], sizeof(*sources));
@@ -280,7 +284,10 @@ static int udp_set_multicast_sources(URLContext *h,
         }
 
         mreqs.imr_multiaddr.s_addr = ((struct sockaddr_in *)addr)->sin_addr.s_addr;
-        mreqs.imr_interface.s_addr = INADDR_ANY;
+        if (local_addr)
+            mreqs.imr_interface= ((struct sockaddr_in *)local_addr)->sin_addr;
+        else
+            mreqs.imr_interface.s_addr= INADDR_ANY;
         mreqs.imr_sourceaddr.s_addr = ((struct sockaddr_in *)&sources[i])->sin_addr.s_addr;
 
         if (setsockopt(sockfd, IPPROTO_IP,
@@ -812,7 +819,7 @@ static int udp_open(URLContext *h, const char *uri, int flags)
             if (s->filters.nb_include_addrs) {
                 if (udp_set_multicast_sources(h, udp_fd,
                                               (struct sockaddr *)&s->dest_addr,
-                                              s->dest_addr_len,
+                                              s->dest_addr_len, &s->local_addr_storage,
                                               s->filters.include_addrs,
                                               s->filters.nb_include_addrs, 1) < 0)
                     goto fail;
@@ -823,7 +830,7 @@ static int udp_open(URLContext *h, const char *uri, int flags)
             if (s->filters.nb_exclude_addrs) {
                 if (udp_set_multicast_sources(h, udp_fd,
                                               (struct sockaddr *)&s->dest_addr,
-                                              s->dest_addr_len,
+                                              s->dest_addr_len, &s->local_addr_storage,
                                               s->filters.exclude_addrs,
                                               s->filters.nb_exclude_addrs, 0) < 0)
                     goto fail;