diff --git a/CHANGELOG b/CHANGELOG
index 3979fde0..c9c0799d 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -19,6 +19,12 @@ HISTORY
 
   ++ New features:
 
+  2007-09-15 Frédéric Bernon
+  * udp.h, udp.c, sockets.c: Changes for "#20503 IGMP Improvement". Add IP_MULTICAST_IF
+    option in socket API, and a new field "multicast_ip" in "struct udp_pcb" (for
+    netconn and raw API users), only if LWIP_IGMP=1. Add getsockopt processing for
+    IP_MULTICAST_TTL and IP_MULTICAST_IF.
+
   2007-09-10 Frédéric Bernon
   * snmp.h, mib2.c: enable to remove SNMP timer (which consumne several cycles
     even when it's not necessary). snmp_agent.txt tell to call snmp_inc_sysuptime()
diff --git a/src/api/sockets.c b/src/api/sockets.c
index 74ee6086..f61cf5a8 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -1108,6 +1108,18 @@ int lwip_getsockopt(int s, int level, int optname, void *optval, socklen_t *optl
         err = EINVAL;
       }
       break;
+#if LWIP_IGMP
+    case IP_MULTICAST_TTL:
+      if (*optlen < sizeof(u8_t)) {
+        err = EINVAL;
+      }
+      break;
+    case IP_MULTICAST_IF:
+      if (*optlen < sizeof(struct in_addr)) {
+        err = EINVAL;
+      }
+      break;
+#endif /* LWIP_IGMP */
 
     default:
       LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, UNIMPL: optname=0x%x, ..)\n",
@@ -1300,6 +1312,18 @@ static void lwip_getsockopt_internal(void *arg)
       LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_TOS) = %d\n",
                   s, *(int *)optval));
       break;
+#if LWIP_IGMP
+    case IP_MULTICAST_TTL:
+      *(u8_t*)optval = sock->conn->pcb.ip->ttl;
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_TTL) = %d\n",
+                  s, *(int *)optval));
+      break;
+    case IP_MULTICAST_IF:
+      ((struct in_addr*) optval)->s_addr = sock->conn->pcb.udp->multicast_ip.addr;
+      LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_IF) = 0x%x\n",
+                  s, *(u32_t *)optval));
+      break;
+#endif /* LWIP_IGMP */
     }  /* switch (optname) */
     break;
 
@@ -1437,16 +1461,27 @@ int lwip_setsockopt(int s, int level, int optname, const void *optval, socklen_t
       break;
 #if LWIP_IGMP
     case IP_MULTICAST_TTL:
-      /* NOTE, some BSD implementation use "int", some others "char" */
-      if ((optlen != sizeof(char)) && (optlen != sizeof(int))) 
+      if (optlen < sizeof(u8_t)) {
         err = EINVAL;
+      }
+      if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP) {
+        err = EAFNOSUPPORT;
+      }
+      break;
+    case IP_MULTICAST_IF:
+      if (optlen < sizeof(struct in_addr)) {
+        err = EINVAL;
+      }
+      if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP) {
+        err = EAFNOSUPPORT;
+      }
       break;
     case IP_ADD_MEMBERSHIP:
     case IP_DROP_MEMBERSHIP:
       if (optlen < sizeof(struct ip_mreq)) {
         err = EINVAL;
       }
-      if ((sock->conn->type == NETCONN_TCP) || (sock->conn->type == NETCONN_RAW)) {
+      if (NETCONNTYPE_GROUP(sock->conn->type) != NETCONN_UDP) {
         err = EAFNOSUPPORT;
       }
       break;
@@ -1622,10 +1657,10 @@ static void lwip_setsockopt_internal(void *arg)
       break;
 #if LWIP_IGMP
     case IP_MULTICAST_TTL:
-      if (optlen == sizeof(int))
-        sock->conn->pcb.tcp->ttl = (u8_t)(*(int*) optval);
-      if (optlen == sizeof(u8_t))
-        sock->conn->pcb.tcp->ttl = (u8_t)(*(u8_t*)optval);
+      sock->conn->pcb.udp->ttl = (u8_t)(*(u8_t*)optval);
+      break;
+    case IP_MULTICAST_IF:
+      sock->conn->pcb.udp->multicast_ip.addr = ((struct in_addr*) optval)->s_addr;
       break;
     case IP_ADD_MEMBERSHIP:
     case IP_DROP_MEMBERSHIP:
diff --git a/src/core/udp.c b/src/core/udp.c
index 8f259a1c..4b102b87 100644
--- a/src/core/udp.c
+++ b/src/core/udp.c
@@ -355,8 +355,14 @@ udp_send(struct udp_pcb *pcb, struct pbuf *p)
       return err;
     }
   }
+
   /* find the outgoing network interface for this packet */
+#if LWIP_IGMP
+  netif = ip_route((ip_addr_ismulticast(&(pcb->remote_ip)))?(&(pcb->multicast_ip)):(&(pcb->remote_ip)));
+#else
   netif = ip_route(&(pcb->remote_ip));
+#endif /* LWIP_IGMP */
+
   /* no outgoing network interface could be found? */
   if (netif == NULL) {
     LWIP_DEBUGF(UDP_DEBUG | 1, ("udp_send: No route to 0x%"X32_F"\n", pcb->remote_ip.addr));
diff --git a/src/include/lwip/udp.h b/src/include/lwip/udp.h
index afc152da..cd0f33cd 100644
--- a/src/include/lwip/udp.h
+++ b/src/include/lwip/udp.h
@@ -77,7 +77,12 @@ struct udp_pcb {
   u8_t flags;
   /* ports are in host byte order */
   u16_t local_port, remote_port;
-  
+
+#if LWIP_IGMP
+  /* outgoing network interface for multicast packets */
+  struct ip_addr multicast_ip;
+#endif /* LWIP_IGMP */
+
 #if LWIP_UDPLITE
   /* used for UDP_LITE only */
   u16_t chksum_len_rx, chksum_len_tx;