If a udp_pcb has a local_ip set, check if it is the same as the one of the netif used for sending to prevent sending from old addresses after a netif address gets changed (partly fixes bug #3168).

CHANGELOG

@@ -158,6 +158,11 @@ HISTORY
 
   ++ Bug fixes:
 
+  2007-05-16 Simon Goldschmidt
+  * api_msg.c, udp.c: If a udp_pcb has a local_ip set, check if it is the same
+    as the one of the netif used for sending to prevent sending from old
+    addresses after a netif address gets changed (partly fixes bug #3168).
+
   2007-05-16 Frédéric Bernon
   * tcpip.c, igmp.h, igmp.c: Fixed bug "#19800 : IGMP: igmp_tick() will not work
     with NO_SYS=1". Note that igmp_init is always in tcpip_thread (and not in 

src/api/api_msg.c

@@ -582,9 +582,9 @@ do_send(struct api_msg_msg *msg)
 #if LWIP_RAW
       case NETCONN_RAW:
         if (msg->msg.b->addr==NULL) {
-          raw_send(msg->conn->pcb.raw, msg->msg.b->p);
+          msg->conn->err = raw_send(msg->conn->pcb.raw, msg->msg.b->p);
         } else {
-          raw_sendto(msg->conn->pcb.raw, msg->msg.b->p, msg->msg.b->addr);
+          msg->conn->err = raw_sendto(msg->conn->pcb.raw, msg->msg.b->p, msg->msg.b->addr);
         }
         break;
 #endif
@@ -595,9 +595,9 @@ do_send(struct api_msg_msg *msg)
         /* FALLTHROUGH */
       case NETCONN_UDP:
         if (msg->msg.b->addr==NULL) {
-          udp_send(msg->conn->pcb.udp, msg->msg.b->p);
+          msg->conn->err = udp_send(msg->conn->pcb.udp, msg->msg.b->p);
         } else {
-          udp_sendto(msg->conn->pcb.udp, msg->msg.b->p, msg->msg.b->addr, msg->msg.b->port);
+          msg->conn->err = udp_sendto(msg->conn->pcb.udp, msg->msg.b->p, msg->msg.b->addr, msg->msg.b->port);
         }
         break;
 #endif /* LWIP_UDP */

src/core/udp.c

@@ -355,6 +355,16 @@ udp_send(struct udp_pcb *pcb, struct pbuf *p)
     /* use outgoing network interface IP address as source address */
     src_ip = &(netif->ip_addr);
   } else {
+    /* check if UDP PCB local IP address is correct */
+    if (!ip_addr_cmp(&(pcb->local_ip), &(netif->ip_addr))) {
+      if (q != p) {
+        /* free the header pbuf */
+        pbuf_free(q);
+        q = NULL;
+        /* p is still referenced by the caller, and will live on */
+      }
+      return ERR_VAL;
+    }
     /* use UDP PCB local IP address as source address */
     src_ip = &(pcb->local_ip);
   }