net/udp: Correct an error introduce in recent fixes for UDP connected sockets. The interaction between psock_udp_send() and psock_udp_sendto() was perverse: It should always pass a NULL destinatino address.

net/udp/udp_psock_send.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * net/udp/udp_psock_send.c
  *
- *   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2015, 2018 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -65,17 +65,6 @@ ssize_t psock_udp_send(FAR struct socket *psock, FAR const void *buf,
                        size_t len)
 {
   FAR struct udp_conn_s *conn;
-  union
-  {
-    struct sockaddr     addr;
-#ifdef CONFIG_NET_IPv4
-    struct sockaddr_in  addr4;
-#endif
-#ifdef CONFIG_NET_IPv6
-    struct sockaddr_in6 addr6;
-#endif
-  } to;
-  socklen_t tolen;
 
   DEBUGASSERT(psock != NULL && psock->s_crefs > 0);
   DEBUGASSERT(psock->s_type == SOCK_DGRAM);
@@ -94,29 +83,5 @@ ssize_t psock_udp_send(FAR struct socket *psock, FAR const void *buf,
 
   /* Yes, then let psock_sendto to the work */
 
-#ifdef CONFIG_NET_IPv4
+  return psock_udp_sendto(psock, buf, len, 0, NULL, 0);
-#ifdef CONFIG_NET_IPv6
-  if (conn->domain == PF_INET)
-#endif
-    {
-      tolen               = sizeof(struct sockaddr_in);
-      to.addr4.sin_family = AF_INET;
-      to.addr4.sin_port   = conn->rport;
-      net_ipv4addr_copy(to.addr4.sin_addr.s_addr, conn->u.ipv4.raddr);
-    }
-#endif /* CONFIG_NET_IPv4 */
-
-#ifdef CONFIG_NET_IPv6
-#ifdef CONFIG_NET_IPv4
-  else
-#endif
-    {
-      tolen               = sizeof(struct sockaddr_in6);
-      to.addr6.sin6_family = AF_INET6;
-      to.addr6.sin6_port   = conn->rport;
-      net_ipv6addr_copy(to.addr6.sin6_addr.s6_addr, conn->u.ipv6.raddr);
-    }
-#endif /* CONFIG_NET_IPv6 */
-
-  return psock_udp_sendto(psock, buf, len, 0, &to.addr, tolen);
 }

net/udp/udp_psock_sendto_buffered.c

@@ -630,6 +630,15 @@ ssize_t psock_udp_sendto(FAR struct socket *psock, FAR const void *buf,
       return -EISCONN;
     }
 
+  /* Otherwise, if the socket is not connected, then a destination address
+   * must be provided.
+   */
+
+  else if (to == NULL && !_SS_ISCONNECTED(psock->s_flags))
+    {
+      return -EDESTADDRREQ;
+    }
+
   /* Make sure that we have the IP address mapping */
 
   conn = (FAR struct udp_conn_s *)psock->s_conn;
@@ -693,8 +702,48 @@ ssize_t psock_udp_sendto(FAR struct socket *psock, FAR const void *buf,
         }
 
       /* Initialize the write buffer */
+      /* Check if the socket is connected */
+
+      if (!_SS_ISCONNECTED(psock->s_flags))
+        {
+          /* Yes.. get the connection address from the connection structure */
+
+#ifdef CONFIG_NET_IPv4
+#ifdef CONFIG_NET_IPv6
+          if (conn->domain == PF_INET)
+#endif
+            {
+              FAR struct sockaddr_in *addr4 =
+                (FAR struct sockaddr_in *)&wrb->wb_dest;
+
+              addr4->sin_family = AF_INET;
+              addr4->sin_port   = conn->rport;
+              net_ipv4addr_copy(addr4->sin_addr.s_addr, conn->u.ipv4.raddr);
+            }
+#endif /* CONFIG_NET_IPv4 */
+
+#ifdef CONFIG_NET_IPv6
+#ifdef CONFIG_NET_IPv4
+          else
+#endif
+            {
+              FAR struct sockaddr_in6 *addr6 =
+                (FAR struct sockaddr_in6 *)&wrb->wb_dest;
+
+              addr6->sin6_family = AF_INET6;
+              addr6->sin6_port   = conn->rport;
+              net_ipv6addr_copy(addr6->sin6_addr.s6_addr, conn->u.ipv6.raddr);
+            }
+#endif /* CONFIG_NET_IPv6 */
+        }
+
+      /* Not connected.  Use the provided destination address */
+
+      else
+        {
+          memcpy(&wrb->wb_dest, to, tolen);
+        }
 
-      memcpy(&wrb->wb_dest, to, tolen);
 #ifdef CONFIG_NET_SOCKOPTS
       wrb->wb_start = clock_systimer();
 #endif

net/udp/udp_psock_sendto_unbuffered.c

@@ -335,6 +335,15 @@ ssize_t psock_udp_sendto(FAR struct socket *psock, FAR const void *buf,
       return -EISCONN;
     }
 
+  /* Otherwise, if the socket is not connected, then a destination address
+   * must be provided.
+   */
+
+  else if (to == NULL && !_SS_ISCONNECTED(psock->s_flags))
+    {
+      return -EDESTADDRREQ;
+    }
+
 #if defined(CONFIG_NET_ARP_SEND) || defined(CONFIG_NET_ICMPv6_NEIGHBOR)
 #ifdef CONFIG_NET_ARP_SEND
 #ifdef CONFIG_NET_ICMPv6_NEIGHBOR
@@ -409,18 +418,25 @@ ssize_t psock_udp_sendto(FAR struct socket *psock, FAR const void *buf,
   state.st_time = clock_systimer();
 #endif
 
-  /* Setup the UDP socket.  udp_connect will set the remote address in the
+  /* Setup the UDP socket.  */
-   * connection structure.
-   */
 
   conn = (FAR struct udp_conn_s *)psock->s_conn;
   DEBUGASSERT(conn);
 
-  ret = udp_connect(conn, to);
+  /* Check if the socket is connected */
-  if (ret < 0)
+
+  if (!_SS_ISCONNECTED(psock->s_flags))
     {
-      nerr("ERROR: udp_connect failed: %d\n", ret);
+      /* No.. Call udp_connect() to set the remote address in the connection
-      goto errout_with_lock;
+       * structure to the sendto() destination address.
+       */
+
+      ret = udp_connect(conn, to);
+      if (ret < 0)
+        {
+          nerr("ERROR: udp_connect failed: %d\n", ret);
+          goto errout_with_lock;
+        }
     }
 
   /* Get the device that will handle the remote packet transfers.  This