fixed bug #45827: recvfrom: TCP window is updated with MSG_PEEK

CHANGELOG

@@ -249,6 +249,9 @@ HISTORY
 
   ++ Bugfixes:
 
+  2015-08-25: Simon Goldschmidt
+  * sockets.c: fixed bug #45827: recvfrom: TCP window is updated with MSG_PEEK
+
   2015-08-20: Manoj Kumar
   * snmp_msg.h, msg_in.c: fixed bug #43790: Sending octet string of Length >255
     from SNMP agent

src/api/sockets.c

@@ -907,11 +907,13 @@ lwip_recvfrom(int s, void *mem, size_t len, int flags,
         } else {
           netbuf_delete((struct netbuf *)buf);
         }
+        buf = NULL;
       }
     }
   } while (!done);
 
-  if ((off > 0) && (NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP)) {
+  if ((off > 0) && (NETCONNTYPE_GROUP(netconn_type(sock->conn)) == NETCONN_TCP) &&
+      ((flags & MSG_PEEK) == 0)) {
     /* update receive window */
     netconn_recved(sock->conn, (u32_t)off);
   }