Fix a bug where recv[from]() would hang when remote host gracefully closed connection

git-svn-id: http://svn.code.sf.net/p/nuttx/code/trunk@5539 42af7a65-404d-4744-a932-0658087f49c3

nuttx/ChangeLog

@@ -3989,3 +3989,7 @@
 	  Marcelo, adapted to use kconfig-frontends.
 	* net/send():  Add logic to work around delayed ACKs by splitting
 	  packets (contributed by Yan T.).
+	* net/recvfrom():  Fix a bug.  When the host closes a connection
+	  (gracefully).  recv[from]() returned success and the closure
+	  was never detected.  Hmmm.. I don't know why the network monitor
+	  did not catch this event.  This is an important bug fix.

nuttx/net/recvfrom.c

@@ -83,7 +83,7 @@ struct recvfrom_s
   FAR struct sockaddr_in    *rf_from;      /* Address of sender */
 #endif
   size_t                     rf_recvlen;   /* The received length */
-  int                        rf_result;    /* OK:success, failure:negated errno */
+  int                        rf_result;    /* Success:OK, failure:negated errno */
 };
 #endif /* CONFIG_NET_UDP || CONFIG_NET_TCP */
 
@@ -553,6 +553,8 @@ static uint16_t recvfrom_tcpinterrupt(struct uip_driver_s *dev, void *conn,
 
       else if ((flags & (UIP_CLOSE|UIP_ABORT|UIP_TIMEDOUT)) != 0)
         {
+          FAR struct socket *psock = 0;
+
           nllvdbg("error\n");
 
           /* Stop further callbacks */
@@ -563,9 +565,29 @@ static uint16_t recvfrom_tcpinterrupt(struct uip_driver_s *dev, void *conn,
 
           /* If the peer gracefully closed the connection, then return zero
            * (end-of-file).  Otherwise, report a not-connected error
+           * _SF_CONNECTED==0 && _SF_CLOSED==1 - the socket was
+           *   gracefully disconnected
+           * _SF_CONNECTED==0 && _SF_CLOSED==0 - the socket was
+           *  rudely disconnected
            */
 
+          psock = pstate->rf_sock;
           if ((flags & UIP_CLOSE) != 0)
+            {
+              psock->s_flags &= ~_SF_CONNECTED;
+              psock->s_flags |= _SF_CLOSED;
+            }
+          else
+            {
+              psock->s_flags &= ~(_SF_CONNECTED |_SF_CLOSED);
+            }
+
+          /* If no data has been received, then return ENOTCONN.
+           * Otherwise, let this return success.  The failure will
+           * be reported the next time that recv[from]() is called.
+           */
+
+          if (pstate->rf_recvlen > 0)
             {
               pstate->rf_result = 0;
             }

nuttx/net/send.c

@@ -324,7 +324,7 @@ static uint16_t send_interrupt(struct uip_driver_s *dev, void *pvconn,
 
               if (next_sndlen > 0 && (next_sndlen - uip_mss(conn)) < 0)
                 {
-                  /* Here, we know that sndlen must be MSS <= sndlen <= 2*MSS
+                  /* Here, we know that sndlen must be MSS < sndlen <= 2*MSS
                    * and so (sndlen / 2) is <= MSS.
                    */