Fix an error the TCP/IP received sequence number counting

git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@4416 7fd9a85b-ad96-42d3-883c-3090e2eb8679

apps/interpreters/ficl/README.txt

@@ -11,7 +11,7 @@ Build Instructions
 
 Disclaimer:  This installation steps have only been exercised using Ficl
 4.1.0.  With new versions you will likely have to make some adjustments
-to this instructtions or to the files within this directory.  This of this
+to this instructtions or to the files within this directory.  Think of this
 information as "recommendations" -- not necessarily proven instructions.
 
 1. CD to apps/interpreters/ficl

nuttx/ChangeLog

@@ -2484,3 +2484,12 @@
 	  the accecpt() and connect() logic.  Contributed by Max Nekludov.
 	* net/recvfrom.c and net/uip/uip_tcpcallback.c:  Fix a leak in the TCP
 	  read-ahead logic.  This is a *critical* bug fix!
+	* net/uip/uip_tcpinput.c:  Correct an error in the TCP stack.  It was
+	  incrementing the received sequence number BEFORE determining if the
+	  incoming data could be handled.  If the data was dropped (usually because
+	  there is insufficient buffering space), then no ACK will be sent and the
+	  sequence number will be wrong.  The end consequence of the bad sequence
+	  number was that the when the dropped packet was re-transmitted, it was
+	  was ignored because its sequence number looked wrong.  Fix was, obviously,
+	  to only increment the recevied sequence number if the TCP data was
+	  accepted.

nuttx/include/net/uip/uip.h

@@ -5,8 +5,8 @@
  * are used by uIP programs as well as internal uIP structures and function
  * declarations.
  *
- *   Copyright (C) 2007-2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2012 Gregory Nutt. All rights reserved.
- *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * This logic was leveraged from uIP which also has a BSD-style license:
  *

nuttx/net/recvfrom.c

@@ -183,11 +183,15 @@ static inline void recvfrom_newtcpdata(FAR struct uip_driver_s *dev,
 
       nsaved = uip_datahandler(conn, buffer, buflen);
 
-      /* There are complicated buffering issues that are not addressed
+      /* There are complicated buffering issues that are not addressed fully
-       * properly here.  For example, what if up_datahandler() cannot buffer
+       * here.  For example, what if up_datahandler() cannot buffer the
-       * the remainder of the packet?  In that case, the data will be dropped
+       * remainder of the packet?  In that case, the data will be dropped but
-       * but still ACKed.  Therefore it will not be resent.  Fixing this could be
+       * still ACKed.  Therefore it would not be resent.
-       * tricky.
+       * 
+       * This is probably not an issue here because we only get here if the
+       * read-ahead buffers are empty and there would have to be something
+       * serioulsy wrong with the configuration not to be able to buffer a
+       * partial packet in this context.
        */
 
 #ifdef CONFIG_DEBUG_NET
@@ -469,7 +473,9 @@ static uint16_t recvfrom_tcpinterrupt(struct uip_driver_s *dev, void *conn,
 
       if ((flags & UIP_NEWDATA) != 0)
         {
-          /* Copy the data from the packet */
+          /* Copy the data from the packet (saving any unused bytes from the
+           * packet in the read-ahead buffer).
+           */
 
           recvfrom_newtcpdata(dev, pstate);
 
@@ -489,10 +495,8 @@ static uint16_t recvfrom_tcpinterrupt(struct uip_driver_s *dev, void *conn,
             {
               nllvdbg("TCP resume\n");
 
-              /* The TCP receive buffer is full.  Return now, perhaps truncating
+              /* The TCP receive buffer is full.  Return now and don't allow
-               * the received data (need to fix that).
+               * any further TCP call backs.
-               *
-               * Don't allow any further TCP call backs.
                */
 
               pstate->rf_cb->flags   = 0;

nuttx/net/uip/uip_tcpinput.c

@@ -2,8 +2,8 @@
  * net/uip/uip_tcpinput.c
  * Handling incoming TCP input
  *
- *   Copyright (C) 2007-2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2012 Gregory Nutt. All rights reserved.
- *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Adapted for NuttX from logic in uIP which also has a BSD-like license:
  *
@@ -43,6 +43,7 @@
  ****************************************************************************/
 
 #include <nuttx/config.h>
+
 #if defined(CONFIG_NET) && defined(CONFIG_NET_TCP)
 
 #include <stdint.h>
@@ -588,6 +589,10 @@ found:
                 goto drop;
               }
 
+            /* Update the sequence number and indicate that the connection has
+             * been closed.
+             */
+
             uip_incr32(conn->rcvseq, dev->d_len + 1);
             flags |= UIP_CLOSE;
 
@@ -631,24 +636,20 @@ found:
           {
             dev->d_urglen   = 0;
 #else /* CONFIG_NET_TCPURGDATA */
-            dev->d_appdata =
+            dev->d_appdata  = ((uint8_t*)dev->d_appdata) + ((pbuf->urgp[0] << 8) | pbuf->urgp[1]);
-              ((uint8_t*)dev->d_appdata) + ((pbuf->urgp[0] << 8) | pbuf->urgp[1]);
+            dev->d_len     -= (pbuf->urgp[0] << 8) | pbuf->urgp[1];
-            dev->d_len    -=
-              (pbuf->urgp[0] << 8) | pbuf->urgp[1];
 #endif /* CONFIG_NET_TCPURGDATA */
           }
 
         /* If d_len > 0 we have TCP data in the packet, and we flag this
-         * by setting the UIP_NEWDATA flag and update the sequence number
+         * by setting the UIP_NEWDATA flag. If the application has stopped
-         * we acknowledge. If the application has stopped the dataflow
+         * the dataflow using uip_stop(), we must not accept any data
-         * using uip_stop(), we must not accept any data packets from the
+         * packets from the remote host.
-         * remote host.
          */
 
         if (dev->d_len > 0 && (conn->tcpstateflags & UIP_STOPPED) == 0)
           {
             flags |= UIP_NEWDATA;
-            uip_incr32(conn->rcvseq, dev->d_len);
           }
 
         /* Check if the available buffer space advertised by the other end
@@ -672,7 +673,7 @@ found:
         conn->mss = tmp16;
 
         /* If this packet constitutes an ACK for outstanding data (flagged
-         * by the UIP_ACKDATA flag, we should call the application since it
+         * by the UIP_ACKDATA flag), we should call the application since it
          * might want to send more data. If the incoming packet had data
          * from the peer (as flagged by the UIP_NEWDATA flag), the
          * application must also be notified.
@@ -691,8 +692,33 @@ found:
 
         if ((flags & (UIP_NEWDATA | UIP_ACKDATA)) != 0)
           {
+            /* Clear sndlen and remember the size in d_len.  The application
+             * may modify d_len and we will need this value later when we
+             * update the sequence number.
+             */
+
             dev->d_sndlen = 0;
-            result        = uip_tcpcallback(dev, conn, flags);
+            len           = dev->d_len;
+
+            /* Provide the packet to the application */
+
+            result = uip_tcpcallback(dev, conn, flags);
+
+            /* If the application successfully handled the incoming data,
+             * then UIP_SNDACK will be set in the result.  In this case,
+             * we need to update the sequence number.  The ACK will be
+             * send by uip_tcpappsend().
+             */
+
+            if ((result & UIP_SNDACK) != 0)
+              {
+                /* Update the sequence number using the saved length */
+
+                uip_incr32(conn->rcvseq, len);
+              }
+
+            /* Send the response, ACKing the data or not, as appropriate */
+
             uip_tcpappsend(dev, conn, result);
             return;
           }

nuttx/net/uip/uip_tcpsend.c

@@ -1,8 +1,8 @@
 /****************************************************************************
  * net/uip/uip_tcpsend.c
  *
- *   Copyright (C) 2007-2010 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2010, 2012 Gregory Nutt. All rights reserved.
- *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Adapted for NuttX from logic in uIP which also has a BSD-like license:
  *