Diff: cyclone_tcp/ipv6/ipv6_pmtu.c

Revision:

0:8918a71cdbe9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cyclone_tcp/ipv6/ipv6_pmtu.c	Sat Feb 04 18:15:49 2017 +0000
@@ -0,0 +1,116 @@
+/**
+ * @file ipv6_pmtu.c
+ * @brief Path MTU Discovery for IPv6
+ *
+ * @section License
+ *
+ * Copyright (C) 2010-2017 Oryx Embedded SARL. All rights reserved.
+ *
+ * This file is part of CycloneTCP Open.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * @author Oryx Embedded SARL (www.oryx-embedded.com)
+ * @version 1.7.6
+ **/
+
+//Switch to the appropriate trace level
+#define TRACE_LEVEL IPV6_TRACE_LEVEL
+
+//Dependencies
+#include "core/net.h"
+#include "core/ip.h"
+#include "ipv6/ipv6.h"
+#include "ipv6/ipv6_pmtu.h"
+#include "ipv6/ndp.h"
+#include "ipv6/ndp_cache.h"
+#include "debug.h"
+
+//Check TCP/IP stack configuration
+#if (IPV6_SUPPORT == ENABLED && IPV6_PMTU_SUPPORT == ENABLED)
+
+
+/**
+ * @brief Retrieve the PMTU for the specified path
+ * @param[in] interface Underlying network interface
+ * @param[in] destAddr Destination IPv6 address
+ * @return PMTU value
+ **/
+
+size_t ipv6GetPathMtu(NetInterface *interface, const Ipv6Addr *destAddr)
+{
+   size_t pathMtu;
+
+#if (NDP_SUPPORT == ENABLED)
+   NdpDestCacheEntry *entry;
+
+   //Search the Destination Cache for the specified IPv6 address
+   entry = ndpFindDestCacheEntry(interface, destAddr);
+
+   //Check whether a matching entry has been found in the Destination Cache
+   if(entry != NULL)
+   {
+      //Use the existing PMTU estimate
+      pathMtu = entry->pathMtu;
+   }
+   else
+   {
+      //If no entry exists in the Destination Cache, the PMTU value for
+      //the path is assumed to be the MTU of the first-hop link
+      pathMtu = interface->ipv6Context.linkMtu;
+   }
+#else
+   //The PMTU value for the path is assumed to be the MTU of the first-hop link
+   pathMtu = interface->ipv6Context.linkMtu;
+#endif
+
+   //Return the PMTU value
+   return pathMtu;
+}
+
+
+/**
+ * @brief Update the PMTU for the specified path
+ * @param[in] interface Underlying network interface
+ * @param[in] destAddr Destination IPv6 address
+ * @param[in] tentativePathMtu Tentative PMTU value
+ **/
+
+void ipv6UpdatePathMtu(NetInterface *interface,
+   const Ipv6Addr *destAddr, size_t tentativePathMtu)
+{
+#if (NDP_SUPPORT == ENABLED)
+   NdpDestCacheEntry *entry;
+
+   //The destination address from the original packet is used to determine
+   //which path the message applies to
+   entry = ndpFindDestCacheEntry(interface, destAddr);
+
+   //Check whether a matching entry has been found in the Destination Cache
+   if(entry != NULL)
+   {
+      //Compare the tentative PMTU to the existing PMTU
+      if(tentativePathMtu < entry->pathMtu)
+      {
+         //If the tentative PMTU is less than the existing PMTU estimate,
+         //the tentative PMTU replaces the existing PMTU
+         entry->pathMtu = tentativePathMtu;
+      }
+   }
+#endif
+}
+
+#endif
+