# HG changeset patch
# User Florian Westphal <fw@strlen.de>
# Date 1212094152 -7200
# Node ID c1de9e827b5f82c13ed5db036a09eea86c69b2d1
# Parent  f19a176ad723ce12db8c2b7d0cff45bcfb539c8e
Add ipv4 header checksum support.

diff -r f19a176ad723 -r c1de9e827b5f src/internet-node/ipv4-header.cc
--- a/src/internet-node/ipv4-header.cc	Thu May 29 21:56:24 2008 +0200
+++ b/src/internet-node/ipv4-header.cc	Thu May 29 22:49:12 2008 +0200
@@ -178,6 +178,20 @@
   return m_goodChecksum;
 }
 
+uint16_t
+Ipv4Header::Checksum(Buffer::Iterator &i)
+{
+  uint32_t sum = 0;
+
+  // doesn't handle ip headers with size != 20 yet
+  for (int j = 0; j < 10 ; j++)
+    sum += i.ReadU16 ();
+
+  while (sum >> 16)
+    sum = (sum >> 16) + sum & 0xFFFFU;
+  return ~sum;
+}
+
 
 TypeId 
 Ipv4Header::GetTypeId (void)
@@ -266,16 +280,12 @@
 
   if (m_calcChecksum) 
     {
-#if 0
-      // XXX we need to add Buffer::Iterator::PeekData method
-      uint8_t *data = start.PeekData ();
-      uint16_t checksum = UtilsChecksumCalculate (0, data, GetSize ());
-      checksum = UtilsChecksumComplete (checksum);
+      i = start;
+      uint16_t checksum = Checksum(i);
       NS_LOG_LOGIC ("checksum=" <<checksum);
       i = start;
       i.Next (10);
       i.WriteU16 (checksum);
-#endif
     }
 }
 uint32_t
@@ -312,18 +322,11 @@
 
   if (m_calcChecksum) 
     {
-#if 0
-      uint8_t *data = start.PeekData ();
-      uint16_t localChecksum = UtilsChecksumCalculate (0, data, headerSize);
-      if (localChecksum == 0xffff) 
-        {
-          m_goodChecksum = true;
-        } 
-      else 
-        {
-          m_goodChecksum = false;
-        }
-#endif
+      i = start;
+      uint16_t checksum = Checksum(i);
+      NS_LOG_LOGIC ("checksum=" <<checksum);
+
+      m_goodChecksum = (checksum == 0);
     }
   return GetSerializedSize ();
 }
diff -r f19a176ad723 -r c1de9e827b5f src/internet-node/ipv4-header.h
--- a/src/internet-node/ipv4-header.h	Thu May 29 21:56:24 2008 +0200
+++ b/src/internet-node/ipv4-header.h	Thu May 29 22:49:12 2008 +0200
@@ -145,7 +145,7 @@
   virtual void Serialize (Buffer::Iterator start) const;
   virtual uint32_t Deserialize (Buffer::Iterator start);
 private:
-
+  static uint16_t Checksum(Buffer::Iterator &i);
   enum FlagsE {
     DONT_FRAGMENT = (1<<0),
     MORE_FRAGMENTS = (1<<1)