From: dw6 <dw6@270642c3-0616-0410-b53a-bc976706d245>
Date: Wed, 25 Jun 2008 15:56:00 +0000 (+0000)
Subject: fix for checksum bug
X-Git-Url: http://g0dil.de/git?a=commitdiff_plain;h=eb5940657b289a192f3bbd2660e8ecf421eb624d;p=senf.git

fix for checksum bug

git-svn-id: https://svn.berlios.de/svnroot/repos/senf/trunk@882 270642c3-0616-0410-b53a-bc976706d245
---

diff --git a/Packets/DefaultBundle/UDPPacket.cc b/Packets/DefaultBundle/UDPPacket.cc
index 892487f..f3cfc56 100644
--- a/Packets/DefaultBundle/UDPPacket.cc
+++ b/Packets/DefaultBundle/UDPPacket.cc
@@ -50,10 +50,7 @@ prefix_ boost::uint16_t senf::UDPPacketParser::calcChecksum()
     const
 {
     IpChecksum summer;
-    summer.feed( i(), i()+checksum_offset );
-    summer.feed( i()+checksum_offset+2, data().end() );
-    
-    // Now on to the awkward part: the IP pseudo header
+    // first on to the awkward part: the IP pseudo header
     IPv4Packet ipv4 (packet().rfind<IPv4Packet>(nothrow));
     if (ipv4) {
         // Pseudo header defined in RFC768
@@ -88,6 +85,11 @@ prefix_ boost::uint16_t senf::UDPPacketParser::calcChecksum()
         }
     }
     
+    // since header are 16 / even 32bit aligned we don't have to care for padding. since IpChecksum 
+    // cares for padding at the final summing we don't have to care is the payload is 16nbit-aligned, too.
+    summer.feed( i(), i()+checksum_offset );
+    summer.feed( i()+checksum_offset+2, data().end() );
+
     boost::uint16_t rv (summer.sum());
     return rv ? rv : 0xffffu;
 }