From 60c2377899bf3dfc2d357efcdbbd242be8b52d0f Mon Sep 17 00:00:00 2001
From: moisesber <moisesber@gmail.com>
Date: Mon, 31 Aug 2015 16:42:43 +0200
Subject: [PATCH] TCP checksum code correction, based on JS Wrench code.
---
.../net/floodlightcontroller/packet/TCP.java | 152 +++++++++++++++---
1 file changed, 126 insertions(+), 26 deletions(-)
diff --git a/src/main/java/net/floodlightcontroller/packet/TCP.java b/src/main/java/net/floodlightcontroller/packet/TCP.java
index 3b794a4ba..1fdf1aafd 100644
--- a/src/main/java/net/floodlightcontroller/packet/TCP.java
+++ b/src/main/java/net/floodlightcontroller/packet/TCP.java
@@ -207,36 +207,136 @@ public class TCP extends BasePacket {
((IPv4)this.parent).setProtocol(IpProtocol.TCP);
// compute checksum if needed
- if (this.checksum == 0) {
- bb.rewind();
- int accumulation = 0;
-
- // compute pseudo header mac
- if (this.parent != null && this.parent instanceof IPv4) {
- IPv4 ipv4 = (IPv4) this.parent;
- accumulation += ((ipv4.getSourceAddress().getInt() >> 16) & 0xffff)
- + (ipv4.getSourceAddress().getInt() & 0xffff);
- accumulation += ((ipv4.getDestinationAddress().getInt() >> 16) & 0xffff)
- + (ipv4.getDestinationAddress().getInt() & 0xffff);
- accumulation += ipv4.getProtocol().getIpProtocolNumber() & 0xff;
- accumulation += length & 0xffff;
- }
+ if (this.checksum == 0) {
- for (int i = 0; i < length / 2; ++i) {
- accumulation += 0xffff & bb.getShort();
- }
- // pad to an even number of shorts
- if (length % 2 > 0) {
- accumulation += (bb.get() & 0xff) << 8;
- }
+ if (this.parent != null && this.parent instanceof IPv4) {
+ //Checksum calculation based on the JSocket Wrench code
+ // https://github.com/ehrmann/jswrench
+ //The original code can be found at
+ //https://github.com/ehrmann/jswrench/blob/master/src/com/act365/net/SocketUtils.java
+ IPv4 ipv4 = (IPv4) this.parent;
- accumulation = ((accumulation >> 16) & 0xffff)
- + (accumulation & 0xffff);
- this.checksum = (short) (~accumulation & 0xffff);
- bb.putShort(16, this.checksum);
- }
+ int bufferlength = length + 12;
+ boolean odd = length % 2 == 1;
+ byte[] source = ipv4.getSourceAddress().getBytes();
+ byte[] destination = ipv4.getDestinationAddress().getBytes();
+
+ if (odd) {
+ ++bufferlength;
+ }
+
+ byte[] buffer = new byte[bufferlength];
+
+ buffer[0] = source[0];
+ buffer[1] = source[1];
+ buffer[2] = source[2];
+ buffer[3] = source[3];
+
+ buffer[4] = destination[0];
+ buffer[5] = destination[1];
+ buffer[6] = destination[2];
+ buffer[7] = destination[3];
+
+ buffer[8] = (byte) 0;
+ buffer[9] = (byte) ipv4.getProtocol().getIpProtocolNumber();
+
+ shortToBytes((short) length, buffer, 10);
+
+ int i = 11;
+
+ while (++i < length + 12) {
+ buffer[i] = data[i + 0 - 12];
+ }
+
+ if (odd) {
+ buffer[i] = (byte) 0;
+ }
+
+ this.checksum = checksum(buffer, buffer.length, 0);
+ } else {
+ bb.rewind();
+ int accumulation = 0;
+ for (int i = 0; i < length / 2; ++i) {
+ accumulation += 0xffff & bb.getShort();
+ }
+ // pad to an even number of shorts
+ if (length % 2 > 0) {
+ accumulation += (bb.get() & 0xff) << 8;
+ }
+
+ accumulation = ((accumulation >> 16) & 0xffff)
+ + (accumulation & 0xffff);
+ this.checksum = (short) (~accumulation & 0xffff);
+ }
+
+ bb.putShort(16, this.checksum);
+ }
+
return data;
}
+
+ //Checksum calculation based on the JSocket Wrench code
+ // https://github.com/ehrmann/jswrench
+ //The original code can be found at
+ //https://github.com/ehrmann/jswrench/blob/master/src/com/act365/net/SocketUtils.java
+ private static long integralFromBytes(byte[] buffer, int offset, int length) {
+
+ long answer = 0;
+
+ while (--length >= 0) {
+ answer = answer << 8;
+ answer |= buffer[offset] >= 0 ? buffer[offset]
+ : 0xffffff00 ^ buffer[offset];
+ ++offset;
+ }
+
+ return answer;
+ }
+
+ //Checksum calculation based on the JSocket Wrench code
+ // https://github.com/ehrmann/jswrench
+ //The original code can be found at
+ //https://github.com/ehrmann/jswrench/blob/master/src/com/act365/net/SocketUtils.java
+ private static void shortToBytes(short value, byte[] buffer, int offset) {
+ buffer[offset + 1] = (byte) (value & 0xff);
+ value = (short) (value >> 8);
+ buffer[offset] = (byte) (value);
+ }
+
+ //Checksum calculation based on the JSocket Wrench code
+ // https://github.com/ehrmann/jswrench
+ //The original code can be found at
+ //https://github.com/ehrmann/jswrench/blob/master/src/com/act365/net/SocketUtils.java
+ private static short checksum(byte[] message, int length, int offset) {
+ // Sum consecutive 16-bit words.
+
+ int sum = 0;
+
+ while (offset < length - 1) {
+
+ sum += (int) integralFromBytes(message, offset, 2);
+
+ offset += 2;
+ }
+
+ if (offset == length - 1) {
+
+ sum += (message[offset] >= 0 ? message[offset]
+ : message[offset] ^ 0xffffff00) << 8;
+ }
+
+ // Add upper 16 bits to lower 16 bits.
+
+ sum = (sum >>> 16) + (sum & 0xffff);
+
+ // Add carry
+
+ sum += sum >>> 16;
+
+ // Ones complement and truncate.
+
+ return (short) ~sum;
+ }
/* (non-Javadoc)
* @see java.lang.Object#hashCode()
--
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