TCP checksum

dangan249 · Nov 5, 2013 · cd61526 · cd61526
1 parent 924fc4a
commit cd61526
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/ccs/neu/edu/andang/TCPHeader.java b/ccs/neu/edu/andang/TCPHeader.java
@@ -42,7 +42,7 @@ public TCPHeader(int source_port, int destination_port, long seq_num, long ack_n
 		this.generateChecksum(tcpPacket, pseudoHeader);
 	}
 
-	private void generateChecksum(byte[] byteArray, byte[] psedoHeader) {
+	private int generateChecksum(byte[] byteArray, byte[] psedoHeader) {
 		long sum = 0; 
 
 		//add TCP pseudo header containing src and dest IP addresses as 16 bit words
@@ -103,7 +103,8 @@ private void generateChecksum(byte[] byteArray, byte[] psedoHeader) {
 		//compute one's complement of sum
 		sum = (~sum&0xFFFF);
 		checksum = (int) sum;
-		System.out.println("The Checksum after one's complement-->"+Integer.toHexString(checksum));		
+		System.out.println("The Checksum after one's complement-->"+Integer.toHexString(checksum));
+		return checksum;
 	}
 
 	// Generate the TCP Header in a byte array format