C Programming TCP Checksum

Question

I have been having trouble doing the checksum for TCP for several days now. I have looked at many sources on the Internet but none of the examples that I have seen show you

Answer 1

I see a couple of things:

• You are not accounting for odd length data by padding with zero.
• You will need to account for network byte order when reading each word from the packet.
• Your use of htonl(0x0000ffff) seems suspicious. Why are you converting a constant to network byte order to combine it with data in host byte order?