[ee122] Project 2 Question regarding MNL and the extra 2 bytes for the port.

phamductri at berkeley.edu phamductri at berkeley.edu
Tue Dec 4 21:07:15 PST 2007

Hello. So I'm having an issue with MNL and grabbing the port of the sender
to be able to send ACKs back to the receiver. I have stop and wait working
just fine with different files for plain vanilla UDP.

Now, for background info for my question.. The spec says that when we use
MNLSendto() that the first two bytes that we get from recvfrom() will
contain the port number of the sender, because the struct sockaddr_in
populated from the recvfrom() call will refer to the port that the
MNLDaemon is running on... r

So far our project is abracted to have a packet class, and each packet can
send and receive itself (more or less). I have statements in both send and
recv (in the packet class) before the call to MNLSendto(), and after the
call from recvfrom() respectively to print out the length of the buffer
being sent/received. They report the exact same length.

Why isn't the extra 2 bytes being padded to provide the port? Am I missing

Also, in TestRecv.c, there is no conversion from network order to host
order. Shouldn't that also be a concern?

I'm referring to the newest version of MNL btw. Version B.

Thanks very much for your time.

Anthony Kilman

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