Implementing Sendall() And Recvall() In C And Python

I'm currently trying to implement a sendall() function in a server written in C, and a recvall() function on the corresponding client written in python. I can get the server and t

Solution 1:

Say you have a perfectly fluent English speaker and a perfectly fluent French speaker. They will not be able to communicate with each other very well. Who is at fault? -- Whoever put the two of them together expecting them to be able to communicate without first agreeing on how they would communicate.

Your send function and your receive function implement totally different protocols. The send function requires the receiver to already know the length of the data to receive. Your receive function requires the sender to send the length prior to the data. So you cannot mix and match them because they do not use the same wire format

Here's some valuable advice gained over decades of experience: Never attempt to use TCP without first documenting the protocol you're going to use on top of TCP at the byte level. As it is, there's no way to know which function is right and which is wrong because nobody has any idea what bytes are supposed to be sent over the wire.

TCP is a byte-stream protocol, and for two programs to work correctly with a TCP connection between them, each must send precisely the stream of bytes the other expects to receive. The best way to make sure this happens is to first document that stream of bytes.

If you have no idea where to start with such documentation, have a look at the simplest existing protocol that's analogous to what you're trying to do. Possible protocols to look at it include HTTP, SMTP, IRC, and DNS.