Simple example has unexpected behaviour

[Zentdayn]

I went on following the tutorial and i tried to make a simple program that would just send back everything that it receives.

https://gist.github.com/Zentdayn/f8613aa8b419d846dc27630be086cb0d

Could someone tell me what's wrong with this?

I seems like tcprecv blocks forever. Changing the timeout to 0 makes it work but the cicle just runs a lot of times, and that's not what i wanted to do. I want it to block until it receives something.

[sustrik]

It sends a reply aftef receiving 512 bytes. Is that what you are want it to do? You are also not flushing the sends.

Maybe what you want is (pseudocode):

while(1) {
    char c;
    tcprecv(&c);
    tcpsend(&c);
    tcpflush();
}

[Zentdayn]

Is reading 1 byte at a time the only way to get notified "early", that is even if the buffer isn't filled completely ? ( without being actively waiting )

I want to parse a protocol with a variable message size how could i do it?

I can't tcprecv(buf) ( with buf being some buffer with a length equal to the maximum length a message could have ) because shorter messages than that would never leave tcprecv.

[sustrik]

Have you looked at tcprecvuntil()?

[Zentdayn]

Yup. That works fine, but it requires me to have a special marker to end messages.

So if i want to parse some message that has a format such as messageID, messageLength, Data i can't use tcprecvuntil right?

[sustrik]

tcprecv(&id, 4);
tcprecv(&length, 4);
tcprecv(buf, length);

[Zentdayn]

Uh that was pretty dumb on my part.

Thanks for your insights.