I need help with TCP sockets (Python)

[una_maquina 35]

Basically I'm having buggy TCP sockets, and if I add a time.sleep(0.10), it magically fixes itself, BUT that's stupid. 

Problem: it's not synchronised, sometimes the data arrives, sometimes it doesn't and just gets lost...

The code is in Python:

class Main():

    END_MESSAGE = "EOXEOEXOXAADSADW"

    def __init__(self, logging_class_instance):
        self.logging_class = logging_class_instance

    def send_data_to_client(self,socket,data,encryption_key):
        try:
            self.logging_class.log("sending data to client",self.logging_class.COLOR_DEFAULT)
            encrypted = AES_encrypt(data+self.END_MESSAGE,encryption_key)
            self.logging_class.log("sending encrypted data: "+str(encrypted)[0:400],self.logging_class.COLOR_DEFAULT)
            socket.sendall(encrypted)
            self.logging_class.log("done sending",self.logging_class.COLOR_GREEN)
            return True
        except Exception as e:
            self.logging_class.log("encountered an error while sending data: "+str(e),self.logging_class.COLOR_RED)
            return False

    def receive_data_from_client(self,socket,encryption_key):
        data = b''
        while True:
            chunk = socket.recv(10240)
            if not chunk:
                raise ValueError("Couldn't receive data, socket disconnected")
            self.logging_class.log("received encrypted data: "+str(chunk),self.logging_class.COLOR_DEFAULT)
            decrypted_chunk = AES_decrypt(chunk,encryption_key)
            data += decrypted_chunk
            if self.END_MESSAGE in decrypted_chunk.decode():
                data = data[:-len(self.END_MESSAGE)]
                break
        length = len(data)
        self.logging_class.log("decrypted data: "+str(data)[0:400],self.logging_class.COLOR_DEFAULT)
        return data

 

Maybe you could recommend me some higher-level networking frameworks or something... (I tried Twisted already, but same thing happens). I also tried using select library, but the same thing happens.

How could I know when the client is listening for data -- AND only then send it to the client? And vice-versa? How to make sure data is 10000% transferred and received?

 

It should be like this:

But this is what tends to happen:

Sometimes no data arrives at all!

[una_maquina 35]

Ok nvm, I've fixed the issue myself. What I did:

I added sock.recv(1024) after sock.sendall(encrypted_data) in my send data function/method.

And I added sock.send(encrypt("OK")) in my receive data function after it receives all the data. Now it's synchronized and all's good.