超时套接字的替代方案

Question

Is there an alternative technique of timeout to interrupt communication with a server in case it has received all the messages?

Let me explain, I want to communicate through an SSL socket with a server (XMPP) unknown to me. The communication is done through XML messages. For each request I can receive one or more response messages of different types. Or a single message that is sent in multiple chunks. Therefore I create a loop to receive all messages related to a request from the server. So I do not know the number and the size of messages for each request a priori. Once the messages are finished, the client waits for no more responses from the Server to stop listening (ie, it waits for the timeout ). However, this results in a long wait (eg, for each request I have to wait 2s which at the end of the communication could be as long as 1 minute for all requests).

Is there a faster way to stop listening when we have received all the messages for each request?

I attach here my code:

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock = ssl.wrap_socket(s, ssl_version=ssl. ssl.PROTOCOL_TLSv1_2)
sock.connect((hostname, port))

sock.timeout(2)

#example for a generic unique message request
sock.sendall(message.encode())

data = “”
while True:
  try:
    response = sock.recv(1024)
    if not response: break
    data += response.decode()
  except socket.timeout:
    break

Answer 1

You know how much data to expect because of the protocol.

The XMPP protocol says ( section 4.2 ) what the start of a stream looks like; ( section 4.3 ) tells you about stream negotiation process which the <stream:features> tag is used for. Don't understand them yet? Section 4.1 tells you about what a stream is and how it works.

In one comment, you complained about receiving a response in multiple chunks. This is absolutely normal in TCP because TCP does not care about chunks. TCP can split up a 1kB message into 1000 1-byte chunks if it feels like it (usually it doesn't feel like it). So you must keep receiving chunks until you see the end of the message.

Actually, XMPP is not even a request-response protocol. The server can send you messages at any time, which are not responses to something you sent, for example it could tell you that someone said "hello" to you. So you might send an IQ request, but the next message you receive might not be an IQ response, it might be a message saying that your friend is now online. You know which message is the response because: the message type is IQ; the 'type' is 'result' or 'error'; and the 'id' is the same as in the request. Section 8.2.3 .