Python client socket can't recieve data from a successful response

July 23, 2022

Socket can’t receive any data from the server, when there is a successful response, but with bad requests it can. Also server responds, just the socket can’t receive data (checked in WireShark)

import socket
import ssl

HOST, PORT = 'example.com', 443

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

ssock = ssl.wrap_socket(sock)
ssock.connect((HOST, PORT))

raw_req = [f'GET / HTTP/1.1', 'Host: {HOST}', 'Connection: keep-alive']
req = '\n'.join(raw_req)

ssock.send(req.encode())

msg = ssock.recv(4096).decode()
print(msg)

ssock.close()

>Solution :

First, the HTTP GET expects two sequences of CR LF characters after the last header not just a single ‘\n’ character. Also, the join() adds the separator between each pair but not at the end so must append data with CR LF + CR LF to be a valid HTTP request.

Second, the 'Host: {HOST}' must be a f-string otherwise the "{HOST}" is not replaced.

import socket
import ssl

HOST, PORT = 'stackoverflow.com', 443

with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
    ssock = ssl.wrap_socket(sock)
    ssock.connect((HOST, PORT))

    raw_req = [f'GET / HTTP/1.1', f'Host: {HOST}', 'Connection: keep-alive']
    req = ('\r\n'.join(raw_req) + "\r\n\r\n").encode()
    print("Request:", req)

    ssock.send(req)

    msg = ssock.recv(4096).decode()
    print("\nResponse:")
    print(msg)

Output:

Request: b'GET / HTTP/1.1\r\nHost: stackoverflow.com\r\nConnection: keep-alive\r\n\r\n'

Response:
HTTP/1.1 200 OK
Connection: keep-alive
content-type: text/html; charset=utf-8
...