srcds_scanner

"""
This program scans for srcds servers from port 27000 - 50000
in your local network.

A prepared broadcast is sent to the port range.
Afterwards the script prints out ip:port of servers.
"""

import binascii
import socket
import time
import logging
import sys


REQUEST = "ff ff ff ff 54 53 6f 75 72 63 65 20 45 6e 67 69 6e 65 20 51 75 65 72 79 00".replace(' ', '')
logging.basicConfig()
logger = logging.getLogger('scanner')


def create_socket():
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    return sock


def send_broadcasts(sock, start, end):
    request = request = binascii.a2b_hex(REQUEST)
    for port in range(start, end + 1):
        sock.sendto(request, ('255.255.255.255', port))


def receive_with_timeout(sock, timeout):
    sock.setblocking(False)
    t_start = time.time()
    while True:
        if time.time() - t_start > timeout:
            break
        try:
            response, addr = sock.recvfrom(1024)
        except BlockingIOError:
            continue
        else:
            print('{}:{}'.format(*addr))


def main():
    logger.debug('Creating socket')
    sock = create_socket()
    logger.debug('Sending Broadcasts')
    send_broadcasts(sock, 27000, 50001)
    logger.debug('Receiving responses')
    receive_with_timeout(sock, 5)


if __name__ == '__main__':
    if len(sys.argv) == 2 and sys.argv[1] == '-v':
        level = logging.DEBUG
    else:
        level = logging.INFO
    logger.setLevel(level)
    main()