mirror of
https://github.com/chocolate-doom/master-server.git
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113 lines
3 KiB
Python
Executable file
113 lines
3 KiB
Python
Executable file
#!/usr/bin/env python
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#
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# Copyright(C) 2010 Simon Howard
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#
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public License
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# as published by the Free Software Foundation; either version 2
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# of the License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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# 02111-1307, USA.
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#
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#
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# Cronjob script that checks the master server is running.
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#
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import socket
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import sys
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import struct
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from select import select
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from time import time
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NET_MASTER_PACKET_TYPE_ADD = 0
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NET_MASTER_PACKET_TYPE_ADD_RESPONSE = 1
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NET_MASTER_PACKET_TYPE_QUERY = 2
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NET_MASTER_PACKET_TYPE_QUERY_RESPONSE = 3
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QUERY_ATTEMPTS = 5
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MASTER_SERVER = "master.chocolate-doom.org"
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UDP_PORT = 2342
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def send_message(sock, addr, message_type, payload=None):
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header = struct.pack(">h", message_type)
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packet = header
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if payload is not None:
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packet += payload
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sock.sendto(packet, addr)
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def get_response(sock, addr, expected_type, timeout):
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""" Wait for a response packet to be received. """
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start_time = time()
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while time() - start_time < timeout:
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r, w, x = select([sock], [], [], 1)
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if sock in r:
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packet, remote_addr = sock.recvfrom(1024)
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type, = struct.unpack(">h", packet[0:2])
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if expected_type == type:
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return type, packet[2:]
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raise Exception("No response received from server in %i seconds"
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% (time() - start_time))
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def read_string(packet):
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terminator = struct.pack("b", 0)
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strlen = packet.index(terminator)
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result = struct.unpack("%ss" % strlen, packet[0:strlen])
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return packet[strlen + 1:], result
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def parse_query_response(packet):
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servers = []
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while len(packet) > 0:
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packet, addr_str = read_string(packet)
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servers.append(addr_str)
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return servers
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def query_master(addr_str):
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""" Query a master server for its list of server IP addresses. """
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addr = (socket.gethostbyname(addr_str), UDP_PORT)
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sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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send_message(sock, addr, NET_MASTER_PACKET_TYPE_QUERY)
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type, response = get_response(sock, addr,
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NET_MASTER_PACKET_TYPE_QUERY_RESPONSE,
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5)
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servers = parse_query_response(response)
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# Try several times, as there might be packet loss.
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failures = 0
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while failures < QUERY_ATTEMPTS:
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try:
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query_master(MASTER_SERVER)
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break
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except:
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failures += 1
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else:
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sys.stderr.write("No response from master server after %i attempts.\n"
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% failures)
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