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https://github.com/chocolate-doom/master-server.git
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Add GPG signature generation, as the first step towards secure demo
support. Subversion-branch: /master Subversion-revision: 2516
This commit is contained in:
Simon Howard
parent
da23130736
commit
6d2987c286
4 changed files with 258 additions and 8 deletions
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@ -27,10 +27,11 @@ import simplejson
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from select import select
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from time import time, strftime
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from master_config import *
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import secure_demo
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# Maximum length of a query response.
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MAX_RESPONSE_LEN = 1000
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MAX_RESPONSE_LEN = 1500
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# Normal packet types.
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@ -45,6 +46,10 @@ NET_MASTER_PACKET_TYPE_QUERY = 2
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NET_MASTER_PACKET_TYPE_QUERY_RESPONSE = 3
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NET_MASTER_PACKET_TYPE_GET_METADATA = 4
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NET_MASTER_PACKET_TYPE_GET_METADATA_RESPONSE = 5
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NET_MASTER_PACKET_TYPE_SIGN_START = 6
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NET_MASTER_PACKET_TYPE_SIGN_START_RESPONSE = 7
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NET_MASTER_PACKET_TYPE_SIGN_END = 8
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NET_MASTER_PACKET_TYPE_SIGN_END_RESPONSE = 9
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def bind_socket_to(sock, config):
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""" Bind the specified socket to the address/port configuration from
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@ -129,6 +134,11 @@ class MasterServer:
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self.sock = self.open_socket(server_address)
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self.query_sock = self.open_socket(query_address)
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if secure_demo.available and SIGNING_KEY:
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self.signer = secure_demo.SecureSigner(SIGNING_KEY)
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else:
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self.signer = None
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def send_query(self, server):
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""" Send a query to the specified server. """
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@ -297,6 +307,41 @@ class MasterServer:
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NET_MASTER_PACKET_TYPE_GET_METADATA_RESPONSE,
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packet)
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def sign_start_message(self, addr):
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""" Generate a signed start message and return to the client. """
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self.log_output(addr, "Start demo")
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if self.signer is None:
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return
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# Generate start message and send it back.
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signature = self.signer.sign_start_message()
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self.send_message(addr, NET_MASTER_PACKET_TYPE_SIGN_START_RESPONSE,
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signature)
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def sign_end_message(self, data, addr):
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""" Generate a signed end message and return to the client. """
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self.log_output(addr, "End demo")
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if self.signer is None:
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return
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# Parse the data. The first part is a 160-bit SHA1 hash, and the
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# rest of the data is the start message.
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demo_hash = data[0:20]
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start_message = data[20:]
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# Parse the start message and verify the signature, then use it
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# to generate an end message along with the hash of the demo.
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signature = self.signer.sign_end_message(start_message, demo_hash)
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if signature is None:
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self.log_output(addr, "Failed to verify start message!")
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else:
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self.send_message(addr, NET_MASTER_PACKET_TYPE_SIGN_END_RESPONSE,
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signature)
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def process_packet(self, data, addr):
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""" Process a packet received from a server. """
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@ -308,6 +353,10 @@ class MasterServer:
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self.process_query(addr)
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elif packet_type == NET_MASTER_PACKET_TYPE_GET_METADATA:
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self.process_metadata_request(addr)
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elif packet_type == NET_MASTER_PACKET_TYPE_SIGN_START:
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self.sign_start_message(addr)
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elif packet_type == NET_MASTER_PACKET_TYPE_SIGN_END:
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self.sign_end_message(data[2:], addr)
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def rx_packet(self):
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""" Invoked when a packet is received. """
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@ -32,6 +32,10 @@ NET_MASTER_PACKET_TYPE_QUERY = 2
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NET_MASTER_PACKET_TYPE_QUERY_RESPONSE = 3
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NET_MASTER_PACKET_TYPE_GET_METADATA = 4
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NET_MASTER_PACKET_TYPE_GET_METADATA_RESPONSE = 5
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NET_MASTER_PACKET_TYPE_SIGN_START = 6
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NET_MASTER_PACKET_TYPE_SIGN_START_RESPONSE = 7
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NET_MASTER_PACKET_TYPE_SIGN_END = 8
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NET_MASTER_PACKET_TYPE_SIGN_END_RESPONSE = 9
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UDP_PORT = 2342
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@ -147,7 +151,8 @@ def get_metadata(addr_str):
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print "Waiting for response..."
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response = get_response(sock, addr, NET_MASTER_PACKET_TYPE_GET_METADATA_RESPONSE)
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response = get_response(sock, addr,
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NET_MASTER_PACKET_TYPE_GET_METADATA_RESPONSE)
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servers = decode_string_list(response)
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@ -161,15 +166,65 @@ def get_metadata(addr_str):
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print "\t\tVersion: %s" % metadata["version"]
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print "\t\tMax. players: %i" % metadata["max_players"]
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if len(sys.argv) > 2 and sys.argv[1] == "query":
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query_master(sys.argv[2])
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elif len(sys.argv) > 2 and sys.argv[1] == "add":
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add_to_master(sys.argv[2])
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elif len(sys.argv) > 2 and sys.argv[1] == "get-metadata":
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get_metadata(sys.argv[2])
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def sign_start(addr_str):
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""" Request a signed start message from the master. """
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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 request
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print "Sending signed start request to master at %s" % str(addr_str)
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send_message(sock, addr, NET_MASTER_PACKET_TYPE_SIGN_START)
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# Receive response
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print "Waiting for response..."
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response = get_response(sock, addr,
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NET_MASTER_PACKET_TYPE_SIGN_START_RESPONSE)
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print response
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def sign_end(addr_str):
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""" Request a signed end message from the server. """
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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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print "Paste the start message, then type ^D"
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start_message = sys.stdin.read()
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fake_sha1 = "3ijAI83u8A(*j98jf3jf"
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print "Sending signed end request to master at %s" % str(addr_str)
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send_message(sock, addr, NET_MASTER_PACKET_TYPE_SIGN_END,
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payload=(fake_sha1 + start_message))
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print "Waiting for response..."
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response = get_response(sock, addr,
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NET_MASTER_PACKET_TYPE_SIGN_END_RESPONSE)
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print response
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commands = [
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("query", query_master),
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("add", add_to_master),
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("get-metadata", get_metadata),
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("sign-start", sign_start),
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("sign-end", sign_end),
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]
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for name, callback in commands:
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if len(sys.argv) > 2 and name == sys.argv[1]:
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callback(sys.argv[2])
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break
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else:
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print "Usage:"
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print "chocolate-master-test.py query <address>"
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print "chocolate-master-test.py add <address>"
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print "chocolate-master-test.py get-metadata <address>"
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print "chocolate-master-test.py sign-start <address>"
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print "chocolate-master-test.py sign-end <address>"
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@ -41,3 +41,8 @@ SERVER_ADDRESS = (None, 2342)
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QUERY_ADDRESS = None
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# ID of the GPG key to use to sign secure demo messages.
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# Use the email address of the key or the hex key ID.
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SIGNING_KEY = None
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141
secure_demo.py
Executable file
141
secure_demo.py
Executable file
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@ -0,0 +1,141 @@
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#!/usr/bin/env python
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#
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# Copyright(C) 2012 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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# This is a library used by the master for the signed demos system. It
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# uses GPG to create signed messages that are returned by the master
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# back to the clients.
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#
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from io import BytesIO
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import os
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import sys
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import time
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NONCE_SIZE = 16 # bytes
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try:
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import gpgme
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available = True
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except ImportError:
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available = False
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def now_string():
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"""Generate an ISO8601 string for the current time."""
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now = time.time()
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return time.strftime('%Y-%m-%dT%H:%M:%SZ', time.gmtime(now))
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def bin_to_hex(data):
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"""Convert a string of binary data into a hex representation."""
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return "".join(map(lambda x: "%02x" % ord(x), data))
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class SecureSigner(object):
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def __init__(self, key):
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"""Initialize a new SecureSigner. Must be passed a key identifier
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string specifying the GPG key to use. """
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self.context = gpgme.Context()
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self.key = self.context.get_key(key)
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self.context.signers = [ self.key ]
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def _generate_start_message(self):
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"""Generate the plaintext used for a start message."""
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nonce = os.urandom(NONCE_SIZE)
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return "\n".join([
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"Start-Time: %s" % now_string(),
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"Nonce: %s" % bin_to_hex(nonce),
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])
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def _sign_plaintext_message(self, message):
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"""Sign a plaintext message."""
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signature = BytesIO()
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self.context.sign(BytesIO(message), signature, gpgme.SIG_MODE_CLEAR)
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return signature.getvalue()
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def sign_start_message(self):
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"""Generate a new signed start message with a random nonce value."""
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message = self._generate_start_message()
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return self._sign_plaintext_message(message)
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def _verify_signature(self, result):
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"""Check the results of a verify operation."""
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if len(result) != 1:
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return False
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# Check the signature is valid:
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signature = result[0]
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if (signature.summary & gpgme.SIGSUM_VALID) == 0:
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return False
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# Check the signature matches the right key:
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for subkey in self.key.subkeys:
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if subkey.fpr == signature.fpr:
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break
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else:
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return False
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return True
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def _verify_start_message(self, signed_message):
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"""Check that a signed message is correctly signed, returning
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the plaintext if it is valid, or None if it is invalid."""
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# Parse the plain text signed message:
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try:
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plaintext = BytesIO()
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result = self.context.verify(BytesIO(signed_message),
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None, plaintext)
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if self._verify_signature(result):
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return plaintext.getvalue()
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except gpgme.GpgmeError:
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pass
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# Failure of some kind occurred: message failed to parse, or
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# did not pass verification, etc.
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return None
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def sign_end_message(self, start_message, demo_hash):
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"""Verify a start message and sign an end message that verifies
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a complete demo."""
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plaintext = self._verify_start_message(start_message)
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if plaintext is None:
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return None
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# We assume the plaintext message ends with a newline.
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if plaintext[-1] != "\n":
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plaintext = plaintext + "\n"
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# Add extra fields to the plaintext, to create the end message.
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message = plaintext + "\n".join([
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"End-Time: %s" % now_string(),
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"Demo-Checksum: %s" % bin_to_hex(demo_hash),
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])
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return self._sign_plaintext_message(message)
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if __name__ == "__main__":
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if len(sys.argv) < 3:
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print "Usage: %s <start|end> <key>" % sys.argv[0]
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sys.exit(1)
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signer = SecureSigner(sys.argv[2])
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if sys.argv[1] == "start":
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print signer.sign_start_message()
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elif sys.argv[1] == "end":
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start_message = sys.stdin.read()
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fake_checksum = "3vism1idm4ibmaJ3nF1f"
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print signer.sign_end_message(start_message, fake_checksum)
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