#!/usr/bin/env python
-# Sample config file:
+"""
+Proxy Utility
+-------------
-# [proxy]
-# listen_port = 8000
-# host = google.com
-# port = 80
-#
-# [allowed]
-# host1 = delx.cjb.net
-# host2 = 333.333.333.333
+With mode=basic any incoming connections on listen_port will be proxied
+to host:port. The proxy will only accept connections from hosts in the
+[allowed] section.
+
+With mode=proxy the first two lines of incoming connections must be
+'host\nport\n'. Once again only connections from hosts in the [allowed]
+section will be accepted. The proxy will connect to host:port and pass
+bytes in both directions.
+
+The final mode, mode=interceptor is designed to be combined with a firewall
+rule and another instance running mode=proxy on another computer.
+Proxies running in interceptor mode listen on all interfaces. They make
+connections to the host:port specified in the config file, passing the
+'capturedhost\ncapturedport\n' onto the destination. They then pass bytes
+in both directions.
+
+
+Example - Basic Forwarder
+-------------------------
+
+Config to forward all packets from port 8000 on localhost to google.com:80
+Connections will be accepted from whatever IP address alpha.example.com
+and beta.example.com point to.
+
+[proxy]
+mode = basic
+listen_port = 8000
+host = google.com
+port = 80
+
+[allowed]
+host1 = alpha.example.com
+host2 = beta.example.com
+
+
+
+Example - Interceptor Proxy Combo
+---------------------------------
+
+Capture all packets destined for port 1935 and send them to an interceptor
+configured to listen on example.com:9997.
+On Linux:
+ # iptables -t nat -A PREROUTING -p tcp --dport 1935
+ -j REDIRECT --to-ports 9997
+ # iptables -t nat -A OUTPUT -p tcp --dport 1935
+ -j REDIRECT --to-ports 9997
+
+On Mac OS X:
+ # ipfw add 50000 fwd 127.0.0.1,9997 tcp from any to any dst-port 1935
+
+Config to forward these connections to proxy.example.com
+
+[proxy]
+mode = interceptor
+listen_port = 9997
+host = proxy.example.com
+port = 9997
+
+
+
+Config file for proxy.example.com
+
+[proxy]
+mode = proxy
+listen_port = 9997
+
+[allowed]
+host1 = alpha.example.com
+host2 = beta.example.com
+
+
+"""
import asyncore
import ConfigParser
import os
import socket
+import struct
import sys
+
+if sys.platform == "linux2":
+ try:
+ socket.SO_ORIGINAL_DST
+ except AttributeError:
+ # There is a missing const in the socket module... So we will add it now
+ socket.SO_ORIGINAL_DST = 80
+
+ def get_original_dest(sock):
+ '''Gets the original destination address for connection that has been
+ redirected by netfilter.'''
+ # struct sockaddr_in {
+ # short sin_family; // e.g. AF_INET
+ # unsigned short sin_port; // e.g. htons(3490)
+ # struct in_addr sin_addr; // see struct in_addr, below
+ # char sin_zero[8]; // zero this if you want to
+ # };
+ # struct in_addr {
+ # unsigned long s_addr; // load with inet_aton()
+ # };
+ # getsockopt(fd, SOL_IP, SO_ORIGINAL_DST, (struct sockaddr_in *)&dstaddr, &dstlen);
+
+ data = sock.getsockopt(socket.SOL_IP, socket.SO_ORIGINAL_DST, 16)
+ _, port, a1, a2, a3, a4 = struct.unpack("!HHBBBBxxxxxxxx", data)
+ address = "%d.%d.%d.%d" % (a1, a2, a3, a4)
+ return address, port
+
+
+elif sys.platform == "darwin":
+ def get_original_dest(sock):
+ '''Gets the original destination address for connection that has been
+ redirected by ipfw.'''
+ return sock.getsockname()
+
+
+
class Proxy(asyncore.dispatcher):
def __init__(self, sock):
asyncore.dispatcher.__init__(self, sock)
self.other = None
self.buffer = ""
-
+
def meet(self, other):
self.other = other
other.other = self
-
+
def handle_error(self):
- print >>sys.stderr, "Connection closed..."
+ print >>sys.stderr, "Proxy error:", sys.exc_info()
self.handle_close()
def handle_read(self):
data = self.recv(8192)
- self.other.buffer += data
-
+ if len(data) > 0:
+ self.other.buffer += data
+
def handle_write(self):
sent = self.send(self.buffer)
self.buffer = self.buffer[sent:]
-
+
+ def writable(self):
+ return len(self.buffer) > 0
+
def handle_close(self):
if not self.other:
return
+ print >>sys.stderr, "Proxy closed"
self.other.close()
self.close()
self.other = None
-class Forwarder(asyncore.dispatcher):
+class ConnectProxy(asyncore.dispatcher):
+ def __init__(self, sock):
+ asyncore.dispatcher.__init__(self, sock)
+ self.buffer = ""
+
+ def handle_error(self):
+ print >>sys.stderr, "ConnectProxy error:", sys.exc_info()
+ self.handle_close()
+
+ def handle_read(self):
+ self.buffer += self.recv(8192)
+ pos1 = self.buffer.find("\n")
+ if pos1 < 0:
+ return
+ host = self.buffer[:pos1].strip()
+ pos1 += 1
+ pos2 = self.buffer[pos1:].find("\n")
+ if pos2 < 0:
+ return
+ pos2 += pos1
+ port = int(self.buffer[pos1:pos2].strip())
+
+ self.buffer = self.buffer[pos2+1:]
+ self.done(host, port)
+
+ def handle_write(self):
+ pass
+
+ def handle_close(self):
+ print >>sys.stderr, "Proxy closed"
+ self.close()
+
+ def done(self, host, port):
+ print >>sys.stderr, "Forwarding connection", host, port
+
+ # Create server proxy
+ server_connection = socket.socket()
+ server_connection.connect((host, port))
+ server = Proxy(server_connection)
+
+ # Morph and connect
+ self.__class__ = Proxy
+ server.meet(self)
+ server.buffer = self.buffer
+ self.buffer = ""
+
+
+class BasicForwarder(asyncore.dispatcher):
def __init__(self, listen_port, host, port, allowed):
asyncore.dispatcher.__init__(self)
self.host = host
self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
self.bind(("", listen_port))
self.listen(5)
-
+
def handle_error(self):
- print >>sys.stderr, "Connection error!", sys.exc_info()
-
+ print >>sys.stderr, "BasicForwarder error:", sys.exc_info()
+
def handle_accept(self):
client_connection, (addr, port) = self.accept()
if addr not in map(socket.gethostbyname, self.allowed):
server = Proxy(server_connection)
server.meet(client)
-def main(listen_port, host, port, allowed):
- proxy = Forwarder(listen_port, host, port, allowed)
+class Forwarder(asyncore.dispatcher):
+ def __init__(self, listen_port, allowed):
+ asyncore.dispatcher.__init__(self)
+ self.allowed = allowed
+ self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
+ self.bind(("", listen_port))
+ self.listen(5)
+
+ def handle_error(self):
+ print >>sys.stderr, "Forwarder error:", sys.exc_info()
+
+ def handle_accept(self):
+ client_connection, (addr, port) = self.accept()
+ if addr not in map(socket.gethostbyname, self.allowed):
+ print >>sys.stderr, "Rejected connection from", addr
+ client_connection.close()
+ return
+
+ print >>sys.stderr, "Accepted connection from", addr, port
+ ConnectProxy(client_connection)
+
+class Interceptor(asyncore.dispatcher):
+ def __init__(self, listen_port, host, port):
+ asyncore.dispatcher.__init__(self)
+ self.host = host
+ self.port = port
+ self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
+ self.bind(("0.0.0.0", listen_port))
+ self.listen(5)
+
+ def handle_error(self):
+ print >>sys.stderr, "Interceptor error!", sys.exc_info()
+
+ def handle_accept(self):
+ # Get sockets
+ client_connection, addr = self.accept()
+ dest = get_original_dest(client_connection)
+ print >>sys.stderr, "Accepted connection from", addr, port
+ server_connection = socket.socket()
+ server_connection.connect((self.host, self.port))
+
+ # Hook them up to the event loop
+ client = Proxy(client_connection)
+ server = Proxy(server_connection)
+ server.buffer += "%s\n%d\n" % dest
+ server.meet(client)
+
+
+def main(listen_port, host, port, mode, allowed):
+ if mode == "basic":
+ proxy = BasicForwarder(listen_port, host, port, allowed)
+ elif mode == "proxy":
+ proxy = Forwarder(listen_port, allowed)
+ elif mode == "interceptor":
+ proxy = Interceptor(listen_port, host, port)
+ else:
+ print >>sys.stderr, "Unknown mode:", mode
+ return 1
asyncore.loop()
+
if __name__ == "__main__":
try:
if sys.argv[1] == "-d":
try:
c = ConfigParser.RawConfigParser()
c.read(config)
- listen_port = c.getint("proxy", "listen_port")
- host = c.get("proxy", "host")
- port = c.getint("proxy", "port")
- allowed = c.items("allowed")
- allowed = [h for _,h in c.items("allowed")]
except:
print >>sys.stderr, "Error parsing config!"
sys.exit(1)
+ def guard(func, message):
+ try:
+ return func()
+ except:
+ print >>sys.stderr, "Error:", message
+ raise
+ sys.exit(1)
+
+ mode = guard(lambda:c.get("proxy", "mode").lower(),
+ "mode is a required field")
+
+ listen_port = guard(lambda:c.getint("proxy", "listen_port"),
+ "listen_port is a required field")
+
+ if mode in ["basic", "interceptor"]:
+ text = "%%s is a required field for mode=%s" % mode
+ host = guard(lambda:c.get("proxy", "host"), text % "host")
+ port = guard(lambda:c.getint("proxy", "port"), text % "port")
+ else:
+ host = None
+ port = None
+
+ if mode in ["basic", "proxy"]:
+ allowed = guard(lambda:c.items("allowed"),
+ "[allowed] section is required for mode=%s" % mode)
+ allowed = [h for _,h in c.items("allowed")]
+ else:
+ allowed = None
+
+
if not daemon:
try:
- main(listen_port, host, port, allowed)
+ main(listen_port, host, port, mode, allowed)
except KeyboardInterrupt:
print
else:
if os.fork() == 0:
# We are the child
try:
- main(listen_port, host, port, allowed)
+ sys.exit(main(listen_port, host, port, allowed))
except KeyboardInterrupt:
print
sys.exit(0)