proxy.py

import sys
import socket
import threading

def server_loop(local_host, local_port, remote_host, remote_port, receive_first):
    
    server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    try:
        server.bind((local_host, local_port))
    
    except:
        print "[!!] Failed to listen on %s:%d" % (local_host, local_port)
        print "[!!] check for other listening sockets or correct permissions."
        sys.exit(0)
    
    print "[*] listening on %s:%d" % (local_host, local_port)

    server.listen(s)

    while True:
        client_socket, addr = server.accept()

        #print out the local connection information
        print "[-->] Received incoming connection from %s:%d" (addr[0], addr[1])

        #start a thread to talk to the remote host
        proxy_thread = threading.Thread(target=proxy_handler, args=(client_socket, remote_host, remote_port, receive_first))

        proxy_thread.start()


def proxy_handler(client_socket, remote_host, remote_port, receive_first):
    
    #connect to the remote host 
    remote_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    remote_socket.connect((remote_host, remote_port))

    #receive data from the remote and end if necessary
    if receive_first:
        
        remote_buffer = receive_from(remote_socket)
        hexdump(remote_buffer)

        #send it to our response handler
        remote_buffer = response_handler(remote_buffer)


        #if we have data to send to our local client, send it 
        if len(remote_buffer):
            print "[<==] Sending %d bytes to localhost." % len(remote_buffer)
            client_socket.send(remote_buffer)
    
    #now lets loop and read from local
        #send to remote, send to local
    #rise, wash, repeat
    while True:
        #read from local host
        local_buffer = receive_from(client_socket)

        if len(local_buffer):
            print "[==>] Received %d bytes from localhost" % len(local_buffer)
            hexdump(local_buffer)

            #send it to our request handler
            local_buffer = request_handler(local_buffer)

            #send off the data to the remote host
            remote_socket.send(local_buffer)
            print "[==>] sent to remote"

            #receive back the response
            remote_buffer = receive_from(remote_socket)

            if len(remote_buffer):
                print "[<==] Received %d bytes from remote" % len(remote_buffer)
                hexdump(remote_buffer)

                #send to our response handler
                remote_buffer = response_handler(remote_buffer)

                #send the response to the local socket
                client_socket.send(remote_buffer)

                print "[<==] Sent to localhost"
            
            #if no more data on either side, close the connections
            if not len(local_buffer) or not len(remote_buffer):
                client_socket.close()
                remote_socket.close()
                print "[*] No more data. Closing connections"

                break


def main():
    #no fancy command line parsing here
    if len(sys.argv[1:]) != 5:
        print "Usage: ./proxy.py [localhost] [localport] [remotehost] [remoteport] [receive_first]"
        print "Example : ./proxy.py 127.0.0.1 9000 10.12.132.1 9000 True"
        sys.exit(0)
    
    #set up local listening paramters
    local_host = sys.argv[1]
    local_port = init(sys.argv[2])

    #setup remote target
    remote_host = sys.argv[3]
    remote_port = init(sys.argv[4])

    #this tells our proxy to connect and receive data before sending to the remote host
    receive_first = sys.argv[5]

    if "True" in receive_first:
        receive_first = True
    else:
        receive_first = False

    #now spin up our listening socket
    server_loop(local_host, local_port, remote_host, remote_port, receive_first)

def hexdump(src, length=16):
    result = []
    digits = 4 if isinstance(src, unicode) else 2
    for i in xrange(0, len(src), length):
        s = src[i:i+length]
        hexa = b' '.join(["%0*X" % (digits, ord(x)) for x in s])
        text = b''.join([x if 0x20 <= ord(x) < 0x7F else b'.' for x in s ])
        result.append(b"%04X    %-*s    %s" % (i, length*(digits + 1), hexa, text))

    print b'\n'.join(result)

def receive_from(connection):
    buffer = ""
    #we set a 2 second timeout; depending on your target(may need to be adjusted)

    connection.settimeout(2)

    try:
        #keep reading into the buffer until there is no more data
        #or we time out
        while True:
            data = connection.recv(4096)
            if not data:
                break
            
            buffer += data
        
    except:
        pass
    
    return buffer

#modify any requests destined for the remote host
def request_handler(buffer):
    #perform packet modifications
    return buffer

#modify any responses destined for the local host
def response_handler(buffer):
    #perform packet modifications
    return buffer