#!/usr/bin/python
 
# Copyright (c) 2013 by Peter_Siegrist(SystemLoesungen)  (PSS @ ZweierNet.ch)
# www.IPv6Tech.ch
#
# All Rights reserved.
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
#
# This is a simple IPv4-IPv6 non-caching HTTP/HTTPS Proxy/Gateway. 
# The Server can make both IPv6, primarily, or IPv4 requestst on behalf of the pure IPv4 clients.
# 
# WebProxy46 does not filter any messages apart from chanching HTTP/1.1 to HTTP/1.0
# because we do not want to filter out subrequests in persistent connections.
# 
# All standard methodes are supported: GET, HEAD, POST, PUT, OPTIONS, TRACE and DELETE.
# The CONNECT method is used for SSL connections. Only port 443 is allowed with this method (HTTP CONNECT Vulnerability)
#
# For using this proxy configure your browser to use proxy service.
# The servers standard binding is port 9090 on address 0.0.0.0
#
# Accepted schemes are HTTP HTTPS and FTP.
# Hostnames in URL's may be given as FQDN, IPv4 dotted address or IPv6 address in square brackets form [xx:xx:xx::x]
#
 
 
import socket
import getopt
import sys
from select import select
import logging
import thread
import struct
import string
 
#-- Vars
 
version = 'WebProxy46/v0.7'
buflen = 8192
listen_host = '0.0.0.0'
listen_port = 9090
debug = False
lfnr = 0
 
 
#-- Threaded Main Object
 
class ProxyHandler:
    def __init__(self, local_conn, local_address):
        global lfnr
        lfnr += 1
        self.lfnr = lfnr
        log(self.lfnr,'NEW Connect ...')
        self.local_client = local_conn
        self.local_client_address = local_address
        self.local_client_buffer = ''
        self.timeout = 60
        self.handle()
        self.local_client.close()
 
    def _set_target_sockopts_ssl(self):
        self.target.setsockopt(socket.SOL_SOCKET,socket.MSG_DONTWAIT,1)
        self.target.setblocking(1)
 
    def handle(self):
        try:
            self.local_client.setblocking(1)
            self.local_client.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER, struct.pack('ii', 1, 20))
            #self.local_client.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 0)
 
            clt_count = 0
            while 1:
                clt_count += 1
                (client_data, _, client_error) = select([self.local_client], [], [], 1)
                if client_data:
                    data = self.local_client.recv(buflen)
                    if len(data) == 0:
                        break
                    self.local_client_buffer += data
                    log2(self.lfnr,"data:%s"%data)
                if client_error:
                    err = select.error
                    log(self.lfnr,"%s - Client_Error select: %s on %s " % (self.af, err, self.local_client_address))
                if clt_count == 1:
                    break
 
 
            if self.local_client_buffer:
                end_head = self.local_client_buffer.find('\n')
                log(self.lfnr,'%s'%self.local_client_buffer[:end_head])
                self.method, self.path, self.protocol = (self.local_client_buffer[:end_head+1]).split()
                self.local_client_buffer = self.local_client_buffer[end_head+1:]
                # we can't handle 1.1 persistent connections in proxys, thanks mozilla :(
                self.protocol = string.replace(self.protocol, 'HTTP/1.1', 'HTTP/1.0')                
 
                if self.method=='CONNECT':
                    self.method_ssl()
                elif self.method in ('OPTIONS', 'GET', 'HEAD', 'POST', 'PUT', 'DELETE', 'TRACE'):
                    self.method_get()
                else:
                    self.method_invalid()           
                try:
                    self.target.close()
                except:
                    pass
        except Exception as uerr:
            log(self.lfnr,'__Unexpected Error__: %s'%uerr)
 
 
    def method_invalid(self):
        log(self.lfnr,'Invalid HTTP Method: %s'%self.method)
        self.local_client.send('HTTP/1.1 501 Not Implemented\r\n'+'Unknown method: %s\r\n\r\n'%self.method)
        self.local_client_buffer = ''
        self.local_client.close()
 
    def method_ssl(self):
        if not self.connect_target(self.path):
            self.local_client.send('HTTP/1.1 500\r\n\r\n')
            self.local_client.send('HTTP/1.1 500 %s\r\nProxy: %s\r\n\r\n'%(self.conn_error,version))
            return False
        #self.local_client.send('HTTP/1.1 200 OK\r\n\r\n')
        self.local_client.send('HTTP/1.1 200 Connection established\r\n'+'Proxy: %s\r\n\r\n'%version)
        self.local_client_buffer = ''
        self.handle_select()        
 
 
    def method_get(self):
        j = self.path.find('://')
        self.scheme = self.path[:j]
        self.path = self.path[j+3:]        
        i = self.path.find('/')
        host = self.path[:i]        
        path = self.path[i:]
        if not self.connect_target(host):
            self.local_client.send('HTTP/1.1 500\r\n\r\n')
            self.local_client.send('HTTP/1.1 500 %s\r\nProxy: %s\r\n\r\n'%(self.conn_error,version))
            return False
        s1 = self.target.send('%s %s %s\r\n'%(self.method, path, self.protocol)+self.local_client_buffer)
        log2(self.lfnr,'SEND_RAW(to %s):%s %s %s\n'%(self.target_addr[0:2],self.method, path, self.protocol)+self.local_client_buffer)
        log(self.lfnr,'SEND_REQUEST(to %s): %s %s %s\n'%(self.target_addr[0:2], self.method, path, self.protocol))
        self.local_client_buffer = ''
        self.handle_select()
 
 
    def connect_target(self, host):
        if host.find('[') != -1:
            j = host.find(']:')
            if j!=-1:
                port = int(host[j+2:])
                host = host[1:j]
            else:
                host = host[1:-1]
                if self.scheme.lower() == 'ftp':
                    port = 21
                else:
                    port = 80
        else:
            i = host.find(':')
            if i!=-1:
                port = int(host[i+1:])
                host = host[:i]
            else:
                if self.scheme.lower() == 'ftp':
                    port = 21
                else:
                    port = 80
 
        if self.method=='CONNECT':
            if port != 443:
                self.conn_error = 'Connection refused. Port %d not allowed in CONNECT method'%port
                return False
        try:
            addrinfo = socket.getaddrinfo(host, port)
        except socket.error as msg:
            log(self.lfnr,"Error resolving %s:%d: %s" % (host, port, msg))
            self.conn_error = 'Error resolving %s:%d: %s'%(host, port,msg[1])
            return False
        for (afm, _, _, _, address) in addrinfo:
            if afm == socket.AF_INET6:
                self.target = socket.socket(socket.AF_INET6)
                self.target_addr = address
                self.af = 'IPv6'
                break
            elif afm == socket.AF_INET:
                self.target = socket.socket(socket.AF_INET)
                self.target_addr = address
                self.af = 'IPv4'
            else:
                log(self.lfnr,"EEERRRRRRRRRRRRRRRRRRRR\n")
        self.target.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 0)
        self.target.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER, struct.pack('ii', 1, 10))      
        try:
            self.target.connect(self.target_addr)
        except socket.error as msg:
            log(self.lfnr,"%s - Error connecting %s:%d (Addr: %s): %s" % (self.af, host, port, self.target_addr, msg))
            self.conn_error = 'Connection failed: %s'%msg[1]
            return False
        else:
            log(self.lfnr,"%s - connect to %s:%d (%s)" % (self.af, host, port, self.target_addr[0:2]))
 
        return True
 
    def handle_select(self):
        self.soc_pair = [self.local_client, self.target]
        count = 0
        rf = 'undefined'
        while 1:
            count += 1
            (recv_data, _, error) = select(self.soc_pair, [], self.soc_pair, 2)
            if recv_data:
                cnt = 0
                for i in recv_data:
                    cnt +=1
                    if i is self.local_client:
                        rf = self.local_client_address
                    else:
                        rf = self.target_addr
                    try:             
                        data = i.recv(buflen)
                    except socket.error as err:
                        log(self.lfnr,'recv error (%s):%s' % (rf, err))
                        if err[0] == 104:   # connection reset by peer
                            continue
                    log2(self.lfnr,'%d %d select handle from: %s LEN: %d' % (count,cnt,rf,len(data)))
                    if len(data) == 0:
                        continue
                    if i is self.local_client:
                        #self.view_sockopts(self.local_client)
                        if 'HTTP/1.' in data:
                            bs = data.find('\n')
                            log(self.lfnr,'%s - Request from %s: %s'%(self.af,self.local_client_address[0:2],data[:bs-1]))
                        rf = self.local_client_address
                        log2(self.lfnr,'DATA(to %s from %s):%s'% (self.target_addr,rf,data[:260]))
                        out = self.target
                    elif i is self.target:
                        if 'HTTP/1.' in data[0:8]:
                            bs = data[0:256].find('\n')
                            log(self.lfnr,'%s - Answer from %s: %s'%(self.af,self.target_addr[0:2],data[:bs-1]))
 
                        rf = self.target_addr
                        log2(self.lfnr,'DATA(to %s from %s):%s'% (self.local_client_address,rf,data[:260]))
                        out = self.local_client
                    else:
                        log(self.lfnr,"EEEEEERRRRRROOOORRRRRRRRR: %s"% i)
 
                    if data:
                        try:
                            sent_byte = out.send(data)
                        except socket.error as err:
                            log(self.lfnr,'send error (%s):%s' % (rf, err))
                        else:
                            log2(self.lfnr,'Sent %d Bytes Data to %s' % (sent_byte,out.getpeername()[0:2]))
                        count = 0
            if error:
                err = select.error
                log(self.lfnr,"%s - Error select: %s on %s:%s " % (self.af, err, self.local_client_address, self.target_addr))
            if count == 10:
                break
 
    def view_sockopts(self,s):
        socket_options = [ (getattr(socket, opt), opt) for opt in dir(socket) if opt.startswith('SO_') ]
        socket_options.sort()
        for num, opt in socket_options:
            try:
                val = s.getsockopt(socket.SOL_SOCKET, num)
                log2(self.lfnr,'%s(%d) defaults to %d' % (opt, num, val))
            except (socket.error) as e:
                log2(self.lfnr,'%s(%d) can\'t help you out there: %s' % (opt, num, str(e)))
 
 
 
# -- Main functions
 
def log(lfnr,msg):
    logging.warn('[%s] %s'%(lfnr,msg))
 
def log2(lfnr,msg):
    if debug:
        logging.warn('[%s] %s'%(lfnr,msg))
 
def usage():
    print(sys.argv[0]),
    print(" [-p port] [-s host] [-l logfile] [-d] [-h]")
    print('')
    print("   -p       - Port to listen on")
    print("   -s       - Host to listen on. If not specified, 0.0.0.0 is used")
    print("   -l       - Path to logfile. If not specified, STDOUT is used")
    print("   -d       - debug messages")
    print('')
 
def main(host, port):
    logfile = None
    try: 
        opts, args = getopt.getopt(sys.argv[1:], "l:hdp:s:", [])
    except getopt.GetoptError:
        usage()
        return 1 
    for opt, value in opts:
        if opt == "-p": port = int(value)
        if opt == "-s": host = value
        if opt == "-l": logfile = value
        if opt == "-d": 
            global debug
            debug = True
        if opt == "-h":
            usage()
            return 0
    if not socket.has_ipv6:
        print("This machine is not IPv6 capable. Exiting.\n")
        exit(1)
 
    logging.basicConfig(format='%(asctime)s %(thread)s: %(message)s',
                        filename=logfile)
 
    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server_socket.bind((host, port))
    log(lfnr,"Start Server")
    log(lfnr,"Listen on %s:%d"%(host, port))
    server_socket.listen(10)
    while 1:
        thread.start_new_thread(ProxyHandler, server_socket.accept())
 
 
if __name__ == '__main__':  
    main(listen_host, listen_port)