__init__.py

import threading
import socket, array
import select
import logging
TES =  'http://localhost:8080/'
failthresh = 10
class TWSProxy(threading.Thread):

    TIMEOUT = 10
    AUTHTIMEOUT = 60
    MAXBUFF = 8192
    MAXHEADERS = 8192

    def __init__(self,socket):
        super().__init__()
        self.csock = socket
        self.ssock = None
        self.authtok = None
        self._timeout = 10



    def inittws(self,closed):
        """ Read from the client socket until one of
            1) We can verify the request based on headers
            2) We hit a timeout (i.e. no more headers will be sent and the client is waiting for a response)
            If we can verify 
            open a new socket to the server and return this
        """

        logger = logging.getLogger()
        bytessofar = 0
        header=bytearray(TWSProxy.MAXHEADERS)
        keepreading = True
        initcount=0
        while keepreading:
            initcount=initcount+1
            r,w,e = select.select([self.csock],[],[],5)
            if len(r) > 0:
                partial = self.csock.recv(TWSProxy.MAXBUFF)
                header[bytessofar:bytessofar+len(partial)] = partial
                bytessofar = bytessofar + len(partial)
                port = TWSProxy.verifyauth(header[0:bytessofar])
                if port is not None:
                    keepreading = False
            else:
                port = TWSProxy.verifyauth(header[0:bytessofar])
                keepreading = False
            if initcount > failthresh:
                keepreading = False

        if port is not None:
            self.ssock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            self.ssock.setblocking(True)
            try:
                self.ssock.connect(('127.0.0.1',port))
                if bytessofar > 0:
                    return (header,bytessofar)
                    #TWSProxy.reliablesend(self.ssock,header[0:bytessofar],bytessofar)
            except ConnectionRefusedError as e:
                self.ssock.close()
                self.csock.close()
                closed.set()
                return (None,None)
        else:
            self.csock.close()
            closed.set()
            return (None,None)

        

    def run(self):
        import logging
        logger = logging.getLogger()
        initshutdown = threading.Event()
        initshutdown.clear()
        (header, bytessofar) = self.inittws(initshutdown)

        t1 = None
        t2 = None
        if not initshutdown.isSet():
            TWSProxy.reliablesend(self.ssock,header[0:bytessofar],bytessofar)
#            TWSProxy.twosocks(self.csock,self.ssock,initshutdown)
            t1 = threading.Thread(target=TWSProxy.sockcopy, args=(self.ssock, self.csock, initshutdown),name='s2c')
            t2 = threading.Thread(target=TWSProxy.sockcopy, args=(self.csock, self.ssock, initshutdown),name='c2s')
            t1.start()
            t2.start()
            t1.join()
            t2.join()
        if self.ssock is not None:
            self.ssock.close()
        if self.csock is not None:
            self.csock.close()

    @staticmethod
    def verifyauth(header):
        import re
        import requests
        logger = logging.getLogger()
        token = b'twsproxyauth=(?P<authtok>\w+)[\W|$]'
        m = re.search(token,header)
        if m:
            authtok = m.groupdict()['authtok']
            s = requests.Session()
            url = TES+'tunnelstat/'+authtok.decode()
            try:
                r = s.get(url)
                port = r.json()
            except:
                raise Exception('unable to get a port number for the authtok {}'.format(r.text))
            return port
        return None
#        if m:
#            print('match verify!',m.group(0))
#            return 8888 
#        else:
#            return None


    @staticmethod
    def reliablesend(socket,buff,msglength):
        totalsent = 0
        while totalsent < msglength:
            sent = socket.send(buff[totalsent:])
            if sent == 0:
                raise RuntimeError("socket connection broken")
            totalsent = totalsent + sent

    @staticmethod
    def twosocks(client,server,initshutdown):
        import threading
        logger=logging.getLogger()
        closed = False
        clientopen = True
        serveropen = True
        shuttype = socket.SHUT_RD
        while serveropen or clientopen:
            r,w,e = select.select([client,server],[],[],TWSProxy.TIMEOUT)
            if client in r:
                try:
                    buff = client.recv(TWSProxy.MAXBUFF)
                    msglength = len(buff)
                    if msglength > 0:
                        TWSProxy.reliablesend(server,buff,msglength)
                    else:
                        clientopen = False
                        server.shutdown(shuttype)
                except:
                        clientopen = False
            if server in r:
                try:
                    buff = server.recv(TWSProxy.MAXBUFF)
                    msglength = len(buff)
                    if msglength > 0:
                        TWSProxy.reliablesend(client,buff,msglength)
                    else:
                        client.shutdown(shuttype)
#                        print("server closed socket for reading")
                        serveropen = False
                except:
                        serveropen = False
        # If the client has finished sending, and we've finished transmitting to the server
        # The server may still have some data to transmit to the client
        closed = False
        while not closed:
            r,w,e = select.select([server],[],[],TWSProxy.TIMEOUT)
            buff = server.recv(TWSProxy.MAXBUFF)
            msglength = len(buff)
            if msglength > 0:
                try:
                    TWSProxy.reliablesend(client,buff,msglength)
                except BrokenPipeError as e:
                    pass
            else:
                closed = True



    @staticmethod
    def sockcopy(src,dest,initshutdown):
        shuttype = socket.SHUT_RD
        import threading
        logger = logging.getLogger()
        closed = False
        name = threading.current_thread().name
        while not closed:
            r,w,e = select.select([src],[],[],TWSProxy.TIMEOUT)
            if len(r) > 0:
                buff = None
                msglength = -1
                try:
                    buff = src.recv(TWSProxy.MAXBUFF)
                    if buff is None:
                        continue
                except ConnectionResetError as e:
                    closed = True
                    continue
                except Exception as e:
                    import traceback
                    logger.error(traceback.format_exc())
                    closed = True
                msglength = len(buff)
                if msglength > 0:
                    TWSProxy.reliablesend(dest,buff,msglength)
                if msglength == 0:
                    #dest.send(buff)
                    dest.shutdown(shuttype)
                    initshutdown.set()
                    closed = True

        dest.shutdown(shuttype)
        initshutdown.set()

def main():
    from . import server
    import logging
    import sys
    logging.basicConfig(filename="/var/log/tws.log",format="%(asctime)s %(levelname)s:%(process)s: %(message)s")
    logger = logging.getLogger()
    logger.setLevel(logging.DEBUG)
    logger.debug("starting TWS proxy")
    port = int(sys.argv[1])
    server = server.TWSServer(port,5)
    logger.debug("initialised server object")
    server.run()