#!/usr/bin/python

import sys, os, socket, time, traceback, random, time
from base64 import b64encode, b64decode
from select import select

buffer_size = 65536
recv_cnt = send_cnt = 0

server_handshake = """HTTP/1.1 101 Web Socket Protocol Handshake\r
Upgrade: WebSocket\r
Connection: Upgrade\r
WebSocket-Origin: %s\r
WebSocket-Location: ws://%s%s\r
WebSocket-Protocol: sample\r
\r
"""

policy_response = """<cross-domain-policy><allow-access-from domain="*" to-ports="*" /></cross-domain-policy>"""

def do_handshake(client):
    handshake = client.recv(1024)
    print "Handshake [%s]" % handshake
    if handshake.startswith("<policy-file-request/>"):
        print "Sending flash policy response"
        client.send(policy_response)
        client.close()
        return False
    req_lines = handshake.split("\r\n")
    _, path, _ = req_lines[0].split(" ")
    _, origin = req_lines[4].split(" ")
    _, host = req_lines[3].split(" ")
    client.send(server_handshake % (origin, host, path))
    return True

def traffic(token="."):
    sys.stdout.write(token)
    sys.stdout.flush()


def decode(buf):
    """ Parse out WebSocket packets. """
    if buf.count('\xff') > 1:
        traffic(str(buf.count('\xff')))
        return [b64decode(d[1:]) for d in buf.split('\xff')]
    else:
        return [b64decode(buf[1:-1])]

def check(buf):
    global recv_cnt

    try:
        data_list = decode(buf)
    except:
        print "\n<BOF>" + repr(buf) + "<EOF>"
        return "Failed to decode"

    err = ""
    for data in data_list:
        if data.count('$') > 1:
            raise Exception("Multiple parts within single packet")
        if len(data) == 0:
            traffic("_")
            continue

        if data[0] != "^":
            err += "buf did not start with '^'\n"
            continue

        try:
            cnt, length, chksum, nums = data[1:-1].split(':')
            cnt    = int(cnt)
            length = int(length)
            chksum = int(chksum)
        except:
            print "\n<BOF>" + repr(data) + "<EOF>"
            err += "Invalid data format\n"
            continue

        if recv_cnt != cnt:
            err += "Expected count %d but got %d\n" % (recv_cnt, cnt)
            recv_cnt = cnt + 1
            continue

        recv_cnt += 1

        if len(nums) != length:
            err += "Expected length %d but got %d\n" % (length, len(nums))
            continue

        inv = nums.translate(None, "0123456789")
        if inv:
            err += "Invalid characters found: %s\n" % inv
            continue

        real_chksum = 0
        for num in nums:
            real_chksum += int(num)

        if real_chksum != chksum:
            err += "Expected checksum %d but real chksum is %d\n" % (chksum, real_chksum)
    return err


def generate():
    global send_cnt
    length = random.randint(10, 100000)
    numlist = rand_array[100000-length:]
    # Error in length
    #numlist.append(5)
    chksum = sum(numlist)
    # Error in checksum
    #numlist[0] = 5
    nums = "".join( [str(n) for n in numlist] )
    data = "^%d:%d:%d:%s$" % (send_cnt, length, chksum, nums)
    send_cnt += 1

    buf = "\x00" + b64encode(data) + "\xff"
    return buf

def responder(client, delay=10):
    global errors
    cqueue = []
    cpartial = ""
    socks = [client]
    last_send = time.time() * 1000

    while True:
        ins, outs, excepts = select(socks, socks, socks, 1)
        if excepts: raise Exception("Socket exception")

        if client in ins:
            buf = client.recv(buffer_size)
            if len(buf) == 0: raise Exception("Client closed")
            #print "Client recv: %s (%d)" % (repr(buf[1:-1]), len(buf))
            if buf[-1] == '\xff':
                if cpartial:
                    err = check(cpartial + buf)
                    cpartial = ""
                else:
                    err = check(buf)
                if err:
                    traffic("}")
                    errors = errors + 1
                    print err
                else:
                    traffic(">")
            else:
                traffic(".>")
                cpartial = cpartial + buf

        now = time.time() * 1000
        if client in outs and now > (last_send + delay):
            last_send = now
            #print "Client send: %s" % repr(cqueue[0])
            client.send(generate())
            traffic("<")

def start_server(listen_port, delay=10):
    global errors, send_cnt, recv_cnt
    lsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    lsock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    lsock.bind(('', listen_port))
    lsock.listen(100)
    while True:
        try:
            csock = None
            print 'listening on port %s' % listen_port
            csock, address = lsock.accept()
            print 'Got client connection from %s' % address[0]
            if not do_handshake(csock):
                continue

            send_cnt = 0
            recv_cnt = 0
            responder(csock, delay=delay)

        except Exception:
            print "accumulated errors:", errors
            errors = 0
            print "Ignoring exception:"
            print traceback.format_exc()
            if csock: csock.close()

if __name__ == '__main__':
    errors = 0
    try:
        if len(sys.argv) < 2: raise
        listen_port = int(sys.argv[1])
        if len(sys.argv) == 3:
            delay = int(sys.argv[2])
        else:
            delay = 10
    except:
        print "Usage: <listen_port> [delay_ms]"
        sys.exit(1)

    print "Prepopulating random array"
    rand_array = []
    for i in range(0, 100000):
        rand_array.append(random.randint(0, 9))

    start_server(listen_port, delay=delay)