# Written by Bram Cohen# see LICENSE.txt for license informationfrom cStringIO import StringIOfrom binascii import b2a_hexfrom socket import error as socketerrorfrom urllib import quotefrom traceback import print_excimport Connectertry:    Trueexcept:    True = 1    False = 0DEBUG = Falseprotocol_name = 'BitTorrent protocol'option_pattern = chr(0)*8def toint(s):    return long(b2a_hex(s), 16)def tobinary(i):    return (chr(i >> 24) + chr((i >> 16) & 0xFF) +         chr((i >> 8) & 0xFF) + chr(i & 0xFF))hexchars = '0123456789ABCDEF'hexmap = []for i in xrange(256):    hexmap.append(hexchars[(i&0xF0)/16]+hexchars[i&0x0F])def tohex(s):    r = []    for c in s:        r.append(hexmap[ord(c)])    return ''.join(r)def make_readable(s):    if not s:        return ''    if quote(s).find('%') >= 0:        return tohex(s)    return '"'+s+'"'   def toint(s):    return long(b2a_hex(s), 16)# header, reserved, download id, my id, [length, message]streamno = 0class StreamCheck:    def __init__(self):        global streamno        self.no = streamno        streamno += 1        self.buffer = StringIO()        self.next_len, self.next_func = 1, self.read_header_len    def read_header_len(self, s):        if ord(s) != len(protocol_name):            print self.no, 'BAD HEADER LENGTH'        return len(protocol_name), self.read_header    def read_header(self, s):        if s != protocol_name:            print self.no, 'BAD HEADER'        return 8, self.read_reserved    def read_reserved(self, s):        return 20, self.read_download_id    def read_download_id(self, s):        if DEBUG:            print self.no, 'download ID ' + tohex(s)        return 20, self.read_peer_id    def read_peer_id(self, s):        if DEBUG:            print self.no, 'peer ID' + make_readable(s)        return 4, self.read_len    def read_len(self, s):        l = toint(s)        if l > 2 ** 23:            print self.no, 'BAD LENGTH: '+str(l)+' ('+s+')'        return l, self.read_message    def read_message(self, s):        if not s:            return 4, self.read_len        m = s[0]        if ord(m) > 8:            print self.no, 'BAD MESSAGE: '+str(ord(m))        if m == Connecter.REQUEST:            if len(s) != 13:                print self.no, 'BAD REQUEST SIZE: '+str(len(s))                return 4, self.read_len            index = toint(s[1:5])            begin = toint(s[5:9])            length = toint(s[9:])            print self.no, 'Request: '+str(index)+': '+str(begin)+'-'+str(begin)+'+'+str(length)        elif m == Connecter.CANCEL:            if len(s) != 13:                print self.no, 'BAD CANCEL SIZE: '+str(len(s))                return 4, self.read_len            index = toint(s[1:5])            begin = toint(s[5:9])            length = toint(s[9:])            print self.no, 'Cancel: '+str(index)+': '+str(begin)+'-'+str(begin)+'+'+str(length)        elif m == Connecter.PIECE:            index = toint(s[1:5])            begin = toint(s[5:9])            length = len(s)-9            print self.no, 'Piece: '+str(index)+': '+str(begin)+'-'+str(begin)+'+'+str(length)        else:            print self.no, 'Message '+str(ord(m))+' (length '+str(len(s))+')'        return 4, self.read_len    def write(self, s):        while True:            i = self.next_len - self.buffer.tell()            if i > len(s):                self.buffer.write(s)                return            self.buffer.write(s[:i])            s = s[i:]            m = self.buffer.getvalue()            self.buffer.reset()            self.buffer.truncate()            x = self.next_func(m)            self.next_len, self.next_func = x