Reader (PPC9) - Advent calendar CTF 2014

reader.py

from socket import socket

code0 = {}

code0["0"] = "100010100"
code0["1"] = "101001000"
code0["2"] = "101000100"
code0["3"] = "101000010"
code0["4"] = "100101000"
code0["5"] = "100100100"
code0["6"] = "100100010"
code0["7"] = "101010000"
code0["8"] = "100010010"
code0["9"] = "100001010"
code0["A"] = "110101000"
code0["B"] = "110100100"
code0["C"] = "110100010"
code0["D"] = "110010100"
code0["E"] = "110010010"
code0["F"] = "110001010"
code0["G"] = "101101000"
code0["H"] = "101100100"
code0["I"] = "101100010"
code0["J"] = "100110100"
code0["K"] = "100011010"
code0["L"] = "101011000"
code0["M"] = "101001100"
code0["N"] = "101000110"
code0["O"] = "100101100"
code0["P"] = "100010110"
code0["Q"] = "110110100"
code0["R"] = "110110010"
code0["S"] = "110101100"
code0["T"] = "110100110"
code0["U"] = "110010110"
code0["V"] = "110011010"
code0["W"] = "101101100"
code0["X"] = "101100110"
code0["Y"] = "100110110"
code0["Z"] = "100111010"
code0["-"] = "100101110"
code0["."] = "111010100"
code0[" "] = "111010010"
code0['"'] = "111001010"
code0["/"] = "101101110"
code0["+"] = "101101110"
code0["%"] = "110101110"
code0["SHIFT1"] = "100100110"
code0["SHIFT2"] = "111011010"
code0["SHIFT3"] = "111010110"
code0["SHIFT4"] = "100110010"
code0["START"] = "101011110"
code0["STOP"] = "1010111101"
code0["UNKNOWN"] = "101110110"

mapping = {v: k for k, v in code0.iteritems()}


s = socket()
s.connect(("adctf2014.katsudon.org", 43010))

while True:
    msg = s.recv(2048)
    msg += s.recv(2048).strip()
    i = 0
    binary = ""
    print msg
    while i < len(msg):
        #print i, repr(msg[i]), binary
        if msg[i] == " ":  # 00
            binary += "00"
            i += 2
        else:
            if msg[i+2] == "\x88":  # 11
                binary += "11"
            elif msg[i+2] == "\x90":  # 01
                binary += "01"
            elif msg[i+2] == "\x8c":  # 10
                binary += "10"
            else:
                print 'UNKNOWN ' + repr(msg[i+2])
                raise Exception
            i += 3
    print binary
    res = ""
    for i in range(0, len(binary), 9):
        if len(binary[i:i+9]) == 9 and len(mapping[binary[i:i+9]]) == 1:
            res += mapping[binary[i:i+9]]
    res = res[:10]
    print res
    s.sendall(res + "\n")