decode.py

import io 

mapping_table = {}

def bigsize_decode(r):
    """Decode an integer from reader `r`"""
    raw = r.read(1)
    if len(raw) != 1:
        return None

    i = int(raw,16)
    if i < 0xFD:
        return i
    elif i == 0xFD:
        return r.read(2).reverse()
    elif i == 0xFE:
        return r.read(4).reverse()
    else:
        return r.read(8).reverse()


def decodeinitMessage(rawMsg):
    res = {}
    res['data'] = {}
    binary = io.BytesIO(rawMsg)
    res['data']['type'] = int(binary.read(2),2)
    res['data']['gflen'] = int(binary.read(2),2)
    res['data']['globalFeatures'] = binary.read(res['gflen'])
    res['data']['flen'] = int(binary.read(2),2)
    res['data']['features'] = binary.read(res['flen'])
    raw = binary.read(1)
    res['tlv_stream']['init_tlvs'] = []
    while len(raw) != 1:
        tmp = []
        tmp.append(bigsize_decode(binary))
        tmp.append(bigsize_decode(binary))
        tmp.append(bigsize_decode(binary))
        raw = binary.read(1)
        res['tlv_stream']['init_tlvs'].append(tmp)
    return res
    
    

print(decodeinitMessage(b''))