b2c1066734
1) Fix bug where it would decode as base64 but not indicate that in the structure 2) Use a list of patterns of youtube object ids so it will not base64 decode those 3) Detect the base64 type. If not possible, outputs base64? 4) Remove unnecessary try-except clause 5) Remove unused filt parameter Signed-off-by: Jesús <heckyel@hyperbola.info>
612 lines
18 KiB
Python
612 lines
18 KiB
Python
# TODO: clean this file up more and heavily refactor
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''' Helper functions for reverse engineering protobuf.
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Basic guide:
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Run interactively with python3 -i proto_debug.py
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The function dec will decode a base64 string
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(regardless of whether it includes = or %3D at the end) to a bytestring
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The function pb (parse_protobuf) will return a list of tuples.
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Each tuple is (wire_type, field_number, field_data)
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The function enc encodes as base64 (inverse of dec)
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The function uenc is like enc but replaces = with %3D
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See https://developers.google.com/protocol-buffers/docs/encoding#structure
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Example usage:
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>>> pb(dec('4qmFsgJcEhhVQ1lPX2phYl9lc3VGUlY0YjE3QUp0QXcaQEVnWjJhV1JsYjNNWUF5QUFNQUU0QWVvREdFTm5Ua1JSVlVWVFEzZHBYM2gwTTBaeFRuRkZiRFZqUWclM0QlM0Q%3D'))
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[(2, 80226972, b'\x12\x18UCYO_jab_esuFRV4b17AJtAw\x1a@EgZ2aWRlb3MYAyAAMAE4AeoDGENnTkRRVUVTQ3dpX3h0M0ZxTnFFbDVjQg%3D%3D')]
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>>> pb(b'\x12\x18UCYO_jab_esuFRV4b17AJtAw\x1a@EgZ2aWRlb3MYAyAAMAE4AeoDGENnTkRRVUVTQ3dpX3h0M0ZxTnFFbDVjQg%3D%3D')
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[(2, 2, b'UCYO_jab_esuFRV4b17AJtAw'), (2, 3, b'EgZ2aWRlb3MYAyAAMAE4AeoDGENnTkRRVUVTQ3dpX3h0M0ZxTnFFbDVjQg%3D%3D')]
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>>> pb(dec(b'EgZ2aWRlb3MYAyAAMAE4AeoDGENnTkRRVUVTQ3dpX3h0M0ZxTnFFbDVjQg%3D%3D'))
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[(2, 2, b'videos'), (0, 3, 3), (0, 4, 0), (0, 6, 1), (0, 7, 1), (2, 61, b'CgNDQUESCwi_xt3FqNqEl5cB')]
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>>> pb(dec(b'CgNDQUESCwi_xt3FqNqEl5cB'))
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[(2, 1, b'CAA'), (2, 2, b'\x08\xbf\xc6\xdd\xc5\xa8\xda\x84\x97\x97\x01')]
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>>> pb(b'\x08\xbf\xc6\xdd\xc5\xa8\xda\x84\x97\x97\x01')
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[(0, 1, 10893665244101960511)]
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>>> pb(dec(b'CAA'))
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[(0, 1, 0)]
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The function recursive_pb will try to do dec/pb recursively automatically.
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It's a dumb function (so might try to dec or pb something that isn't really
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base64 or protobuf) so be careful.
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The function pp will pretty print the recursive structure:
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>>> pp(recursive_pb('4qmFsgJcEhhVQ1lPX2phYl9lc3VGUlY0YjE3QUp0QXcaQEVnWjJhV1JsYjNNWUF5QUFNQUU0QWVvREdFTm5Ua1JSVlVWVFEzZHBYM2gwTTBaeFRuRkZiRFZqUWclM0QlM0Q%3D'))
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('base64p',
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[
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[2, 80226972,
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[
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[2, 2, b'UCYO_jab_esuFRV4b17AJtAw'],
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[2, 3,
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('base64p',
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[
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[2, 2, b'videos'],
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[0, 3, 3],
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[0, 4, 0],
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[0, 6, 1],
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[0, 7, 1],
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[2, 61,
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('base64?',
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[
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[2, 1, b'CAA'],
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[2, 2,
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[
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[0, 1, 10893665244101960511],
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]
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],
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]
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)
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],
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]
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)
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],
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]
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],
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]
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)
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- base64 means a base64 encode with equals sign paddings
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- base64s means a base64 encode without padding
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- base64p means a url base64 encode with equals signs replaced with %3D
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- base64? means the base64 type cannot be inferred because of the length
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make_proto is the inverse function. It will take a recursive_pb structure and
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make a ctoken out of it, so in general,
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x == make_proto(recursive_pb(x))
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There are some other functions I wrote while reverse engineering stuff
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that may or may not be useful.
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'''
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import urllib.request
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import urllib.parse
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import re
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import time
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import json
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import os
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import pprint
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# ------ from proto.py -----------------------------------------------
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from math import ceil
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import base64
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import io
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def byte(n):
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return bytes((n,))
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def varint_encode(offset):
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'''In this encoding system, for each 8-bit byte, the first bit is 1 if there are more bytes, and 0 is this is the last one.
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The next 7 bits are data. These 7-bit sections represent the data in Little endian order. For example, suppose the data is
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aaaaaaabbbbbbbccccccc (each of these sections is 7 bits). It will be encoded as:
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1ccccccc 1bbbbbbb 0aaaaaaa
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This encoding is used in youtube parameters to encode offsets and to encode the length for length-prefixed data.
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See https://developers.google.com/protocol-buffers/docs/encoding#varints for more info.'''
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needed_bytes = ceil(offset.bit_length()/7) or 1 # (0).bit_length() returns 0, but we need 1 in that case.
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encoded_bytes = bytearray(needed_bytes)
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for i in range(0, needed_bytes - 1):
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encoded_bytes[i] = (offset & 127) | 128 # 7 least significant bits
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offset = offset >> 7
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encoded_bytes[-1] = offset & 127 # leave first bit as zero for last byte
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return bytes(encoded_bytes)
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def varint_decode(encoded):
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decoded = 0
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for i, byte in enumerate(encoded):
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decoded |= (byte & 127) << 7*i
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if not (byte & 128):
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break
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return decoded
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def string(field_number, data):
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data = as_bytes(data)
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return _proto_field(2, field_number, varint_encode(len(data)) + data)
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nested = string
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def uint(field_number, value):
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return _proto_field(0, field_number, varint_encode(value))
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def _proto_field(wire_type, field_number, data):
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''' See https://developers.google.com/protocol-buffers/docs/encoding#structure '''
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return varint_encode((field_number << 3) | wire_type) + data
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def percent_b64encode(data):
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return base64.urlsafe_b64encode(data).replace(b'=', b'%3D')
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def unpadded_b64encode(data):
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return base64.urlsafe_b64encode(data).replace(b'=', b'')
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def as_bytes(value):
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if isinstance(value, str):
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return value.encode('utf-8')
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return value
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def read_varint(data):
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result = 0
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i = 0
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while True:
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try:
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byte = data.read(1)[0]
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except IndexError:
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if i == 0:
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raise EOFError()
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raise Exception('Unterminated varint starting at ' + str(data.tell() - i))
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result |= (byte & 127) << 7*i
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if not byte & 128:
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break
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i += 1
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return result
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def read_group(data, end_sequence):
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start = data.tell()
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index = data.original.find(end_sequence, start)
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if index == -1:
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raise Exception('Unterminated group')
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data.seek(index + len(end_sequence))
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return data.original[start:index]
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def parse(data, include_wire_type=False):
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'''Returns a dict mapping field numbers to values
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data is the protobuf structure, which must not be b64-encoded'''
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if include_wire_type:
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return {field_number: [wire_type, value]
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for wire_type, field_number, value in read_protobuf(data)}
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return {field_number: value
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for _, field_number, value in read_protobuf(data)}
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base64_enc_funcs = {
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'base64': base64.urlsafe_b64encode,
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'base64s': unpadded_b64encode,
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'base64p': percent_b64encode,
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'base64?': base64.urlsafe_b64encode,
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}
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def _make_protobuf(data):
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# must be dict mapping field_number to [wire_type, value]
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if isinstance(data, dict):
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new_data = []
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for field_num, (wire_type, value) in sorted(data.items()):
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new_data.append((wire_type, field_num, value))
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data = new_data
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if isinstance(data, str):
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return data.encode('utf-8')
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elif len(data) == 2 and data[0] in list(base64_enc_funcs.keys()):
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return base64_enc_funcs[data[0]](_make_protobuf(data[1]))
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elif isinstance(data, list):
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result = b''
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for field in data:
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if field[0] == 0:
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result += uint(field[1], field[2])
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elif field[0] == 2:
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result += string(field[1], _make_protobuf(field[2]))
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else:
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raise NotImplementedError('Wire type ' + str(field[0])
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+ ' not implemented')
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return result
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return data
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def make_protobuf(data):
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return _make_protobuf(data).decode('ascii')
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make_proto = make_protobuf
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def _set_protobuf_value(data, *path, value):
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if not path:
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return value
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op = path[0]
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if op in base64_enc_funcs:
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inner_data = b64_to_bytes(data)
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return base64_enc_funcs[op](
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_set_protobuf_value(inner_data, *path[1:], value=value)
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)
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pb_dict = parse(data, include_wire_type=True)
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pb_dict[op][1] = _set_protobuf_value(
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pb_dict[op][1], *path[1:], value=value
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)
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return _make_protobuf(pb_dict)
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def set_protobuf_value(data, *path, value):
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'''Set a field's value in a raw protobuf structure
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path is a list of field numbers and/or base64 encoding directives
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The directives are
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base64: normal base64 encoding with equal signs padding
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base64s ("stripped"): no padding
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base64p: %3D instead of = for padding
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return new_protobuf, err'''
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try:
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new_protobuf = _set_protobuf_value(data, *path, value=value)
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return new_protobuf.decode('ascii'), None
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except Exception:
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return None, traceback.format_exc()
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def b64_to_bytes(data):
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if isinstance(data, bytes):
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data = data.decode('ascii')
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data = data.replace("%3D", "=")
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return base64.urlsafe_b64decode(data + "="*((4 - len(data) % 4) % 4))
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# --------------------------------------------------------------------
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dec = b64_to_bytes
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def get_b64_type(data):
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'''return base64, base64s, base64p, or base64?'''
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if isinstance(data, str):
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data = data.encode('ascii')
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if data.endswith(b'='):
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return 'base64'
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if data.endswith(b'%3D'):
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return 'base64p'
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# Length of data means it wouldn't have an equals sign,
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# so we can't tell which type it is.
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if len(data) % 4 == 0:
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return 'base64?'
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return 'base64s'
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def enc(t):
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return base64.urlsafe_b64encode(t).decode('ascii')
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def uenc(t):
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return enc(t).replace("=", "%3D")
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def b64_to_ascii(t):
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return base64.urlsafe_b64decode(t).decode('ascii', errors='replace')
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def b64_to_bin(t):
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decoded = base64.urlsafe_b64decode(t)
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# print(len(decoded)*8)
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return " ".join(["{:08b}".format(x) for x in decoded])
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def bytes_to_bin(t):
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return " ".join(["{:08b}".format(x) for x in t])
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def bin_to_bytes(t):
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return int(t, 2).to_bytes((len(t) + 7) // 8, 'big')
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def bytes_to_hex(t):
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return ' '.join(hex(n)[2:].zfill(2) for n in t)
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tohex = bytes_to_hex
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fromhex = bytes.fromhex
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def aligned_ascii(data):
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return ' '.join(' ' + chr(n) if n in range(32, 128) else ' _' for n in data)
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def parse_protobuf(data, mutable=False, spec=()):
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data_original = data
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data = io.BytesIO(data)
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data.original = data_original
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while True:
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try:
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tag = read_varint(data)
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except EOFError:
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break
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wire_type = tag & 7
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field_number = tag >> 3
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if wire_type == 0:
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value = read_varint(data)
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elif wire_type == 1:
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value = data.read(8)
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elif wire_type == 2:
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length = read_varint(data)
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value = data.read(length)
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elif wire_type == 3:
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end_bytes = varint_encode((field_number << 3) | 4)
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value = read_group(data, end_bytes)
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elif wire_type == 5:
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value = data.read(4)
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else:
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raise Exception("Unknown wire type: " + str(wire_type) + ", Tag: " + bytes_to_hex(varint_encode(tag)) + ", at position " + str(data.tell()))
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if mutable:
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yield [wire_type, field_number, value]
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else:
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yield (wire_type, field_number, value)
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read_protobuf = parse_protobuf
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def pb(data, mutable=False):
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return list(parse_protobuf(data, mutable=mutable))
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def bytes_to_base4(data):
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result = ''
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for b in data:
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result += str(b >> 6) + str((b >> 4) & 0b11) + str((b >> 2) & 0b11) + str(b & 0b11)
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return result
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import re
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import struct
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import binascii
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# Base32 encoding/decoding must be done in Python
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_b32alphabet = b'abcdefghijklmnopqrstuvwxyz012345'
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_b32tab2 = None
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_b32rev = None
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bytes_types = (bytes, bytearray) # Types acceptable as binary data
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def _bytes_from_decode_data(s):
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if isinstance(s, str):
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try:
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return s.encode('ascii')
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except UnicodeEncodeError:
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raise ValueError('string argument should contain only ASCII characters')
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if isinstance(s, bytes_types):
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return s
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try:
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return memoryview(s).tobytes()
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except TypeError:
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raise TypeError("argument should be a bytes-like object or ASCII "
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"string, not %r" % s.__class__.__name__) from None
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def b32decode(s, casefold=False, map01=None):
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"""Decode the Base32 encoded bytes-like object or ASCII string s.
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Optional casefold is a flag specifying whether a lowercase alphabet is
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acceptable as input. For security purposes, the default is False.
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RFC 3548 allows for optional mapping of the digit 0 (zero) to the
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letter O (oh), and for optional mapping of the digit 1 (one) to
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either the letter I (eye) or letter L (el). The optional argument
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map01 when not None, specifies which letter the digit 1 should be
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mapped to (when map01 is not None, the digit 0 is always mapped to
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the letter O). For security purposes the default is None, so that
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0 and 1 are not allowed in the input.
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The result is returned as a bytes object. A binascii.Error is raised if
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the input is incorrectly padded or if there are non-alphabet
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characters present in the input.
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"""
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global _b32rev
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# Delay the initialization of the table to not waste memory
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# if the function is never called
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if _b32rev is None:
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_b32rev = {v: k for k, v in enumerate(_b32alphabet)}
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s = _bytes_from_decode_data(s)
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if len(s) % 8:
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raise binascii.Error('Incorrect padding')
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# Handle section 2.4 zero and one mapping. The flag map01 will be either
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# False, or the character to map the digit 1 (one) to. It should be
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# either L (el) or I (eye).
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if map01 is not None:
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map01 = _bytes_from_decode_data(map01)
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assert len(map01) == 1, repr(map01)
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s = s.translate(bytes.maketrans(b'01', b'O' + map01))
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if casefold:
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s = s.upper()
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# Strip off pad characters from the right. We need to count the pad
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# characters because this will tell us how many null bytes to remove from
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# the end of the decoded string.
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l = len(s)
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s = s.rstrip(b'=')
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padchars = l - len(s)
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# Now decode the full quanta
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decoded = bytearray()
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b32rev = _b32rev
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for i in range(0, len(s), 8):
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quanta = s[i: i + 8]
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acc = 0
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try:
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for c in quanta:
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acc = (acc << 5) + b32rev[c]
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except KeyError:
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raise binascii.Error('Non-base32 digit found') from None
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decoded += acc.to_bytes(5, 'big')
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# Process the last, partial quanta
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if padchars:
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acc <<= 5 * padchars
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last = acc.to_bytes(5, 'big')
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if padchars == 1:
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decoded[-5:] = last[:-1]
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elif padchars == 3:
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decoded[-5:] = last[:-2]
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elif padchars == 4:
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decoded[-5:] = last[:-3]
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elif padchars == 6:
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decoded[-5:] = last[:-4]
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else:
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raise binascii.Error('Incorrect padding')
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return bytes(decoded)
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def dec32(data):
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if isinstance(data, bytes):
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data = data.decode('ascii')
|
|
return b32decode(data + "="*((8 - len(data)%8)%8))
|
|
|
|
|
|
_patterns = [
|
|
(b'UC', 24), # channel
|
|
(b'PL', 34), # playlist
|
|
(b'LL', 24), # liked videos playlist
|
|
(b'UU', 24), # user uploads playlist
|
|
(b'RD', 15), # radio mix
|
|
(b'RD', 43), # radio mix
|
|
(b'', 11), # video
|
|
(b'Ug', 26), # comment
|
|
(b'Ug', 49), # comment reply (of form parent_id.reply_id)
|
|
(b'9', 22), # comment reply id
|
|
]
|
|
def is_youtube_object_id(data):
|
|
try:
|
|
if isinstance(data, str):
|
|
data = data.encode('ascii')
|
|
except Exception:
|
|
return False
|
|
|
|
for start_sequence, length in _patterns:
|
|
if len(data) == length and data.startswith(start_sequence):
|
|
return True
|
|
|
|
return False
|
|
|
|
|
|
def recursive_pb(data):
|
|
try:
|
|
# check if this fits the basic requirements for base64
|
|
if isinstance(data, str) or all(i > 32 for i in data):
|
|
if len(data) > 11 and not is_youtube_object_id(data):
|
|
raw_data = b64_to_bytes(data)
|
|
b64_type = get_b64_type(data)
|
|
|
|
rpb = recursive_pb(raw_data)
|
|
if rpb == raw_data:
|
|
# could not interpret as protobuf, probably not b64
|
|
return data
|
|
return (b64_type, rpb)
|
|
else:
|
|
return data
|
|
except Exception as e:
|
|
return data
|
|
|
|
try:
|
|
result = pb(data, mutable=True)
|
|
except Exception as e:
|
|
return data
|
|
|
|
for tuple in result:
|
|
if tuple[0] == 2:
|
|
tuple[2] = recursive_pb(tuple[2])
|
|
|
|
return result
|
|
|
|
|
|
|
|
def indent_lines(lines, indent):
|
|
return re.sub(r'^', ' '*indent, lines, flags=re.MULTILINE)
|
|
|
|
|
|
def _pp(obj, indent): # not my best work
|
|
if isinstance(obj, tuple):
|
|
if len(obj) == 3: # (wire_type, field_number, data)
|
|
return obj.__repr__()
|
|
else: # (base64, [...])
|
|
return ('(' + obj[0].__repr__() + ',\n'
|
|
+ indent_lines(_pp(obj[1], indent), indent) + '\n'
|
|
+ ')')
|
|
elif isinstance(obj, list):
|
|
# [wire_type, field_number, data]
|
|
if (len(obj) == 3
|
|
and not any(isinstance(x, (list, tuple)) for x in obj)
|
|
):
|
|
return obj.__repr__()
|
|
|
|
# [wire_type, field_number, [...]]
|
|
elif (len(obj) == 3
|
|
and not any(isinstance(x, (list, tuple)) for x in obj[0:2])
|
|
):
|
|
return ('[' + obj[0].__repr__() + ', ' + obj[1].__repr__() + ',\n'
|
|
+ indent_lines(_pp(obj[2], indent), indent) + '\n'
|
|
+ ']')
|
|
else:
|
|
s = '[\n'
|
|
for x in obj:
|
|
s += indent_lines(_pp(x, indent), indent) + ',\n'
|
|
s += ']'
|
|
return s
|
|
else:
|
|
return obj.__repr__()
|
|
|
|
|
|
def pp(obj, indent=1):
|
|
'''Pretty prints the recursive pb structure'''
|
|
print(_pp(obj, indent))
|
|
|
|
|
|
desktop_user_agent = 'Mozilla/5.0 (Windows NT 6.1; rv:52.0) Gecko/20100101 Firefox/52.0'
|
|
desktop_headers = (
|
|
('Accept', '*/*'),
|
|
('Accept-Language', 'en-US,en;q=0.5'),
|
|
('X-YouTube-Client-Name', '1'),
|
|
('X-YouTube-Client-Version', '2.20180830'),
|
|
) + (('User-Agent', desktop_user_agent),)
|
|
|
|
mobile_user_agent = 'Mozilla/5.0 (Linux; Android 7.0; Redmi Note 4 Build/NRD90M) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Mobile Safari/537.36'
|
|
mobile_headers = (
|
|
('Accept', '*/*'),
|
|
('Accept-Language', 'en-US,en;q=0.5'),
|
|
('X-YouTube-Client-Name', '2'),
|
|
('X-YouTube-Client-Version', '2.20180830'),
|
|
) + (('User-Agent', mobile_user_agent),)
|