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Extraction: Move non-stateful signature decryption functionality into yt_data_extract

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This commit is contained in:
James Taylor
2019-12-19 21:28:21 -08:00
parent 4a3529df95
commit 6b7a1212e3
3 changed files with 110 additions and 86 deletions
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97
youtube/watch.py
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@@ -11,7 +11,6 @@ import gevent
import os
import math
import traceback
import re
import urllib
try:
@@ -175,101 +174,29 @@ def save_decrypt_cache():
f.write(json.dumps({'version': 1, 'decrypt_cache':decrypt_cache}, indent=4, sort_keys=True))
f.close()
# adapted from youtube-dl and invidious:
# https://github.com/omarroth/invidious/blob/master/src/invidious/helpers/signatures.cr
decrypt_function_re = re.compile(r'function\(a\)\{(a=a\.split\(""\)[^\}]+)\}')
op_with_arg_re = re.compile(r'[^\.]+\.([^\(]+)\(a,(\d+)\)')
def decrypt_signatures(info):
'''return error string, or False if no errors'''
if ('formats' not in info) or (not info['formats']) or (not info['formats'][0]['s']):
return False # No decryption needed
if not yt_data_extract.requires_decryption(info):
return False
if not info['player_name']:
return 'Could not find player name'
if not info['base_js']:
return 'Failed to find base.js'
player_name = yt_data_extract.get(info['base_js'].split('/'), -2)
if not player_name:
return 'Could not find player name'
player_name = info['player_name']
if player_name in decrypt_cache:
print('Using cached decryption function for: ' + player_name)
decryption_function = decrypt_cache[player_name]
info['decryption_function'] = decrypt_cache[player_name]
else:
base_js = util.fetch_url(info['base_js'], debug_name='base.js', report_text='Fetched player ' + player_name)
base_js = base_js.decode('utf-8')
decrypt_function_match = decrypt_function_re.search(base_js)
if decrypt_function_match is None:
return 'Could not find decryption function in base.js'
function_body = decrypt_function_match.group(1).split(';')[1:-1]
if not function_body:
return 'Empty decryption function body'
var_name = yt_data_extract.get(function_body[0].split('.'), 0)
if var_name is None:
return 'Could not find var_name'
var_body_match = re.search(r'var ' + re.escape(var_name) + r'=\{(.*?)\};', base_js, flags=re.DOTALL)
if var_body_match is None:
return 'Could not find var_body'
operations = var_body_match.group(1).replace('\n', '').split('},')
if not operations:
return 'Did not find any definitions in var_body'
operations[-1] = operations[-1][:-1] # remove the trailing '}' since we split by '},' on the others
operation_definitions = {}
for op in operations:
colon_index = op.find(':')
opening_brace_index = op.find('{')
if colon_index == -1 or opening_brace_index == -1:
return 'Could not parse operation'
op_name = op[:colon_index]
op_body = op[opening_brace_index+1:]
if op_body == 'a.reverse()':
operation_definitions[op_name] = 0
elif op_body == 'a.splice(0,b)':
operation_definitions[op_name] = 1
elif op_body.startswith('var c=a[0]'):
operation_definitions[op_name] = 2
else:
return 'Unknown op_body: ' + op_body
decryption_function = []
for op_with_arg in function_body:
match = op_with_arg_re.fullmatch(op_with_arg)
if match is None:
return 'Could not parse operation with arg'
op_name = match.group(1)
if op_name not in operation_definitions:
return 'Unknown op_name: ' + op_name
op_argument = match.group(2)
decryption_function.append([operation_definitions[op_name], int(op_argument)])
decrypt_cache[player_name] = decryption_function
err = yt_data_extract.extract_decryption_function(info, base_js)
if err:
return err
decrypt_cache[player_name] = info['decryption_function']
save_decrypt_cache()
for format in info['formats']:
if not format['s'] or not format['sp'] or not format['url']:
print('Warning: s, sp, or url not in format')
continue
a = list(format['s'])
for op, argument in decryption_function:
if op == 0:
a.reverse()
elif op == 1:
a = a[argument:]
else:
operation_2(a, argument)
signature = ''.join(a)
format['url'] += '&' + format['sp'] + '=' + signature
return False
def operation_2(a, b):
c = a[0]
a[0] = a[b % len(a)]
a[b % len(a)] = c
err = yt_data_extract.decrypt_signatures(info)
return err
headers = (
('Accept', '*/*'),