Telethon/telethon/helpers.py
Dmitry D. Chernov c8f16a4e89 Fix a couple of inconsistencies in the public interface (#1102)
* Create `_NOT_A_REQUEST` when needed. Currently, modifications    
  in the raised exception would be "global".    
* `retries` parameters were actually attempts. This has been fixed    
  to actually be the amount of retries, so 0 now means don't retry.    
* Helper function to deal with retries instead of using a range with    
  different styles every time.
2019-02-06 19:41:45 +01:00

133 lines
3.5 KiB
Python

"""Various helpers not related to the Telegram API itself"""
import os
import struct
from hashlib import sha1, sha256
# region Multiple utilities
def generate_random_long(signed=True):
"""Generates a random long integer (8 bytes), which is optionally signed"""
return int.from_bytes(os.urandom(8), signed=signed, byteorder='little')
def ensure_parent_dir_exists(file_path):
"""Ensures that the parent directory exists"""
parent = os.path.dirname(file_path)
if parent:
os.makedirs(parent, exist_ok=True)
def add_surrogate(text):
return ''.join(
# SMP -> Surrogate Pairs (Telegram offsets are calculated with these).
# See https://en.wikipedia.org/wiki/Plane_(Unicode)#Overview for more.
''.join(chr(y) for y in struct.unpack('<HH', x.encode('utf-16le')))
if (0x10000 <= ord(x) <= 0x10FFFF) else x for x in text
)
def del_surrogate(text):
return text.encode('utf-16', 'surrogatepass').decode('utf-16')
def strip_text(text, entities):
"""
Strips whitespace from the given text modifying the provided entities.
This assumes that there are no overlapping entities, that their length
is greater or equal to one, and that their length is not out of bounds.
"""
if not entities:
return text.strip()
while text and text[-1].isspace():
e = entities[-1]
if e.offset + e.length == len(text):
if e.length == 1:
del entities[-1]
if not entities:
return text.strip()
else:
e.length -= 1
text = text[:-1]
while text and text[0].isspace():
for i in reversed(range(len(entities))):
e = entities[i]
if e.offset != 0:
e.offset -= 1
continue
if e.length == 1:
del entities[0]
if not entities:
return text.lstrip()
else:
e.length -= 1
text = text[1:]
return text
def retry_range(retries):
"""
Generates an integer sequence starting from 1. If `retries` is
negative or ``None`` then sequence is infinite, otherwise it will
end at `retries + 1`.
"""
yield 1
if retries is None:
retries = -1
attempt = 0
while attempt != retries:
attempt += 1
yield 1 + attempt
# endregion
# region Cryptographic related utils
def generate_key_data_from_nonce(server_nonce, new_nonce):
"""Generates the key data corresponding to the given nonce"""
server_nonce = server_nonce.to_bytes(16, 'little', signed=True)
new_nonce = new_nonce.to_bytes(32, 'little', signed=True)
hash1 = sha1(new_nonce + server_nonce).digest()
hash2 = sha1(server_nonce + new_nonce).digest()
hash3 = sha1(new_nonce + new_nonce).digest()
key = hash1 + hash2[:12]
iv = hash2[12:20] + hash3 + new_nonce[:4]
return key, iv
# endregion
# region Custom Classes
class TotalList(list):
"""
A list with an extra `total` property, which may not match its `len`
since the total represents the total amount of items *available*
somewhere else, not the items *in this list*.
"""
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.total = 0
def __str__(self):
return '[{}, total={}]'.format(
', '.join(str(x) for x in self), self.total)
def __repr__(self):
return '[{}, total={}]'.format(
', '.join(repr(x) for x in self), self.total)
# endregion