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# Copyright 2012-2015, Damian Johnson and The Tor Project
# See LICENSE for licensing information
"""
Miscellaneous utility functions for working with tor.
.. versionadded:: 1.2.0
**Module Overview:**
::
is_valid_fingerprint - checks if a string is a valid tor relay fingerprint
is_valid_nickname - checks if a string is a valid tor relay nickname
is_valid_circuit_id - checks if a string is a valid tor circuit id
is_valid_stream_id - checks if a string is a valid tor stream id
is_valid_connection_id - checks if a string is a valid tor connection id
is_valid_hidden_service_address - checks if a string is a valid hidden service address
is_hex_digits - checks if a string is only made up of hex digits
"""
import re
# The control-spec defines the following as...
#
# Fingerprint = "$" 40*HEXDIG
# NicknameChar = "a"-"z" / "A"-"Z" / "0" - "9"
# Nickname = 1*19 NicknameChar
#
# CircuitID = 1*16 IDChar
# IDChar = ALPHA / DIGIT
#
# HEXDIG is defined in RFC 5234 as being uppercase and used in RFC 5987 as
# case insensitive. Tor doesn't define this in the spec so flipping a coin
# and going with case insensitive.
NICKNAME_PATTERN = re.compile('^[a-zA-Z0-9]{1,19}$')
CIRC_ID_PATTERN = re.compile('^[a-zA-Z0-9]{1,16}$')
# Hidden service addresses are sixteen base32 characters.
HS_ADDRESS_PATTERN = re.compile('^[a-z2-7]{16}$')
def is_valid_fingerprint(entry, check_prefix = False):
"""
Checks if a string is a properly formatted relay fingerprint. This checks for
a '$' prefix if check_prefix is true, otherwise this only validates the hex
digits.
:param str entry: string to be checked
:param bool check_prefix: checks for a '$' prefix
:returns: **True** if the string could be a relay fingerprint, **False** otherwise
"""
try:
if check_prefix:
if not entry or entry[0] != '$':
return False
entry = entry[1:]
return is_hex_digits(entry, 40)
except TypeError:
return False
def is_valid_nickname(entry):
"""
Checks if a string is a valid format for being a nickname.
:param str entry: string to be checked
:returns: **True** if the string could be a nickname, **False** otherwise
"""
try:
return bool(NICKNAME_PATTERN.match(entry))
except TypeError:
return False
def is_valid_circuit_id(entry):
"""
Checks if a string is a valid format for being a circuit identifier.
:returns: **True** if the string could be a circuit id, **False** otherwise
"""
try:
return bool(CIRC_ID_PATTERN.match(entry))
except TypeError:
return False
def is_valid_stream_id(entry):
"""
Checks if a string is a valid format for being a stream identifier.
Currently, this is just an alias to :func:`~stem.util.tor_tools.is_valid_circuit_id`.
:returns: **True** if the string could be a stream id, **False** otherwise
"""
return is_valid_circuit_id(entry)
def is_valid_connection_id(entry):
"""
Checks if a string is a valid format for being a connection identifier.
Currently, this is just an alias to :func:`~stem.util.tor_tools.is_valid_circuit_id`.
:returns: **True** if the string could be a connection id, **False** otherwise
"""
return is_valid_circuit_id(entry)
def is_valid_hidden_service_address(entry):
"""
Checks if a string is a valid format for being a hidden service address (not
including the '.onion' suffix).
:returns: **True** if the string could be a hidden service address, **False** otherwise
"""
try:
return bool(HS_ADDRESS_PATTERN.match(entry))
except TypeError:
return False
def is_hex_digits(entry, count):
"""
Checks if a string is the given number of hex digits. Digits represented by
letters are case insensitive.
:param str entry: string to be checked
:param int count: number of hex digits to be checked for
:returns: **True** if the given number of hex digits, **False** otherwise
"""
try:
if len(entry) != count:
return False
int(entry, 16) # attempt to convert it as hex
return True
except (ValueError, TypeError):
return False
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