Source code for gluon.utils

#!/usr/bin/env python
# -*- coding: utf-8 -*-

| This file is part of the web2py Web Framework
| Copyrighted by Massimo Di Pierro <>
| License: LGPLv3 (

This file specifically includes utilities for security.

import threading
import struct
import uuid
import random
import inspect
import time
import os
import re
import sys
import logging
import socket
import base64
import zlib

_struct_2_long_long = struct.Struct('=QQ')

python_version = sys.version_info[0]

if python_version == 2:
    import cPickle as pickle
    import pickle

import hashlib
from hashlib import md5, sha1, sha224, sha256, sha384, sha512

    from Crypto.Cipher import AES
except ImportError:
    import gluon.contrib.aes as AES

import hmac

if hasattr(hashlib, "pbkdf2_hmac"):
[docs] def pbkdf2_hex(data, salt, iterations=1000, keylen=24, hashfunc=None): hashfunc = hashfunc or sha1 return hashlib.pbkdf2_hmac(hashfunc().name, data, salt, iterations, keylen).encode("hex")
HAVE_PBKDF2 = True else: try: try: from gluon.contrib.pbkdf2_ctypes import pbkdf2_hex except (ImportError, AttributeError): from gluon.contrib.pbkdf2 import pbkdf2_hex HAVE_PBKDF2 = True except ImportError: try: from .pbkdf2 import pbkdf2_hex HAVE_PBKDF2 = True except (ImportError, ValueError): HAVE_PBKDF2 = False HAVE_COMPARE_DIGEST = False if hasattr(hmac, 'compare_digest'): HAVE_COMPARE_DIGEST = True logger = logging.getLogger("web2py")
[docs]def AES_new(key, IV=None): """ Returns an AES cipher object and random IV if None specified """ if IV is None: IV = fast_urandom16() return, AES.MODE_CBC, IV), IV
[docs]def compare(a, b): """ Compares two strings and not vulnerable to timing attacks """ if HAVE_COMPARE_DIGEST: return hmac.compare_digest(a, b) result = len(a) ^ len(b) for i in xrange(len(b)): result |= ord(a[i%len(a)]) ^ ord(b[i]) return result == 0
[docs]def md5_hash(text): """ Generates a md5 hash with the given text """ return md5(text).hexdigest()
[docs]def simple_hash(text, key='', salt='', digest_alg='md5'): """ Generates hash with the given text using the specified digest hashing algorithm """ if not digest_alg: raise RuntimeError("simple_hash with digest_alg=None") elif not isinstance(digest_alg, str): # manual approach h = digest_alg(text + key + salt) elif digest_alg.startswith('pbkdf2'): # latest and coolest! iterations, keylen, alg = digest_alg[7:-1].split(',') return pbkdf2_hex(text, salt, int(iterations), int(keylen), get_digest(alg)) elif key: # use hmac digest_alg = get_digest(digest_alg) h = + salt, text, digest_alg) else: # compatible with third party systems h = get_digest(digest_alg)() h.update(text + salt) return h.hexdigest()
[docs]def get_digest(value): """ Returns a hashlib digest algorithm from a string """ if not isinstance(value, str): return value value = value.lower() if value == "md5": return md5 elif value == "sha1": return sha1 elif value == "sha224": return sha224 elif value == "sha256": return sha256 elif value == "sha384": return sha384 elif value == "sha512": return sha512 else: raise ValueError("Invalid digest algorithm: %s" % value)
DIGEST_ALG_BY_SIZE = { 128 / 4: 'md5', 160 / 4: 'sha1', 224 / 4: 'sha224', 256 / 4: 'sha256', 384 / 4: 'sha384', 512 / 4: 'sha512', }
[docs]def get_callable_argspec(fn): if inspect.isfunction(fn) or inspect.ismethod(fn): inspectable = fn elif inspect.isclass(fn): inspectable = fn.__init__ elif hasattr(fn, '__call__'): inspectable = fn.__call__ else: inspectable = fn return inspect.getargspec(inspectable)
[docs]def pad(s, n=32, padchar=' '): return s + (32 - len(s) % 32) * padchar
[docs]def secure_dumps(data, encryption_key, hash_key=None, compression_level=None): if not hash_key: hash_key = sha1(encryption_key).hexdigest() dump = pickle.dumps(data, pickle.HIGHEST_PROTOCOL) if compression_level: dump = zlib.compress(dump, compression_level) key = pad(encryption_key)[:32] cipher, IV = AES_new(key) encrypted_data = base64.urlsafe_b64encode(IV + cipher.encrypt(pad(dump))) signature =, encrypted_data).hexdigest() return signature + ':' + encrypted_data
[docs]def secure_loads(data, encryption_key, hash_key=None, compression_level=None): if ':' not in data: return None if not hash_key: hash_key = sha1(encryption_key).hexdigest() signature, encrypted_data = data.split(':', 1) actual_signature =, encrypted_data).hexdigest() if not compare(signature, actual_signature): return None key = pad(encryption_key)[:32] encrypted_data = base64.urlsafe_b64decode(encrypted_data) IV, encrypted_data = encrypted_data[:16], encrypted_data[16:] cipher, _ = AES_new(key, IV=IV) try: data = cipher.decrypt(encrypted_data) data = data.rstrip(' ') if compression_level: data = zlib.decompress(data) return pickle.loads(data) except Exception, e: return None
### compute constant CTOKENS
[docs]def initialize_urandom(): """ This function and the web2py_uuid follow from the following discussion: `` At startup web2py compute a unique ID that identifies the machine by adding uuid.getnode() + int(time.time() * 1e3) This is a 48-bit number. It converts the number into 16 8-bit tokens. It uses this value to initialize the entropy source ('/dev/urandom') and to seed random. If os.random() is not supported, it falls back to using random and issues a warning. """ node_id = uuid.getnode() microseconds = int(time.time() * 1e6) ctokens = [((node_id + microseconds) >> ((i % 6) * 8)) % 256 for i in range(16)] random.seed(node_id + microseconds) try: os.urandom(1) have_urandom = True try: # try to add process-specific entropy frandom = open('/dev/urandom', 'wb') try: if python_version == 2: frandom.write(''.join(chr(t) for t in ctokens)) # python 2 else: frandom.write(bytes([]).join(bytes([t]) for t in ctokens)) # python 3 finally: frandom.close() except IOError: # works anyway pass except NotImplementedError: have_urandom = False logger.warning( """Cryptographically secure session management is not possible on your system because your system does not provide a cryptographically secure entropy source. This is not specific to web2py; consider deploying on a different operating system.""") if python_version == 2: packed = ''.join(chr(x) for x in ctokens) # python 2 else: packed = bytes([]).join(bytes([x]) for x in ctokens) # python 3 unpacked_ctokens = _struct_2_long_long.unpack(packed) return unpacked_ctokens, have_urandom
UNPACKED_CTOKENS, HAVE_URANDOM = initialize_urandom()
[docs]def fast_urandom16(urandom=[], locker=threading.RLock()): """ This is 4x faster than calling os.urandom(16) and prevents the "too many files open" issue with concurrent access to os.urandom() """ try: return urandom.pop() except IndexError: try: locker.acquire() ur = os.urandom(16 * 1024) urandom += [ur[i:i + 16] for i in xrange(16, 1024 * 16, 16)] return ur[0:16] finally: locker.release()
[docs]def web2py_uuid(ctokens=UNPACKED_CTOKENS): """ This function follows from the following discussion: `` It works like uuid.uuid4 except that tries to use os.urandom() if possible and it XORs the output with the tokens uniquely associated with this machine. """ rand_longs = (random.getrandbits(64), random.getrandbits(64)) if HAVE_URANDOM: urand_longs = _struct_2_long_long.unpack(fast_urandom16()) byte_s = _struct_2_long_long.pack(rand_longs[0] ^ urand_longs[0] ^ ctokens[0], rand_longs[1] ^ urand_longs[1] ^ ctokens[1]) else: byte_s = _struct_2_long_long.pack(rand_longs[0] ^ ctokens[0], rand_longs[1] ^ ctokens[1]) return str(uuid.UUID(bytes=byte_s, version=4))
REGEX_IPv4 = re.compile('(\d+)\.(\d+)\.(\d+)\.(\d+)')
[docs]def is_valid_ip_address(address): """ Examples: Better than a thousand words:: >>> is_valid_ip_address('127.0') False >>> is_valid_ip_address('') True >>> is_valid_ip_address('2001:660::1') True """ # deal with special cases if address.lower() in ('', 'localhost', '::1', '::ffff:'): return True elif address.lower() in ('unknown', ''): return False elif address.count('.') == 3: # assume IPv4 if address.startswith('::ffff:'): address = address[7:] if hasattr(socket, 'inet_aton'): # try validate using the OS try: socket.inet_aton(address) return True except socket.error: # invalid address return False else: # try validate using Regex match = REGEX_IPv4.match(address) if match and all(0 <= int( < 256 for i in (1, 2, 3, 4)): return True return False elif hasattr(socket, 'inet_pton'): # assume IPv6, try using the OS try: socket.inet_pton(socket.AF_INET6, address) return True except socket.error: # invalid address return False else: # do not know what to do? assume it is a valid address return True
[docs]def is_loopback_ip_address(ip=None, addrinfo=None): """ Determines whether the address appears to be a loopback address. This assumes that the IP is valid. """ if addrinfo: # see socket.getaddrinfo() for layout of addrinfo tuple if addrinfo[0] == socket.AF_INET or addrinfo[0] == socket.AF_INET6: ip = addrinfo[4] if not isinstance(ip, basestring): return False # IPv4 or IPv6-embedded IPv4 or IPv4-compatible IPv6 if ip.count('.') == 3: return ip.lower().startswith(('127', '::127', '0:0:0:0:0:0:127', '::ffff:127', '0:0:0:0:0:ffff:127')) return ip == '::1' or ip == '0:0:0:0:0:0:0:1' # IPv6 loopback
[docs]def getipaddrinfo(host): """ Filter out non-IP and bad IP addresses from getaddrinfo """ try: return [addrinfo for addrinfo in socket.getaddrinfo(host, None) if (addrinfo[0] == socket.AF_INET or addrinfo[0] == socket.AF_INET6) and isinstance(addrinfo[4][0], basestring)] except socket.error: return []