Don't use the socket module to validate that IP addresses are valid

This largely reverts commit 25771fe. Evidently the socket builtin doens't
always know what an IPv6 address looks like...

  https://trac.torproject.org/projects/tor/ticket/13904

1 files changed, 33 insertions, 10 deletions

diff --git a/stem/util/connection.py b/stem/util/connection.py
index df918d2d..f5ca3f4d 100644
--- a/stem/util/connection.py
+++ b/stem/util/connection.py
@@ -46,7 +46,6 @@ import hmac
 import os
 import platform
 import re
-import socket
 
 import stem.util.proc
 import stem.util.system
@@ -334,12 +333,23 @@ def is_valid_ipv4_address(address):
   :returns: **True** if input is a valid IPv4 address, **False** otherwise
   """
 
-  try:
-    packed = socket.inet_pton(socket.AF_INET, address)
-    return socket.inet_ntop(socket.AF_INET, packed) == address
-  except (TypeError, socket.error):
+  if not isinstance(address, (bytes, unicode)):
     return False
 
+  # checks if theres four period separated values
+
+  if address.count('.') != 3:
+     return False
+
+  # checks that each value in the octet are decimal values between 0-255
+  for entry in address.split('.'):
+    if not entry.isdigit() or int(entry) < 0 or int(entry) > 255:
+      return False
+    elif entry[0] == '0' and len(entry) > 1:
+      return False  # leading zeros, for instance in '1.2.3.001'
+
+  return True
+
 
 def is_valid_ipv6_address(address, allow_brackets = False):
   """
@@ -355,11 +365,24 @@ def is_valid_ipv6_address(address, allow_brackets = False):
     if address.startswith('[') and address.endswith(']'):
       address = address[1:-1]
 
-  try:
-    socket.inet_pton(socket.AF_INET6, address)
-    return True
-  except (TypeError, socket.error):
-    return False
+  # addresses are made up of eight colon separated groups of four hex digits
+  # with leading zeros being optional
+  # https://en.wikipedia.org/wiki/IPv6#Address_format
+
+  colon_count = address.count(':')
+
+  if colon_count > 7:
+    return False  # too many groups
+  elif colon_count != 7 and '::' not in address:
+    return False  # not enough groups and none are collapsed
+  elif address.count('::') > 1 or ':::' in address:
+    return False  # multiple groupings of zeros can't be collapsed
+
+  for entry in address.split(':'):
+    if not re.match('^[0-9a-fA-f]{0,4}$', entry):
+      return False
+
+  return True
 
 
 def is_valid_port(entry, allow_zero = False):