# This code was mostly based on ipaddr-py # Copyright 2007 Google Inc. http://code.google.com/p/ipaddr-py/ # Licensed under the Apache License, Version 2.0 (the "License"). from django.core.exceptions import ValidationError from django.utils.six.moves import xrange def clean_ipv6_address(ip_str, unpack_ipv4=False, error_message="This is not a valid IPv6 address"): """ Cleans a IPv6 address string. Validity is checked by calling is_valid_ipv6_address() - if an invalid address is passed, ValidationError is raised. Replaces the longest continious zero-sequence with "::" and removes leading zeroes and makes sure all hextets are lowercase. Args: ip_str: A valid IPv6 address. unpack_ipv4: if an IPv4-mapped address is found, return the plain IPv4 address (default=False). error_message: A error message for in the ValidationError. Returns: A compressed IPv6 address, or the same value """ best_doublecolon_start = -1 best_doublecolon_len = 0 doublecolon_start = -1 doublecolon_len = 0 if not is_valid_ipv6_address(ip_str): raise ValidationError(error_message) # This algorithm can only handle fully exploded # IP strings ip_str = _explode_shorthand_ip_string(ip_str) ip_str = _sanitize_ipv4_mapping(ip_str) # If needed, unpack the IPv4 and return straight away # - no need in running the rest of the algorithm if unpack_ipv4: ipv4_unpacked = _unpack_ipv4(ip_str) if ipv4_unpacked: return ipv4_unpacked hextets = ip_str.split(":") for index in range(len(hextets)): # Remove leading zeroes hextets[index] = hextets[index].lstrip('0') if not hextets[index]: hextets[index] = '0' # Determine best hextet to compress if hextets[index] == '0': doublecolon_len += 1 if doublecolon_start == -1: # Start of a sequence of zeros. doublecolon_start = index if doublecolon_len > best_doublecolon_len: # This is the longest sequence of zeros so far. best_doublecolon_len = doublecolon_len best_doublecolon_start = doublecolon_start else: doublecolon_len = 0 doublecolon_start = -1 # Compress the most suitable hextet if best_doublecolon_len > 1: best_doublecolon_end = (best_doublecolon_start + best_doublecolon_len) # For zeros at the end of the address. if best_doublecolon_end == len(hextets): hextets += [''] hextets[best_doublecolon_start:best_doublecolon_end] = [''] # For zeros at the beginning of the address. if best_doublecolon_start == 0: hextets = [''] + hextets result = ":".join(hextets) return result.lower() def _sanitize_ipv4_mapping(ip_str): """ Sanitize IPv4 mapping in a expanded IPv6 address. This converts ::ffff:0a0a:0a0a to ::ffff:10.10.10.10. If there is nothing to sanitize, returns an unchanged string. Args: ip_str: A string, the expanded IPv6 address. Returns: The sanitized output string, if applicable. """ if not ip_str.lower().startswith('0000:0000:0000:0000:0000:ffff:'): # not an ipv4 mapping return ip_str hextets = ip_str.split(':') if '.' in hextets[-1]: # already sanitized return ip_str ipv4_address = "%d.%d.%d.%d" % ( int(hextets[6][0:2], 16), int(hextets[6][2:4], 16), int(hextets[7][0:2], 16), int(hextets[7][2:4], 16), ) result = ':'.join(hextets[0:6]) result += ':' + ipv4_address return result def _unpack_ipv4(ip_str): """ Unpack an IPv4 address that was mapped in a compressed IPv6 address. This converts 0000:0000:0000:0000:0000:ffff:10.10.10.10 to 10.10.10.10. If there is nothing to sanitize, returns None. Args: ip_str: A string, the expanded IPv6 address. Returns: The unpacked IPv4 address, or None if there was nothing to unpack. """ if not ip_str.lower().startswith('0000:0000:0000:0000:0000:ffff:'): return None hextets = ip_str.split(':') return hextets[-1] def is_valid_ipv6_address(ip_str): """ Ensure we have a valid IPv6 address. Args: ip_str: A string, the IPv6 address. Returns: A boolean, True if this is a valid IPv6 address. """ from django.core.validators import validate_ipv4_address # We need to have at least one ':'. if ':' not in ip_str: return False # We can only have one '::' shortener. if ip_str.count('::') > 1: return False # '::' should be encompassed by start, digits or end. if ':::' in ip_str: return False # A single colon can neither start nor end an address. if ((ip_str.startswith(':') and not ip_str.startswith('::')) or (ip_str.endswith(':') and not ip_str.endswith('::'))): return False # We can never have more than 7 ':' (1::2:3:4:5:6:7:8 is invalid) if ip_str.count(':') > 7: return False # If we have no concatenation, we need to have 8 fields with 7 ':'. if '::' not in ip_str and ip_str.count(':') != 7: # We might have an IPv4 mapped address. if ip_str.count('.') != 3: return False ip_str = _explode_shorthand_ip_string(ip_str) # Now that we have that all squared away, let's check that each of the # hextets are between 0x0 and 0xFFFF. for hextet in ip_str.split(':'): if hextet.count('.') == 3: # If we have an IPv4 mapped address, the IPv4 portion has to # be at the end of the IPv6 portion. if not ip_str.split(':')[-1] == hextet: return False try: validate_ipv4_address(hextet) except ValidationError: return False else: try: # a value error here means that we got a bad hextet, # something like 0xzzzz if int(hextet, 16) < 0x0 or int(hextet, 16) > 0xFFFF: return False except ValueError: return False return True def _explode_shorthand_ip_string(ip_str): """ Expand a shortened IPv6 address. Args: ip_str: A string, the IPv6 address. Returns: A string, the expanded IPv6 address. """ if not _is_shorthand_ip(ip_str): # We've already got a longhand ip_str. return ip_str new_ip = [] hextet = ip_str.split('::') # If there is a ::, we need to expand it with zeroes # to get to 8 hextets - unless there is a dot in the last hextet, # meaning we're doing v4-mapping if '.' in ip_str.split(':')[-1]: fill_to = 7 else: fill_to = 8 if len(hextet) > 1: sep = len(hextet[0].split(':')) + len(hextet[1].split(':')) new_ip = hextet[0].split(':') for _ in xrange(fill_to - sep): new_ip.append('0000') new_ip += hextet[1].split(':') else: new_ip = ip_str.split(':') # Now need to make sure every hextet is 4 lower case characters. # If a hextet is < 4 characters, we've got missing leading 0's. ret_ip = [] for hextet in new_ip: ret_ip.append(('0' * (4 - len(hextet)) + hextet).lower()) return ':'.join(ret_ip) def _is_shorthand_ip(ip_str): """Determine if the address is shortened. Args: ip_str: A string, the IPv6 address. Returns: A boolean, True if the address is shortened. """ if ip_str.count('::') == 1: return True if any(len(x) < 4 for x in ip_str.split(':')): return True return False