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nefarious: properly decode IPv6 addresses, move IP decoding into separate function

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This commit is contained in:
James Lu 2016-04-23 10:44:17 -07:00
parent 9f454402d2
commit 0e0d96efc6
1 changed files with 56 additions and 32 deletions
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88
protocols/nefarious.py
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@ -2,7 +2,6 @@
nefarious.py: Nefarious IRCu protocol module for PyLink.
"""
import re
import sys
import os
import base64
@ -89,6 +88,61 @@ class P10Protocol(Protocol):
def _send(self, source, text):
self.irc.send("%s %s" % (source, text))
@staticmethod
def decode_p10_ip(ip):
"""Decodes a P10 IP."""
# Many thanks to Jobe @ evilnet for the code on what to do here. :) -GL
if len(ip) == 6: # IPv4
# Pad the characters with two \x00's (represented in P10 B64 as AA)
ip = 'AA' + ip
# Decode it via Base64, dropping the initial padding characters.
ip = base64.b64decode(ip, altchars='[]')[2:]
# Convert the IP to a string.
return socket.inet_ntoa(ip)
elif len(ip) <= 24 or '_' in ip: # IPv6
s = ''
# P10-encoded IPv6 addresses are formed with chunks, where each 16-bit
# portion of the address (each part between :'s) is encoded as 3 B64 chars.
# A single :: is translated into an underscore (_).
# https://github.com/evilnet/nefarious2/blob/master/doc/p10.txt#L723
# Example: 1:2::3 -> AABAAC_AAD
# Treat the part before and after the _ as two separate pieces (head and tail).
head = ip
tail = ''
byteshead = b''
bytestail = b''
if '_' in ip:
head, tail = ip.split('_')
# Each B64-encoded section is 3 characters long. Split them up and
# iterate.
for section in range(0, len(head), 3):
byteshead += base64.b64decode('A' + head[section:section+3], '[]')[1:]
for section in range(0, len(tail), 3):
bytestail += base64.b64decode('A' + tail[section:section+3], '[]')[1:]
ipbytes = byteshead
# Figure out how many 0's the center _ actually represents.
# Subtract 16 (the amount of chunks in a v6 address) by
# the length of the head and tail sections.
pad = 16 - len(byteshead) - len(bytestail)
ipbytes += (b'\x00' * pad) # Pad with zeros.
ipbytes += bytestail
ip = socket.inet_ntop(socket.AF_INET6, ipbytes)
if ip.startswith(':'):
# HACK: prevent ::1 from being treated as end-of-line
# when sending to other IRCds.
ip = '0' + ip
return ip
@staticmethod
def _getCommand(token):
"""Returns the command name for the given token."""
@ -716,39 +770,9 @@ class P10Protocol(Protocol):
nick = args[0]
ts, ident, host = args[2:5]
# XXX: Is realhost ever sent?
realhost = host
# Thanks to Jobe @ evilnet for the code on what to do here. :) -GL
ip = args[-3]
if len(ip) == 6: # IPv4
# Pad the characters with two \x00's (represented in P10 B64 as AA)
ip = 'AA' + ip
# Decode it via Base64, dropping the initial padding characters.
ip = base64.b64decode(ip, altchars='[]')[2:]
# Convert the IP to a string.
ip = socket.inet_ntoa(ip)
elif len(ip) <= 24 or '_' in ip: # IPv6
s = ''
# P10-encoded IPv6 addresses are formed with chunks, where each 16-bit
# portion of the address (each part between :'s) is encoded as 3 B64 chars.
# A single :: is translated into an underscore (_).
# https://github.com/evilnet/nefarious2/blob/master/doc/p10.txt#L723
# Example: 1:2::3 -> AABAAC_AAD
for b64chunk in re.findall('([A-Z]{3}|_)', ip):
if b64chunk == '_':
s += ':'
else:
ipchunk = base64.b64decode('A' + b64chunk, '[]')[1:]
for char in ipchunk:
s += str(char)
s += ':'
ip = s.rstrip(':')
ip = self.decode_p10_ip(ip)
uid = args[-2]
realname = args[-1]