| 1 | # ldd - DNS implementation in Python |
| 2 | # Copyright (C) 2006 Fredrik Tolf <fredrik@dolda2000.com> |
| 3 | # |
| 4 | # This program is free software; you can redistribute it and/or modify |
| 5 | # it under the terms of the GNU General Public License as published by |
| 6 | # the Free Software Foundation; either version 2 of the License, or |
| 7 | # (at your option) any later version. |
| 8 | # |
| 9 | # This program is distributed in the hope that it will be useful, |
| 10 | # but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | # GNU General Public License for more details. |
| 13 | # |
| 14 | # You should have received a copy of the GNU General Public License |
| 15 | # along with this program; if not, write to the Free Software |
| 16 | # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 17 | |
| 18 | import socket |
| 19 | import time |
| 20 | import fcntl |
| 21 | import struct |
| 22 | |
| 23 | import server |
| 24 | |
| 25 | def linuxifip4hack(ifname): |
| 26 | req = ifname + ("\0" * (32 - len(ifname))) |
| 27 | sk = socket.socket() |
| 28 | res = fcntl.ioctl(sk.fileno(), 0x8915, req) |
| 29 | sk.close() |
| 30 | sockaddr = res[16:] |
| 31 | return sockaddr[4:8] |
| 32 | |
| 33 | class valuecache: |
| 34 | def __init__(self, func, expire): |
| 35 | self.func = func |
| 36 | self.expire = expire |
| 37 | self.last = 0 |
| 38 | |
| 39 | def __call__(self, *args): |
| 40 | now = int(time.time()) |
| 41 | if self.last == 0 or now - self.last > self.expire: |
| 42 | self.val = self.func(*(args)) |
| 43 | self.last = now |
| 44 | return self.val |
| 45 | |
| 46 | class prefix6to4(server.handler): |
| 47 | def __init__(self, next, v4addr): |
| 48 | self.next = next |
| 49 | if callable(v4addr): |
| 50 | self.packed = v4addr |
| 51 | elif len(v4addr) == 4: |
| 52 | self.packed = v4addr |
| 53 | else: |
| 54 | self.packed = socket.inet_pton(socket.AF_INET, v4addr) |
| 55 | |
| 56 | def handle(self, *args): |
| 57 | resp = self.next.handle(*args) |
| 58 | if resp is None: |
| 59 | return None |
| 60 | for rr in resp.allrrs(): |
| 61 | if rr.head.istype("AAAA"): |
| 62 | addr = rr.data["address"] |
| 63 | if addr[0:6] == "\x20\x02\x00\x00\x00\x00": |
| 64 | packed = self.packed |
| 65 | if callable(packed): |
| 66 | packed = packed() |
| 67 | addr = addr[0:2] + packed + addr[6:] |
| 68 | rr.data["address"] = addr |
| 69 | return resp |
| 70 | |
| 71 | class addrfilter(server.handler): |
| 72 | def __init__(self, default = None, matchers = []): |
| 73 | self.matchers = matchers |
| 74 | self.default = default |
| 75 | |
| 76 | def setdefault(self, handler): |
| 77 | self.default = handler |
| 78 | |
| 79 | def addmatcher(self, af, prefix, preflen, handler): |
| 80 | self.matchers += [(af, socket.inet_pton(af, prefix), preflen, handler)] |
| 81 | |
| 82 | def handle(self, query, pkt, origin): |
| 83 | matchlen = -1 |
| 84 | match = self.default |
| 85 | if pkt.addr is not None: |
| 86 | for af, prefix, preflen, handler in self.matchers: |
| 87 | if pkt.addr[0] == af: |
| 88 | addr = socket.inet_pton(af, pkt.addr[1]) |
| 89 | bytes = preflen >> 3 |
| 90 | restmask = 255 ^ ((1 << (8 - (preflen & 7))) - 1) |
| 91 | if prefix[0:bytes] == addr[0:bytes] and \ |
| 92 | (ord(prefix[bytes]) & restmask) == (ord(addr[bytes]) & restmask): |
| 93 | if preflen > matchlen: |
| 94 | matchlen = preflen |
| 95 | match = handler |
| 96 | if match is not None: |
| 97 | return match.handle(query, pkt, origin) |
| 98 | return None |