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1 | # -*- python -*- |
2 | ||
040ff511 IJ |
3 | import twisted |
4 | from twisted.internet import reactor | |
b0cfbfce IJ |
5 | |
6 | import ipaddress | |
7 | from ipaddress import AddressValueError | |
8 | ||
040ff511 IJ |
9 | import hippotat.slip as slip |
10 | ||
b0cfbfce IJ |
11 | #---------- packet parsing ---------- |
12 | ||
13 | def packet_addrs(packet): | |
14 | version = packet[0] >> 4 | |
15 | if version == 4: | |
16 | addrlen = 4 | |
17 | saddroff = 3*4 | |
18 | factory = ipaddress.IPv4Address | |
19 | elif version == 6: | |
20 | addrlen = 16 | |
21 | saddroff = 2*4 | |
22 | factory = ipaddress.IPv6Address | |
23 | else: | |
24 | raise ValueError('unsupported IP version %d' % version) | |
25 | saddr = factory(packet[ saddroff : saddroff + addrlen ]) | |
26 | daddr = factory(packet[ saddroff + addrlen : saddroff + addrlen*2 ]) | |
27 | return (saddr, daddr) | |
28 | ||
29 | #---------- address handling ---------- | |
30 | ||
31 | def ipaddr(input): | |
32 | try: | |
33 | r = ipaddress.IPv4Address(input) | |
34 | except AddressValueError: | |
35 | r = ipaddress.IPv6Address(input) | |
36 | return r | |
37 | ||
38 | def ipnetwork(input): | |
39 | try: | |
40 | r = ipaddress.IPv4Network(input) | |
41 | except NetworkValueError: | |
42 | r = ipaddress.IPv6Network(input) | |
43 | return r | |
040ff511 IJ |
44 | |
45 | #---------- ipif (SLIP) subprocess ---------- | |
46 | ||
47 | class _IpifProcessProtocol(twisted.internet.protocol.ProcessProtocol): | |
48 | def __init__(self, router): | |
49 | self._buffer = b'' | |
50 | self._router = router | |
51 | def connectionMade(self): pass | |
52 | def outReceived(self, data): | |
53 | #print('RECV ', repr(data)) | |
54 | self._buffer += data | |
55 | packets = slip.decode(self._buffer) | |
56 | self._buffer = packets.pop() | |
57 | for packet in packets: | |
58 | if not len(packet): continue | |
59 | (saddr, daddr) = packet_addrs(packet) | |
60 | self._router(packet, saddr, daddr) | |
61 | def processEnded(self, status): | |
62 | status.raiseException() | |
63 | ||
64 | def start_ipif(command, router): | |
65 | global ipif | |
66 | ipif = _IpifProcessProtocol(router) | |
67 | reactor.spawnProcess(ipif, | |
68 | '/bin/sh',['sh','-xc', command], | |
69 | childFDs={0:'w', 1:'r', 2:2}) | |
70 | ||
71 | def queue_inbound(packet): | |
72 | ipif.transport.write(slip.delimiter) | |
73 | ipif.transport.write(slip.encode(packet)) | |
74 | ipif.transport.write(slip.delimiter) | |
75 | ||
650a3251 IJ |
76 | #---------- packet queue ---------- |
77 | ||
78 | class PacketQueue(): | |
79 | def __init__(self, max_queue_time): | |
80 | self._max_queue_time = max_queue_time | |
81 | self._pq = collections.deque() # packets | |
82 | ||
83 | def append(self, packet): | |
84 | self._pq.append((time.monotonic(), packet)) | |
85 | ||
86 | def nonempty(self): | |
87 | while True: | |
88 | try: (queuetime, packet) = self._pq[0] | |
89 | except IndexError: return False | |
90 | ||
91 | age = time.monotonic() - queuetime | |
92 | if age > self.max_queue_time: | |
93 | # strip old packets off the front | |
94 | self._pq.popleft() | |
95 | continue | |
96 | ||
97 | return True | |
98 | ||
99 | def popleft(self): | |
100 | # caller must have checked nonempty | |
101 | try: (dummy, packet) = self._pq[0] | |
102 | except IndexError: return None | |
103 | return packet |