# $Id: rip.py 23 2006-11-08 15:45:33Z dugsong $

"""Routing Information Protocol."""

import dpkt

# RIP v2 - RFC 2453
# http://tools.ietf.org/html/rfc2453

REQUEST = 1
RESPONSE = 2

class RIP(dpkt.Packet):
    __hdr__ = (
        ('cmd', 'B', REQUEST),
        ('v', 'B', 2),
        ('rsvd', 'H', 0)
        )

    def unpack(self, buf):
        dpkt.Packet.unpack(self, buf)
        l = []
        self.auth = None
        while self.data:
            rte = RTE(self.data[:20])
            if rte.family == 0xFFFF:
                self.auth = Auth(self.data[:20])
            else:
                l.append(rte)
            self.data = self.data[20:]
        self.data = self.rtes = l

    def __len__(self):
        len = self.__hdr_len__
        if self.auth:
            len += len(self.auth)
        len += sum(map(len, self.rtes))
        return len

    def __str__(self):
        auth = ''
        if self.auth:
            auth = str(self.auth)
        return self.pack_hdr() + \
               auth + \
               ''.join(map(str, self.rtes))

class RTE(dpkt.Packet):
    __hdr__ = (
        ('family', 'H', 2),
        ('route_tag', 'H', 0),
        ('addr', 'I', 0),
        ('subnet', 'I', 0),
        ('next_hop', 'I', 0),
        ('metric', 'I', 1)
        )

class Auth(dpkt.Packet):
    __hdr__ = (
        ('rsvd', 'H', 0xFFFF),
        ('type', 'H', 2),
        ('auth', '16s', 0)
        )

if __name__ == '__main__':
    import unittest

    class RIPTestCase(unittest.TestCase):
        def testPack(self):
            r = RIP(self.s)
            self.failUnless(self.s == str(r))

        def testUnpack(self):
            r = RIP(self.s)
            self.failUnless(r.auth == None)
            self.failUnless(len(r.rtes) == 2)

            rte = r.rtes[1]
            self.failUnless(rte.family == 2)
            self.failUnless(rte.route_tag == 0)
            self.failUnless(rte.metric == 1)

        s = '\x02\x02\x00\x00\x00\x02\x00\x00\x01\x02\x03\x00\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x02\x00\x00\xc0\xa8\x01\x08\xff\xff\xff\xfc\x00\x00\x00\x00\x00\x00\x00\x01'
    unittest.main()