Source code for dpkt.ppp

# $Id: 65 2010-03-26 02:53:51Z dugsong $
# -*- coding: utf-8 -*-
"""Point-to-Point Protocol."""
from __future__ import absolute_import

import struct

from . import dpkt

# XXX - finish later

PPP_IP = 0x21  # Internet Protocol
PPP_IP6 = 0x57  # Internet Protocol v6

# Protocol field compression
PFC_BIT = 0x01

[docs]class PPP(dpkt.Packet): # Note: This class is subclassed in PPPoE """Point-to-Point Protocol. TODO: Longer class information.... Attributes: __hdr__: Header fields of PPP. TODO. """ __hdr__ = ( ('addr', 'B', 0xff), ('cntrl', 'B', 3), ('p', 'B', PPP_IP), ) _protosw = {}
[docs] @classmethod def set_p(cls, p, pktclass): cls._protosw[p] = pktclass
[docs] @classmethod def get_p(cls, p): return cls._protosw[p]
[docs] def unpack(self, buf): dpkt.Packet.unpack(self, buf) if self.p & PFC_BIT == 0: try: self.p = struct.unpack('>H', buf[2:4])[0] except struct.error: raise dpkt.NeedData =[1:] try: = self._protosw[self.p]( setattr(self,, except (KeyError, struct.error, dpkt.UnpackError): pass
[docs] def pack_hdr(self): try: if self.p > 0xff: return struct.pack('>BBH', self.addr, self.cntrl, self.p) return dpkt.Packet.pack_hdr(self) except struct.error as e: raise dpkt.PackError(str(e))
def __load_protos(): g = globals() for k, v in g.items(): if k.startswith('PPP_'): name = k[4:] modname = name.lower() try: mod = __import__(modname, g, level=1) PPP.set_p(v, getattr(mod, name)) except (ImportError, AttributeError): continue def _mod_init(): """Post-initialization called when all dpkt modules are fully loaded""" if not PPP._protosw: __load_protos()
[docs]def test_ppp(): # Test protocol compression s = b"\xff\x03\x21" p = PPP(s) assert p.p == 0x21 s = b"\xff\x03\x00\x21" p = PPP(s) assert p.p == 0x21
[docs]def test_ppp_short(): s = b"\xff\x03\x00" import pytest pytest.raises(dpkt.NeedData, PPP, s)
[docs]def test_packing(): p = PPP() assert p.pack_hdr() == b"\xff\x03\x21" p.p = 0xc021 # LCP assert p.pack_hdr() == b"\xff\x03\xc0\x21"
if __name__ == '__main__': # Runs all the test associated with this class/file test_ppp()