142 lines
3.9 KiB
Python
142 lines
3.9 KiB
Python
# SPDX-License-Identifier: ISC
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# Copyright 2023 6WIND S.A.
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# Authored by Farid Mihoub <farid.mihoub@6wind.com>
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#
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import ipaddress
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import struct
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from .af import AddressFamily, AF
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from .rd import RouteDistinguisher
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def decode_label(label):
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# from frr
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# frr encode just one label
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return (label[0] << 12) | (label[1] << 4) | (label[2] & 0xF0) >> 4
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def padding(databin, len_):
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"""
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Assumption:
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One nlri per update/withdraw message, so we can add
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a padding to the prefix without worrying about its length
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"""
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if len(databin) >= len_:
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return databin
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return databin + b"\0" * (len_ - len(databin))
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def dissect_nlri(nlri_data, afi, safi):
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"""
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Exract nlri information based on the address family
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"""
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addr_family = AddressFamily(afi, safi)
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if addr_family == AF.IPv6_VPN:
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return NlriIPv6Vpn.parse(nlri_data)
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elif addr_family == AF.IPv4_VPN:
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return NlriIPv4Vpn.parse(nlri_data)
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elif addr_family == AF.IPv6_UNICAST:
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return NlriIPv6Unicast.parse(nlri_data)
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return {"ip_prefix": "Unknown"}
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# ------------------------------------------------------------------------------
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class NlriIPv4Unicast:
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@staticmethod
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def parse(data):
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"""parses prefixes from withdrawn_routes or nrli data"""
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(prefix_len,) = struct.unpack_from("!B", data)
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prefix = padding(data[1:], 4)
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return {"ip_prefix": f"{ipaddress.IPv4Address(prefix)}/{prefix_len}"}
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# ------------------------------------------------------------------------------
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class NlriIPv6Unicast:
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@staticmethod
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def parse(data):
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"""parses prefixes from withdrawn_routes or nrli data"""
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(prefix_len,) = struct.unpack_from("!B", data)
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prefix = padding(data[1:], 16)
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return {"ip_prefix": f"{ipaddress.IPv6Address(prefix)}/{prefix_len}"}
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# ------------------------------------------------------------------------------
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class NlriIPv4Vpn:
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UNPACK_STR = "!B3s8s"
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@classmethod
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def parse(cls, data):
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(bit_len, label, rd) = struct.unpack_from(cls.UNPACK_STR, data)
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offset = struct.calcsize(cls.UNPACK_STR)
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ipv4 = padding(data[offset:], 4)
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# prefix_len = total_bits_len - label_bits_len - rd_bits_len
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prefix_len = bit_len - 3 * 8 - 8 * 8
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return {
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"label": decode_label(label),
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"rd": str(RouteDistinguisher(rd)),
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"ip_prefix": f"{ipaddress.IPv4Address(ipv4)}/{prefix_len}",
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}
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# ------------------------------------------------------------------------------
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class NlriIPv6Vpn:
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UNPACK_STR = "!B3s8s"
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@classmethod
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def parse(cls, data):
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# rfc 3107, 8227
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(bit_len, label, rd) = struct.unpack_from(cls.UNPACK_STR, data)
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offset = struct.calcsize(cls.UNPACK_STR)
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ipv6 = padding(data[offset:], 16)
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prefix_len = bit_len - 3 * 8 - 8 * 8
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return {
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"label": decode_label(label),
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"rd": str(RouteDistinguisher(rd)),
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"ip_prefix": f"{ipaddress.IPv6Address(ipv6)}/{prefix_len}",
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}
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# ------------------------------------------------------------------------------
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class NlriIPv4Mpls:
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pass
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# ------------------------------------------------------------------------------
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class NlriIPv6Mpls:
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pass
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# ------------------------------------------------------------------------------
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class NlriIPv4FlowSpec:
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pass
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# ------------------------------------------------------------------------------
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class NlriIPv6FlowSpec:
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pass
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# ------------------------------------------------------------------------------
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class NlriVpn4FlowSpec:
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pass
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# ------------------------------------------------------------------------------
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class NlriVpn6FlowSpec:
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pass
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# ------------------------------------------------------------------------------
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class NlriL2EVPN:
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pass
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# ------------------------------------------------------------------------------
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class NlriL2VPNFlowSpec:
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pass
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