# SPDX-License-Identifier: GPL-2.0-only
# This file is part of Scapy
# See https://scapy.net/ for more information

"""
ERSPAN - Encapsulated Remote SPAN

https://datatracker.ietf.org/doc/html/draft-foschiano-erspan-03
"""

# scapy.contrib.description = ERSPAN - Encapsulated Remote SPAN
# scapy.contrib.status = loads

# This file inspired by scapy-vxlan

from scapy.packet import Packet, bind_layers
from scapy.fields import BitField, BitEnumField, XIntField, \
    XShortField
from scapy.layers.l2 import Ether, GRE


class ERSPAN(Packet):
    """
    A generic ERSPAN packet
    """
    name = "ERSPAN"
    fields_desc = []

    @classmethod
    def dispatch_hook(cls, _pkt=None, *args, **kargs):
        if _pkt:
            ver = _pkt[0] >> 4
            if ver == 1:
                return ERSPAN_II
            elif ver == 2:
                return ERSPAN_III
            else:
                return ERSPAN_I
        if cls == ERSPAN:
            return ERSPAN_II
        return cls


class ERSPAN_I(ERSPAN):
    name = "ERSPAN I"
    match_subclass = True
    fields_desc = []


class ERSPAN_II(ERSPAN):
    name = "ERSPAN II"
    match_subclass = True
    fields_desc = [BitField("ver", 1, 4),
                   BitField("vlan", 0, 12),
                   BitField("cos", 0, 3),
                   BitField("en", 0, 2),
                   BitField("t", 0, 1),
                   BitField("session_id", 0, 10),
                   BitField("reserved", 0, 12),
                   BitField("index", 0, 20),
                   ]


class ERSPAN_III(ERSPAN):
    name = "ERSPAN III"
    match_subclass = True
    fields_desc = [BitField("ver", 2, 4),
                   BitField("vlan", 0, 12),
                   BitField("cos", 0, 3),
                   BitField("bso", 0, 2),
                   BitField("t", 0, 1),
                   BitField("session_id", 0, 10),
                   XIntField("timestamp", 0x00000000),
                   XShortField("sgt_other", 0x00000000),
                   BitField("p", 0, 1),
                   BitEnumField("ft", 0, 5,
                                {0: "Ethernet", 2: "IP"}),
                   BitField("hw", 0, 6),
                   BitField("d", 0, 1),
                   BitEnumField("gra", 0, 2,
                                {0: "100us", 1: "100ns", 2: "IEEE 1588"}),
                   BitField("o", 0, 1)
                   ]


class ERSPAN_PlatformSpecific(Packet):
    name = "PlatformSpecific"
    fields_desc = [BitField("platf_id", 0, 6),
                   BitField("info1", 0, 26),
                   XIntField("info2", 0x00000000)]


bind_layers(ERSPAN_I, Ether)
bind_layers(ERSPAN_II, Ether)
bind_layers(ERSPAN_III, Ether, o=0)
bind_layers(ERSPAN_III, ERSPAN_PlatformSpecific, o=1)
bind_layers(ERSPAN_PlatformSpecific, Ether)

bind_layers(GRE, ERSPAN, proto=0x88be, seqnum_present=0)
bind_layers(GRE, ERSPAN_II, proto=0x88be, seqnum_present=1)
bind_layers(GRE, ERSPAN_III, proto=0x22eb)