/* packet-igrp.c

 * Routines for IGRP dissection

 * Copyright 2000, Paul Ionescu <paul@acorp.ro>

 *

 * See

 *

 *   http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a00800c8ae1.shtml

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

 * Copied from packet-syslog.c

 *

 * SPDX-License-Identifier: GPL-2.0-or-later

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/expert.h>

#include <epan/to_str.h>

#include <epan/ipproto.h>

#include <epan/tfs.h>

#include <epan/unit_strings.h>

void proto_register_igrp(void);

void proto_reg_handoff_igrp(void);

#define IGRP_HEADER_LENGTH 12

#define IGRP_ENTRY_LENGTH 14

static dissector_handle_t igrp_handle;

static int proto_igrp;

static int hf_igrp_update;

static int hf_igrp_as;

/* Generated from convert_proto_tree_add_text.pl */

static int hf_igrp_load;

static int hf_igrp_bandwidth;

static int hf_igrp_command;

static int hf_igrp_reliability;

static int hf_igrp_network;

static int hf_igrp_version;

static int hf_igrp_interior_routes;

static int hf_igrp_mtu;

static int hf_igrp_hop_count;

static int hf_igrp_exterior_routes;

static int hf_igrp_delay;

static int hf_igrp_checksum;

static int hf_igrp_system_routes;

static int ett_igrp;

static int ett_igrp_vektor;

static int ett_igrp_net;

static expert_field ei_igrp_version;

static void dissect_vektor_igrp (packet_info *pinfo, tvbuff_t *tvb, proto_tree *igrp_vektor_tree, uint8_t network);

static int dissect_igrp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)

{

  uint8_t ver_and_opcode,version,opcode,network;

  int offset=IGRP_HEADER_LENGTH;

  uint16_t ninterior,nsystem,nexterior;

  const uint8_t *ipsrc;

  proto_item *ti;

  proto_tree *igrp_tree, *igrp_vektor_tree;

  tvbuff_t   *next_tvb;

  col_set_str(pinfo->cinfo, COL_PROTOCOL, "IGRP");

  col_clear(pinfo->cinfo, COL_INFO);

  ver_and_opcode = tvb_get_uint8(tvb,0);

  switch (ver_and_opcode) {

  case 0x11:

    col_set_str(pinfo->cinfo, COL_INFO, "Response" );

    break;

  case 0x12:

    col_set_str(pinfo->cinfo, COL_INFO, "Request" );

    break;

  default:

    col_set_str(pinfo->cinfo, COL_INFO, "Unknown version or opcode");

  }

  if (tree) {

    ti = proto_tree_add_protocol_format(tree, proto_igrp, tvb, 0, -1,

                                        "Cisco IGRP");

    igrp_tree = proto_item_add_subtree(ti, ett_igrp);

    version = (ver_and_opcode&0xf0)>>4 ; /* version is the fist half of the byte */

    opcode = ver_and_opcode&0x0f ;       /* opcode is the last half of the byte */

    ti = proto_tree_add_item(igrp_tree, hf_igrp_version, tvb, 0, 1, ENC_BIG_ENDIAN);

    if (version != 1)

        expert_add_info(pinfo, ti, &ei_igrp_version);

    ti = proto_tree_add_item(igrp_tree, hf_igrp_command, tvb, 0, 1, ENC_BIG_ENDIAN);

    if (opcode==1)

        proto_item_append_text(ti, " (Response)");

    else

        proto_item_append_text(ti, " (Request)");

    proto_tree_add_item(igrp_tree, hf_igrp_update, tvb, 1,1, ENC_BIG_ENDIAN);

    proto_tree_add_item(igrp_tree, hf_igrp_as, tvb, 2,2, ENC_BIG_ENDIAN);

    ninterior = tvb_get_ntohs(tvb,4);

    nsystem = tvb_get_ntohs(tvb,6);

    nexterior = tvb_get_ntohs(tvb,8);

    /* this is a ugly hack to find the first byte of the IP source address */

    if (pinfo->net_src.type == AT_IPv4) {

      ipsrc = (const uint8_t *)pinfo->net_src.data;

      network = ipsrc[0];

    } else

      network = 0; /* XXX - shouldn't happen */

    ti = proto_tree_add_item(igrp_tree, hf_igrp_interior_routes, tvb, 4, 2, ENC_BIG_ENDIAN);

    for( ; ninterior>0 ; ninterior-- ) {

      igrp_vektor_tree =  proto_item_add_subtree(ti,ett_igrp_vektor);

      next_tvb = tvb_new_subset_length_caplen(tvb, offset, IGRP_ENTRY_LENGTH, -1);

      dissect_vektor_igrp (pinfo,next_tvb,igrp_vektor_tree,network);

      offset+=IGRP_ENTRY_LENGTH;

    }

    ti = proto_tree_add_item(igrp_tree, hf_igrp_system_routes, tvb, 6, 2, ENC_BIG_ENDIAN);

    for( ; nsystem>0 ; nsystem-- ) {

      igrp_vektor_tree =  proto_item_add_subtree(ti,ett_igrp_vektor);

      next_tvb = tvb_new_subset_length_caplen(tvb, offset, IGRP_ENTRY_LENGTH, -1);

      dissect_vektor_igrp (pinfo,next_tvb,igrp_vektor_tree,0);

      offset+=IGRP_ENTRY_LENGTH;

    }

    ti = proto_tree_add_item(igrp_tree, hf_igrp_exterior_routes, tvb, 8, 2, ENC_BIG_ENDIAN);

    for( ; nexterior>0 ; nexterior-- ) {

      igrp_vektor_tree =  proto_item_add_subtree(ti,ett_igrp_vektor);

      next_tvb = tvb_new_subset_length_caplen(tvb, offset, IGRP_ENTRY_LENGTH, -1);

      dissect_vektor_igrp (pinfo,next_tvb,igrp_vektor_tree,0);

      offset+=IGRP_ENTRY_LENGTH;

    }

    proto_tree_add_checksum(igrp_tree, tvb, 10, hf_igrp_checksum, -1, NULL, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);

  }

  return tvb_captured_length(tvb);

}

static void dissect_vektor_igrp (packet_info *pinfo, tvbuff_t *tvb, proto_tree *igrp_vektor_tree, uint8_t network)

{

  union {

    uint8_t addr_bytes[4];

    uint32_t addr_word;

  } addr;

  address ip_addr;

  if (network != 0) {

    /*

     * Interior route; network is the high-order byte, and the three

     * bytes in the vector are the lower 3 bytes.

     */

    addr.addr_bytes[0]=network;

    addr.addr_bytes[1]=tvb_get_uint8(tvb,0);

    addr.addr_bytes[2]=tvb_get_uint8(tvb,1);

    addr.addr_bytes[3]=tvb_get_uint8(tvb,2);

  } else {

    /*

     * System or exterior route; the three bytes in the vector are

     * the three high-order bytes, and the low-order byte is 0.

     */

    addr.addr_bytes[0]=tvb_get_uint8(tvb,0);

    addr.addr_bytes[1]=tvb_get_uint8(tvb,1);

    addr.addr_bytes[2]=tvb_get_uint8(tvb,2);

    addr.addr_bytes[3]=0;

  }

  set_address(&ip_addr, AT_IPv4, 4, &addr);

  igrp_vektor_tree = proto_tree_add_subtree_format(igrp_vektor_tree, tvb, 0 ,14,

                                                   ett_igrp_net, NULL, "Entry for network %s", address_to_str(pinfo->pool, &ip_addr));

  proto_tree_add_ipv4(igrp_vektor_tree, hf_igrp_network, tvb, 0, 3, addr.addr_word);

  proto_tree_add_item(igrp_vektor_tree, hf_igrp_delay, tvb, 3, 3, ENC_BIG_ENDIAN);

  proto_tree_add_item(igrp_vektor_tree, hf_igrp_bandwidth, tvb, 6, 3, ENC_BIG_ENDIAN);

  proto_tree_add_item(igrp_vektor_tree, hf_igrp_mtu, tvb, 9, 2, ENC_BIG_ENDIAN);

  proto_tree_add_item(igrp_vektor_tree, hf_igrp_reliability, tvb, 11, 1, ENC_BIG_ENDIAN);

  proto_tree_add_item(igrp_vektor_tree, hf_igrp_load, tvb, 12, 1, ENC_BIG_ENDIAN);

  proto_tree_add_item(igrp_vektor_tree, hf_igrp_hop_count, tvb, 13, 1, ENC_BIG_ENDIAN);

}

/* Register the protocol with Wireshark */

void proto_register_igrp(void)

{

  /* Setup list of header fields */

  static hf_register_info hf[] = {

    { &hf_igrp_update,

      { "Update Release",           "igrp.update",

      FT_UINT8, BASE_DEC, NULL, 0x0 ,

      "Update Release number", HFILL }

    },

    { &hf_igrp_as,

      { "Autonomous System",           "igrp.as",

      FT_UINT16, BASE_DEC, NULL, 0x0 ,

      "Autonomous System number", HFILL }

    },

    /* Generated from convert_proto_tree_add_text.pl */

    { &hf_igrp_version, { "IGRP Version", "igrp.version", FT_UINT8, BASE_DEC, NULL, 0xF0, NULL, HFILL }},

    { &hf_igrp_command, { "Command", "igrp.command", FT_UINT8, BASE_DEC, NULL, 0x0F, NULL, HFILL }},

    { &hf_igrp_interior_routes, { "Interior routes", "igrp.interior_routes", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_igrp_system_routes, { "System routes", "igrp.system_routes", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_igrp_exterior_routes, { "Exterior routes", "igrp.exterior_routes", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_igrp_checksum, { "Checksum", "igrp.checksum", FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL }},

    { &hf_igrp_network, { "Network", "igrp.network", FT_IPv4, BASE_NONE, NULL, 0x0, NULL, HFILL }},

    { &hf_igrp_delay, { "Delay", "igrp.delay", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_igrp_bandwidth, { "Bandwidth", "igrp.bandwidth", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_igrp_mtu, { "MTU", "igrp.mtu", FT_UINT16, BASE_DEC|BASE_UNIT_STRING, UNS(&units_byte_bytes), 0x0, NULL, HFILL }},

    { &hf_igrp_reliability, { "Reliability", "igrp.reliability", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_igrp_load, { "Load", "igrp.load", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_igrp_hop_count, { "Hop count", "igrp.hop_count", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

  };

  /* Setup protocol subtree array */

  static int *ett[] = {

    &ett_igrp,

    &ett_igrp_vektor,

    &ett_igrp_net

  };

  static ei_register_info ei[] = {

    { &ei_igrp_version, { "igrp.version.invalid", PI_PROTOCOL, PI_WARN, "Unknown Version, The dissection may be inaccurate", EXPFILL }},

  };

  expert_module_t* expert_igrp;

  /* Register the protocol name and description */

  proto_igrp = proto_register_protocol("Cisco Interior Gateway Routing Protocol",

                                       "IGRP", "igrp");

  igrp_handle = register_dissector("igrp", dissect_igrp, proto_igrp);

  /* Required function calls to register the header fields and subtrees used */

  proto_register_field_array(proto_igrp, hf, array_length(hf));

  proto_register_subtree_array(ett, array_length(ett));

  expert_igrp = expert_register_protocol(proto_igrp);

  expert_register_field_array(expert_igrp, ei, array_length(ei));

}

void

proto_reg_handoff_igrp(void)

{

  dissector_add_uint("ip.proto", IP_PROTO_IGRP, igrp_handle);

}

/*    IGRP Packet structure:

HEADER structure + k * VECTOR structure

where: k = (Number of Interior routes) + (Number of System routes) + (Number of Exterior routes)

HEADER structure is 12 bytes as follows :

4  bits         Version (only version 1 is defined)

4  bits         Opcode (1=Replay, 2=Request)

8  bits         Update Release

16 bits         Autonomous system number

16 bits         Number of Interior routes

16 bits         Number of System routes

16 bits         Number of Exterior routes

16 bits         Checksum

-------

12 bytes in header

VECTOR structure is 14 bytes as follows :

24 bits         Network

24 bits         Delay

24 bits         Bandwidth

16 bits         MTU

8  bits         Reliability

8  bits         Load

8  bits         Hop count

-------

14 bytes in 1 vector

It is interesting how is coded an ip network address in 3 bytes because IGRP is a classful routing protocol:

If it is a interior route then this 3 bytes are the final bytes, and the first one is taken from the source ip address of the ip packet

If it is a system route or a exterior route then this 3 bytes are the first three and the last byte is not important

If the Delay is 0xFFFFFF then the network is unreachable

*/

/*

 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html

 *

 * Local Variables:

 * c-basic-offset: 2

 * tab-width: 8

 * indent-tabs-mode: nil

 * End:

 *

 * ex: set shiftwidth=2 tabstop=8 expandtab:

 * :indentSize=2:tabSize=8:noTabs=true:

 */