/* packet-mpls.c

 * Routines for MPLS data packet disassembly

 * RFC 3032

 *

 * (c) Copyright Ashok Narayanan <ashokn@cisco.com>

 *

 * (c) Copyright 2006, _FF_ Francesco Fondelli <francesco.fondelli@gmail.com>

 *     - added MPLS OAM support, ITU-T Y.1711

 *     - PW Associated Channel Header dissection as per RFC 4385

 *     - PW MPLS Control Word dissection as per RFC 4385

 *     - mpls subdissector table indexed by label value

 *     - enhanced "what's past last mpls label?" heuristic

 *

 * (c) Copyright 2011, Shobhank Sharma <ssharma5@ncsu.edu>

 *     - Removed some mpls preferences which are no longer relevant/needed like

 *       decode PWAC payloads as PPP traffic and assume all channel types except

 *       0x21 are raw BFD.

 *     - MPLS extension from PW-ACH to MPLS Generic Associated Channel as per RFC 5586

 *     - Updated Pseudowire Associated Channel Types as per http://www.iana.org/assignments/pwe3-parameters

 *

 * (c) Copyright 2011, Jaihari Kalijanakiraman <jaiharik@ipinfusion.com>

 *                     Krishnamurthy Mayya <krishnamurthy.mayya@ipinfusion.com>

 *                     Nikitha Malgi       <malgi.nikitha@ipinfusion.com>

 *     - Identification of BFD CC, BFD CV and ON-Demand CV ACH types as per RFC 6428, RFC 6426

 *       respectively and the corresponding decoding of messages

 *     - Decoding support for MPLS-TP Lock Instruct as per RFC 6435

 *     - Decoding support for MPLS-TP Fault-Management as per RFC 6427

 *

 * (c) Copyright 2012, Aditya Ambadkar and Diana Chris <arambadk,dvchris@ncsu.edu>

 *   -  Added preference to select BOS label as flowlabel as per RFC 6391

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

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

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/expert.h>

#include <epan/ppptypes.h>

#include <epan/etypes.h>

#include <epan/prefs.h>

#include <epan/ipproto.h>

#include <epan/decode_as.h>

#include <epan/proto_data.h>

#include "packet-ppp.h"

#include "packet-mpls.h"

#include "packet-pw-common.h"

#include "packet-bfd.h"

#include "packet-juniper.h"

#include "packet-sflow.h"

#include "packet-l2tp.h"

#include "packet-vxlan.h"

#include "packet-nsh.h"

void proto_register_mpls(void);

void proto_reg_handoff_mpls(void);

static int proto_mpls;

static int proto_pw_ach;

static int proto_pw_ach_mcc;

static int proto_pw_mcw;

static int ett_mpls;

static int ett_mpls_pw_ach;

static int ett_mpls_pw_ach_mcc;

static int ett_mpls_pw_mcw;

static char PW_ACH[50] = "PW Associated Channel Header";

const value_string special_labels[] = {

    {MPLS_LABEL_IP4_EXPLICIT_NULL,   "IPv4 Explicit-Null"},

    {MPLS_LABEL_ROUTER_ALERT,        "Router Alert"},

    {MPLS_LABEL_IP6_EXPLICIT_NULL,   "IPv6 Explicit-Null"},

    {MPLS_LABEL_IMPLICIT_NULL,       "Implicit-Null"},

    {MPLS_LABEL_OAM_ALERT,           "OAM Alert"},

    {MPLS_LABEL_GACH,                "Generic Associated Channel Label (GAL)"},

    {MPLS_LABEL_ELI,                 "Entropy Label Indicator (ELI)"},

    {0, NULL }

};

static dissector_table_t   pw_ach_subdissector_table;

static dissector_table_t   pw_ach_mcc_subdissector_table;

static dissector_handle_t dissector_ipv6;

static dissector_handle_t dissector_ip;

static dissector_handle_t dissector_pw_ach;

static dissector_handle_t dissector_pw_eth_heuristic;

static dissector_handle_t mpls_handle;

static dissector_handle_t mpls_pwcw_handle;

static dissector_handle_t mpls_mcc_handle;

/*

 * RFC 8469 deprecated Ethernet without CW, so default this to false.

 * https://datatracker.ietf.org/doc/html/rfc8469

 */

static bool mpls_try_heuristic_first;

/* For RFC6391 - Flow aware transport of pseudowire over a mpls PSN*/

static bool mpls_bos_flowlabel;

static int hf_mpls_label;

static int hf_mpls_label_special;

static int hf_mpls_exp;

static int hf_mpls_bos;

static int hf_mpls_ttl;

static int hf_mpls_pw_ach_ver;

static int hf_mpls_pw_ach_res;

static int hf_mpls_pw_ach_channel_type;

static int hf_mpls_pw_ach_mcc_proto;

static int hf_mpls_pw_mcw_flags;

static int hf_mpls_pw_mcw_length;

static int hf_mpls_pw_mcw_sequence_number;

static expert_field ei_mpls_pw_ach_error_processing_message;

static expert_field ei_mpls_pw_ach_res;

static expert_field ei_mpls_pw_mcw_error_processing_message;

static expert_field ei_mpls_invalid_label;

#if 0 /*not used yet*/

/*

 * MPLS PW types

 * http://www.iana.org/assignments/pwe3-parameters

 */

static const value_string mpls_pw_types[] = {

    { 0x0001, "Frame Relay DLCI ( Martini Mode )"              },

    { 0x0002, "ATM AAL5 SDU VCC transport"                     },

    { 0x0003, "ATM transparent cell transport"                 },

    { 0x0004, "Ethernet Tagged Mode"                           },

    { 0x0005, "Ethernet"                                       },

    { 0x0006, "HDLC"                                           },

    { 0x0007, "PPP"                                            },

    { 0x0008, "SONET/SDH Circuit Emulation Service Over MPLS"  },

    { 0x0009, "ATM n-to-one VCC cell transport"                },

    { 0x000A, "ATM n-to-one VPC cell transport"                },

    { 0x000B, "IP Layer2 Transport"                            },

    { 0x000C, "ATM one-to-one VCC Cell Mode"                   },

    { 0x000D, "ATM one-to-one VPC Cell Mode"                   },

    { 0x000E, "ATM AAL5 PDU VCC transport"                     },

    { 0x000F, "Frame-Relay Port mode"                          },

    { 0x0010, "SONET/SDH Circuit Emulation over Packet"        },

    { 0x0011, "Structure-agnostic E1 over Packet"              },

    { 0x0012, "Structure-agnostic T1 (DS1) over Packet"        },

    { 0x0013, "Structure-agnostic E3 over Packet"              },

    { 0x0014, "Structure-agnostic T3 (DS3) over Packet"        },

    { 0x0015, "CESoPSN basic mode"                             },

    { 0x0016, "TDMoIP AAL1 Mode"                               },

    { 0x0017, "CESoPSN TDM with CAS"                           },

    { 0x0018, "TDMoIP AAL2 Mode"                               },

    { 0x0019, "Frame Relay DLCI"                               },

    { 0x001A, "ROHC Transport Header-compressed Packets"       },/*[RFC4995][RFC4901]*/

    { 0x001B, "ECRTP Transport Header-compressed Packets"      },/*[RFC3545][RFC4901]*/

    { 0x001C, "IPHC Transport Header-compressed Packets"       },/*[RFC2507][RFC4901]*/

    { 0x001D, "cRTP Transport Header-compressed Packets"       },/*[RFC2508][RFC4901]*/

    { 0x001E, "ATM VP Virtual Trunk"                           },/*[MFA9]*/

    { 0x001F, "FC Port Mode"                                   },/*[RFC6307]*/

    { 0, NULL }

};

static value_string_ext mpls_pw_types_ext = VALUE_STRING_EXT_INIT(mpls_pw_types);

#endif

/*

 * MPLS PW Associated Channel Types

 * as per https://www.iana.org/assignments/pwe3-parameters

 * now known as MPLS Generalized Associated Channel (G-ACh) Types (including Pseudowire

 * Associated Channel Types) as per https://www.iana.org/assignments/g-ach-parameters

 * and RFC 5885 clause 3.2

 */

static const value_string mpls_pwac_types[] = {

    { 0x0000, "Reserved"},

    { 0x0001, "Management Communication Channel (MCC)"},

    { 0x0002, "Signaling Communication Channel (SCC)"},

    { 0x0007, "BFD Control, PW-ACH-encapsulated (BFD Without IP/UDP Headers)" },

    { 0x0008, "S-BFD Control, PW-ACH/L2SS encapsulation (without IP/UDP Headers)"},

    { 0x0009, "MPLS-TP Dual-Homing Coordination message"},

    { 0x000A, "MPLS Direct Loss Measurement (DLM)"},

    { 0x000B, "MPLS Inferred Loss Measurement (ILM)"},

    { 0x000C, "MPLS Delay Measurement (DM)"},

    { 0x000D, "MPLS Direct Loss and Delay Measurement (DLM+DM)"},

    { 0x000E, "MPLS Inferred Loss and Delay Measurement (ILM+DM)"},

    { 0x000F, "Residence Time Measurement"},

    { 0x0010, "Time Bucket Jitter Measurement"},

    { 0x0011, "Multi-packet Delay Measurement"},

    { 0x0012, "Average Delay Measurement"},

    { 0x0021, "IPv4 packet" },

    { 0x0022, "MPLS-TP CC message"},

    { 0x0023, "MPLS-TP CV message"},

    { 0x0024, "Protection State Coordination Protocol (PSC)"},

    { 0x0025, "On-Demand CV"},

    { 0x0026, "LI"},

    { 0x0027, "Pseudo-Wire OAM"},

    { 0x0028, "MAC Withdraw OAM Msg"},

    { 0x0029, "PW Status Refresh Reduction"},

    { 0x002A, "Ring Protection Switching (RPS) Protocol"},

    { 0x0057, "IPv6 packet" },

    { 0x0058, "Fault OAM"},

    { 0x0059, "G-ACh Advertisement Protocol"},

    { 0x7FF8, "Reserved for Experimental Use"},

    { 0x7FF9, "Reserved for Experimental Use"},

    { 0x7FFA, "Reserved for Experimental Use"},

    { 0x7FFB, "Reserved for Experimental Use"},

    { 0x7FFC, "Reserved for Experimental Use"},

    { 0x7FFD, "Reserved for Experimental Use"},

    { 0x7FFE, "Reserved for Experimental Use"},

    { 0x7FFF, "Reserved for Experimental Use"},

    { 0x8902, "MPLS-TP OAM"},

    { 0, NULL }

};

static value_string_ext mpls_pwac_types_ext = VALUE_STRING_EXT_INIT(mpls_pwac_types);

static dissector_table_t mpls_subdissector_table;

/*

 * Post-stack First Nibble

 * https://datatracker.ietf.org/doc/html/draft-ietf-mpls-1stnibble-06

 */

static dissector_table_t mpls_pfn_subdissector_table;

static heur_dissector_list_t mpls_heur_subdissector_list;

static void mpls_prompt(packet_info *pinfo, char* result)

{

    snprintf(result, MAX_DECODE_AS_PROMPT_LEN, "Data after label %u as",

        GPOINTER_TO_UINT(p_get_proto_data(pinfo->pool, pinfo, proto_mpls, 0)));

}

static void *mpls_value(packet_info *pinfo)

{

    return p_get_proto_data(pinfo->pool, pinfo, proto_mpls, 0);

}

static void mpls_pfn_prompt(packet_info *pinfo, char* result)

{

    snprintf(result, MAX_DECODE_AS_PROMPT_LEN, "Data after post-stack first nibble %u as",

        GPOINTER_TO_UINT(p_get_proto_data(pinfo->pool, pinfo, proto_mpls, 1)));

}

static void *mpls_pfn_value(packet_info *pinfo)

{

    return p_get_proto_data(pinfo->pool, pinfo, proto_mpls, 1);

}

static void pw_ach_prompt(packet_info *pinfo, char* result)

{

    snprintf(result, MAX_DECODE_AS_PROMPT_LEN, "Channel type 0x%x as",

        GPOINTER_TO_UINT(p_get_proto_data(pinfo->pool, pinfo, proto_pw_ach, 0)));

}

static void *pw_ach_value(packet_info *pinfo)

{

    return p_get_proto_data(pinfo->pool, pinfo, proto_pw_ach, 0);

}

/*

 * Given a 4-byte MPLS label starting at offset "offset", in tvbuff "tvb",

 * decode it.

 * Return the label in "label", EXP bits in "exp",

 * bottom_of_stack in "bos", and TTL in "ttl"

 */

void

decode_mpls_label(tvbuff_t *tvb, int offset,

                       uint32_t *label, uint8_t *exp,

                       uint8_t  *bos, uint8_t *ttl)

{

    uint8_t octet0 = tvb_get_uint8(tvb, offset+0);

    uint8_t octet1 = tvb_get_uint8(tvb, offset+1);

    uint8_t octet2 = tvb_get_uint8(tvb, offset+2);

    *label = (octet0 << 12) + (octet1 << 4) + ((octet2 >> 4) & 0xff);

    *exp = (octet2 >> 1) & 0x7;

    *bos = (octet2 & 0x1);

    *ttl = tvb_get_uint8(tvb, offset+3);

}

/*

 * PW Associated Channel Header Management Communication

 * Network (MCN) dissection as per RFC 5718.

 */

static int

dissect_pw_ach_mcc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)

{

    tvbuff_t   *next_tvb;

    proto_tree *mpls_pw_ach_mcc_tree;

    proto_item *ti;

    uint32_t    pid;

    ti = proto_tree_add_item(tree, proto_pw_ach_mcc, tvb, 0,2, ENC_NA);

    mpls_pw_ach_mcc_tree = proto_item_add_subtree(ti, ett_mpls_pw_ach_mcc);

    proto_tree_add_item_ret_uint(mpls_pw_ach_mcc_tree, hf_mpls_pw_ach_mcc_proto,tvb, 0, 2, ENC_BIG_ENDIAN, &pid);

    next_tvb = tvb_new_subset_remaining(tvb, 2);

    if (!dissector_try_uint(pw_ach_mcc_subdissector_table, pid, next_tvb, pinfo, tree))

    {

        call_data_dissector(next_tvb, pinfo, tree);

    }

    return tvb_captured_length(tvb);

}

/*

 * FF: PW Associated Channel Header dissection as per RFC 4385.

 */

static int

dissect_pw_ach(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)

{

    tvbuff_t   *next_tvb;

    unsigned    channel_type;

    if (tvb_reported_length_remaining(tvb, 0) < 4) {

        proto_tree_add_expert(tree, pinfo, &ei_mpls_pw_ach_error_processing_message, tvb, 0, -1);

        return tvb_captured_length(tvb);

    }

    channel_type = tvb_get_ntohs(tvb, 2);

    p_add_proto_data(pinfo->pool, pinfo, proto_pw_ach, 0, GUINT_TO_POINTER(channel_type));

    proto_tree *mpls_pw_ach_tree;

    proto_item *ti;

    uint16_t    res;

    ti = proto_tree_add_item(tree, proto_pw_ach, tvb, 0, 4, ENC_NA);

    mpls_pw_ach_tree = proto_item_add_subtree(ti, ett_mpls_pw_ach);

    proto_tree_add_item(mpls_pw_ach_tree, hf_mpls_pw_ach_ver,

                        tvb, 0, 1, ENC_BIG_ENDIAN);

    res = tvb_get_uint8(tvb, 1);

    ti = proto_tree_add_uint(mpls_pw_ach_tree, hf_mpls_pw_ach_res,

                                    tvb, 1, 1, res);

    if (res != 0)

        expert_add_info(pinfo, ti, &ei_mpls_pw_ach_res);

    proto_tree_add_item(mpls_pw_ach_tree, hf_mpls_pw_ach_channel_type,

                        tvb, 2, 2, ENC_BIG_ENDIAN);

    next_tvb = tvb_new_subset_remaining(tvb, 4);

    if (!dissector_try_uint(pw_ach_subdissector_table, channel_type, next_tvb, pinfo, tree))

    {

        call_data_dissector(next_tvb, pinfo, tree);

    }

    if (channel_type == PW_ACH_TYPE_BFD_CV)

    {

        /* The BFD dissector has already been called, this is called in addition

           XXX - Perhaps a new dissector function that combines both is preferred.*/

        dissect_bfd_mep(next_tvb, tree, 0);

    }

    return tvb_captured_length(tvb);

}

bool

dissect_try_cw_first_nibble( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )

{

    uint8_t nibble;

    nibble = (tvb_get_uint8(tvb, 0 ) >> 4) & 0x0F;

    switch ( nibble )

    {

        case 6:

            /*

             * XXX - this could be from an pseudo-wire without a control

             * word, with the packet's first nibble being 6.

             */

            call_dissector(dissector_ipv6, tvb, pinfo, tree);

            return true;

        case 4:

            /*

             * XXX - this could be from an pseudo-wire without a control

             * word, with the packet's first nibble being 4.

             */

            call_dissector(dissector_ip, tvb, pinfo, tree);

            return true;

        case 1:

            /*

             * XXX - this could be from an pseudo-wire without a control

             * word, with the packet's first nibble being 1.

             */

            call_dissector(dissector_pw_ach, tvb, pinfo, tree );

            return true;

        default:

            break;

    }

    return false;

}

/*

 * FF: Generic/Preferred PW MPLS Control Word dissection as per RFC 4385.

 */

static int

dissect_pw_mcw(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)

{

    tvbuff_t *next_tvb;

    if (tvb_reported_length_remaining(tvb, 0) < 4) {

        proto_tree_add_expert(tree, pinfo, &ei_mpls_pw_mcw_error_processing_message, tvb, 0, -1);

        return tvb_captured_length(tvb);

    }

    if ( dissect_try_cw_first_nibble( tvb, pinfo, tree ))

        return tvb_captured_length(tvb);

    if (tree) {

        proto_tree  *mpls_pw_mcw_tree;

        proto_item  *ti;

        ti = proto_tree_add_item(tree, proto_pw_mcw, tvb, 0, 4, ENC_NA);

        mpls_pw_mcw_tree = proto_item_add_subtree(ti, ett_mpls_pw_mcw);

        proto_tree_add_item(mpls_pw_mcw_tree, hf_mpls_pw_mcw_flags,

                            tvb, 0, 2, ENC_BIG_ENDIAN);

        /* bits 4 to 7 and FRG bits are displayed together */

        proto_tree_add_item(mpls_pw_mcw_tree, hf_mpls_pw_mcw_length,

                            tvb, 1, 1, ENC_BIG_ENDIAN);

        proto_tree_add_item(mpls_pw_mcw_tree, hf_mpls_pw_mcw_sequence_number,

                            tvb, 2, 2, ENC_BIG_ENDIAN);

    }

    next_tvb = tvb_new_subset_remaining(tvb, 4);

    call_data_dissector(next_tvb, pinfo, tree);

    return tvb_captured_length(tvb);

}

static int

dissect_mpls(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)

{

    int       offset = 0;

    uint32_t  label  = MPLS_LABEL_INVALID;

    uint8_t   exp;

    uint8_t   bos;

    uint8_t   ttl;

    tvbuff_t *next_tvb;

    int       found;

    uint8_t   first_nibble;

    struct mplsinfo mplsinfo;

    heur_dtbl_entry_t *hdtbl_entry;

    dissector_handle_t payload_handle;

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

    col_set_str(pinfo->cinfo, COL_INFO, "MPLS Label Switched Packet");

    /* Ensure structure is initialized */

    memset(&mplsinfo, 0, sizeof(struct mplsinfo));

    /* Start Decoding Here. */

    while (tvb_reported_length_remaining(tvb, offset) > 0) {

        decode_mpls_label(tvb, offset, &label, &exp, &bos, &ttl);

        /*

         * FF: export (last shim in stack) info to subdissectors and

         * update pinfo

         */

        mplsinfo.label = label;

        p_add_proto_data(pinfo->pool, pinfo, proto_mpls, 0, GUINT_TO_POINTER(label));

        mplsinfo.exp   = exp;

        mplsinfo.bos   = bos;

        mplsinfo.ttl   = ttl;

        if (tree) {

            proto_item *ti;

            proto_tree *mpls_tree;

            ti = proto_tree_add_item(tree, proto_mpls, tvb, offset, 4, ENC_NA);

            mpls_tree = proto_item_add_subtree(ti, ett_mpls);

            if (mpls_bos_flowlabel && bos) {

                proto_item_append_text(ti, ", Label: %u (Flow Label)", label);

            } else {

                proto_item_append_text(ti, ", Label: %u", label);

            }

            if (label <= MPLS_LABEL_MAX_RESERVED){

                proto_tree_add_item(mpls_tree, hf_mpls_label_special, tvb,

                                    offset, 4, ENC_BIG_ENDIAN);

                proto_item_append_text(ti, " (%s)",

                                       val_to_str_const(label, special_labels, "Reserved - Unknown"));

            } else {

                proto_tree_add_item(mpls_tree, hf_mpls_label, tvb, offset, 4,

                                    ENC_BIG_ENDIAN);

            }

            proto_tree_add_item(mpls_tree, hf_mpls_exp, tvb, offset, 4,

                                ENC_BIG_ENDIAN);

            proto_item_append_text(ti, ", Exp: %u", exp);

            proto_tree_add_item(mpls_tree, hf_mpls_bos , tvb, offset, 4,

                                ENC_BIG_ENDIAN);

            proto_item_append_text(ti, ", S: %u", bos);

            proto_tree_add_item(mpls_tree, hf_mpls_ttl, tvb, offset, 4,

                                ENC_BIG_ENDIAN);

            proto_item_append_text(ti, ", TTL: %u", ttl);

        }

        offset += 4;

        if ((label == MPLS_LABEL_GACH) && !bos) {

            proto_tree_add_expert(tree, pinfo, &ei_mpls_invalid_label, tvb, 0, -1);

        }

        if ((label == MPLS_LABEL_GACH) && bos) {

            (void) g_strlcpy(PW_ACH, "Generic Associated Channel Header",50);

            next_tvb = tvb_new_subset_remaining(tvb, offset);

            call_dissector(dissector_pw_ach, next_tvb, pinfo, tree );

            return tvb_captured_length(tvb);

        }

        else

            (void) g_strlcpy(PW_ACH, "PW Associated Channel Header",50);

        if (bos)

            break;

    }

    first_nibble = (tvb_get_uint8(tvb, offset) >> 4) & 0x0F;

    p_add_proto_data(pinfo->pool, pinfo, proto_mpls, 1, GUINT_TO_POINTER(first_nibble));

    next_tvb = tvb_new_subset_remaining(tvb, offset);

    /*

     * Is there an explicit label-to-dissector binding?

     * If so, use it.

     */

    found = dissector_try_uint_with_data(mpls_subdissector_table, label,

                               next_tvb, pinfo, tree, false, &mplsinfo);

    if (found) {

        /* Yes, there is. */

        return tvb_captured_length(tvb);

    }

    /*

     * Do we try heuristic dissectors first? This is necessary for, e.g.,

     * Ethernet without CW where the address begins with a 4 or 6 nibble.

     */

    if (mpls_try_heuristic_first) {

        if (dissector_try_heuristic(mpls_heur_subdissector_list, next_tvb, pinfo,

                                    tree, &hdtbl_entry, NULL)) {

            return tvb_captured_length(tvb);

        }

    }

    /*

     * Use the 1st nibble logic (see BCP 128 (RFC 4928), RFC 4385 and 5586).

     * https://datatracker.ietf.org/doc/html/draft-ietf-mpls-1stnibble-06

     */

    if (dissector_try_uint_with_data(mpls_pfn_subdissector_table, first_nibble,

        next_tvb, pinfo, tree, false, &mplsinfo)) {

        payload_handle = dissector_get_uint_handle(mpls_pfn_subdissector_table, first_nibble);

        if (payload_handle == dissector_ip || payload_handle == dissector_ipv6) {

            /* IPv4 and IPv6 dissectors may reduce the length of the tvb.

               We need to do the same, so that any Ethernet trailer is detected.

             */

            set_actual_length(tvb, offset+tvb_reported_length(next_tvb));

        }

        return tvb_captured_length(tvb);

    }

    if (!mpls_try_heuristic_first) {

        if (dissector_try_heuristic(mpls_heur_subdissector_list, next_tvb, pinfo,

                                    tree, &hdtbl_entry, NULL)) {

            return tvb_captured_length(tvb);

        }

    }

    call_data_dissector(next_tvb, pinfo, tree);

    return tvb_captured_length(tvb);

}

void

proto_register_mpls(void)

{

    static hf_register_info mplsf_info[] = {

        /* MPLS header fields */

        {&hf_mpls_label,

         {"MPLS Label", "mpls.label",

          FT_UINT32, BASE_DEC_HEX, NULL, 0xFFFFF000,

          NULL, HFILL }

        },

        {&hf_mpls_label_special,

         {"MPLS Label", "mpls.label",

          FT_UINT32, BASE_DEC_HEX, VALS(special_labels), 0xFFFFF000,

          NULL, HFILL }

        },

        {&hf_mpls_exp,

         {"MPLS Experimental Bits", "mpls.exp",

          FT_UINT32, BASE_DEC, NULL, 0x00000E00,

          NULL, HFILL }

        },

        {&hf_mpls_bos,

         {"MPLS Bottom Of Label Stack", "mpls.bottom",

          FT_UINT32, BASE_DEC, NULL, 0x00000100,

          NULL, HFILL }

        },

        {&hf_mpls_ttl,

         {"MPLS TTL", "mpls.ttl",

          FT_UINT32, BASE_DEC, NULL, 0x000000FF,

          NULL, HFILL }

        },

        /* PW Associated Channel Header fields */

        {&hf_mpls_pw_ach_ver,

         {"Channel Version", "pwach.ver",

          FT_UINT8, BASE_DEC, NULL, 0x0F,

          "PW Associated Channel Version", HFILL }

        },

        {&hf_mpls_pw_ach_res,

         {"Reserved", "pwach.res",

          FT_UINT8, BASE_HEX, NULL, 0x0,

          NULL, HFILL }

        },

        {&hf_mpls_pw_ach_channel_type,

         {"Channel Type", "pwach.channel_type",

          FT_UINT16, BASE_HEX|BASE_EXT_STRING, &mpls_pwac_types_ext, 0x0,

          "PW Associated Channel Type", HFILL }

        },

        /* Generic/Preferred PW MPLS MCC Control Word fields */

        {&hf_mpls_pw_ach_mcc_proto,

         {"Protocol Id", "mcc.proto",

          FT_UINT16, BASE_HEX|BASE_EXT_STRING, &mpls_pwac_types_ext, 0x0,

          "MCC Protocol", HFILL }

        },

        /* Generic/Preferred PW MPLS Control Word fields */

        {&hf_mpls_pw_mcw_flags,

         {"Flags", "pwmcw.flags",

          FT_UINT16, BASE_HEX, NULL, 0x0FC0,

          "Generic/Preferred PW MPLS Control Word Flags", HFILL }

        },

        {&hf_mpls_pw_mcw_length,

         {"Length", "pwmcw.length",

          FT_UINT8, BASE_DEC, NULL, 0x3F,

          "Generic/Preferred PW MPLS Control Word Length", HFILL }

        },

        {&hf_mpls_pw_mcw_sequence_number,

         {"Sequence Number", "pwmcw.sequence_number",

          FT_UINT16, BASE_DEC, NULL, 0x0,

          "Generic/Preferred PW MPLS Control Word Sequence Number", HFILL }

        },

    };

    static int *ett[] = {

        &ett_mpls,

        &ett_mpls_pw_ach,

        &ett_mpls_pw_ach_mcc,

        &ett_mpls_pw_mcw,

    };

    static ei_register_info ei[] = {

        { &ei_mpls_pw_ach_error_processing_message, { "pwach.error_processing_message", PI_MALFORMED, PI_ERROR, "Error processing Message", EXPFILL }},

        { &ei_mpls_pw_ach_res, { "pwach.res.not_zero", PI_PROTOCOL, PI_WARN, "Error: this byte is reserved and must be 0", EXPFILL }},

        { &ei_mpls_pw_mcw_error_processing_message, { "pwmcw.error_processing_message", PI_MALFORMED, PI_ERROR, "Error processing Message", EXPFILL }},

        { &ei_mpls_invalid_label, { "mpls.invalid_label", PI_PROTOCOL, PI_WARN, "Invalid Label", EXPFILL }},

    };

    /* Decode As handling */

    static build_valid_func mpls_da_build_value[1] = {mpls_value};

    static decode_as_value_t mpls_da_values = {mpls_prompt, 1, mpls_da_build_value};

    static decode_as_t mpls_da = {"mpls", "mpls.label", 1, 0, &mpls_da_values, NULL, NULL,

                                  decode_as_default_populate_list, decode_as_default_reset, decode_as_default_change, NULL};

    static build_valid_func mpls_pfn_da_build_value[1] = {mpls_pfn_value};

    static decode_as_value_t mpls_pfn_da_values = {mpls_pfn_prompt, 1, mpls_pfn_da_build_value};

    static decode_as_t mpls_pfn_da = {"mpls", "mpls.pfn", 1, 0, &mpls_pfn_da_values, NULL, NULL,

                                  decode_as_default_populate_list, decode_as_default_reset, decode_as_default_change, NULL};

    static build_valid_func pw_ach_da_build_value[1] = {pw_ach_value};

    static decode_as_value_t pw_ach_da_values = {pw_ach_prompt, 1, pw_ach_da_build_value};

    static decode_as_t pw_ach_da = {"pwach", "pwach.channel_type", 1, 0, &pw_ach_da_values, NULL, NULL,

                                  decode_as_default_populate_list, decode_as_default_reset, decode_as_default_change, NULL};

    expert_module_t* expert_mpls;

    module_t * module_mpls;

    proto_mpls = proto_register_protocol("MultiProtocol Label Switching Header", "MPLS", "mpls");

    proto_pw_ach = proto_register_protocol(PW_ACH, "PW Associated Channel", "pwach");

    proto_pw_mcw = proto_register_protocol("PW MPLS Control Word (generic/preferred)", "Generic PW (with CW)", "pwmcw");

    proto_pw_ach_mcc = proto_register_protocol("Management Communication Channel (MCC)", "PW Associated Management Communication Channel", "mcc");

    proto_register_field_array(proto_mpls, mplsf_info, array_length(mplsf_info));

    proto_register_subtree_array(ett, array_length(ett));

    expert_mpls = expert_register_protocol(proto_mpls);

    expert_register_field_array(expert_mpls, ei, array_length(ei));

    mpls_handle = register_dissector("mpls", dissect_mpls, proto_mpls);

    mpls_mcc_handle = register_dissector("mplsmcc", dissect_pw_ach_mcc, proto_pw_ach_mcc);

    mpls_pwcw_handle = register_dissector("mplspwcw", dissect_pw_mcw, proto_pw_mcw);

    dissector_pw_ach = register_dissector("mplspwach", dissect_pw_ach, proto_pw_ach );

    /* FF: mpls subdissector table is indexed by label */

    mpls_subdissector_table = register_dissector_table("mpls.label",

                                                       "MPLS label",

                                                       proto_mpls, FT_UINT32, BASE_DEC);

    mpls_pfn_subdissector_table = register_dissector_table("mpls.pfn",

                                                           "MPLS post-stack first nibble",

                                                           proto_mpls, FT_UINT8, BASE_HEX);

    mpls_heur_subdissector_list = register_heur_dissector_list_with_description("mpls", "MPLS payload", proto_mpls);

    pw_ach_subdissector_table  = register_dissector_table("pwach.channel_type", "PW Associated Channel Type", proto_pw_ach, FT_UINT16, BASE_HEX);

    pw_ach_mcc_subdissector_table  = register_dissector_table("mcc.proto", "PW Associated Management Communication Channel Protocol", proto_pw_ach_mcc, FT_UINT16, BASE_HEX);

    module_mpls = prefs_register_protocol( proto_mpls, NULL );

    prefs_register_obsolete_preference(module_mpls, "mplspref.payload");

    prefs_register_bool_preference(module_mpls, "try_heuristic_first",

                                "Try heuristic sub-dissectors first",

                                "Try to decode a packet heuristically, e.g. as "

                                "Ethernet without control word, before trying "

                                "sub-dissectors based upon the first nibble.",

                                &mpls_try_heuristic_first);

    /* RFC6391: Flow aware transport of pseudowire*/

    prefs_register_bool_preference(module_mpls,

                                    "flowlabel_in_mpls_header",

                                    "Assume bottom of stack label as Flow label",

                                    "Lowest label is used to segregate flows inside a pseudowire",

                                    &mpls_bos_flowlabel);

    register_decode_as(&mpls_da);

    register_decode_as(&mpls_pfn_da);

    register_decode_as(&pw_ach_da);

}

void

proto_reg_handoff_mpls(void)

{

    dissector_add_uint("ethertype", ETHERTYPE_MPLS, mpls_handle);

    dissector_add_uint("ethertype", ETHERTYPE_MPLS_MULTI, mpls_handle);

    dissector_add_uint("ppp.protocol", PPP_MPLS_UNI, mpls_handle);

    dissector_add_uint("ppp.protocol", PPP_MPLS_MULTI, mpls_handle);

    dissector_add_uint("chdlc.protocol", ETHERTYPE_MPLS, mpls_handle);

    dissector_add_uint("chdlc.protocol", ETHERTYPE_MPLS_MULTI, mpls_handle);

    dissector_add_uint("gre.proto", ETHERTYPE_MPLS, mpls_handle);

    dissector_add_uint("gre.proto", ETHERTYPE_MPLS_MULTI, mpls_handle);

    dissector_add_uint("ip.proto", IP_PROTO_MPLS_IN_IP, mpls_handle);

    dissector_add_uint("juniper.proto", JUNIPER_PROTO_MPLS, mpls_handle);

    dissector_add_uint("juniper.proto", JUNIPER_PROTO_IP_MPLS, mpls_handle);

    dissector_add_uint("juniper.proto", JUNIPER_PROTO_IP6_MPLS, mpls_handle);

    dissector_add_uint("juniper.proto", JUNIPER_PROTO_CLNP_MPLS, mpls_handle);

    dissector_add_for_decode_as("pwach.channel_type", mpls_handle);

    dissector_add_uint("sflow_245.header_protocol", SFLOW_245_HEADER_MPLS, mpls_handle);

    dissector_add_for_decode_as("l2tp.pw_type", mpls_handle);

    dissector_add_uint_with_preference("udp.port", UDP_PORT_MPLS_OVER_UDP, mpls_handle);

    dissector_add_uint("vxlan.next_proto", VXLAN_MPLS, mpls_handle);

    dissector_add_uint("nsh.next_proto", NSH_MPLS, mpls_handle);

    dissector_add_uint( "mpls.label", MPLS_LABEL_INVALID, mpls_pwcw_handle);

    dissector_add_uint("pwach.channel_type", PW_ACH_TYPE_MCC, mpls_mcc_handle);

    dissector_ipv6                  = find_dissector_add_dependency("ipv6", proto_pw_mcw );

    dissector_ip                    = find_dissector_add_dependency("ip", proto_pw_mcw );

    dissector_pw_eth_heuristic      = find_dissector_add_dependency("pw_eth_heuristic", proto_pw_mcw);

    /*

     * Our previous default behavior has been to try the Eth CW heuristic

     * on first nibble 0. Continue doing that. For other first nibbles

     * registered to dissectors, "try heuristic first" can be enabled.

     */

    dissector_add_for_decode_as("mpls.pfn", mpls_pwcw_handle);

    dissector_add_uint("mpls.pfn", 0, dissector_pw_eth_heuristic);

    dissector_add_uint("mpls.pfn", 1, dissector_pw_ach);

    dissector_add_uint("mpls.pfn", 4, dissector_ip);

    dissector_add_uint("mpls.pfn", 6, dissector_ipv6);

}

/*

 * Editor modelines

 *

 * Local Variables:

 * c-basic-offset: 4

 * tab-width: 8

 * indent-tabs-mode: nil

 * End:

 *

 * ex: set shiftwidth=4 tabstop=8 expandtab:

 * :indentSize=4:tabSize=8:noTabs=true:

 */