/* packet-shim6.c

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

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

 *

 * RFC 5533

 *

 * SHIM6 support added by Matthijs Mekking <matthijs@NLnetLabs.nl>

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/expert.h>

#include <epan/tfs.h>

#include <wsutil/array.h>

#include <epan/in_cksum.h>

#include <epan/iana-info.h>

#include "packet-ip.h"

void proto_register_shim6(void);

void proto_reg_handoff_shim6(void);

static dissector_handle_t shim6_handle;

/* SHIM6 header */

struct ip6_shim {

    uint8_t ip6s_nxt; /* next header */

    uint8_t ip6s_len; /* header extension length */

    uint8_t ip6s_p;   /* P field and first 7 bits of remainder */

    /* followed by shim6 specific data*/

};

/* SHIM6 control message types */

#define SHIM6_TYPE_I1           0x01    /* 0 000 0001 */

#define SHIM6_TYPE_R1           0x02    /* 0 000 0010 */

#define SHIM6_TYPE_I2           0x03    /* 0 000 0011 */

#define SHIM6_TYPE_R2           0x04    /* 0 000 0100 */

#define SHIM6_TYPE_R1BIS        0x05    /* 0 000 0101 */

#define SHIM6_TYPE_I2BIS        0x06    /* 0 000 0110 */

#define SHIM6_TYPE_UPD_REQ      0x40    /* 0 100 0000 = 64 */

#define SHIM6_TYPE_UPD_ACK      0x41    /* 0 100 0001 = 65 */

#define SHIM6_TYPE_KEEPALIVE    0x42    /* 0 100 0010 = 66 */

#define SHIM6_TYPE_PROBE        0x43    /* 0 100 0011 = 67 */

/* SHIM6 Options */

#define SHIM6_OPT_RESPVAL       0x01    /* 0 000 0001 */

#define SHIM6_OPT_LOCLIST       0x02    /* 0 000 0010 */

#define SHIM6_OPT_LOCPREF       0x03    /* 0 000 0011 */

#define SHIM6_OPT_CGAPDM        0x04    /* 0 000 0100 */

#define SHIM6_OPT_CGASIG        0x05    /* 0 000 0101 */

#define SHIM6_OPT_ULIDPAIR      0x06    /* 0 000 0110 */

#define SHIM6_OPT_FII           0x07    /* 0 000 0111 */

/* SHIM6 Bitmasks */

#define SHIM6_BITMASK_P         0x80    /* 1 000 0000 */

#define SHIM6_BITMASK_TYPE      0x7F    /* 0 111 1111 */

#define SHIM6_BITMASK_PROTOCOL  0x01    /* 0 000 0001 */

#define SHIM6_BITMASK_SPECIFIC  0xFE    /* 1 111 1110 */

#define SHIM6_BITMASK_R         0x80    /* 1 000 0000 */

#define SHIM6_BITMASK_CT        0x7F    /* 0 111 1111 */

#define SHIM6_BITMASK_OPT_TYPE  0xFFFE  /* 1 111 1111    1 111 1110 */

#define SHIM6_BITMASK_CRITICAL  0x01    /* 0 000 0001 */

#define SHIM6_BITMASK_PRECVD    0xF0    /* 1 111 0000 */

#define SHIM6_BITMASK_PSENT     0x0F    /* 0 000 1111 */

#define SHIM6_BITMASK_STA       0xC0    /* 1 100 0000 */

/* SHIM6 Verification Methods */

#define SHIM6_VERIF_HBA         0x01    /* 0 000 0001 */

#define SHIM6_VERIF_CGA         0x02    /* 0 000 0010 */

/* SHIM6 Flags */

#define SHIM6_FLAG_BROKEN       0x01    /* 0 000 0001 */

#define SHIM6_FLAG_TEMPORARY    0x02    /* 0 000 0010 */

/* SHIM6 REAP States */

#define SHIM6_REAP_OPERATIONAL  0x00    /* 0 000 0000 */

#define SHIM6_REAP_EXPLORING    0x01    /* 0 000 0001 */

#define SHIM6_REAP_INBOUNDOK    0x02    /* 0 000 0010 */

static int proto_shim6;

static int hf_shim6_nxt;

static int hf_shim6_len;

static int hf_shim6_len_oct;

static int hf_shim6_p;

/* context tag is 49 bits, cannot be used for filter yet */

static int hf_shim6_ct;

static int hf_shim6_type;

static int hf_shim6_proto;

static int hf_shim6_checksum;

static int hf_shim6_checksum_status;

static int hf_shim6_inonce; /* also for request nonce */

static int hf_shim6_rnonce;

static int hf_shim6_reserved;

static int hf_shim6_reserved2;

static int hf_shim6_precvd;

static int hf_shim6_psent;

static int hf_shim6_psrc;

static int hf_shim6_pdst;

static int hf_shim6_pnonce;

static int hf_shim6_pdata;

static int hf_shim6_sulid;

static int hf_shim6_rulid;

static int hf_shim6_reap;

static int hf_shim6_opt_type;

static int hf_shim6_opt_len;

static int hf_shim6_opt_total_len;

static int hf_shim6_opt_loc_verif_methods;

static int hf_shim6_opt_critical;

static int hf_shim6_opt_loclist;

static int hf_shim6_locator;

static int hf_shim6_loc_flag;

static int hf_shim6_loc_prio;

static int hf_shim6_loc_weight;

static int hf_shim6_opt_locnum;

static int hf_shim6_opt_elemlen;

static int hf_shim6_opt_fii;

static int hf_shim6_validator;

static int hf_shim6_cga_parameter_data_structure;

static int hf_shim6_cga_signature;

static int hf_shim6_padding;

static int ett_shim6_proto;

static int ett_shim6_option;

static int ett_shim6_locators;

static int ett_shim6_verif_methods;

static int ett_shim6_loc_pref;

static int ett_shim6_probes_sent;

static int ett_shim6_probe_sent;

static int ett_shim6_probes_rcvd;

static int ett_shim6_probe_rcvd;

static int ett_shim6_cksum;

static expert_field ei_shim6_opt_elemlen_invalid;

static expert_field ei_shim6_checksum_bad;

static const value_string shimoptvals[] = {

    { SHIM6_OPT_RESPVAL,  "Responder Validator Option" },

    { SHIM6_OPT_LOCLIST,  "Locator List Option" },

    { SHIM6_OPT_LOCPREF,  "Locator Preferences Option" },

    { SHIM6_OPT_CGAPDM,   "CGA Parameter Data Structure Option" },

    { SHIM6_OPT_CGASIG,   "CGA Signature Option" },

    { SHIM6_OPT_ULIDPAIR, "ULID Pair Option" },

    { SHIM6_OPT_FII,      "Forked Instance Identifier Option" },

    { 0, NULL }

};

static const value_string shimverifmethods[] = {

    { SHIM6_VERIF_HBA, "HBA" },

    { SHIM6_VERIF_CGA, "CGA" },

    { 0, NULL }

};

static const value_string shimflags[] _U_ = {

    { SHIM6_FLAG_BROKEN,    "BROKEN" },

    { SHIM6_FLAG_TEMPORARY, "TEMPORARY" },

    { 0, NULL }

};

static const value_string shimreapstates[] = {

    { SHIM6_REAP_OPERATIONAL, "Operational" },

    { SHIM6_REAP_EXPLORING,   "Exploring" },

    { SHIM6_REAP_INBOUNDOK,   "InboundOK" },

    { 0, NULL }

};

static const value_string shim6_protocol[] = {

    { 0, "SHIM6" },

    { 1, "HIP" },

    { 0, NULL }

};

static void

dissect_shim6_opt_loclist(proto_tree * opt_tree, tvbuff_t * tvb, int *offset)

{

    proto_tree *subtree;

    unsigned    count;

    unsigned    optlen;

    proto_tree_add_item(opt_tree, hf_shim6_opt_loclist, tvb, *offset, 4, ENC_BIG_ENDIAN);

    *offset += 4;

    optlen = tvb_get_uint8(tvb, *offset);

    proto_tree_add_item(opt_tree, hf_shim6_opt_locnum, tvb, *offset, 1, ENC_BIG_ENDIAN);

    *offset += 1;

    /* Verification Methods */

    subtree = proto_tree_add_subtree(opt_tree, tvb, *offset, optlen,

                             ett_shim6_verif_methods, NULL, "Locator Verification Methods");

    for (count=0; count < optlen; count++)

        proto_tree_add_item(subtree, hf_shim6_opt_loc_verif_methods, tvb,

                            *offset+count, 1, ENC_BIG_ENDIAN);

    *offset += optlen;

    /* Padding, included in length field */

    if ((7 - optlen % 8) > 0) {

        proto_tree_add_item(opt_tree, hf_shim6_padding, tvb, *offset, (7 - optlen % 8), ENC_NA);

        *offset += (7 - optlen % 8);

    }

    /* Locators */

    subtree = proto_tree_add_subtree(opt_tree, tvb, *offset, 16 * optlen, ett_shim6_locators, NULL, "Locators");

    for (count=0; count < optlen; count++) {

        proto_tree_add_item(subtree, hf_shim6_locator, tvb, *offset, 16, ENC_NA);

        *offset += 16;

    }

}

static void

dissect_shim6_opt_loc_pref(proto_tree * opt_tree, tvbuff_t * tvb, int *offset, int len, packet_info *pinfo)

{

    proto_tree *subtree;

    int         optlen;

    int         count;

    proto_tree_add_item(opt_tree, hf_shim6_opt_loclist, tvb, *offset, 4, ENC_BIG_ENDIAN);

    *offset += 4;

    optlen = tvb_get_uint8(tvb, *offset);

    proto_tree_add_item(opt_tree, hf_shim6_opt_elemlen, tvb, *offset, 1, ENC_BIG_ENDIAN);

    if (optlen < 1 || optlen > 3) {

        proto_tree_add_expert_format(opt_tree, pinfo, &ei_shim6_opt_elemlen_invalid, tvb, *offset, 1,

                                     "Invalid element length: %u", optlen);

        return;

    }

    *offset += 1;

    /* Locator Preferences */

    count = 1;

    while (*offset < len) {

        subtree = proto_tree_add_subtree_format(opt_tree, tvb, *offset, optlen, ett_shim6_loc_pref, NULL,

                                                "Locator Preferences %u", count);

        /* Flags */

        if (optlen >= 1)

            proto_tree_add_item(subtree, hf_shim6_loc_flag, tvb, *offset, 1, ENC_BIG_ENDIAN);

        /* Priority */

        if (optlen >= 2)

            proto_tree_add_item(subtree, hf_shim6_loc_prio, tvb, *offset+1, 1, ENC_BIG_ENDIAN);

        /* Weight */

        if (optlen >= 3)

            proto_tree_add_item(subtree, hf_shim6_loc_weight, tvb, *offset+2, 1, ENC_BIG_ENDIAN);

        /*

         * Shim6 Draft 08 doesn't specify the format when the Element length is

         * more than three, except that any such formats MUST be defined so that

         * the first three octets are the same as in the above case, that is, a

         * of a 1 octet flags field followed by a 1 octet priority field, and a

         * 1 octet weight field.

         */

        *offset += optlen;

        count++;

    }

}

static int

dissect_shimopts(tvbuff_t *tvb, int offset, proto_tree *tree, packet_info *pinfo)

{

    int          len, total_len;

    int          padding;

    proto_tree  *opt_tree;

    proto_item  *ti;

    offset += 4;

    len = tvb_get_ntohs(tvb, offset+2);

    padding = 7 - ((len + 3) % 8);

    total_len = 4 + len + padding;

    if (tree)

    {

        /* Option Type */

        opt_tree = proto_tree_add_subtree(tree, tvb, offset, total_len, ett_shim6_option, NULL,

                            val_to_str_const( (tvb_get_ntohs(tvb, offset) & SHIM6_BITMASK_OPT_TYPE) >> 1, shimoptvals, "Unknown Option Type"));

        proto_tree_add_item(opt_tree, hf_shim6_opt_type, tvb, offset, 2, ENC_BIG_ENDIAN);

        /* Critical */

        proto_tree_add_item(opt_tree, hf_shim6_opt_critical, tvb, offset+1, 1, ENC_BIG_ENDIAN);

        /* Content Length */

        proto_tree_add_item(opt_tree, hf_shim6_opt_len, tvb, offset + 2, 2, ENC_BIG_ENDIAN);

        ti = proto_tree_add_uint(opt_tree, hf_shim6_opt_total_len, tvb, offset+2, 2, total_len);

        proto_item_set_generated(ti);

        /* Option Type Specific */

        switch (tvb_get_ntohs(tvb, offset) >> 1)

        {

        case SHIM6_OPT_RESPVAL:

            proto_tree_add_item(opt_tree, hf_shim6_validator, tvb, offset, len, ENC_NA);

            offset += len;

            if (total_len-(len+4) > 0)

                proto_tree_add_item(opt_tree, hf_shim6_padding, tvb, offset, total_len-(len+4), ENC_NA);

            break;

        case SHIM6_OPT_LOCLIST:

            dissect_shim6_opt_loclist(opt_tree, tvb, &offset);

            break;

        case SHIM6_OPT_LOCPREF:

            dissect_shim6_opt_loc_pref(opt_tree, tvb, &offset, offset+len+4, pinfo);

            if (total_len-(len+4) > 0)

                proto_tree_add_item(opt_tree, hf_shim6_padding, tvb, offset, total_len-(len+4), ENC_NA);

            break;

        case SHIM6_OPT_CGAPDM:

            proto_tree_add_item(opt_tree, hf_shim6_cga_parameter_data_structure, tvb, offset, len, ENC_NA);

            offset += len;

            if (total_len-(len+4) > 0)

                proto_tree_add_item(opt_tree, hf_shim6_padding, tvb, offset, total_len-(len+4), ENC_NA);

            break;

        case SHIM6_OPT_CGASIG:

            proto_tree_add_item(opt_tree, hf_shim6_cga_signature, tvb, offset, len, ENC_NA);

            offset += len;

            if (total_len-(len+4) > 0)

                proto_tree_add_item(opt_tree, hf_shim6_padding, tvb, offset, total_len-(len+4), ENC_NA);

            break;

        case SHIM6_OPT_ULIDPAIR:

            proto_tree_add_item(opt_tree, hf_shim6_reserved, tvb, offset, 4, ENC_NA);

            offset += 4;

            proto_tree_add_item(opt_tree, hf_shim6_sulid, tvb, offset, 16, ENC_NA);

            offset += 16;

            proto_tree_add_item(opt_tree, hf_shim6_rulid, tvb, offset, 16, ENC_NA);

            offset += 16;

            break;

        case SHIM6_OPT_FII:

            proto_tree_add_item(opt_tree, hf_shim6_opt_fii, tvb, offset, 4, ENC_BIG_ENDIAN);

            offset += 4;

            break;

        default:

            break;

        }

    }

    return total_len;

}

static void

dissect_shim6_ct(packet_info *pinfo, proto_tree * shim_tree, int hf_item, tvbuff_t * tvb, int offset, const char * label)

{

    uint8_t tmp[6];

    const char *ct_str;

    tmp[0] = tvb_get_uint8(tvb, offset++);

    tmp[1] = tvb_get_uint8(tvb, offset++);

    tmp[2] = tvb_get_uint8(tvb, offset++);

    tmp[3] = tvb_get_uint8(tvb, offset++);

    tmp[4] = tvb_get_uint8(tvb, offset++);

    tmp[5] = tvb_get_uint8(tvb, offset++);

    ct_str = wmem_strdup_printf(pinfo->pool,

                                "%s: %02X %02X %02X %02X %02X %02X", label,

                                tmp[0] & SHIM6_BITMASK_CT, tmp[1], tmp[2],

                                tmp[3], tmp[4], tmp[5]

        );

    proto_tree_add_none_format(shim_tree, hf_item, tvb, offset - 6, 6, "%s", ct_str);

}

static void

dissect_shim6_probes(proto_tree * shim_tree, tvbuff_t * tvb, int offset,

                     const char * label, unsigned nbr_probe,

                     bool probes_rcvd)

{

    proto_tree *probes_tree;

    proto_tree *probe_tree;

    int         ett_probes;

    int         ett_probe;

    unsigned    count;

    if (probes_rcvd) {

        ett_probes = ett_shim6_probes_rcvd;

        ett_probe = ett_shim6_probe_rcvd;

    } else {

        ett_probes = ett_shim6_probes_sent;

        ett_probe = ett_shim6_probe_sent;

    }

    probes_tree = proto_tree_add_subtree(shim_tree, tvb, offset, 40 * nbr_probe, ett_probes, NULL, label);

    for (count=0; count < nbr_probe; count++) {

        probe_tree = proto_tree_add_subtree_format(probes_tree, tvb, offset, 40,

                                            ett_probe, NULL, "Probe %u", count+1);

        proto_tree_add_item(probe_tree, hf_shim6_psrc, tvb, offset, 16, ENC_NA);

        offset += 16;

        proto_tree_add_item(probe_tree, hf_shim6_pdst, tvb, offset, 16, ENC_NA);

        offset += 16;

        proto_tree_add_item(probe_tree, hf_shim6_pnonce, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

        proto_tree_add_item(probe_tree, hf_shim6_pdata, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

    }

}

/* Dissect SHIM6 data: control messages */

static int

dissect_shimctrl(packet_info *pinfo, tvbuff_t *tvb, int offset, unsigned type, proto_tree *shim_tree)

{

    uint8_t      tmp;

    const char *sta;

    unsigned     probes_sent;

    unsigned     probes_rcvd;

    switch (type)

    {

    case SHIM6_TYPE_I1:

        dissect_shim6_ct(pinfo, shim_tree, hf_shim6_ct, tvb, offset, "Initiator Context Tag");

        offset += 6;

        proto_tree_add_item(shim_tree, hf_shim6_inonce, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

        break;

    case SHIM6_TYPE_R1:

        proto_tree_add_item(shim_tree, hf_shim6_reserved2, tvb, offset, 2, ENC_NA);

        offset += 2;

        proto_tree_add_item(shim_tree, hf_shim6_inonce, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

        proto_tree_add_item(shim_tree, hf_shim6_rnonce, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

        break;

    case SHIM6_TYPE_I2:

        dissect_shim6_ct(pinfo, shim_tree, hf_shim6_ct, tvb, offset, "Initiator Context Tag");

        offset += 6;

        proto_tree_add_item(shim_tree, hf_shim6_inonce, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

        proto_tree_add_item(shim_tree, hf_shim6_rnonce, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

        proto_tree_add_item(shim_tree, hf_shim6_reserved2, tvb, offset, 4, ENC_NA);

        offset += 4;

        break;

    case SHIM6_TYPE_R2:

        dissect_shim6_ct(pinfo, shim_tree, hf_shim6_ct, tvb, offset, "Responder Context Tag");

        offset += 6;

        proto_tree_add_item(shim_tree, hf_shim6_inonce, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

        break;

    case SHIM6_TYPE_R1BIS:

        dissect_shim6_ct(pinfo, shim_tree, hf_shim6_ct, tvb, offset, "Packet Context Tag");

        offset += 6;

        proto_tree_add_item(shim_tree, hf_shim6_rnonce, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

        break;

    case SHIM6_TYPE_I2BIS:

        dissect_shim6_ct(pinfo, shim_tree, hf_shim6_ct, tvb, offset, "Initiator Context Tag");

        offset += 6;

        proto_tree_add_item(shim_tree, hf_shim6_inonce, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

        proto_tree_add_item(shim_tree, hf_shim6_rnonce, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

        proto_tree_add_item(shim_tree, hf_shim6_reserved2, tvb, offset, 6, ENC_NA);

        offset += 6;

        dissect_shim6_ct(pinfo, shim_tree, hf_shim6_ct, tvb, offset, "Initiator Context Tag");

        offset += 6;

        break;

    case SHIM6_TYPE_UPD_REQ:

    case SHIM6_TYPE_UPD_ACK:

        dissect_shim6_ct(pinfo, shim_tree, hf_shim6_ct, tvb, offset, "Receiver Context Tag");

        offset += 6;

        proto_tree_add_item(shim_tree, hf_shim6_rnonce, tvb, offset, 4, ENC_BIG_ENDIAN);

        offset += 4;

        break;

    case SHIM6_TYPE_KEEPALIVE:

        dissect_shim6_ct(pinfo, shim_tree, hf_shim6_ct, tvb, offset, "Receiver Context Tag");

        offset += 6;

        proto_tree_add_item(shim_tree, hf_shim6_reserved2, tvb, offset, 4, ENC_NA);

        offset += 4;

        break;

    case SHIM6_TYPE_PROBE:

        dissect_shim6_ct(pinfo, shim_tree, hf_shim6_ct, tvb, offset, "Receiver Context Tag");

        offset += 6;

        tmp = tvb_get_uint8(tvb, offset);

        probes_sent = tmp & SHIM6_BITMASK_PSENT;

        probes_rcvd = (tmp & SHIM6_BITMASK_PRECVD) >> 4;

        proto_tree_add_item(shim_tree, hf_shim6_psent, tvb,

                            offset, 1, ENC_BIG_ENDIAN);

        proto_tree_add_item(shim_tree, hf_shim6_precvd, tvb,

                            offset, 1, ENC_BIG_ENDIAN);

        offset += 1;

        sta = val_to_str_const((tvb_get_uint8(tvb, offset) & SHIM6_BITMASK_STA) >> 6,

                               shimreapstates, "Unknown REAP State");

        proto_tree_add_uint_format_value(shim_tree, hf_shim6_reap, tvb,

                                         offset, 1, (tvb_get_uint8(tvb, offset) & SHIM6_BITMASK_STA) >> 6,

                                         "%s", sta);

        proto_tree_add_item(shim_tree, hf_shim6_reserved2, tvb, offset, 3, ENC_NA);

        offset += 3;

        /* Probes Sent */

        if (probes_sent) {

            dissect_shim6_probes(shim_tree, tvb, offset, "Probes Sent",

                                 probes_sent, false);

            offset += 40 * probes_sent;

        }

        /* Probes Received */

        if (probes_rcvd) {

            dissect_shim6_probes(shim_tree, tvb, offset, "Probes Received",

                                 probes_rcvd, true);

            offset += 40 * probes_rcvd;

        }

        break;

    default:

        break;

    }

    return offset;

}

/* Dissect SHIM6 data: payload, common part, options */

static const value_string shimctrlvals[] = {

    { SHIM6_TYPE_I1,        "I1" },

    { SHIM6_TYPE_R1,        "R1" },

    { SHIM6_TYPE_I2,        "I2" },

    { SHIM6_TYPE_R2,        "R2" },

    { SHIM6_TYPE_R1BIS,     "R1bis" },

    { SHIM6_TYPE_I2BIS,     "I2bis" },

    { SHIM6_TYPE_UPD_REQ,   "Update Request" },

    { SHIM6_TYPE_UPD_ACK,   "Update Acknowledgment" },

    { SHIM6_TYPE_KEEPALIVE, "Keepalive" },

    { SHIM6_TYPE_PROBE,     "Probe" },

    { 0, NULL }

};

static int

dissect_shim6(tvbuff_t *tvb, packet_info * pinfo, proto_tree *tree, void* data)

{

    struct ip6_shim  shim;

    int              offset = 0, len;

    proto_tree      *shim_tree, *root_tree;

    proto_item      *ti, *ti_len;

    uint8_t          tmp[5];

    tvbuff_t        *next_tvb;

    tvb_memcpy(tvb, (uint8_t *)&shim, offset, sizeof(shim));

    len = (shim.ip6s_len + 1) << 3;

    if (shim.ip6s_p & SHIM6_BITMASK_P) {

        col_append_sep_str(pinfo->cinfo, COL_INFO, " , ", "Shim6 (Payload)");

    }

    else {

        col_append_sep_fstr(pinfo->cinfo, COL_INFO, " , ", "Shim6 (%s)",

                        val_to_str_const(shim.ip6s_p & SHIM6_BITMASK_TYPE, shimctrlvals, "Unknown"));

    }

    root_tree = p_ipv6_pinfo_select_root(pinfo, tree);

    p_ipv6_pinfo_add_len(pinfo, len);

    ti = proto_tree_add_item(root_tree, proto_shim6, tvb, offset, len, ENC_NA);

    shim_tree = proto_item_add_subtree(ti, ett_shim6_proto);

    /* Next Header */

    proto_tree_add_uint_format_value(shim_tree, hf_shim6_nxt, tvb,

                                     offset, 1, shim.ip6s_nxt,

                                     "%s (%u)", ipprotostr(shim.ip6s_nxt), shim.ip6s_nxt);

    offset += 1;

    /* Header Extension Length */

    ti_len = proto_tree_add_item(shim_tree, hf_shim6_len, tvb, offset, 1, ENC_BIG_ENDIAN);

    ti = proto_tree_add_uint(shim_tree, hf_shim6_len_oct, tvb, offset, 1, len);

    proto_item_append_text(ti, " bytes");

    proto_item_set_generated(ti);

    proto_item_set_hidden(ti);

    proto_item_append_text(ti_len, " (%d bytes)", len);

    offset += 1;

    /* P Field */

    proto_tree_add_item(shim_tree, hf_shim6_p, tvb, offset, 1, ENC_BIG_ENDIAN);

    if (shim.ip6s_p & SHIM6_BITMASK_P) {

        tmp[0] = tvb_get_uint8(tvb, offset+1);

        tmp[1] = tvb_get_uint8(tvb, offset+2);

        tmp[2] = tvb_get_uint8(tvb, offset+3);

        tmp[3] = tvb_get_uint8(tvb, offset+4);

        tmp[4] = tvb_get_uint8(tvb, offset+5);

        /* Payload Extension Header */

        proto_tree_add_none_format(shim_tree, hf_shim6_ct, tvb,

                                   offset, 6,

                                   "Receiver Context Tag: %02x %02x %02x %02x %02x %02x",

                                   shim.ip6s_p & SHIM6_BITMASK_CT, tmp[0], tmp[1], tmp[2], tmp[3], tmp[4]);

    } else {

        /* Control Message */

        uint16_t csum;

        int advance;

        /* Message Type */

        proto_tree_add_item(shim_tree, hf_shim6_type, tvb, offset, 1, ENC_BIG_ENDIAN);

        /* Protocol bit (Must be zero for SHIM6) */

        proto_tree_add_item(shim_tree, hf_shim6_proto, tvb, offset, 1, ENC_BIG_ENDIAN);

        offset++;

        /* Checksum */

        csum = ip_checksum_tvb(tvb, 0, len);

        proto_tree_add_checksum(shim_tree, tvb, offset, hf_shim6_checksum, hf_shim6_checksum_status, &ei_shim6_checksum_bad, pinfo, csum,

                                ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_IN_CKSUM);

        if (csum != 0)

            col_append_str(pinfo->cinfo, COL_INFO, " [Shim6 CHECKSUM INCORRECT]");

        offset += 2;

        /* Type specific data */

        advance = dissect_shimctrl(pinfo, tvb, offset, shim.ip6s_p & SHIM6_BITMASK_TYPE, shim_tree);

        offset += advance;

        /* Options */

        while (offset < len) {

            offset += dissect_shimopts(tvb, offset, shim_tree, pinfo);

        }

    }

    next_tvb = tvb_new_subset_remaining(tvb, len);

    ipv6_dissect_next(shim.ip6s_nxt, next_tvb, pinfo, tree, (ws_ip6 *)data);

    return tvb_captured_length(tvb);

}

void

proto_register_shim6(void)

{

    static hf_register_info hf_shim6[] = {

        { &hf_shim6_nxt,

            { "Next Header", "shim6.nxt",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_len,

            { "Length", "shim6.len",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                "Extension header length in 8-octet words (minus 1)", HFILL }

        },

        { &hf_shim6_len_oct,

            { "Length", "shim6.len_oct",

                FT_UINT16, BASE_DEC, NULL, 0x0,

                "Extension header length in octets", HFILL }

        },

        { &hf_shim6_p,

            { "P Bit", "shim6.p",

                FT_BOOLEAN, 8, NULL, SHIM6_BITMASK_P,

                NULL, HFILL }

        },

        { &hf_shim6_ct,

            { "Context Tag", "shim6.ct",

                FT_NONE, BASE_NONE, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_type,

            { "Message Type", "shim6.type",

                FT_UINT8, BASE_DEC, VALS(shimctrlvals), SHIM6_BITMASK_TYPE,

                NULL, HFILL }

        },

        { &hf_shim6_proto,

            { "Protocol", "shim6.proto",

                FT_UINT8, BASE_DEC, VALS(shim6_protocol), SHIM6_BITMASK_PROTOCOL,

                NULL, HFILL }

        },

        { &hf_shim6_checksum,

            { "Checksum", "shim6.checksum",

                FT_UINT16, BASE_HEX, NULL, 0x0,

                "Shim6 Checksum", HFILL }

        },

        { &hf_shim6_checksum_status,

            { "Checksum Status", "shim6.checksum.status",

                FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_inonce,

            { "Initiator Nonce", "shim6.inonce",

                FT_UINT32, BASE_DEC_HEX, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_rnonce,

            { "Responder Nonce", "shim6.rnonce",

                FT_UINT32, BASE_DEC_HEX, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_reserved,

            { "Reserved", "shim6.reserved",

                FT_BYTES, BASE_NONE, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_reserved2,

            { "Reserved2", "shim6.reserved2",

                FT_BYTES, BASE_NONE, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_precvd,

            { "Probes Received", "shim6.precvd",

                FT_UINT8, BASE_DEC, NULL, SHIM6_BITMASK_PRECVD,

                NULL, HFILL }

        },

        { &hf_shim6_psent,

            { "Probes Sent", "shim6.psent",

                FT_UINT8, BASE_DEC, NULL, SHIM6_BITMASK_PSENT,

                NULL, HFILL }

        },

        { &hf_shim6_psrc,

            { "Source Address", "shim6.psrc",

                FT_IPv6, BASE_NONE, NULL, 0x0,

                "Shim6 Probe Source Address", HFILL }

        },

        { &hf_shim6_pdst,

            { "Destination Address", "shim6.pdst",

                FT_IPv6, BASE_NONE, NULL, 0x0,

                "Shim6 Probe Destination Address", HFILL }

        },

        { &hf_shim6_pnonce,

            { "Nonce", "shim6.pnonce",

                FT_UINT32, BASE_DEC_HEX, NULL, 0x0,

                "Shim6 Probe Nonce", HFILL }

        },

        { &hf_shim6_pdata,

            { "Data", "shim6.pdata",

                FT_UINT32, BASE_HEX, NULL, 0x0,

                "Shim6 Probe Data", HFILL }

        },

        { &hf_shim6_sulid,

            { "Sender ULID", "shim6.sulid",

                FT_IPv6, BASE_NONE, NULL, 0x0,

                "Shim6 Sender ULID", HFILL }

        },

        { &hf_shim6_rulid,

            { "Receiver ULID", "shim6.rulid",

                FT_IPv6, BASE_NONE, NULL, 0x0,

                "Shim6 Receiver ULID", HFILL }

        },

        { &hf_shim6_reap,

            { "REAP State", "shim6.reap",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_opt_type,

            { "Option Type", "shim6.opt.type",

                FT_UINT16, BASE_DEC, VALS(shimoptvals), SHIM6_BITMASK_OPT_TYPE,

                "Shim6 Option Type", HFILL }

        },

        { &hf_shim6_opt_critical,

            { "Option Critical Bit", "shim6.opt.critical",

                FT_BOOLEAN, 8, TFS(&tfs_yes_no), SHIM6_BITMASK_CRITICAL,

                "true: option is critical, false: option is not critical", HFILL }

        },

        { &hf_shim6_opt_len,

            { "Content Length", "shim6.opt.len",

                FT_UINT16, BASE_DEC, NULL, 0x0,

                "Content Length Option", HFILL }

        },

        { &hf_shim6_opt_total_len,

            { "Total Length", "shim6.opt.total_len",

                FT_UINT16, BASE_DEC, NULL, 0x0,

                "Total Option Length", HFILL }

        },

        { &hf_shim6_opt_loc_verif_methods,

            { "Verification Method", "shim6.opt.verif_method",

                FT_UINT8, BASE_DEC, VALS(shimverifmethods), 0x0,

                "Locator Verification Method", HFILL }

        },

        { &hf_shim6_opt_loclist,

            { "Locator List Generation", "shim6.opt.loclist",

                FT_UINT32, BASE_DEC_HEX, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_locator,

            { "Locator", "shim6.locator",

                FT_IPv6, BASE_NONE, NULL, 0x0,

                "Shim6 Locator", HFILL }

        },

        { &hf_shim6_opt_locnum,

            { "Num Locators", "shim6.opt.locnum",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                "Number of locators in Locator List", HFILL }

        },

        { &hf_shim6_opt_elemlen,

            { "Element Length", "shim6.opt.elemlen",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                "Length of Elements in Locator Preferences Option", HFILL }

        },

        { &hf_shim6_loc_flag,

            { "Flags", "shim6.loc.flags",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                "Locator Preferences Flags", HFILL }

        },

        { &hf_shim6_loc_prio,

            { "Priority", "shim6.loc.prio",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                "Locator Preferences Priority", HFILL }

        },

        { &hf_shim6_loc_weight,

            { "Weight", "shim6.loc.weight",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                "Locator Preferences Weight", HFILL }

        },

        { &hf_shim6_opt_fii,

            { "Forked Instance Identifier", "shim6.opt.fii",

                FT_UINT32, BASE_DEC_HEX, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_validator,

            { "Validator", "shim6.validator",

                FT_BYTES, BASE_NONE, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_cga_parameter_data_structure,

            { "CGA Parameter Data Structure", "shim6.cga_parameter_data_structure",

                FT_BYTES, BASE_NONE, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_cga_signature,

            { "CGA Signature", "shim6.cga_signature",

                FT_BYTES, BASE_NONE, NULL, 0x0,

                NULL, HFILL }

        },

        { &hf_shim6_padding,

            { "Padding", "shim6.padding",

                FT_BYTES, BASE_NONE, NULL, 0x0,

                NULL, HFILL }

        }

    };

    static int *ett_shim6[] = {

        &ett_shim6_proto,

        &ett_shim6_option,

        &ett_shim6_locators,

        &ett_shim6_verif_methods,

        &ett_shim6_loc_pref,

        &ett_shim6_probes_sent,

        &ett_shim6_probes_rcvd,

        &ett_shim6_probe_sent,

        &ett_shim6_probe_rcvd,

        &ett_shim6_cksum

    };

    static ei_register_info ei_shim6[] = {

        { &ei_shim6_opt_elemlen_invalid,

            { "shim6.opt.elemlen.invalid", PI_MALFORMED, PI_ERROR,

                "Invalid element length", EXPFILL }

        },

        { &ei_shim6_checksum_bad,

            { "shim6.checksum_bad.expert", PI_CHECKSUM, PI_ERROR,

                "Bad checksum", EXPFILL }

        }

    };

    expert_module_t* expert_shim6;

    proto_shim6 = proto_register_protocol("Shim6 Protocol", "Shim6", "shim6");

    proto_register_field_array(proto_shim6, hf_shim6, array_length(hf_shim6));

    proto_register_subtree_array(ett_shim6, array_length(ett_shim6));

    expert_shim6 = expert_register_protocol(proto_shim6);

    expert_register_field_array(expert_shim6, ei_shim6, array_length(ei_shim6));

    shim6_handle = register_dissector("shim6", dissect_shim6, proto_shim6);

}

void

proto_reg_handoff_shim6(void)

{

    dissector_add_uint("ip.proto", IP_PROTO_SHIM6, shim6_handle);

}

/*

 * 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:

 */