/* packet-pim.c
 * Routines for PIM disassembly
 * (c) Copyright Jun-ichiro itojun Hagino <itojun@itojun.org>
 *
 * $Id: packet-pim.c 32735 2010-05-10 15:54:57Z wmeier $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <stddef.h>  /* For offsetof */
#include <glib.h>

#include <epan/packet.h>
#include <epan/ipproto.h>
#include <epan/afn.h>
#include "packet-ipv6.h"
#include <epan/in_cksum.h>
#include "packet-pim.h"

#define PIM_TYPE(x)     ((x) & 0x0f)
#define PIM_VER(x)      (((x) & 0xf0) >> 4)

enum pimv2_addrtype {
    pimv2_unicast, pimv2_group, pimv2_source
};

static int proto_pim = -1;
static int hf_pim_version = -1;
static int hf_pim_type = -1;
static int hf_pim_code = -1;
static int hf_pim_cksum = -1;
static int hf_pim_res_bytes = -1;

static gint ett_pim = -1;

static dissector_handle_t ip_handle;
static dissector_handle_t ipv6_handle;

/*
 * For PIM v1, see
 *
 *      ftp://ftp.usc.edu/pub/csinfo/tech-reports/papers/95-599.ps.Z
 */
static const char *
dissect_pimv1_addr(tvbuff_t *tvb, int offset) {
    guint16 flags_masklen;

    flags_masklen = tvb_get_ntohs(tvb, offset);
    if (flags_masklen & 0x0180) {
        return ep_strdup_printf("(%s%s%s) ",
                                flags_masklen & 0x0100 ? "S" : "",
                                flags_masklen & 0x0080 ? "W" : "",
                                flags_masklen & 0x0040 ? "R" : "");
    } else {
        return ep_strdup_printf("%s/%u",
                                ip_to_str(tvb_get_ptr(tvb, offset + 2, 4)), flags_masklen & 0x3f);
    }
}

static const value_string type1vals[] = {
    { 0, "Query" },
    { 1, "Register" },
    { 2, "Register-stop" },
    { 3, "Join/Prune" },
    { 4, "RP-Reachable" },
    { 5, "Assert" },
    { 6, "Graft" },
    { 7, "Graft-Ack" },
    { 8, "Mode" },
    { 0, NULL },
};

/* This function is only called from the IGMP dissector */
int
dissect_pimv1(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
              int offset) {
    guint8 pim_type;
    guint8 pim_ver;
    guint length, pim_length;
    guint16 pim_cksum, computed_cksum;
    vec_t cksum_vec[1];
    proto_tree *pim_tree = NULL;
    proto_item *ti;
    proto_tree *pimopt_tree = NULL;
    proto_item *tiopt;

    if (!proto_is_protocol_enabled(find_protocol_by_id(proto_pim))) {
        /*
         * We are not enabled; skip entire packet to be nice to the
         * IGMP layer (so clicking on IGMP will display the data).
         */
        return offset+tvb_length_remaining(tvb, offset);
    }

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "PIMv1");
    col_clear(pinfo->cinfo, COL_INFO);

    ti = proto_tree_add_item(tree, proto_pim, tvb, offset, -1, FALSE);
    pim_tree = proto_item_add_subtree(ti, ett_pim);

    /* Put IGMP type, 0x14, into the tree */
    proto_tree_add_text(pim_tree, tvb, offset, 1,
                        "Type: PIM (0x14)");
    offset += 1;

    pim_type = tvb_get_guint8(tvb, offset);
    if (check_col(pinfo->cinfo, COL_INFO))
        col_add_str(pinfo->cinfo, COL_INFO,
                    val_to_str(pim_type, type1vals, "Unknown (%u)"));

    proto_tree_add_uint(pim_tree, hf_pim_code, tvb, offset, 1, pim_type);
    offset += 1;

    pim_cksum = tvb_get_ntohs(tvb, offset);
    pim_ver = PIM_VER(tvb_get_guint8(tvb, offset + 2));
    if (pim_ver != 1) {
        /*
         * Not PIMv1 - what gives?
         */
        proto_tree_add_uint(pim_tree, hf_pim_cksum, tvb,
                            offset, 2, pim_cksum);

        offset += 2;
        proto_tree_add_item(pim_tree, hf_pim_version, tvb, offset, 1, FALSE);
        return offset+tvb_length_remaining(tvb, offset);
    }

    /*
     * Well, it's PIM v1, so we can check whether this is a
     * Register message, and thus can figure out how much to
     * checksum and whether to make the columns read-only.
     */
    length = tvb_length(tvb);
    if (pim_type == 1) {
        /*
         * Register message - the PIM header is 8 bytes long.
         * Also set the columns non-writable. Otherwise the IPv4 or
         * IPv6 dissector for the encapsulated packet that caused
         * this register will overwrite the PIM info in the columns.
         */
        pim_length = 8;
        col_set_writable(pinfo->cinfo, FALSE);
    } else {
        /*
         * Other message - checksum the entire packet.
         */
        pim_length = tvb_reported_length(tvb);
    }

    if (!pinfo->fragmented && length >= pim_length) {
        /*
         * The packet isn't part of a fragmented datagram and isn't
         * truncated, so we can checksum it.
         */
        cksum_vec[0].ptr = tvb_get_ptr(tvb, 0, pim_length);
        cksum_vec[0].len = pim_length;
        computed_cksum = in_cksum(&cksum_vec[0], 1);
        if (computed_cksum == 0) {
            proto_tree_add_uint_format(pim_tree, hf_pim_cksum, tvb,
                                       offset, 2, pim_cksum,
                                       "Checksum: 0x%04x [correct]",
                                       pim_cksum);
        } else {
            proto_tree_add_uint_format(pim_tree, hf_pim_cksum, tvb,
                                       offset, 2, pim_cksum,
                                       "Checksum: 0x%04x [incorrect, should be 0x%04x]",
                                       pim_cksum, in_cksum_shouldbe(pim_cksum, computed_cksum));
        }
    } else {
        proto_tree_add_uint(pim_tree, hf_pim_cksum, tvb,
                            offset, 2, pim_cksum);
    }
    offset += 2;

    proto_tree_add_item(pim_tree, hf_pim_version, tvb, offset, 1, FALSE);
    offset += 1;

    offset += 3;        /* skip reserved stuff */

    if (tvb_reported_length_remaining(tvb, offset) > 0) {
        tiopt = proto_tree_add_text(pim_tree, tvb, offset, -1,
                                    "PIM parameters");
        pimopt_tree = proto_item_add_subtree(tiopt, ett_pim);
    } else
        goto done;

    /* version 1 decoder */
    switch (pim_type) {
    case 0:     /* query */
    {
        guint8 mode;
        guint16 holdtime;
        static const value_string pimv1_modevals[] = {
            { 0, "Dense" },
            { 1, "Sparse" },
            { 2, "Sparse-Dense" },
            { 0, NULL },
        };

        mode = tvb_get_guint8(tvb, offset) >> 4;
        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "Mode: %s",
                            val_to_str(mode, pimv1_modevals, "Unknown (%u)"));
        offset += 2;
        holdtime = tvb_get_ntohs(tvb, offset);
        proto_tree_add_text(pimopt_tree, tvb, offset, 2,
                            "Holdtime: %u%s", holdtime,
                            holdtime == 0xffff ? " (infty)" : "");
        offset += 2;
        break;
    }

    case 1:     /* register */
    {
        guint8 v_hl;
        tvbuff_t *next_tvb;

        /*
         * The rest of the packet is a multicast data packet.
         */
        next_tvb = tvb_new_subset_remaining(tvb, offset);

        /*
         * It's an IP packet - determine whether it's IPv4 or IPv6.
         */
        v_hl = tvb_get_guint8(tvb, offset);
        switch((v_hl & 0xf0) >> 4) {
        case 0:     /* Null-Register dummy header.
                     * Has the same address family as the encapsulating PIM packet,
                     * e.g. an IPv6 data packet is encapsulated in IPv6 PIM packet.
                     */
            if (pinfo->src.type == AT_IPv4) {
                proto_tree_add_text(pimopt_tree, tvb, offset, -1,
                                    "IPv4 dummy header");
                proto_tree_add_text(pimopt_tree, tvb, offset + 12, 4,
                                    "Source: %s",
                                    ip_to_str(tvb_get_ptr(tvb, offset + 12, 4)));
                proto_tree_add_text(pimopt_tree, tvb, offset + 16, 4,
                                    "Group: %s",
                                    ip_to_str(tvb_get_ptr(tvb, offset + 16, 4)));
            } else if (pinfo->src.type == AT_IPv6) {
                struct ip6_hdr ip6_hdr;
                tvb_memcpy(tvb, (guint8 *)&ip6_hdr, offset,
                           sizeof ip6_hdr);
                proto_tree_add_text(pimopt_tree, tvb, offset, -1,
                                    "IPv6 dummy header");
                proto_tree_add_text(pimopt_tree, tvb,
                                    offset + offsetof(struct ip6_hdr, ip6_src), 16,
                                    "Source: %s",
                                    ip6_to_str(&ip6_hdr.ip6_src));
                proto_tree_add_text(pimopt_tree, tvb,
                                    offset + offsetof(struct ip6_hdr, ip6_dst), 16,
                                    "Group: %s",
                                    ip6_to_str(&ip6_hdr.ip6_dst));
            } else
                proto_tree_add_text(pimopt_tree, tvb, offset, -1,
                                    "Dummy header for an unknown protocol");
            break;
        case 4: /* IPv4 */
#if 0
            call_dissector(ip_handle, next_tvb, pinfo, tree);
#else
            call_dissector(ip_handle, next_tvb, pinfo, pimopt_tree);
#endif
            break;
        case 6: /* IPv6 */
#if 0
            call_dissector(ipv6_handle, next_tvb, pinfo, tree);
#else
            call_dissector(ipv6_handle, next_tvb, pinfo, pimopt_tree);
#endif
            break;
        default:
            proto_tree_add_text(pimopt_tree, tvb, offset, -1,
                                "Unknown IP version %d", (v_hl & 0xf0) >> 4);
            break;
        }
        break;
    }

    case 2:     /* register-stop */
    {
        proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                            "Group: %s",
                            ip_to_str(tvb_get_ptr(tvb, offset, 4)));
        offset += 4;
        proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                            "Source: %s",
                            ip_to_str(tvb_get_ptr(tvb, offset, 4)));
        offset += 4;
        break;
    }

    case 3:     /* join/prune */
    case 6:     /* graft */
    case 7:     /* graft-ack */
    {
        int off;
        const char *s;
        int ngroup, i, njoin, nprune, j;
        guint16 holdtime;
        guint8 mask_len;
        guint8 adr_len;
        proto_tree *grouptree = NULL;
        proto_item *tigroup;
        proto_tree *subtree = NULL;
        proto_item *tisub;

        proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                            "Upstream-neighbor: %s",
                            ip_to_str(tvb_get_ptr(tvb, offset, 4)));
        offset += 4;

        offset += 2;    /* skip reserved stuff */

        holdtime = tvb_get_ntohs(tvb, offset);
        proto_tree_add_text(pimopt_tree, tvb, offset, 2,
                            "Holdtime: %u%s", holdtime,
                            holdtime == 0xffff ? " (infty)" : "");
        offset += 2;

        offset += 1;    /* skip reserved stuff */

        mask_len = tvb_get_guint8(tvb, offset);
        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "Mask length: %u", mask_len);
        offset += 1;

        adr_len = tvb_get_guint8(tvb, offset);
        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "Address length: %u", adr_len);
        offset += 1;

        ngroup = tvb_get_guint8(tvb, offset);
        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "Groups: %u", ngroup);
        offset += 1;

        for (i = 0; i < ngroup; i++) {
            /*
             * XXX - does the group address have the length "adr_len"
             * and the group mask the length "mask_len"?
             */
            tigroup = proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                                          "Group %d: %s", i,
                                          ip_to_str(tvb_get_ptr(tvb, offset, 4)));
            grouptree = proto_item_add_subtree(tigroup, ett_pim);
            offset += 4;

            proto_tree_add_text(grouptree, tvb, offset, 4,
                                "Group %d Mask: %s", i,
                                ip_to_str(tvb_get_ptr(tvb, offset, 4)));
            offset += 4;

            njoin = tvb_get_ntohs(tvb, offset);
            nprune = tvb_get_ntohs(tvb, offset + 2);

            tisub = proto_tree_add_text(grouptree, tvb, offset, 2,
                                        "Join: %d", njoin);
            subtree = proto_item_add_subtree(tisub, ett_pim);
            off = offset + 4;
            for (j = 0; j < njoin; j++) {
                s = dissect_pimv1_addr(tvb, off);
                proto_tree_add_text(subtree, tvb, off, 6,
                                    "IP address: %s", s);
                off += 6;
            }

            tisub = proto_tree_add_text(grouptree, tvb, offset + 2, 2,
                                        "Prune: %d", nprune);
            subtree = proto_item_add_subtree(tisub, ett_pim);
            for (j = 0; j < nprune; j++) {
                s = dissect_pimv1_addr(tvb, off);
                proto_tree_add_text(subtree, tvb, off, 6,
                                    "IP address: %s", s);
                off += 6;
            }
            offset = off;
        }
        break;
    }

    case 4:     /* rp-reachability */
    {
        guint16 holdtime;

        proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                            "Group Address: %s",
                            ip_to_str(tvb_get_ptr(tvb, offset, 4)));
        offset += 4;

        proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                            "Group Mask: %s",
                            ip_to_str(tvb_get_ptr(tvb, offset, 4)));
        offset += 4;

        proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                            "RP Address: %s",
                            ip_to_str(tvb_get_ptr(tvb, offset, 4)));
        offset += 4;

        offset += 2;    /* skip reserved stuff */

        holdtime = tvb_get_ntohs(tvb, offset);
        proto_tree_add_text(pimopt_tree, tvb, offset, 2,
                            "Holdtime: %u%s", holdtime,
                            holdtime == 0xffff ? " (infty)" : "");
        offset += 2;
        break;
    }

    case 5:     /* assert */
    {
        proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                            "Group Address: %s",
                            ip_to_str(tvb_get_ptr(tvb, offset, 4)));
        offset += 4;

        proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                            "Group Mask: %s",
                            ip_to_str(tvb_get_ptr(tvb, offset, 4)));
        offset += 4;

        proto_tree_add_text(pimopt_tree, tvb, offset, 1, "%s",
                            decode_boolean_bitfield(tvb_get_guint8(tvb, offset), 0x80, 8,
                                                    "RP Tree", "Not RP Tree"));
        proto_tree_add_text(pimopt_tree, tvb, offset, 4, "Preference: %u",
                            tvb_get_ntohl(tvb, offset) & 0x7fffffff);
        offset += 4;

        proto_tree_add_text(pimopt_tree, tvb, offset, 4, "Metric: %u",
                            tvb_get_ntohl(tvb, offset));

        break;
    }

    default:
        break;
    }
done:;

    return offset+tvb_length_remaining(tvb, offset);
}

static const char *
dissect_pim_addr(tvbuff_t *tvb, int offset, enum pimv2_addrtype at,
                 int *advance) {
    emem_strbuf_t *strbuf;
    guint8 af;
    guint8 et;
    guint8 flags;
    guint8 mask_len;
    int len = 0;

    af = tvb_get_guint8(tvb, offset);
    if (af != AFNUM_INET && af != AFNUM_INET6) {
        /*
         * We don't handle the other formats, and addresses don't include
         * a length field, so we can't even show them as raw bytes.
         */
        return NULL;
    }

    et = tvb_get_guint8(tvb, offset + 1);
    if (et != 0) {
        /*
         * The only defined encoding type is 0, for the native encoding;
         * again, as addresses don't include a length field, we can't
         * even show addresses with a different encoding type as raw
         * bytes.
         */
        return NULL;
    }

    strbuf = ep_strbuf_new_label(NULL);
    switch (at) {
    case pimv2_unicast:
        switch (af) {
        case AFNUM_INET:
            len = 4;
            ep_strbuf_printf(strbuf, "%s", ip_to_str(tvb_get_ptr(tvb, offset + 2, len)));
            break;

        case AFNUM_INET6:
            len = 16;
            ep_strbuf_printf(strbuf, "%s", ip6_to_str((const struct e_in6_addr *)tvb_get_ptr(tvb, offset + 2, len)));
            break;
        }
        if (advance)
            *advance = 2 + len;
        break;

    case pimv2_group:
        mask_len = tvb_get_guint8(tvb, offset + 3);
        switch (af) {
        case AFNUM_INET:
            len = 4;
            ep_strbuf_printf(strbuf, "%s/%u",
                             ip_to_str(tvb_get_ptr(tvb, offset + 4, len)), mask_len);
            break;

        case AFNUM_INET6:
            len = 16;
            ep_strbuf_printf(strbuf, "%s/%u",
                             ip6_to_str((const struct e_in6_addr *)tvb_get_ptr(tvb, offset + 4, len)), mask_len);
            break;
        }
        if (advance)
            *advance = 4 + len;
        break;

    case pimv2_source:
        flags = tvb_get_guint8(tvb, offset + 2);
        mask_len = tvb_get_guint8(tvb, offset + 3);
        switch (af) {
        case AFNUM_INET:
            len = 4;
            ep_strbuf_printf(strbuf, "%s/%u",
                             ip_to_str(tvb_get_ptr(tvb, offset + 4, len)), mask_len);
            break;

        case AFNUM_INET6:
            len = 16;
            ep_strbuf_printf(strbuf, "%s/%u",
                             ip6_to_str((const struct e_in6_addr *)tvb_get_ptr(tvb, offset + 4, len)), mask_len);
            break;
        }
        if (flags) {
            ep_strbuf_append_printf(strbuf,
                                    " (%s%s%s)",
                                    flags & 0x04 ? "S" : "",
                                    flags & 0x02 ? "W" : "",
                                    flags & 0x01 ? "R" : "");
        }
        if (advance)
            *advance = 4 + len;
        break;
    default:
        return NULL;
    }

    return strbuf->str;
}

static const value_string type2vals[] = {
    { 0, "Hello" },
    { 1, "Register" },
    { 2, "Register-stop" },
    { 3, "Join/Prune" },
    { 4, "Bootstrap" },
    { 5, "Assert" },
    { 6, "Graft" },
    { 7, "Graft-Ack" },
    { 8, "Candidate-RP-Advertisement" },
    { 9, "State-Refresh" },
    { 0, NULL }
};

/*
 * For PIM v2, see RFC 4601, RFC 3973 and draft-ietf-pim-sm-v2-new-03
 * (when PIM is run over IPv6, the rules for computing the PIM checksum
 * from the draft in question, not from RFC 2362, should be used).
 */
static void
dissect_pim(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) {
    int offset = 0;
    guint8 pim_typever;
    guint length, pim_length;
    guint16 pim_cksum, computed_cksum;
    vec_t cksum_vec[4];
    guint32 phdr[2];
    const char *typestr;
    proto_tree *pim_tree = NULL;
    proto_item *ti;
    proto_tree *pimopt_tree = NULL;
    proto_item *tiopt;

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "PIM");
    col_clear(pinfo->cinfo, COL_INFO);

    pim_typever = tvb_get_guint8(tvb, 0);

    switch (PIM_VER(pim_typever)) {
    case 2:
        typestr = val_to_str(PIM_TYPE(pim_typever), type2vals, "Unknown (%u)");
        break;
    case 1:     /* PIMv1 - we should never see this */
    default:
        typestr = "Unknown";
        break;
    }

    if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
        col_add_fstr(pinfo->cinfo, COL_PROTOCOL, "PIMv%d",
                     PIM_VER(pim_typever));
    }
    if (check_col(pinfo->cinfo, COL_INFO))
        col_add_str(pinfo->cinfo, COL_INFO, typestr);

    ti = proto_tree_add_item(tree, proto_pim, tvb, offset, -1, FALSE);
    pim_tree = proto_item_add_subtree(ti, ett_pim);

    proto_tree_add_item(pim_tree, hf_pim_version, tvb, offset, 1, FALSE);
    proto_tree_add_item(pim_tree, hf_pim_type, tvb, offset, 1, FALSE);
    proto_tree_add_item(pim_tree, hf_pim_res_bytes, tvb, offset + 1, 1, FALSE);
    pim_cksum = tvb_get_ntohs(tvb, offset + 2);
    length = tvb_length(tvb);
    if (PIM_VER(pim_typever) == 2) {
        /*
         * Well, it's PIM v2, so we can check whether this is a Register
         * message, and thus can figure out how much to checksum and
         * whether to make the columns read-only.
         */
        if (PIM_TYPE(pim_typever) == 1) {
            /*
             * Register message - the PIM header is 8 bytes long.
             * Also set the columns non-writable. Otherwise the IPv4 or
             * IPv6 dissector for the encapsulated packet that caused
             * this register will overwrite the PIM info in the columns.
             */
            pim_length = 8;
            col_set_writable(pinfo->cinfo, FALSE);
        } else {
            /*
             * Other message - checksum the entire packet.
             */
            pim_length = tvb_reported_length(tvb);
        }
    } else {
        /*
         * We don't know what type of message this is, so say that
         * the length is 0, to force it not to be checksummed.
         */
        pim_length = 0;
    }
    if (!pinfo->fragmented && length >= pim_length) {
        /*
         * The packet isn't part of a fragmented datagram and isn't
         * truncated, so we can checksum it.
         */

        switch (pinfo->src.type) {
        case AT_IPv4:
            cksum_vec[0].ptr = tvb_get_ptr(tvb, 0, pim_length);
            cksum_vec[0].len = pim_length;
            computed_cksum = in_cksum(&cksum_vec[0], 1);
            break;
        case AT_IPv6:
            /* Set up the fields of the pseudo-header. */
            cksum_vec[0].ptr = pinfo->src.data;
            cksum_vec[0].len = pinfo->src.len;
            cksum_vec[1].ptr = pinfo->dst.data;
            cksum_vec[1].len = pinfo->dst.len;
            cksum_vec[2].ptr = (const guint8 *)&phdr;
            phdr[0] = g_htonl(pim_length);
            phdr[1] = g_htonl(IP_PROTO_PIM);
            cksum_vec[2].len = 8;
            cksum_vec[3].ptr = tvb_get_ptr(tvb, 0, pim_length);
            cksum_vec[3].len = pim_length;
            computed_cksum = in_cksum(&cksum_vec[0], 4);
            break;
        default:
            /* PIM is available for IPv4 and IPv6 right now */
            computed_cksum = 0; /* squelch GCC complaints */
            DISSECTOR_ASSERT_NOT_REACHED();
            break;
        }

        if (computed_cksum == 0) {
            proto_tree_add_uint_format(pim_tree, hf_pim_cksum, tvb,
                                       offset + 2, 2, pim_cksum,
                                       "Checksum: 0x%04x [correct]",
                                       pim_cksum);
        } else {
            proto_tree_add_uint_format(pim_tree, hf_pim_cksum, tvb,
                                       offset + 2, 2, pim_cksum,
                                       "Checksum: 0x%04x [incorrect, should be 0x%04x]",
                                       pim_cksum, in_cksum_shouldbe(pim_cksum, computed_cksum));
        }
    } else {
        proto_tree_add_uint(pim_tree, hf_pim_cksum, tvb,
                            offset + 2, 2, pim_cksum);
    }

    offset += 4;

    if (tvb_reported_length_remaining(tvb, offset) > 0) {
        tiopt = proto_tree_add_text(pim_tree, tvb, offset, -1,
                                    "PIM parameters");
        pimopt_tree = proto_item_add_subtree(tiopt, ett_pim);
    } else
        goto done;

    if (PIM_VER(pim_typever) != 2)
        goto done;

    /* version 2 decoder */
    switch (PIM_TYPE(pim_typever)) {
    case 0:     /*hello*/
    {
        while (tvb_reported_length_remaining(tvb, offset) >= 2) {
            guint16 hello_opt, opt_len;
            guint16 holdtime;
            guint16 lan_delay;
            guint16 override_interval;
            guint32 priority;
            guint32 opt_value = 0;

            hello_opt = tvb_get_ntohs(tvb, offset);
            opt_len = tvb_get_ntohs(tvb, offset + 2);

            if(opt_len == 2)
                opt_value = tvb_get_ntohs(tvb, offset + 4);
            if(opt_len == 4)
                opt_value = tvb_get_ntohl(tvb, offset + 4);

            switch(hello_opt) {
            case 1: /* holdtime */
                holdtime = opt_value;
                proto_tree_add_text(pimopt_tree, tvb, offset, 4 + opt_len,
                                    "Holdtime (%u): %us %s", hello_opt, holdtime,
                                    holdtime == 0xffff ? " (infty)" : "");
                break;
            case 2: /* LAN prune delay
                     *
                     * 0                   1                   2                   3
                     * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                     * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     * |            Type = 2           |           Length = 4          |
                     * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     * |T|       LAN Prune Delay       |       Override Interval       |
                     * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     */
            {
                proto_tree *sub_tree = NULL;
                proto_item *landelay_option;

                landelay_option = proto_tree_add_text(pimopt_tree, tvb, offset, 4 + opt_len,
                                                      "LAN Prune Delay (%u)", hello_opt);
                sub_tree = proto_item_add_subtree(landelay_option, ett_pim);

                lan_delay = (opt_value & 0x7fff0000) >> 16;
                override_interval = opt_value & 0x0000ffff;
                proto_tree_add_text(sub_tree, tvb, offset + 4, 1,
                                    "T bit is %s",
                                    (opt_value & 0x80000000) ? "set" : "not set");
                proto_tree_add_text(sub_tree, tvb, offset + 4, 2,
                                    "LAN Delay: %ums", lan_delay);
                proto_tree_add_text(sub_tree, tvb, offset + 6, 2,
                                    "Override Interval: %ums", override_interval);
                break;
            }
            case 19: /* priority */
                priority = opt_value;
                proto_tree_add_text(pimopt_tree, tvb, offset, 4 + opt_len,
                                    "DR Priority (%u): %u", hello_opt, priority);
                break;
            case 20: /* generation ID */
                proto_tree_add_text(pimopt_tree, tvb, offset, 4 + opt_len,
                                    "Generation ID (%u): %d", hello_opt, opt_value);
                break;

            case 24: /* address list */
            case 65001: /* address list (old implementations) */
            {
                int i;
                proto_tree *sub_tree = NULL;
                proto_item *addrlist_option;

                addrlist_option = proto_tree_add_text(pimopt_tree, tvb, offset, 4 + opt_len,
                                                      "%sAddress List (%u)",
                                                      hello_opt == 65001 ? "old " : "",
                                                      hello_opt);
                sub_tree = proto_item_add_subtree(addrlist_option, ett_pim);

                for (i = offset + 4; i < offset + 4 + opt_len; ) {
                    int advance;
                    const char *s;

                    s = dissect_pim_addr(tvb, i, pimv2_unicast, &advance);
                    if (s == NULL)
                        break;
                    proto_tree_add_text(sub_tree, tvb, offset, 
                                        advance, "Address: %s", s);
                    i += advance;
                }
                break;
            }
            default:
                proto_tree_add_text(pimopt_tree, tvb, offset, 4 + opt_len,
                                    "Unknown option (%u), length: %u, value: 0x%x",
                                    hello_opt, opt_len, opt_value);
                break;
            }
            offset += 4 + opt_len;
        }
        break;
    }

    case 1:     /* register */
    {
        guint32 flags;
        guint8 v_hl;
        tvbuff_t *next_tvb;
        proto_tree *flag_tree = NULL;
        proto_item *tiflag;

        flags = tvb_get_ntohl(tvb, offset);
        tiflag = proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                                     "Flags: 0x%08x", flags);
        flag_tree = proto_item_add_subtree(tiflag, ett_pim);
        proto_tree_add_text(flag_tree, tvb, offset, 1, "%s",
                            decode_boolean_bitfield(flags, 0x80000000, 32,
                                                    "Border", "Not border"));
        proto_tree_add_text(flag_tree, tvb, offset, 1, "%s",
                            decode_boolean_bitfield(flags, 0x40000000, 32,
                                                    "Null-Register", "Not Null-Register"));
        offset += 4;

        /*
         * The rest of the packet is a multicast data packet.
         */
        next_tvb = tvb_new_subset_remaining(tvb, offset);

        /*
         * It's an IP packet - determine whether it's IPv4 or IPv6.
         */
        v_hl = tvb_get_guint8(tvb, offset);
        switch((v_hl & 0xf0) >> 4) {
        case 0:     /* Null-Register dummy header.
                     * Has the same address family as the encapsulating PIM packet,
                     * e.g. an IPv6 data packet is encapsulated in IPv6 PIM packet.
                     */
            if (pinfo->src.type == AT_IPv4) {
                proto_tree_add_text(pimopt_tree, tvb, offset, -1,
                                    "IPv4 dummy header");
                proto_tree_add_text(pimopt_tree, tvb, offset + 12, 4,
                                    "Source: %s",
                                    ip_to_str(tvb_get_ptr(tvb, offset + 12, 4)));
                proto_tree_add_text(pimopt_tree, tvb, offset + 16, 4,
                                    "Group: %s",
                                    ip_to_str(tvb_get_ptr(tvb, offset + 16, 4)));
            } else if (pinfo->src.type == AT_IPv6) {
                struct ip6_hdr ip6_hdr;
                tvb_memcpy(tvb, (guint8 *)&ip6_hdr, offset,
                           sizeof ip6_hdr);
                proto_tree_add_text(pimopt_tree, tvb, offset, -1,
                                    "IPv6 dummy header");
                proto_tree_add_text(pimopt_tree, tvb,
                                    offset + offsetof(struct ip6_hdr, ip6_src), 16,
                                    "Source: %s",
                                    ip6_to_str(&ip6_hdr.ip6_src));
                proto_tree_add_text(pimopt_tree, tvb,
                                    offset + offsetof(struct ip6_hdr, ip6_dst), 16,
                                    "Group: %s",
                                    ip6_to_str(&ip6_hdr.ip6_dst));
            } else
                proto_tree_add_text(pimopt_tree, tvb, offset, -1,
                                    "Dummy header for an unknown protocol");
            break;
        case 4: /* IPv4 */
#if 0
            call_dissector(ip_handle, next_tvb, pinfo, tree);
#else
            call_dissector(ip_handle, next_tvb, pinfo, pimopt_tree);
#endif
            break;
        case 6: /* IPv6 */
#if 0
            call_dissector(ipv6_handle, next_tvb, pinfo, tree);
#else
            call_dissector(ipv6_handle, next_tvb, pinfo, pimopt_tree);
#endif
            break;
        default:
            proto_tree_add_text(pimopt_tree, tvb, offset, -1,
                                "Unknown IP version %d", (v_hl & 0xf0) >> 4);
            break;
        }
        break;
    }

    case 2:     /* register-stop */
    {
        int advance;
        const char *s;

        s = dissect_pim_addr(tvb, offset, pimv2_group, &advance);
        if (s == NULL)
            break;
        proto_tree_add_text(pimopt_tree, tvb, offset, advance, "Group: %s", s);
        offset += advance;
        s = dissect_pim_addr(tvb, offset, pimv2_unicast, &advance);
        if (s == NULL)
            break;
        proto_tree_add_text(pimopt_tree, tvb, offset, advance, "Source: %s", s);
        break;
    }

    case 3:     /* join/prune */
    case 6:     /* graft */
    case 7:     /* graft-ack */
    {
        int advance;
        int off;
        const char *s;
        int ngroup, i, njoin, nprune, j;
        guint16 holdtime;
        proto_tree *grouptree = NULL;
        proto_item *tigroup;
        proto_tree *subtree = NULL;
        proto_item *tisub;

        s = dissect_pim_addr(tvb, offset, pimv2_unicast, &advance);
        if (s == NULL)
            break;
        proto_tree_add_text(pimopt_tree, tvb, offset, advance,
                            "Upstream-neighbor: %s", s);
        offset += advance;

        offset += 1;    /* skip reserved field */

        ngroup = tvb_get_guint8(tvb, offset);
        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "Groups: %u", ngroup);
        offset += 1;

        holdtime = tvb_get_ntohs(tvb, offset);
        proto_tree_add_text(pimopt_tree, tvb, offset, 2,
                            "Holdtime: %u%s", holdtime,
                            holdtime == 0xffff ? " (infty)" : "");

        offset += 2;

        for (i = 0; i < ngroup; i++) {
            s = dissect_pim_addr(tvb, offset, pimv2_group, &advance);
            if (s == NULL)
                goto breakbreak3;
            tigroup = proto_tree_add_text(pimopt_tree, tvb, offset, advance,
                                          "Group %d: %s", i, s);
            grouptree = proto_item_add_subtree(tigroup, ett_pim);
            offset += advance;

            njoin = tvb_get_ntohs(tvb, offset);
            nprune = tvb_get_ntohs(tvb, offset + 2);

            tisub = proto_tree_add_text(grouptree, tvb, offset, 2,
                                        "Join: %d", njoin);
            subtree = proto_item_add_subtree(tisub, ett_pim);
            off = offset + 4;
            for (j = 0; j < njoin; j++) {
                s = dissect_pim_addr(tvb, off, pimv2_source,
                                     &advance);
                if (s == NULL)
                    goto breakbreak3;
                proto_tree_add_text(subtree, tvb, off, advance,
                                    "IP address: %s", s);
                off += advance;
            }

            tisub = proto_tree_add_text(grouptree, tvb, offset + 2, 2,
                                        "Prune: %d", nprune);
            subtree = proto_item_add_subtree(tisub, ett_pim);
            for (j = 0; j < nprune; j++) {
                s = dissect_pim_addr(tvb, off, pimv2_source,
                                     &advance);
                if (s == NULL)
                    goto breakbreak3;
                proto_tree_add_text(subtree, tvb, off, advance,
                                    "IP address: %s", s);
                off += advance;
            }
            offset = off;
        }
    breakbreak3:
        break;
    }

    case 4:     /* bootstrap */
    {
        const char *s;
        int advance;
        int i, j;
        int frpcnt;
        guint16 holdtime;
        proto_tree *grouptree = NULL;
        proto_item *tigroup;

        proto_tree_add_text(pimopt_tree, tvb, offset, 2,
                            "Fragment tag: 0x%04x", tvb_get_ntohs(tvb, offset));
        offset += 2;

        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "Hash mask len: %u", tvb_get_guint8(tvb, offset));
        offset += 1;
        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "BSR priority: %u", tvb_get_guint8(tvb, offset));
        offset += 1;

        s = dissect_pim_addr(tvb, offset, pimv2_unicast, &advance);
        if (s == NULL)
            break;
        proto_tree_add_text(pimopt_tree, tvb, offset, advance, "BSR: %s", s);
        offset += advance;

        for (i = 0; tvb_reported_length_remaining(tvb, offset) > 0; i++) {
            s = dissect_pim_addr(tvb, offset, pimv2_group, &advance);
            if (s == NULL)
                goto breakbreak4;
            tigroup = proto_tree_add_text(pimopt_tree, tvb, offset, advance,
                                          "Group %d: %s", i, s);
            grouptree = proto_item_add_subtree(tigroup, ett_pim);
            offset += advance;

            proto_tree_add_text(grouptree, tvb, offset, 1,
                                "RP count: %u", tvb_get_guint8(tvb, offset));
            offset += 1;
            frpcnt = tvb_get_guint8(tvb, offset);
            proto_tree_add_text(grouptree, tvb, offset, 1,
                                "FRP count: %u", frpcnt);
            offset += 3;

            for (j = 0; j < frpcnt; j++) {
                s = dissect_pim_addr(tvb, offset, pimv2_unicast, &advance);
                if (s == NULL)
                    goto breakbreak4;
                proto_tree_add_text(grouptree, tvb, offset, advance,
                                    "RP %d: %s", j, s);
                offset += advance;

                holdtime = tvb_get_ntohs(tvb, offset);
                proto_tree_add_text(grouptree, tvb, offset, 2,
                                    "Holdtime: %u%s", holdtime,
                                    holdtime == 0xffff ? " (infty)" : "");
                offset += 2;
                proto_tree_add_text(grouptree, tvb, offset, 1,
                                    "Priority: %u", tvb_get_guint8(tvb, offset));
                offset += 2;    /* also skips reserved field */
            }
        }

    breakbreak4:
        break;
    }

    case 5:     /* assert */
    {
        const char *s;
        int advance;

        s = dissect_pim_addr(tvb, offset, pimv2_group, &advance);
        if (s == NULL)
            break;
        proto_tree_add_text(pimopt_tree, tvb, offset, advance, "Group: %s", s);
        offset += advance;

        s = dissect_pim_addr(tvb, offset, pimv2_unicast, &advance);
        if (s == NULL)
            break;
        proto_tree_add_text(pimopt_tree, tvb, offset, advance, "Source: %s", s);
        offset += advance;

        proto_tree_add_text(pimopt_tree, tvb, offset, 1, "%s",
                            decode_boolean_bitfield(tvb_get_guint8(tvb, offset), 0x80, 8,
                                                    "RP Tree", "Not RP Tree"));
        proto_tree_add_text(pimopt_tree, tvb, offset, 4, "Preference: %u",
                            tvb_get_ntohl(tvb, offset) & 0x7fffffff);
        offset += 4;

        proto_tree_add_text(pimopt_tree, tvb, offset, 4, "Metric: %u",
                            tvb_get_ntohl(tvb, offset));

        break;
    }

    case 8:     /* Candidate-RP-Advertisement */
    {
        const char *s;
        int advance;
        int pfxcnt;
        guint16 holdtime;
        int i;

        pfxcnt = tvb_get_guint8(tvb, offset);
        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "Prefix-count: %u", pfxcnt);
        offset += 1;
        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "Priority: %u", tvb_get_guint8(tvb, offset));
        offset += 1;
        holdtime = tvb_get_ntohs(tvb, offset);
        proto_tree_add_text(pimopt_tree, tvb, offset, 2,
                            "Holdtime: %u%s", holdtime,
                            holdtime == 0xffff ? " (infty)" : "");
        offset += 2;

        s = dissect_pim_addr(tvb, offset, pimv2_unicast, &advance);
        if (s == NULL)
            break;
        proto_tree_add_text(pimopt_tree, tvb, offset, advance, "RP: %s", s);
        offset += advance;

        for (i = 0; i < pfxcnt; i++) {
            s = dissect_pim_addr(tvb, offset, pimv2_group, &advance);
            if (s == NULL)
                goto breakbreak8;
            proto_tree_add_text(pimopt_tree, tvb, offset, advance,
                                "Group %d: %s", i, s);
            offset += advance;
        }
    breakbreak8:
        break;
    }

    case 9:     /* State-Refresh */
    {
        const char *s;
        int advance;

        s = dissect_pim_addr(tvb, offset, pimv2_group, &advance);
        if (s == NULL)
            break;
        proto_tree_add_text(pimopt_tree, tvb, offset, advance,
                            "Group: %s", s);
        offset += advance;

        s = dissect_pim_addr(tvb, offset, pimv2_unicast, &advance);
        if (s == NULL)
            break;
        proto_tree_add_text(pimopt_tree, tvb, offset, advance,
                            "Source: %s", s);
        offset += advance;

        s = dissect_pim_addr(tvb, offset, pimv2_unicast, &advance);
        if (s == NULL)
            break;
        proto_tree_add_text(pimopt_tree, tvb, offset, advance,
                            "Originator: %s", s);
        offset += advance;

        proto_tree_add_text(pimopt_tree, tvb, offset, 1, "Rendezvous Point Tree %s",
                            decode_boolean_bitfield(tvb_get_guint8(tvb, offset), 1, 1,
                                                    "set", "clear"));
        proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                            "Metric Preference: %u", tvb_get_ntohl(tvb, offset) & 0x7FFFFFFF);
        offset += 4;

        proto_tree_add_text(pimopt_tree, tvb, offset, 4,
                            "Metric: %u", tvb_get_ntohl(tvb, offset));
        offset += 4;

        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "Masklen: %u", tvb_get_guint8(tvb, offset));
        offset += 1;

        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "TTL: %u", tvb_get_guint8(tvb, offset));
        offset += 1;

        proto_tree_add_text(pimopt_tree, tvb, offset, 1, "Prune indicator %s",
                            decode_boolean_bitfield(tvb_get_guint8(tvb, offset), 0x80, 8,
                                                    "set", "clear"));
        proto_tree_add_text(pimopt_tree, tvb, offset, 1, "Prune now %s",
                            decode_boolean_bitfield(tvb_get_guint8(tvb, offset), 0x40, 8,
                                                    "set", "clear"));
        proto_tree_add_text(pimopt_tree, tvb, offset, 1, "Assert override %s",
                            decode_boolean_bitfield(tvb_get_guint8(tvb, offset), 0x20, 8,
                                                    "set", "clear"));
        offset += 1;

        proto_tree_add_text(pimopt_tree, tvb, offset, 1,
                            "Interval: %u", tvb_get_guint8(tvb, offset));
        offset += 1;

        break;
    }

    default:
        break;
    }
done:;
}

void
proto_register_pim(void)
{
    static hf_register_info hf[] =
        {
            { &hf_pim_version,
              { "Version", "pim.version",
                FT_UINT8, BASE_DEC, NULL, 0xf0,
                NULL, HFILL }
            },
            { &hf_pim_type,
              { "Type", "pim.type",
                FT_UINT8, BASE_DEC, VALS(type2vals), 0x0f,
                NULL, HFILL }
            },
            { &hf_pim_code,
              { "Code", "pim.code",
                FT_UINT8, BASE_DEC, VALS(type1vals), 0x0,
                NULL, HFILL }
            },
            { &hf_pim_cksum,
              { "Checksum", "pim.cksum",
                FT_UINT16, BASE_HEX, NULL, 0x0,
                NULL, HFILL }
            },
            { &hf_pim_res_bytes,
              { "Reserved byte(s)", "pim.res_bytes",
                FT_BYTES, BASE_NONE, NULL, 0x0,
                NULL, HFILL }
            },
        };
    static gint *ett[] = {
        &ett_pim,
    };

    proto_pim = proto_register_protocol("Protocol Independent Multicast",
                                        "PIM", "pim");
    proto_register_field_array(proto_pim, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
}

void
proto_reg_handoff_pim(void)
{
    dissector_handle_t pim_handle;

    pim_handle = create_dissector_handle(dissect_pim, proto_pim);
    dissector_add("ip.proto", IP_PROTO_PIM, pim_handle);

    /*
     * Get handles for the IPv4 and IPv6 dissectors.
     */
    ip_handle = find_dissector("ip");
    ipv6_handle = find_dissector("ipv6");
}
