/* packet-flip.c

 * Routines for FLIP packet dissection

 *

 * Copyright 2009, Juha Siltanen <juha.siltanen@nsn.com>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

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

 */

/*

 * FLIP (Flow Layer Internal Protocol) is a proprietary protocol

 * developed by Nokia Solutions and Networks (previous was 'Nokia Siemens Networks').

 */

/*

 * Version information

 *

 * Version 0.0.1, November 23rd, 2009.

 *

 * Support for the basic and checksum headers.

 *

 * Version 0.0.2, August 26th, 2010.

 *

 * Support for payload dissecting.

 *

 * Version 0.0.3, September 14th, 2010.

 *

 * Bugfix: sorting by protocol didn't always fill in the protocol column.

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/etypes.h>

#include <epan/decode_as.h>

#include <epan/in_cksum.h>

#include <epan/tfs.h>

#include <epan/prefs.h>

void proto_register_flip(void);

void proto_reg_handoff_flip(void);

static dissector_handle_t flip_handle;

static int proto_flip;

/* BASIC */

static int hf_flip_basic_e;

static int hf_flip_basic_reserved;

static int hf_flip_basic_flowid;

static int hf_flip_basic_seqnum;

static int hf_flip_basic_len;

/* CHECKSUM */

static int hf_flip_chksum_etype;

static int hf_flip_chksum_spare;

static int hf_flip_chksum_e;

static int hf_flip_chksum_chksum;

#define FLIP_BASIC            (0)

#define FLIP_CHKSUM           (1)

#define FLIP_BASIC_HDR_LEN         (8)

#define FLIP_CHKSUM_HDR_LEN        (4)

#define FLIP_EXTENSION_HDR_MIN_LEN (4)

static const value_string flip_etype[] = {

    { FLIP_CHKSUM, "Checksum" },

    { 0,           NULL }

};

static dissector_table_t subdissector_table;

static int ett_flip;

static int ett_flip_basic;

static int ett_flip_chksum;

static int ett_flip_payload;

static void flip_prompt(packet_info *pinfo _U_, char* result)

{

    snprintf(result, MAX_DECODE_AS_PROMPT_LEN, "Decode FLIP payload protocol as");

}

/* Dissect the checksum extension header. */

static int

dissect_flip_chksum_hdr(tvbuff_t    *tvb,

                        packet_info *pinfo,

                        proto_tree  *tree,

                        uint16_t    computed_chksum,

                        bool        *ext_hdr_follows_ptr)

{

    proto_tree *chksum_hdr_tree;

    uint32_t dw;

    uint8_t  chksum_hdr_etype;

    uint8_t  chksum_hdr_ext;

    uint16_t chksum_hdr_chksum;

    int bytes_dissected;

    int offset;

    chksum_hdr_tree = NULL;

    bytes_dissected = 0;

    offset          = 0;

    dw = tvb_get_ntohl(tvb, offset);

    chksum_hdr_etype  = (uint8_t) ((dw & 0xFF000000) >> 24);

    chksum_hdr_ext    = (uint8_t) ((dw & 0x00010000) >> 16);

    chksum_hdr_chksum = (uint16_t) (dw & 0x0000FFFF);

    /* The actually shouldn't be any headers after checksum. */

    if (chksum_hdr_ext == 1) {

        *ext_hdr_follows_ptr = true;

    }

    else {

        *ext_hdr_follows_ptr = false;

    }

    if (tree) {

        chksum_hdr_tree = proto_tree_add_subtree(tree, tvb, offset + 0, 4,

                            ett_flip_chksum, NULL, "Checksum Header");

        /* ETYPE: 8 bits */

        proto_tree_add_uint_format_value(chksum_hdr_tree, hf_flip_chksum_etype,

                                         tvb, offset + 0, 1, dw,

                                         "%s", val_to_str_const(chksum_hdr_etype,

                                                                flip_etype,

                                                                "Unknown"));

        /* SPARE: 7 bits */

        proto_tree_add_item(chksum_hdr_tree, hf_flip_chksum_spare, tvb, offset, 4, ENC_BIG_ENDIAN);

        /* EXT HDR: 1 bit */

        proto_tree_add_item(chksum_hdr_tree, hf_flip_chksum_e,

                                         tvb, offset, 4, ENC_BIG_ENDIAN);

        /* CHKSUM: 16 bits. */

        proto_tree_add_uint_format_value(

            chksum_hdr_tree,

            hf_flip_chksum_chksum,

            tvb, offset + 2, 2,

            chksum_hdr_chksum,

            "0x%04x [%s] (computed 0x%04x)",

            chksum_hdr_chksum,

            ((chksum_hdr_chksum == computed_chksum) ? "Correct" : "Incorrect"),

            computed_chksum);

    }

    /* Show faulty checksums. */

    if (computed_chksum != chksum_hdr_chksum) {

        col_add_fstr(pinfo->cinfo, COL_INFO,

                     "Checksum 0x%04x [%s] (computed 0x%04x)",

                     chksum_hdr_chksum,

                     "Incorrect",

                     computed_chksum);

    }

    bytes_dissected += FLIP_CHKSUM_HDR_LEN;

    return bytes_dissected;

} /* dissect_flip_chksum_hdr() */

/* Protocol dissection */

static int

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

{

    proto_item *ti = NULL;

    proto_tree *flip_tree = NULL;

    proto_tree *basic_hdr_tree = NULL;

    tvbuff_t   *flip_tvb;

    uint32_t dw1;

    /* Basic header fields. */

    uint8_t  basic_hdr_ext;

    uint32_t basic_hdr_flow_id;

    uint16_t basic_hdr_len;

    bool ext_hdr = false;

    int bytes_dissected = 0;

    int payload_len;

    int frame_len;

    int flip_len;

    int offset = 0;

    /* Error handling for basic header. */

    bool is_faulty_frame = false;

    /* Show this protocol as FLIP. */

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

    /*

     * The frame can be faulty in several ways:

     * - too short (even for the basic header)

     * - length inconsistent (header and frame info different)

     * - checksum doesn't check out

     * - extension header is indicated, but the frame is too short for it

     * - unknown extension header type

     */

    /* Check that there's enough data at least for the basic header. */

    frame_len = tvb_captured_length(tvb);

    if (frame_len < FLIP_BASIC_HDR_LEN) {

        return 0;

    }

    bytes_dissected += FLIP_BASIC_HDR_LEN;

    /* Process the first 32 bits of the basic header. */

    dw1 = tvb_get_ntohl(tvb, offset + 0);

    basic_hdr_ext      = ((dw1 & 0x80000000) >> 31);

    basic_hdr_flow_id  = (dw1 & 0x0FFFFFFF);

    /* Process the second 32 bits of the basic header. */

    basic_hdr_len    = (uint16_t) (tvb_get_ntohl(tvb, offset + 4) & 0x0000FFFF);

    /* Does the basic header indicate that an extension is next? */

    if (basic_hdr_ext == 1) {

        ext_hdr = true;

    }

    flip_len = basic_hdr_len;

    /*

     * Check the length value.

     */

    if ((flip_len < FLIP_BASIC_HDR_LEN) || (flip_len > frame_len)) {

        /* Faulty frame. Show the basic header anyway for debugging. */

        is_faulty_frame = true;

    }

    /* Fill in the info column. */

    col_add_fstr(pinfo->cinfo, COL_INFO,

                 "FlowID %s", val_to_str(pinfo->pool, basic_hdr_flow_id, NULL, "0x%08x"));

    flip_tvb = tvb_new_subset_length(tvb, 0, frame_len);

    /* We are asked for details. */

    if (tree) {

        ti = proto_tree_add_protocol_format(

                tree, proto_flip, flip_tvb, 0, flip_len,

                "NSN FLIP, FlowID %s",

                val_to_str(pinfo->pool, basic_hdr_flow_id, NULL, "0x%08x"));

        flip_tree = proto_item_add_subtree(ti, ett_flip);

        /* basic header */

        basic_hdr_tree = proto_tree_add_subtree(flip_tree, flip_tvb, offset, 8, ett_flip_basic, NULL, "Basic Header");

        /* Extension header follows? 1 bit. */

        proto_tree_add_item(basic_hdr_tree, hf_flip_basic_e, flip_tvb, offset, 4, ENC_BIG_ENDIAN);

        /* Reserved: 3 bits. */

        proto_tree_add_item(basic_hdr_tree, hf_flip_basic_reserved, flip_tvb, offset, 4, ENC_BIG_ENDIAN);

        /* Flow ID: 28 bits. */

        proto_tree_add_item(basic_hdr_tree, hf_flip_basic_flowid, flip_tvb, offset, 4, ENC_BIG_ENDIAN);

        /* Sequence number: 16 bits. */

        proto_tree_add_item(basic_hdr_tree, hf_flip_basic_seqnum, flip_tvb, offset + 4, 2, ENC_BIG_ENDIAN);

        /* Packet length: 16 bits. */

        proto_tree_add_item(basic_hdr_tree, hf_flip_basic_len, flip_tvb, offset + 6, 2, ENC_BIG_ENDIAN);

    }

    offset += FLIP_BASIC_HDR_LEN;

    /*

     * Process faults found when parsing the basic header.

     */

    if (is_faulty_frame == true) {

        if (flip_len > frame_len) {

            col_add_fstr(pinfo->cinfo, COL_INFO,

                         "Length mismatch: frame %d bytes, hdr %d bytes",

                         frame_len, flip_len);

        }

        else if (flip_len < FLIP_BASIC_HDR_LEN) {

            col_add_fstr(pinfo->cinfo, COL_INFO,

                         "Invalid length in basic header: %d bytes", flip_len);

        }

        goto DISSECT_FLIP_EXIT;

    }

    /*

     * Now we know that the basic header is sensible.

     */

    payload_len  = basic_hdr_len - FLIP_BASIC_HDR_LEN;

    /*

     * Dissect extension headers (if any).

     */

    if ((ext_hdr == true) && (payload_len < FLIP_EXTENSION_HDR_MIN_LEN)) {

        col_set_str(pinfo->cinfo, COL_INFO,

                    "Extension header indicated, but not enough data");

        goto DISSECT_FLIP_EXIT;

    }

    while ((ext_hdr == true) && (payload_len >= FLIP_EXTENSION_HDR_MIN_LEN)) {

        /* Detect the next header type. */

        uint8_t ext_hdr_type;

        int     bytes_handled;

        uint16_t computed_chksum;

        tvbuff_t *chksum_tvb;

        ext_hdr_type = tvb_get_uint8(flip_tvb, offset);

        switch (ext_hdr_type) {

        case FLIP_CHKSUM:

            /* Calculate checksum, let the chksum dissector verify it. */

            {

                vec_t   vec[2];

                SET_CKSUM_VEC_TVB(vec[0], flip_tvb, 0, bytes_dissected + 2);

                SET_CKSUM_VEC_TVB(vec[1], flip_tvb, bytes_dissected + 4,

                                  flip_len - (bytes_dissected + 4));

                computed_chksum = in_cksum(&vec[0], 2);

                /* Checksums handled in network order. */

                computed_chksum = g_htons(computed_chksum);

            }

            chksum_tvb = tvb_new_subset_length(flip_tvb, offset,

                                        FLIP_CHKSUM_HDR_LEN);

            /* Note that flip_tree is NULL if no details are requested. */

            bytes_handled = dissect_flip_chksum_hdr(chksum_tvb,

                                                    pinfo,

                                                    flip_tree,

                                                    computed_chksum,

                                                    &ext_hdr);

            bytes_dissected += bytes_handled;

            payload_len     -= bytes_handled;

            offset          += bytes_handled;

            break;

        default:

            /* Unknown header type. */

            col_add_fstr(pinfo->cinfo, COL_INFO,

                         "Invalid extension header type 0x%02x", ext_hdr_type);

            goto DISSECT_FLIP_EXIT;

            break;

        }

    }

    /*

     * Show payload (if any) as bytes.

     */

    if (payload_len > 0) {

        tvbuff_t           *payload_tvb;

        int                data_len;

        payload_tvb = tvb_new_subset_length(flip_tvb, offset, payload_len);

        data_len = dissector_try_payload_with_data(subdissector_table, payload_tvb, pinfo, tree, true, NULL);

        if (data_len <= 0)

        {

            data_len = call_data_dissector(payload_tvb, pinfo, tree);

        }

        bytes_dissected += data_len;

    } /* if (payload_len > 0) */

DISSECT_FLIP_EXIT:

    return bytes_dissected;

} /* dissect_flip() */

/* Protocol initialization */

void

proto_register_flip(void)

{

    static hf_register_info hf[] = {

        /*

         * Basic header.

         */

        {&hf_flip_basic_e,

         {"Extension Header Follows", "flip.basic.e", FT_BOOLEAN, 32,

          TFS(&tfs_yes_no), 0x80000000, NULL, HFILL}

        },

        {&hf_flip_basic_reserved,

         {"Reserved", "flip.basic.reserved", FT_UINT32, BASE_DEC,

          NULL, 0x70000000, "Basic Header Reserved", HFILL}

        },

        {&hf_flip_basic_flowid,

         {"FlowID", "flip.basic.flowid", FT_UINT32, BASE_HEX,

          NULL, 0x0FFFFFFF, "Basic Header Flow ID", HFILL}

        },

        {&hf_flip_basic_seqnum,

         {"Seqnum", "flip.basic.seqnum", FT_UINT16, BASE_DEC_HEX,

          NULL, 0x0, "Basic Header Sequence Number", HFILL}

        },

        {&hf_flip_basic_len,

         {"Len", "flip.basic.len", FT_UINT16, BASE_DEC_HEX,

          NULL, 0x0, "Basic Header Packet Length", HFILL}

        },

        /*

         * Checksum header.

         */

        {&hf_flip_chksum_etype,

         {"Extension Type", "flip.chksum.etype", FT_UINT32, BASE_DEC,

          VALS(flip_etype), 0xFF000000, "Checksum Header Extension Type", HFILL}

        },

        {&hf_flip_chksum_spare,

         {"Spare", "flip.chksum.spare", FT_UINT32, BASE_DEC_HEX,

          NULL, 0x00FE0000, "Checksum Header Spare", HFILL}

        },

        {&hf_flip_chksum_e,

         {"Extension Header Follows", "flip.chksum.e", FT_BOOLEAN, 32,

          TFS(&tfs_yes_no), 0x00010000, NULL, HFILL}

        },

        {&hf_flip_chksum_chksum,

         {"Checksum", "flip.chksum.chksum", FT_UINT32, BASE_HEX,

          NULL, 0x0000FFFF, NULL, HFILL}

        }

    };

    static int *ett[] = {

        &ett_flip,

        &ett_flip_basic,

        &ett_flip_chksum,

        &ett_flip_payload

    };

    module_t *flip_module;

    proto_flip = proto_register_protocol("NSN FLIP", "FLIP", "flip");

    flip_handle = register_dissector("flip", dissect_flip, proto_flip);

    proto_register_field_array(proto_flip, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

    flip_module = prefs_register_protocol_obsolete(proto_flip);

    /* Register preferences - now obsolete because of Decode As*/

    prefs_register_obsolete_preference(flip_module, "decoding_mode");

    prefs_register_obsolete_preference(flip_module, "heur_enabled_protocols");

    prefs_register_obsolete_preference(flip_module, "heur_decode_rtp");

    prefs_register_obsolete_preference(flip_module, "heur_decode_rtcp");

    prefs_register_obsolete_preference(flip_module, "forced_protocol");

    prefs_register_obsolete_preference(flip_module, "forced_decode");

    subdissector_table = register_decode_as_next_proto(proto_flip, "flip.payload", "FLIP payload", flip_prompt);

} /* proto_register_flip() */

/* Protocol handoff */

void

proto_reg_handoff_flip(void)

{

    dissector_add_uint("ethertype", ETHERTYPE_FLIP, flip_handle);

} /* proto_reg_handoff_flip() */

/*

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

 *

 * Local variables:

 * c-basic-offset: 4

 * tab-width: 8

 * indent-tabs-mode: nil

 * End:

 *

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

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

 */