/*

 * packet-fcoe.c

 * Routines for FCoE dissection - Fibre Channel over Ethernet

 * Copyright (c) 2006 Nuova Systems, Inc. (jre@nuovasystems.com)

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

 * Based on packet-fcip.c, Copyright 2001, Dinesh G Dutt (ddutt@cisco.com)

 *

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

 */

/*

 * For FCoE protocol details, see http://fcoe.com.

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/prefs.h>

#include <epan/crc32-tvb.h>

#include <epan/expert.h>

#include "packet-fc.h"

void proto_register_fcoe(void);

void proto_reg_handoff_fcoe(void);

#define FCOE_HEADER_LEN   14        /* header: version, SOF, and padding */

#define FCOE_TRAILER_LEN   8        /* trailer: CRC, EOF, and padding */

typedef enum {

    FCOE_EOFn    = 0x41,

    FCOE_EOFt    = 0x42,

    FCOE_EOFrt   = 0x44,

    FCOE_EOFdt   = 0x46,

    FCOE_EOFni   = 0x49,

    FCOE_EOFdti  = 0x4E,

    FCOE_EOFrti  = 0x4F,

    FCOE_EOFa    = 0x50

} fcoe_eof_t;

typedef enum {

    FCOE_SOFf    = 0x28,

    FCOE_SOFi4   = 0x29,

    FCOE_SOFi2   = 0x2D,

    FCOE_SOFi3   = 0x2E,

    FCOE_SOFn4   = 0x31,

    FCOE_SOFn2   = 0x35,

    FCOE_SOFn3   = 0x36,

    FCOE_SOFc4   = 0x39

} fcoe_sof_t;

static const value_string fcoe_eof_vals[] = {

    {FCOE_EOFn,   "EOFn" },

    {FCOE_EOFt,   "EOFt" },

    {FCOE_EOFrt,  "EOFrt" },

    {FCOE_EOFdt,  "EOFdt" },

    {FCOE_EOFni,  "EOFni" },

    {FCOE_EOFdti, "EOFdti" },

    {FCOE_EOFrti, "EOFrti" },

    {FCOE_EOFa,   "EOFa" },

    {0, NULL}

};

static const value_string fcoe_sof_vals[] = {

    {FCOE_SOFf, "SOFf" },

    {FCOE_SOFi4, "SOFi4" },

    {FCOE_SOFi2, "SOFi2" },

    {FCOE_SOFi3, "SOFi3" },

    {FCOE_SOFn4, "SOFn4" },

    {FCOE_SOFn2, "SOFn2" },

    {FCOE_SOFn3, "SOFn3" },

    {FCOE_SOFc4, "SOFc4" },

    {0, NULL}

};

static int proto_fcoe;

static int hf_fcoe_ver;

static int hf_fcoe_len;

static int hf_fcoe_sof;

static int hf_fcoe_eof;

static int hf_fcoe_crc;

static int hf_fcoe_crc_status;

static int ett_fcoe;

static expert_field ei_fcoe_crc;

static dissector_handle_t fc_handle;

static dissector_handle_t fcoe_handle;

/* Looks for the EOF at a given offset. Returns NULL if the EOF is not

 * present, is not one of the known values, or if the next three bytes, if

 * present, are not padding. Otherwise returns the entry from the EOF

 * value_string. Intended for use with the newer T11 version, where the frame

 * length is not explicitly set (and padding is used). */

static const char *

fcoe_get_eof(tvbuff_t *tvb, int eof_offset)

{

    uint8_t     eof          = 0;

    const char *eof_str;

    int         padding_remaining;

    if (!tvb_bytes_exist(tvb, eof_offset, 1)) {

        return NULL;

    }

    padding_remaining = MIN(tvb_captured_length_remaining(tvb, eof_offset+1),3);

    if (tvb_memeql(tvb, eof_offset+1, (const uint8_t*)"\x00\x00\x00", padding_remaining)) {

        return NULL;

    }

    eof = tvb_get_uint8(tvb, eof_offset);

    eof_str = try_val_to_str(eof, fcoe_eof_vals);

    return eof_str;

}

static int

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

{

    int         crc_offset;

    int         eof_offset;

    int         frame_len    = 0;

    int         header_len   = FCOE_HEADER_LEN;

    unsigned    version;

    const char *ver;

    uint16_t    len_sof;

    uint8_t     sof          = 0;

    uint8_t     eof          = 0;

    const char *eof_str;

    const char *crc_msg;

    const char *len_msg;

    proto_item *ti;

    proto_tree *fcoe_tree;

    tvbuff_t   *next_tvb;

    bool        crc_exists;

    uint32_t    crc_computed = 0;

    uint32_t    crc          = 0;

    fc_data_t fc_data;

    /*

     * For now, handle both the version defined before and after August 2007.

     * In the newer version, byte 1 is reserved and always zero.  In the old

     * version, it'll never be zero.

     */

    if (tvb_get_uint8(tvb, 1)) {

        header_len = 2;

        len_sof = tvb_get_ntohs(tvb, 0);

        frame_len = (len_sof & 0x3ff0) >> 2;

        if (len_sof >= 4) {

            /* This length includes the CRC; subtract it off.

             * If it's less than 4, that's bogus; we'll warn

             * about an invalid length below and not try to

             * dissect the CRC, so we don't have to throw a

             * ReportedBoundsError here (but don't want to

             * overflow.)

             */

            len_sof -= 4;

        }

        sof = len_sof & 0xf;

        sof |= (sof < 8) ? 0x30 : 0x20;

        version = len_sof >> 14;

        ver = "pre-T11 ";

        if (version != 0)

            ver = wmem_strdup_printf(pinfo->pool, ver, "pre-T11 ver %d ", version);

        eof_offset = header_len + frame_len + 4;

        eof_str = "none";

        if (tvb_bytes_exist(tvb, eof_offset, 1)) {

            eof = tvb_get_uint8(tvb, eof_offset);

            eof_str = val_to_str(pinfo->pool, eof, fcoe_eof_vals, "0x%x");

        }

        /* Old format has a length field, so we can help the Ethernet dissector

         * guess about the FCS; note this format does not pad after the EOF */

        set_actual_length(tvb, eof_offset+1);

    } else {

        sof = tvb_get_uint8(tvb, FCOE_HEADER_LEN - 1);

        /*

         * Only version 0 is defined at this point.

         * Don't print the version in the short summary if it is zero.

         */

        ver = "";

        version = tvb_get_uint8(tvb, 0) >> 4;

        if (version != 0)

            ver = wmem_strdup_printf(pinfo->pool, ver, "ver %d ", version);

        frame_len = tvb_reported_length_remaining(tvb, FCOE_HEADER_LEN);

        if (frame_len >= FCOE_TRAILER_LEN) {

            /* The frame is claimed to be long enough for a trailer.

             * Slice it off. Otherwise (which doesn't make sense), just

             * ignore it and the eof_offset will be off the edge and the

             * various tvb_bytes_exist checks will prevent exceptions.

             */

            frame_len -= FCOE_TRAILER_LEN;

        }

        eof_offset = header_len + frame_len + 4;

        if (NULL == (eof_str = fcoe_get_eof(tvb, eof_offset))) {

            /* We didn't find the EOF, look 4 bytes earlier */

            if (NULL != (eof_str = fcoe_get_eof(tvb, eof_offset-4))) {

                /* Found it, so it seems there's an Ethernet FCS. */

                frame_len -= 4;

                set_actual_length(tvb, eof_offset);

                eof_offset -= 4;

            } else {

                if (tvb_bytes_exist(tvb, eof_offset, 1)) {

                    /* Hmm, we have enough bytes to look for the EOF

                     * but it's an unexpected value. */

                    eof = tvb_get_uint8(tvb, eof_offset);

                    eof_str = wmem_strdup_printf(pinfo->pool, "0x%x", eof);

                } else {

                    /* We just didn't capture enough to get the EOF */

                    eof_str = "none";

                }

            }

        }

    }

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

    crc_offset = header_len + frame_len;

    next_tvb = tvb_new_subset_length(tvb, header_len, frame_len);

    /*

     * Check the CRC.

     */

    crc_msg = "";

    crc_exists = tvb_bytes_exist(tvb, crc_offset, 4);

    if (crc_exists) {

        crc = tvb_get_ntohl(tvb, crc_offset);

        crc_computed = crc32_802_tvb(next_tvb, frame_len);

        if (crc != crc_computed) {

            crc_msg = " [bad FC CRC]";

        }

    }

    len_msg = "";

    if ((frame_len % 4) != 0 || frame_len < 24) {

        len_msg = " [invalid length]";

    }

    ti = proto_tree_add_protocol_format(tree, proto_fcoe, tvb, 0,

                                        header_len,

                                        "FCoE %s(%s/%s) %d bytes%s%s", ver,

                                        val_to_str(pinfo->pool, sof, fcoe_sof_vals,

                                                   "0x%x"),

                                        eof_str, frame_len, crc_msg,

                                        len_msg);

    /* Dissect the FCoE header */

    fcoe_tree = proto_item_add_subtree(ti, ett_fcoe);

    proto_tree_add_uint(fcoe_tree, hf_fcoe_ver, tvb, 0, 1, version);

    if (tvb_get_uint8(tvb, 1)) {

        proto_tree_add_uint(fcoe_tree, hf_fcoe_len, tvb, 0, 2, frame_len);

    }

    proto_tree_add_uint(fcoe_tree, hf_fcoe_sof, tvb,

                        header_len - 1, 1, sof);

    /*

     * Create the CRC information.

     */

    if (crc_exists) {

        proto_tree_add_checksum(fcoe_tree, tvb, crc_offset, hf_fcoe_crc, hf_fcoe_crc_status, &ei_fcoe_crc, pinfo, crc_computed, ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY);

        proto_tree_set_appendix(fcoe_tree, tvb, crc_offset,

                                tvb_captured_length_remaining (tvb, crc_offset));

    } else {

        proto_tree_add_checksum(fcoe_tree, tvb, crc_offset, hf_fcoe_crc, hf_fcoe_crc_status, &ei_fcoe_crc, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NOT_PRESENT);

    }

    /*

     * Interpret the EOF.

     */

    if (tvb_bytes_exist(tvb, eof_offset, 1)) {

        proto_tree_add_item(fcoe_tree, hf_fcoe_eof, tvb, eof_offset, 1, ENC_BIG_ENDIAN);

    }

    /* Set the SOF/EOF flags in the packet_info header */

    fc_data.sof_eof = 0;

    if (sof == FCOE_SOFi3 || sof == FCOE_SOFi2 || sof == FCOE_SOFi4) {

        fc_data.sof_eof = FC_DATA_SOF_FIRST_FRAME;

    } else if (sof == FCOE_SOFf) {

        fc_data.sof_eof = FC_DATA_SOF_SOFF;

    }

    if (eof != FCOE_EOFn) {

        fc_data.sof_eof |= FC_DATA_EOF_LAST_FRAME;

    } else if (eof != FCOE_EOFt) {

        fc_data.sof_eof |= FC_DATA_EOF_INVALID;

    }

    /* Call the FC Dissector if this is carrying an FC frame */

    fc_data.ethertype = ETHERTYPE_UNK;

    if (fc_handle) {

        call_dissector_with_data(fc_handle, next_tvb, pinfo, tree, &fc_data);

    } else {

        call_data_dissector(next_tvb, pinfo, tree);

    }

    return tvb_captured_length(tvb);

}

void

proto_register_fcoe(void)

{

    module_t *fcoe_module;

    /* Setup list of header fields  See Section 1.6.1 for details*/

    static hf_register_info hf[] = {

        { &hf_fcoe_sof,

          {"SOF", "fcoe.sof", FT_UINT8, BASE_HEX, VALS(fcoe_sof_vals), 0,

           NULL, HFILL}},

        { &hf_fcoe_eof,

          {"EOF", "fcoe.eof", FT_UINT8, BASE_HEX, VALS(fcoe_eof_vals), 0,

           NULL, HFILL}},

        { &hf_fcoe_ver,

          {"Version", "fcoe.ver", FT_UINT32, BASE_DEC, NULL, 0, NULL, HFILL}},

        { &hf_fcoe_len,

          {"Frame length", "fcoe.len", FT_UINT32,

            BASE_DEC, NULL, 0, NULL, HFILL}},

        { &hf_fcoe_crc,

          {"CRC", "fcoe.crc", FT_UINT32, BASE_HEX, NULL, 0, NULL, HFILL}},

        { &hf_fcoe_crc_status,

          {"CRC Status", "fcoe.crc.status", FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0,

            NULL, HFILL }}

    };

    static int *ett[] = {

        &ett_fcoe,

    };

    static ei_register_info ei[] = {

        { &ei_fcoe_crc, { "fcoe.crc.bad", PI_CHECKSUM, PI_ERROR, "Bad checksum", EXPFILL }},

    };

    expert_module_t* expert_fcoe;

    /* Register the protocol name and description */

    proto_fcoe = proto_register_protocol("Fibre Channel over Ethernet",

        "FCoE", "fcoe");

    fcoe_handle = register_dissector("fcoe", dissect_fcoe, proto_fcoe);

    /* Required function calls to register the header fields and

     * subtrees used */

    proto_register_field_array(proto_fcoe, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

    expert_fcoe = expert_register_protocol(proto_fcoe);

    expert_register_field_array(expert_fcoe, ei, array_length(ei));

    fcoe_module = prefs_register_protocol_obsolete(proto_fcoe);

    prefs_register_obsolete_preference(fcoe_module, "ethertype");

}

void

proto_reg_handoff_fcoe(void)

{

    dissector_add_uint("ethertype", ETHERTYPE_FCOE, fcoe_handle);

    fc_handle   = find_dissector_add_dependency("fc", proto_fcoe);

}

/*

 * 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:

 */