/* packet-bzr.c

 * Routines for Bazaar packet dissection

 * Copyright 2011,2013 Jelmer Vernooij <jelmer@samba.org>

 *

 * http://doc.bazaar.canonical.com/developers/network-protocol.html

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

 * Copied from packet-pop.c

 *

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

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/prefs.h>

void proto_register_bzr(void);

void proto_reg_handoff_bzr(void);

static int proto_bzr;

static int ett_bzr;

static int ett_prefixed_bencode;

static int ett_prefixed_bytes;

static int hf_bzr_prefixed_bencode;

static int hf_bzr_prefixed_bencode_len;

static int hf_bzr_bytes;

static int hf_bzr_bytes_data;

static int hf_bzr_bytes_length;

static int hf_bzr_result;

static int hf_bzr_packet_protocol_version;

static int hf_bzr_packet_kind;

static dissector_handle_t bencode_handle;

static dissector_handle_t bzr_handle;

#define REQUEST_VERSION_TWO   "bzr request 2\n"

#define RESPONSE_VERSION_TWO  "bzr response 2\n"

#define MESSAGE_VERSION_THREE "bzr message 3 (bzr 1.6)\n"

#define TCP_PORT_BZR   4155

static const value_string message_part_kind[] = {

    {'s', "Structure"},

    {'b', "Bytes"},

    {'o', "Single byte"},

    {'e', "End"},

    {0, NULL}

};

static const value_string message_results[] = {

    {'S', "Success"},

    {'E', "Error"},

    {0, NULL}

};

/* desegmentation of Bazaar over TCP */

static bool bzr_desegment = true;

static unsigned get_bzr_prefixed_len(tvbuff_t *tvb, int offset)

{

    unsigned header_len;

    header_len = tvb_get_ntohl(tvb, offset);

    return 4 + header_len;

}

static unsigned

get_bzr_pdu_len(packet_info *pinfo _U_, tvbuff_t *tvb, int offset)

{

    int    next_offset;

    int    len = 0, current_len;

    int    protocol_version_len;

    uint8_t cmd = 0;

    /* Protocol version */

    protocol_version_len = tvb_find_line_end(tvb, offset, -1, &next_offset,

                                             true);

    if (protocol_version_len == -1) /* End of the packet not seen yet */

        return -1;

    len += protocol_version_len + 1;

    /* Headers */

    current_len = len;

    len += get_bzr_prefixed_len(tvb, next_offset);

    if (current_len > len) /* Make sure we're not going backwards */

        return -1;

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

        cmd = tvb_get_uint8(tvb, offset + len);

        len += 1;

        switch (cmd) {

        case 's':

        case 'b':

            current_len = len;

            len += get_bzr_prefixed_len(tvb, offset + len);

            if (current_len > len) /* Make sure we're not going backwards */

                return -1;

            break;

        case 'o':

            len += 1;

            break;

        case 'e':

            return len;

        }

    }

    return -1;

}

static int

dissect_prefixed_bencode(tvbuff_t *tvb, int offset, packet_info *pinfo,

                         proto_tree *tree)

{

    uint32_t    plen;

    proto_tree *prefixed_bencode_tree;

    proto_item *ti;

    tvbuff_t *subtvb;

    plen = tvb_get_ntohl(tvb, offset);

    ti = proto_tree_add_item(tree, hf_bzr_prefixed_bencode, tvb, offset, -1,

                             ENC_NA);

    prefixed_bencode_tree = proto_item_add_subtree(ti, ett_prefixed_bencode);

    proto_tree_add_item(prefixed_bencode_tree, hf_bzr_prefixed_bencode_len,

                        tvb, offset, 4, ENC_BIG_ENDIAN);

    subtvb = tvb_new_subset_length(tvb, offset+4, plen);

    call_dissector(bencode_handle, subtvb, pinfo, prefixed_bencode_tree);

    proto_item_set_len(ti, 4 + plen);

    return 4 + plen;

}

static int

dissect_prefixed_bytes(tvbuff_t *tvb, int offset, packet_info *pinfo _U_,

                       proto_tree *tree)

{

    uint32_t    plen;

    proto_tree *prefixed_bytes_tree;

    proto_item *ti;

    plen = tvb_get_ntohl(tvb, offset);

    ti = proto_tree_add_item(tree, hf_bzr_bytes, tvb, offset, -1, ENC_NA);

    prefixed_bytes_tree = proto_item_add_subtree(ti, ett_prefixed_bytes);

    proto_tree_add_item(prefixed_bytes_tree, hf_bzr_bytes_length,

                        tvb, offset, 4, ENC_BIG_ENDIAN);

    proto_tree_add_item(prefixed_bytes_tree, hf_bzr_bytes_data,

                        tvb, offset+4, plen, ENC_NA);

    proto_item_set_len(ti, 4 + plen);

    return 4 + plen;

}

static int

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

{

    uint8_t cmd = 0;

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

        cmd = tvb_get_uint8(tvb, offset);

        proto_tree_add_item(tree, hf_bzr_packet_kind, tvb, offset, 1, ENC_ASCII);

        offset += 1;

        switch (cmd) {

        case 's':

            offset += dissect_prefixed_bencode(tvb, offset, pinfo, tree);

            break;

        case 'b':

            offset += dissect_prefixed_bytes(tvb, offset, pinfo, tree);

            break;

        case 'o':

            proto_tree_add_item(tree, hf_bzr_result, tvb, offset, 1,

                                ENC_ASCII);

            offset += 1;

            break;

        case 'e':

            break;

        }

    }

    return offset;

}

static void

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

{

    proto_tree *bzr_tree;

    proto_item *ti;

    int         offset = 0;

    int         protocol_version_len;

    ti = proto_tree_add_item(tree, proto_bzr, tvb, offset, -1, ENC_NA);

    bzr_tree = proto_item_add_subtree(ti, ett_bzr);

    protocol_version_len = tvb_find_line_end(tvb, offset, -1, &offset, true);

    if (protocol_version_len == -1) /* Invalid packet */

        return;

    if (bzr_tree)

    {

        proto_tree_add_item(bzr_tree, hf_bzr_packet_protocol_version, tvb, 0,

                            protocol_version_len+1, ENC_ASCII);

    }

    offset += dissect_prefixed_bencode(tvb, offset, pinfo, bzr_tree);

    /*offset +=*/ dissect_body(tvb, offset, pinfo, bzr_tree);

}

static int

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

{

    int       offset = 0, pdu_len;

    tvbuff_t *next_tvb;

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

    col_set_str(pinfo->cinfo, COL_INFO, "Bazaar Smart Protocol");

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

        pdu_len = get_bzr_pdu_len(pinfo, tvb, offset);

        if (pdu_len == -1) {

            if (pinfo->can_desegment && bzr_desegment) {

                pinfo->desegment_offset = offset;

                pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;

                return tvb_captured_length(tvb);

            } else {

                pdu_len = tvb_reported_length_remaining(tvb, offset);

            }

        }

        next_tvb = tvb_new_subset_length(tvb, offset, pdu_len);

        dissect_bzr_pdu(next_tvb, pinfo, tree);

        offset += pdu_len;

    }

    return tvb_captured_length(tvb);

}

void

proto_register_bzr(void)

{

    static hf_register_info hf[] = {

        { &hf_bzr_packet_kind,

          { "Packet kind", "bzr.kind", FT_CHAR, BASE_HEX,

            VALS(message_part_kind), 0x0, NULL, HFILL },

        },

        { &hf_bzr_packet_protocol_version,

          { "Protocol version", "bzr.protocol_version", FT_STRING, BASE_NONE,

            NULL, 0x0, NULL, HFILL },

        },

        { &hf_bzr_prefixed_bencode,

          { "Bencode packet", "bzr.bencode", FT_NONE, BASE_NONE, NULL, 0x0,

            "Serialized structure of integers, dictionaries, strings and "

            "lists.", HFILL },

        },

        { &hf_bzr_prefixed_bencode_len,

          { "Bencode packet length", "bzr.bencode.length", FT_UINT32,

            BASE_HEX, NULL, 0x0, NULL, HFILL },

        },

        { &hf_bzr_bytes,

          { "Prefixed bytes", "bzr.bytes", FT_NONE, BASE_NONE, NULL, 0x0,

            "Bytes field with prefixed 32-bit length", HFILL },

        },

        { &hf_bzr_bytes_data,

          { "Prefixed bytes data", "bzr.bytes.data", FT_BYTES, BASE_NONE,

            NULL, 0x0, NULL, HFILL },

        },

        { &hf_bzr_bytes_length,

          { "Prefixed bytes length", "bzr.bytes.length", FT_UINT32, BASE_HEX,

            NULL, 0x0, NULL, HFILL },

        },

        { &hf_bzr_result,

          { "Result", "bzr.result", FT_CHAR, BASE_HEX,

            VALS(message_results), 0x0,

            "Command result (success or failure with error message)", HFILL

          },

        },

    };

    static int *ett[] = {

        &ett_bzr,

        &ett_prefixed_bencode,

        &ett_prefixed_bytes,

    };

    module_t *bzr_module;

    proto_bzr = proto_register_protocol("Bazaar Smart Protocol", "Bazaar", "bzr");

    bzr_handle = register_dissector("bzr", dissect_bzr, proto_bzr);

    proto_register_field_array(proto_bzr, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

    bzr_module = prefs_register_protocol(proto_bzr, NULL);

    prefs_register_bool_preference(bzr_module, "desegment",

                                   "Reassemble Bazaar messages spanning multiple TCP segments",

                                   "Whether the Bazaar dissector should reassemble messages spanning multiple TCP segments."

                                   " To use this option, you must also enable \"Allow subdissectors to reassemble TCP streams\""

                                   " in the TCP protocol settings.",

                                   &bzr_desegment);

}

void

proto_reg_handoff_bzr(void)

{

    bencode_handle = find_dissector_add_dependency("bencode", proto_bzr);

    dissector_add_uint_with_preference("tcp.port", TCP_PORT_BZR, bzr_handle);

}

/*

 * 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:

 */