/* packet-distcc.c

 * Routines for distcc dissection

 * Copyright 2003, Brad Hards <bradh@frogmouth.net>

 * Copyright 2003, Ronnie Sahlberg, added TCP desegmentation.

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

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

 */

/*

 * This dissector supports version 1 of the DISTCC protocol:

 *

 *    https://github.com/distcc/distcc/blob/master/doc/protocol-1.txt

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/expert.h>

#include <epan/prefs.h>

#include <wsutil/strtoi.h>

static int proto_distcc;

static int hf_distcc_version;

static int hf_distcc_argc;

static int hf_distcc_argv;

static int hf_distcc_doti_source;

static int hf_distcc_stat;

static int hf_distcc_serr;

static int hf_distcc_sout;

static int hf_distcc_doto_object;

static int ett_distcc;

static expert_field ei_distcc_short_pdu;

static bool distcc_desegment = true;

#define TCP_PORT_DISTCC 3632

void proto_register_distcc(void);

extern void proto_reg_handoff_distcc(void);

static dissector_handle_t distcc_handle;

/*

 * Check that the value of a token, "parameter" octets at "offset", is all

 * there.  If it is not and TCP can give us more data, ask for the rest of

 * the PDU, starting at the token, and stop; otherwise dissect what there

 * is (the caller marks the item as short).

 */

#define CHECK_PDU_LEN(x) \

    if(parameter>(unsigned)tvb_captured_length_remaining(tvb, offset)){\

        if(distcc_desegment && pinfo->can_desegment &&\

           tvb_captured_length_remaining(tvb, offset)==tvb_reported_length_remaining(tvb, offset)){\

            pinfo->desegment_offset=offset-12;\

            pinfo->desegment_len=parameter-(unsigned)tvb_captured_length_remaining(tvb, offset);\

            return tvb_captured_length(tvb);\

        }\

        len=tvb_captured_length_remaining(tvb, offset);\

        col_append_str(pinfo->cinfo, COL_INFO, "[Short " x " PDU] ");\

    }

static int

dissect_distcc_dist(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, uint32_t parameter)

{

    proto_tree_add_uint_format(tree, hf_distcc_version, tvb, offset-12, 12, parameter, "DIST: %u", parameter);

    col_append_fstr(pinfo->cinfo, COL_INFO, "DIST:%u ", parameter);

    return offset;

}

static int

dissect_distcc_done(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, uint32_t parameter)

{

    proto_tree_add_uint_format(tree, hf_distcc_version, tvb, offset-12, 12, parameter, "DONE: %u", parameter);

    col_append_fstr(pinfo->cinfo, COL_INFO, "DONE:%u ", parameter);

    return offset;

}

static int

dissect_distcc_stat(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, uint32_t parameter)

{

    proto_tree_add_uint_format(tree, hf_distcc_stat, tvb, offset-12, 12, parameter, "STAT: %u", parameter);

    col_append_fstr(pinfo->cinfo, COL_INFO, "STAT:%u ", parameter);

    return offset;

}

static int

dissect_distcc_argc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, uint32_t parameter)

{

    proto_tree_add_uint(tree, hf_distcc_argc, tvb, offset-12, 12, parameter);

    col_append_fstr(pinfo->cinfo, COL_INFO, "ARGC:%u ", parameter);

    return offset;

}

static int

dissect_distcc_argv(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, unsigned parameter)

{

    int len=(int)parameter;

    char *argv;

    proto_item* ti;

    /* see if we need to desegment the PDU */

    CHECK_PDU_LEN("ARGV");

    /*

     * XXX - we have no idea what encoding is being used, other than

     * it being some flavor of "extended ASCII"; these days, it's

     * *probably* UTF-8, but it could conceivably be something else.

     */

    ti = proto_tree_add_item_ret_display_string(tree, hf_distcc_argv, tvb, offset, len, ENC_ASCII|ENC_NA, pinfo->pool, &argv);

    col_append_fstr(pinfo->cinfo, COL_INFO, "%s ", argv);

    if(len!=(int)parameter){

        expert_add_info_format(pinfo, ti, &ei_distcc_short_pdu, "[Short ARGV PDU]");

    }

    return offset+len;

}

static int

dissect_distcc_serr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, unsigned parameter)

{

    int len=(int)parameter;

    char *serr;

    proto_item* ti;

    /* see if we need to desegment the PDU */

    CHECK_PDU_LEN("SERR");

    /*

     * XXX - we have no idea what encoding is being used, other than

     * it being some flavor of "extended ASCII"; these days, it's

     * *probably* UTF-8, but it could conceivably be something else.

     */

    ti = proto_tree_add_item_ret_display_string(tree, hf_distcc_serr, tvb, offset, len, ENC_ASCII|ENC_NA, pinfo->pool, &serr);

    col_append_fstr(pinfo->cinfo, COL_INFO, "SERR:%s ", serr);

    if(len!=(int)parameter){

        expert_add_info_format(pinfo, ti, &ei_distcc_short_pdu, "[Short SERR PDU]");

    }

    return offset+len;

}

static int

dissect_distcc_sout(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, unsigned parameter)

{

    int len=(int)parameter;

    char *sout;

    proto_item* ti;

    /* see if we need to desegment the PDU */

    CHECK_PDU_LEN("SOUT");

    /*

     * XXX - we have no idea what encoding is being used, other than

     * it being some flavor of "extended ASCII"; these days, it's

     * *probably* UTF-8, but it could conceivably be something else.

     */

    ti = proto_tree_add_item_ret_display_string(tree, hf_distcc_sout, tvb, offset, len, ENC_ASCII|ENC_NA, pinfo->pool, &sout);

    col_append_fstr(pinfo->cinfo, COL_INFO, "SOUT:%s ", sout);

    if(len!=(int)parameter){

        expert_add_info_format(pinfo, ti, &ei_distcc_short_pdu, "[Short SOUT PDU]");

    }

    return offset+len;

}

static int

dissect_distcc_doti(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, unsigned parameter)

{

    int len=(int)parameter;

    proto_item* ti;

    /* see if we need to desegment the PDU */

    CHECK_PDU_LEN("DOTI");

    col_append_str(pinfo->cinfo, COL_INFO, "DOTI source ");

    ti = proto_tree_add_item(tree, hf_distcc_doti_source, tvb, offset, len, ENC_ASCII);

    if(len!=(int)parameter){

        expert_add_info_format(pinfo, ti, &ei_distcc_short_pdu, "[Short DOTI PDU]");

    }

    return offset+len;

}

static int

dissect_distcc_doto(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, unsigned parameter)

{

    int len=(int)parameter;

    proto_item* ti;

    /* see if we need to desegment the PDU */

    CHECK_PDU_LEN("DOTO");

    col_append_str(pinfo->cinfo, COL_INFO, "DOTO object ");

    ti = proto_tree_add_item(tree, hf_distcc_doto_object, tvb, offset, len, ENC_NA);

    if(len!=(int)parameter){

        expert_add_info_format(pinfo, ti, &ei_distcc_short_pdu, "[Short DOTO PDU]");

    }

    return offset+len;

}

/* Packet dissection routine called by tcp (& udp) when port 3632 detected */

static int

dissect_distcc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data _U_)

{

    int offset=0;

    proto_tree *tree=NULL;

    proto_item *item=NULL;

    char buf[13];

    uint32_t parameter;

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

    col_clear(pinfo->cinfo, COL_INFO);

    if (parent_tree) {

        item = proto_tree_add_item(parent_tree, proto_distcc, tvb, offset,

            -1, ENC_NA);

        tree = proto_item_add_subtree(item, ett_distcc);

    }

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

        if (tvb_captured_length_remaining(tvb, offset) < 12) {

            /* the token is split over segments */

            if (distcc_desegment && pinfo->can_desegment &&

                tvb_captured_length_remaining(tvb, offset) == tvb_reported_length_remaining(tvb, offset)) {

                pinfo->desegment_offset = offset;

                pinfo->desegment_len = 12 - tvb_captured_length_remaining(tvb, offset);

                return tvb_captured_length(tvb);

            }

            proto_tree_add_expert_format_remaining(tree, pinfo, &ei_distcc_short_pdu, tvb, offset, "[Short token]");

            break;

        }

        /* read the raw token (4 bytes) and parameter (8 bytes) */

        tvb_memcpy(tvb, buf, offset, 12);

        buf[12] = '\0';

        offset+=12;

        /* get the parameter value */

        if (!ws_hexstrtou32(buf + 4, NULL, &parameter))

            return offset;

        if(!strncmp(buf, "DIST", 4)){

            offset=dissect_distcc_dist(tvb, pinfo, tree, offset, parameter);

        } else if(!strncmp(buf, "ARGC", 4)){

            offset=dissect_distcc_argc(tvb, pinfo, tree, offset, parameter);

        } else if(!strncmp(buf, "ARGV", 4)){

            offset=dissect_distcc_argv(tvb, pinfo, tree, offset, parameter);

        } else if(!strncmp(buf, "DOTI", 4)){

            offset=dissect_distcc_doti(tvb, pinfo, tree, offset, parameter);

        } else if(!strncmp(buf, "DONE", 4)){

            offset=dissect_distcc_done(tvb, pinfo, tree, offset, parameter);

        } else if(!strncmp(buf, "STAT", 4)){

            offset=dissect_distcc_stat(tvb, pinfo, tree, offset, parameter);

        } else if(!strncmp(buf, "SERR", 4)){

            offset=dissect_distcc_serr(tvb, pinfo, tree, offset, parameter);

        } else if(!strncmp(buf, "SOUT", 4)){

            offset=dissect_distcc_sout(tvb, pinfo, tree, offset, parameter);

        } else if(!strncmp(buf, "DOTO", 4)){

            offset=dissect_distcc_doto(tvb, pinfo, tree, offset, parameter);

        } else {

            call_data_dissector(tvb, pinfo, tree);

            break;

        }

    }

    return tvb_captured_length(tvb);

}

/* Register protocol with Wireshark. */

void

proto_register_distcc(void)

{

    static hf_register_info hf[] = {

    {&hf_distcc_version,

     {"DISTCC Version", "distcc.version",

      FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL }

    },

    {&hf_distcc_argc,

     {"ARGC", "distcc.argc",

      FT_UINT32, BASE_DEC, NULL, 0x0, "Number of arguments", HFILL }

    },

    {&hf_distcc_argv,

     {"ARGV", "distcc.argv",

      FT_STRING, BASE_NONE, NULL, 0x0, "ARGV argument", HFILL }

    },

    {&hf_distcc_doti_source,

     {"Source", "distcc.doti_source",

      FT_STRING, BASE_NONE, NULL, 0x0, "DOTI Preprocessed Source File (.i)", HFILL }

    },

    {&hf_distcc_stat,

     {"Status", "distcc.status",

      FT_UINT32, BASE_DEC, NULL, 0x0, "Unix wait status for command completion", HFILL }

    },

    {&hf_distcc_serr,

     {"SERR", "distcc.serr",

      FT_STRING, BASE_NONE, NULL, 0x0, "STDERR output", HFILL }

    },

    {&hf_distcc_sout,

     {"SOUT", "distcc.sout",

      FT_STRING, BASE_NONE, NULL, 0x0, "STDOUT output", HFILL }

    },

    {&hf_distcc_doto_object,

     {"Object", "distcc.doto_object",

      FT_BYTES, BASE_NONE, NULL, 0x0, "DOTO Compiled object file (.o)", HFILL }

    }

    };

    static int *ett[] = {

        &ett_distcc,

    };

    static ei_register_info ei[] = {

        { &ei_distcc_short_pdu, { "distcc.short_pdu", PI_MALFORMED, PI_ERROR, "Short PDU", EXPFILL }},

    };

    module_t *distcc_module;

    expert_module_t* expert_distcc;

    proto_distcc = proto_register_protocol("Distcc Distributed Compiler", "DISTCC", "distcc");

    proto_register_field_array(proto_distcc, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

    expert_distcc = expert_register_protocol(proto_distcc);

    expert_register_field_array(expert_distcc, ei, array_length(ei));

    distcc_module = prefs_register_protocol(proto_distcc, NULL);

    prefs_register_bool_preference(distcc_module, "desegment_distcc_over_tcp",

        "Reassemble DISTCC-over-TCP messages spanning multiple TCP segments",

        "Whether the DISTCC 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.",

        &distcc_desegment);

    distcc_handle = register_dissector("distcc", dissect_distcc, proto_distcc);

}

void

proto_reg_handoff_distcc(void)

{

    dissector_add_uint_with_preference("tcp.port", TCP_PORT_DISTCC, distcc_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:

 */