sharkd.c

/* sharkd.c
 *
 * Daemon variant of Wireshark
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#include <config.h>
#define WS_LOG_DOMAIN  LOG_DOMAIN_MAIN

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <limits.h>
#include <signal.h>

#include <glib.h>

#include <epan/exceptions.h>
#include <epan/epan.h>

#include <wsutil/clopts_common.h>
#include <wsutil/cmdarg_err.h>
#include <wsutil/filesystem.h>
#include <wsutil/file_util.h>
#include <wsutil/privileges.h>
#include <wsutil/wslog.h>
#include <wsutil/version_info.h>
#include <wiretap/wtap_opttypes.h>

#include <epan/decode_as.h>
#include <epan/timestamp.h>
#include <epan/packet.h>
#include "frame_tvbuff.h"
#include <epan/disabled_protos.h>
#include <epan/prefs.h>
#include <epan/column.h>
#include <epan/print.h>
#include <epan/addr_resolv.h>
#include "ui/util.h"
#include "ui/ws_ui_util.h"
#include "ui/decode_as_utils.h"
#include "wsutil/filter_files.h"
#include "ui/tap_export_pdu.h"
#include "ui/failure_message.h"
#include <wiretap/wtap.h>
#include <epan/epan_dissect.h>
#include <epan/tap.h>
#include <epan/uat-int.h>
#include <epan/secrets.h>

#include <wsutil/codecs.h>

#include <wsutil/str_util.h>
#include <wsutil/utf8_entities.h>

#ifdef HAVE_PLUGINS
#include <wsutil/plugins.h>
#endif

#include "sharkd.h"

#define SHARKD_INIT_FAILED 1
#define SHARKD_EPAN_INIT_FAIL 2

capture_file cfile;

static uint32_t cum_bytes;
static frame_data ref_frame;

static void sharkd_cmdarg_err(const char *msg_format, va_list ap);
static void sharkd_cmdarg_err_cont(const char *msg_format, va_list ap);

static void
print_current_user(void)
{
    char *cur_user, *cur_group;

    if (started_with_special_privs()) {
        cur_user = get_cur_username();
        cur_group = get_cur_groupname();
        fprintf(stderr, "Running as user \"%s\" and group \"%s\".",
                cur_user, cur_group);
        g_free(cur_user);
        g_free(cur_group);
        if (running_with_special_privs()) {
            fprintf(stderr, " This could be dangerous.");
        }
        fprintf(stderr, "\n");
    }
}

int
main(int argc, char *argv[])
{
    char                *configuration_init_error;

    char                *err_msg = NULL;
    e_prefs             *prefs_p;
    int                  ret = EXIT_SUCCESS;

    cmdarg_err_init(sharkd_cmdarg_err, sharkd_cmdarg_err_cont);

    /* Initialize log handler early so we can have proper logging during startup. */
    ws_log_init("sharkd", vcmdarg_err);

    /* Early logging command-line initialization. */
    ws_log_parse_args(&argc, argv, vcmdarg_err, SHARKD_INIT_FAILED);

    ws_noisy("Finished log init and parsing command line log arguments");

    /*
     * Get credential information for later use, and drop privileges
     * before doing anything else.
     * Let the user know if anything happened.
     */
    init_process_policies();
    relinquish_special_privs_perm();
    print_current_user();

    /*
     * Attempt to get the pathname of the executable file.
     */
    configuration_init_error = configuration_init(argv[0], NULL);
    if (configuration_init_error != NULL) {
        fprintf(stderr, "sharkd: Can't get pathname of sharkd program: %s.\n",
                configuration_init_error);
    }

    /* Initialize the version information. */
    ws_init_version_info("Sharkd",
                         epan_gather_compile_info,
                         epan_gather_runtime_info);

    if (sharkd_init(argc, argv) < 0)
    {
        printf("cannot initialize sharkd\n");
        ret = SHARKD_INIT_FAILED;
        goto clean_exit;
    }

    init_report_failure_message("sharkd");

    timestamp_set_type(TS_RELATIVE);
    timestamp_set_precision(TS_PREC_AUTO);
    timestamp_set_seconds_type(TS_SECONDS_DEFAULT);

    /*
     * Libwiretap must be initialized before libwireshark is, so that
     * dissection-time handlers for file-type-dependent blocks can
     * register using the file type/subtype value for the file type.
     */
    wtap_init(true);

    /* Register all dissectors; we must do this before checking for the
       "-G" flag, as the "-G" flag dumps information registered by the
       dissectors, and we must do it before we read the preferences, in
       case any dissectors register preferences. */
    if (!epan_init(NULL, NULL, true)) {
        ret = SHARKD_EPAN_INIT_FAIL;
        goto clean_exit;
    }

    codecs_init();

    /* Load libwireshark settings from the current profile. */
    prefs_p = epan_load_settings();

    if (!color_filters_init(&err_msg, NULL)) {
        fprintf(stderr, "%s\n", err_msg);
        g_free(err_msg);
    }

    cap_file_init(&cfile);

    /* Notify all registered modules that have had any of their preferences
       changed either from one of the preferences file or from the command
       line that their preferences have changed. */
    prefs_apply_all();

    /* Build the column format array */
    build_column_format_array(&cfile.cinfo, prefs_p->num_cols, true);

#ifdef HAVE_MAXMINDDB
    /* mmdbresolve is started from mmdb_resolve_start(), which is called from epan_load_settings via: read_prefs -> (...) uat_load_all -> maxmind_db_post_update_cb.
     * Need to stop it, otherwise all sharkd will have same mmdbresolve process, including pipe descriptors to read and write. */
    uat_get_table_by_name("MaxMind Database Paths")->reset_cb();
#endif

    ret = sharkd_loop(argc, argv);
clean_exit:
    col_cleanup(&cfile.cinfo);
    codecs_cleanup();
    wtap_cleanup();
    free_progdirs();
    return ret;
}

static epan_t *
sharkd_epan_new(capture_file *cf)
{
    static const struct packet_provider_funcs funcs = {
        cap_file_provider_get_frame_ts,
        cap_file_provider_get_interface_name,
        cap_file_provider_get_interface_description,
        cap_file_provider_get_modified_block
    };

    return epan_new(&cf->provider, &funcs);
}

static bool
process_packet(capture_file *cf, epan_dissect_t *edt,
        int64_t offset, wtap_rec *rec, Buffer *buf)
{
    frame_data     fdlocal;
    bool           passed;

    /* If we're not running a display filter and we're not printing any
       packet information, we don't need to do a dissection. This means
       that all packets can be marked as 'passed'. */
    passed = true;

    /* The frame number of this packet, if we add it to the set of frames,
       would be one more than the count of frames in the file so far. */
    frame_data_init(&fdlocal, cf->count + 1, rec, offset, cum_bytes);

    /* If we're going to print packet information, or we're going to
       run a read filter, or display filter, or we're going to process taps, set up to
       do a dissection and do so. */
    if (edt) {
        if (gbl_resolv_flags.mac_name || gbl_resolv_flags.network_name ||
                gbl_resolv_flags.transport_name)
            /* Grab any resolved addresses */
            host_name_lookup_process();

        /* If we're running a read filter, prime the epan_dissect_t with that
           filter. */
        if (cf->rfcode)
            epan_dissect_prime_with_dfilter(edt, cf->rfcode);

        if (cf->dfcode)
            epan_dissect_prime_with_dfilter(edt, cf->dfcode);

        /* This is the first and only pass, so prime the epan_dissect_t
           with the hfids postdissectors want on the first pass. */
        prime_epan_dissect_with_postdissector_wanted_hfids(edt);

        frame_data_set_before_dissect(&fdlocal, &cf->elapsed_time,
                &cf->provider.ref, cf->provider.prev_dis);
        if (cf->provider.ref == &fdlocal) {
            ref_frame = fdlocal;
            cf->provider.ref = &ref_frame;
        }

        epan_dissect_run(edt, cf->cd_t, rec,
                frame_tvbuff_new_buffer(&cf->provider, &fdlocal, buf),
                &fdlocal, NULL);

        /* Run the read filter if we have one. */
        if (cf->rfcode)
            passed = dfilter_apply_edt(cf->rfcode, edt);
    }

    if (passed) {
        frame_data_set_after_dissect(&fdlocal, &cum_bytes);
        cf->provider.prev_cap = cf->provider.prev_dis = frame_data_sequence_add(cf->provider.frames, &fdlocal);

        /* If we're not doing dissection then there won't be any dependent frames.
         * More importantly, edt.pi.fd.dependent_frames won't be initialized because
         * epan hasn't been initialized.
         * if we *are* doing dissection, then mark the dependent frames, but only
         * if a display filter was given and it matches this packet.
         */
        if (edt && cf->dfcode) {
            if (dfilter_apply_edt(cf->dfcode, edt) && edt->pi.fd->dependent_frames) {
                g_hash_table_foreach(edt->pi.fd->dependent_frames, find_and_mark_frame_depended_upon, cf->provider.frames);
            }
        }

        cf->count++;
    } else {
        /* if we don't add it to the frame_data_sequence, clean it up right now
         * to avoid leaks */
        frame_data_destroy(&fdlocal);
    }

    if (edt)
        epan_dissect_reset(edt);

    return passed;
}


static int
load_cap_file(capture_file *cf, int max_packet_count, int64_t max_byte_count)
{
    int          err;
    char        *err_info = NULL;
    int64_t      data_offset;
    wtap_rec     rec;
    Buffer       buf;
    epan_dissect_t *edt = NULL;

    {
        /* Allocate a frame_data_sequence for all the frames. */
        cf->provider.frames = new_frame_data_sequence();

        {
            bool create_proto_tree;

            /*
             * Determine whether we need to create a protocol tree.
             * We do if:
             *
             *    we're going to apply a read filter;
             *
             *    we're going to apply a display filter;
             *
             *    a postdissector wants field values or protocols
             *    on the first pass.
             */
            create_proto_tree =
                (cf->rfcode != NULL || cf->dfcode != NULL || postdissectors_want_hfids());

            /* We're not going to display the protocol tree on this pass,
               so it's not going to be "visible". */
            edt = epan_dissect_new(cf->epan, create_proto_tree, false);
        }

        wtap_rec_init(&rec);
        ws_buffer_init(&buf, 1514);

        while (wtap_read(cf->provider.wth, &rec, &buf, &err, &err_info, &data_offset)) {
            if (process_packet(cf, edt, data_offset, &rec, &buf)) {
                wtap_rec_reset(&rec);
                /* Stop reading if we have the maximum number of packets;
                 * When the -c option has not been used, max_packet_count
                 * starts at 0, which practically means, never stop reading.
                 * (unless we roll over max_packet_count ?)
                 */
                if ( (--max_packet_count == 0) || (max_byte_count != 0 && data_offset >= max_byte_count)) {
                    err = 0; /* This is not an error */
                    break;
                }
            }
        }

        if (edt) {
            epan_dissect_free(edt);
            edt = NULL;
        }

        wtap_rec_cleanup(&rec);
        ws_buffer_free(&buf);

        /* Close the sequential I/O side, to free up memory it requires. */
        wtap_sequential_close(cf->provider.wth);

        /* Allow the protocol dissectors to free up memory that they
         * don't need after the sequential run-through of the packets. */
        postseq_cleanup_all_protocols();

        cf->provider.prev_dis = NULL;
        cf->provider.prev_cap = NULL;
    }

    if (err != 0) {
        cfile_read_failure_message(cf->filename, err, err_info);
    }

    return err;
}

cf_status_t
cf_open(capture_file *cf, const char *fname, unsigned int type, bool is_tempfile, int *err)
{
    wtap  *wth;
    char *err_info;

    wth = wtap_open_offline(fname, type, err, &err_info, true);
    if (wth == NULL)
        goto fail;

    /* The open succeeded.  Fill in the information for this file. */

    cf->provider.wth = wth;
    cf->f_datalen = 0; /* not used, but set it anyway */

    /* Set the file name because we need it to set the follow stream filter.
       XXX - is that still true?  We need it for other reasons, though,
       in any case. */
    cf->filename = g_strdup(fname);

    /* Indicate whether it's a permanent or temporary file. */
    cf->is_tempfile = is_tempfile;

    /* No user changes yet. */
    cf->unsaved_changes = false;

    cf->cd_t      = wtap_file_type_subtype(cf->provider.wth);
    cf->open_type = type;
    cf->count     = 0;
    cf->drops_known = false;
    cf->drops     = 0;
    cf->snap      = wtap_snapshot_length(cf->provider.wth);
    nstime_set_zero(&cf->elapsed_time);
    cf->provider.ref = NULL;
    cf->provider.prev_dis = NULL;
    cf->provider.prev_cap = NULL;

    /* Create new epan session for dissection. */
    epan_free(cf->epan);
    cf->epan = sharkd_epan_new(cf);

    cf->state = FILE_READ_IN_PROGRESS;

    wtap_set_cb_new_ipv4(cf->provider.wth, add_ipv4_name);
    wtap_set_cb_new_ipv6(cf->provider.wth, (wtap_new_ipv6_callback_t) add_ipv6_name);
    wtap_set_cb_new_secrets(cf->provider.wth, secrets_wtap_callback);

    return CF_OK;

fail:
    cfile_open_failure_message(fname, *err, err_info);
    return CF_ERROR;
}

/*
 * Report an error in command-line arguments.
 */
static void
sharkd_cmdarg_err(const char *msg_format, va_list ap)
{
    fprintf(stderr, "sharkd: ");
    vfprintf(stderr, msg_format, ap);
    fprintf(stderr, "\n");
}

/*
 * Report additional information for an error in command-line arguments.
 */
static void
sharkd_cmdarg_err_cont(const char *msg_format, va_list ap)
{
    vfprintf(stderr, msg_format, ap);
    fprintf(stderr, "\n");
}

cf_status_t
sharkd_cf_open(const char *fname, unsigned int type, bool is_tempfile, int *err)
{
    return cf_open(&cfile, fname, type, is_tempfile, err);
}

int
sharkd_load_cap_file(void)
{
    return load_cap_file(&cfile, 0, 0);
}

frame_data *
sharkd_get_frame(uint32_t framenum)
{
    return frame_data_sequence_find(cfile.provider.frames, framenum);
}

enum dissect_request_status
sharkd_dissect_request(uint32_t framenum, uint32_t frame_ref_num,
        uint32_t prev_dis_num, wtap_rec *rec, Buffer *buf,
        column_info *cinfo, uint32_t dissect_flags,
        sharkd_dissect_func_t cb, void *data,
        int *err, char **err_info)
{
    frame_data *fdata;
    epan_dissect_t edt;
    bool create_proto_tree;

    fdata = sharkd_get_frame(framenum);
    if (fdata == NULL)
        return DISSECT_REQUEST_NO_SUCH_FRAME;

    if (!wtap_seek_read(cfile.provider.wth, fdata->file_off, rec, buf, err, err_info)) {
        if (cinfo != NULL)
            col_fill_in_error(cinfo, fdata, false, false /* fill_fd_columns */);
        return DISSECT_REQUEST_READ_ERROR; /* error reading the record */
    }

    create_proto_tree = ((dissect_flags & SHARKD_DISSECT_FLAG_PROTO_TREE) ||
            ((dissect_flags & SHARKD_DISSECT_FLAG_COLOR) && color_filters_used()) ||
            (cinfo && have_custom_cols(cinfo)));
    epan_dissect_init(&edt, cfile.epan, create_proto_tree, (dissect_flags & SHARKD_DISSECT_FLAG_PROTO_TREE));

    if (dissect_flags & SHARKD_DISSECT_FLAG_COLOR) {
        color_filters_prime_edt(&edt);
        fdata->need_colorize = 1;
    }

    if (cinfo)
        col_custom_prime_edt(&edt, cinfo);

    /*
     * XXX - need to catch an OutOfMemoryError exception and
     * attempt to recover from it.
     */
    fdata->ref_time = (framenum == frame_ref_num);
    fdata->frame_ref_num = frame_ref_num;
    fdata->prev_dis_num = prev_dis_num;
    epan_dissect_run(&edt, cfile.cd_t, rec,
            frame_tvbuff_new_buffer(&cfile.provider, fdata, buf),
            fdata, cinfo);

    if (cinfo) {
        /* "Stringify" non frame_data vals */
        epan_dissect_fill_in_columns(&edt, false, true/* fill_fd_columns */);
    }

    cb(&edt, (dissect_flags & SHARKD_DISSECT_FLAG_PROTO_TREE) ? edt.tree : NULL,
            cinfo, (dissect_flags & SHARKD_DISSECT_FLAG_BYTES) ? edt.pi.data_src : NULL,
            data);

    wtap_rec_reset(rec);
    epan_dissect_cleanup(&edt);
    return DISSECT_REQUEST_SUCCESS;
}

int
sharkd_retap(void)
{
    uint32_t         framenum;
    frame_data      *fdata;
    Buffer           buf;
    wtap_rec         rec;
    int err;
    char *err_info = NULL;

    unsigned      tap_flags;
    bool          create_proto_tree;
    epan_dissect_t edt;
    column_info   *cinfo;

    /* Get the union of the flags for all tap listeners. */
    tap_flags = union_of_tap_listener_flags();

    /* If any tap listeners require the columns, construct them. */
    cinfo = (tap_listeners_require_columns()) ? &cfile.cinfo : NULL;

    /*
     * Determine whether we need to create a protocol tree.
     * We do if:
     *
     *    one of the tap listeners is going to apply a filter;
     *
     *    one of the tap listeners requires a protocol tree.
     */
    create_proto_tree =
        (have_filtering_tap_listeners() || (tap_flags & TL_REQUIRES_PROTO_TREE));

    wtap_rec_init(&rec);
    ws_buffer_init(&buf, 1514);
    epan_dissect_init(&edt, cfile.epan, create_proto_tree, false);

    reset_tap_listeners();

    for (framenum = 1; framenum <= cfile.count; framenum++) {
        fdata = sharkd_get_frame(framenum);

        if (!wtap_seek_read(cfile.provider.wth, fdata->file_off, &rec, &buf, &err, &err_info))
            break;

        fdata->ref_time = false;
        fdata->frame_ref_num = (framenum != 1) ? 1 : 0;
        fdata->prev_dis_num = framenum - 1;
        epan_dissect_run_with_taps(&edt, cfile.cd_t, &rec,
                frame_tvbuff_new_buffer(&cfile.provider, fdata, &buf),
                fdata, cinfo);
        wtap_rec_reset(&rec);
        epan_dissect_reset(&edt);
    }

    wtap_rec_cleanup(&rec);
    ws_buffer_free(&buf);
    epan_dissect_cleanup(&edt);

    draw_tap_listeners(true);

    return 0;
}

int
sharkd_filter(const char *dftext, uint8_t **result)
{
    dfilter_t  *dfcode = NULL;

    uint32_t framenum, prev_dis_num = 0;
    uint32_t frames_count;
    Buffer buf;
    wtap_rec rec;
    int err;
    char *err_info = NULL;

    uint8_t *result_bits;
    uint8_t passed_bits;

    epan_dissect_t edt;

    if (!dfilter_compile(dftext, &dfcode, NULL)) {
        return -1;
    }

    /* if dfilter_compile() success, but (dfcode == NULL) all frames are matching */
    if (dfcode == NULL) {
        *result = NULL;
        return 0;
    }

    frames_count = cfile.count;

    wtap_rec_init(&rec);
    ws_buffer_init(&buf, 1514);
    epan_dissect_init(&edt, cfile.epan, true, false);

    passed_bits = 0;
    result_bits = (uint8_t *) g_malloc(2 + (frames_count / 8));

    for (framenum = 1; framenum <= frames_count; framenum++) {
        frame_data *fdata = sharkd_get_frame(framenum);

        if ((framenum & 7) == 0) {
            result_bits[(framenum / 8) - 1] = passed_bits;
            passed_bits = 0;
        }

        if (!wtap_seek_read(cfile.provider.wth, fdata->file_off, &rec, &buf, &err, &err_info))
            break;

        /* frame_data_set_before_dissect */
        epan_dissect_prime_with_dfilter(&edt, dfcode);

        fdata->ref_time = false;
        fdata->frame_ref_num = (framenum != 1) ? 1 : 0;
        fdata->prev_dis_num = prev_dis_num;
        epan_dissect_run(&edt, cfile.cd_t, &rec,
                frame_tvbuff_new_buffer(&cfile.provider, fdata, &buf),
                fdata, NULL);

        if (dfilter_apply_edt(dfcode, &edt)) {
            passed_bits |= (1 << (framenum % 8));
            prev_dis_num = framenum;
        }

        /* if passed or ref -> frame_data_set_after_dissect */

        wtap_rec_reset(&rec);
        epan_dissect_reset(&edt);
    }

    if ((framenum & 7) == 0)
        framenum--;
    result_bits[framenum / 8] = passed_bits;

    wtap_rec_cleanup(&rec);
    ws_buffer_free(&buf);
    epan_dissect_cleanup(&edt);

    dfilter_free(dfcode);

    *result = result_bits;

    return framenum;
}

/*
 * Get the modified block if available, nothing otherwise.
 * Must be cloned if changes desired.
 */
wtap_block_t
sharkd_get_modified_block(const frame_data *fd)
{
    return cap_file_provider_get_modified_block(&cfile.provider, fd);
}

/*
 * Gets the modified block if available, otherwise the packet's default block,
 * or a new packet block.
 * User must wtap_block_unref() it when done.
 */
wtap_block_t
sharkd_get_packet_block(const frame_data *fd)
{
    if (fd->has_modified_block)
        return wtap_block_ref(cap_file_provider_get_modified_block(&cfile.provider, fd));
    else
    {
        wtap_rec rec; /* Record metadata */
        Buffer buf;   /* Record data */
        wtap_block_t block;
        int err;
        char *err_info;

        wtap_rec_init(&rec);
        ws_buffer_init(&buf, 1514);

        if (!wtap_seek_read(cfile.provider.wth, fd->file_off, &rec, &buf, &err, &err_info))
        { /* XXX, what we can do here? */ }

        /* rec.block is owned by the record, steal it before it is gone. */
        block = wtap_block_ref(rec.block);

        wtap_rec_cleanup(&rec);
        ws_buffer_free(&buf);
        return block;
    }
}

int
sharkd_set_modified_block(frame_data *fd, wtap_block_t new_block)
{
    cap_file_provider_set_modified_block(&cfile.provider, fd, new_block);
    return 0;
}