wireshark/ui/capture_ui_utils.c

/* capture_ui_utils.c
 * Utilities for capture user interfaces
 *
 * 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"

#ifdef HAVE_LIBPCAP

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <glib.h>

#include "epan/prefs.h"
#include "epan/ex-opt.h"
#include "capture/capture_ifinfo.h"
#include "ui/capture_ui_utils.h"
#include "ui/capture_globals.h"
#include "wiretap/wtap.h"
#include "epan/to_str.h"
#include "wsutil/strtoi.h"

/*
 * In a list of interface information, in the form of a comma-separated
 * list of {name}({property}) items, find the entry for a particular
 * interface, and return a pointer a g_malloced string containing
 * the property.
 */
static char *
capture_dev_get_if_property(const char *pref, const char *if_name)
{
    char **if_tokens;
    char *property = NULL;
    int i;

    if (if_name == NULL || strlen(if_name) < 1) {
        return NULL;
    }

    if (pref == NULL || strlen(pref) < 1) {
        /* There is no interface information list. */
        return NULL;
    }

    /*
     * Split the list into a sequence of items.
     *
     * XXX - this relies on the items not themselves containing commas.
     */
    if_tokens = g_strsplit(pref, ",", -1);
    for (i = 0; if_tokens[i] != NULL; i++) {
        char *opening_parenp, *closing_parenp;

        /*
         * Separate this item into name and property.
         * The first opening parenthesis and the last closing parenthesis
         * surround the property.  Any other parentheses are part of
         * the property.
         */
        opening_parenp = strchr(if_tokens[i], '(');
        if (opening_parenp == NULL) {
            /* No opening parenthesis. Give up. */
            break;
        }
        closing_parenp = strrchr(if_tokens[i], ')');
        if (closing_parenp == NULL || closing_parenp <= opening_parenp) {
            /* No closing parenthesis or invalid input. Give up. */
            break;
        }
        *opening_parenp = '\0'; /* Split {name} from what follows */
        *closing_parenp = '\0'; /* Terminate {property} */
        if (strcmp(if_tokens[i], if_name) == 0) {
            if (strlen(opening_parenp + 1) > 0) {
                property = g_strdup(opening_parenp + 1);
            }
            break;
        }
    }
    g_strfreev(if_tokens);

    return property;
}

/*
 * Find a property that should be an integral value, and return the
 * value or, if it's not found or not a valid integral value, -1.
 */
static int
capture_dev_get_if_int_property(const char *pref, const char *if_name)
{
    char *property_string;
    int property;

    property_string = capture_dev_get_if_property(pref, if_name);
    if (property_string == NULL) {
        /* No property found for this interface. */
        return -1;
    }
    if (!ws_strtoi(property_string, NULL, &property)) {
        /* Syntax error or range error */
        g_free(property_string);
        return -1;
    }

    g_free(property_string);
    return property;
}

/*
 * Find user-specified capture device description that matches interface
 * name, if any.
 */
char *
capture_dev_user_descr_find(const char *if_name)
{
    char *descr = capture_dev_get_if_property(prefs.capture_devices_descr, if_name);
    if (descr == NULL && g_strcmp0(if_name, "-") == 0) {
        /*
         * Strictly speaking, -X (extension) options are for modules, e.g. Lua
         * and using one here stretches that definition. However, this doesn't
         * waste a single-letter option on something that might be rarely used
         * and is backward-compatible to 1.0.
         */
        descr = g_strdup(ex_opt_get_nth("stdin_descr", 0));
    }
    return descr;
}

int
capture_dev_user_linktype_find(const char *if_name)
{
    return capture_dev_get_if_int_property(prefs.capture_devices_linktypes, if_name);
}

int
capture_dev_user_buffersize_find(const char *if_name)
{
    return capture_dev_get_if_int_property(prefs.capture_devices_buffersize, if_name);
}

bool
capture_dev_user_snaplen_find(const char *if_name, bool *hassnap, int *snaplen)
{
    bool found = false;
    char **if_tokens;
    int i;

    if (if_name == NULL || strlen(if_name) < 1) {
        return false;
    }

    if ((prefs.capture_devices_snaplen == NULL) ||
            (*prefs.capture_devices_snaplen == '\0')) {
        /* There are no snap lengths defined */
        return false;
    }

    /*
     * Split the list into a sequence of items.
     *
     * XXX - this relies on the items not themselves containing commas.
     */
    if_tokens = g_strsplit(prefs.capture_devices_snaplen, ",", -1);
    for (i = 0; if_tokens[i] != NULL; i++) {
        char *colonp;
        const char *next;
        int value;

        /*
         * This one's a bit ugly.
         * The syntax of the item is {name}:{hassnap}({snaplen}),
         * where {hassnap} is 0 if the interface shouldn't have a snapshot
         * length and 1 if it should, and {snaplen} is the maximum snapshot
         * length if {hassnap} is 0 and the specified snapshot length if
         * {hassnap} is 1.
         *
         * Sadly, : was a bad choice of separator, given that, on some OSes,
         * an interface can have a colon in its name.
         *
         * So we look for the *last* colon in the string.
         */
        colonp = strrchr(if_tokens[i], ':');
        if (colonp == NULL) {
            /* No separating colon. Give up. */
            break;
        }
        *colonp = '\0'; /* Split {name} from what follows */
        if (strcmp(if_tokens[i], if_name) == 0) {
            /* OK, this matches. */
            if (*(colonp + 1) == '0') {
                /* {hassnap} is false, so just set the snaplen to WTAP_MAX_PACKET_SIZE_STANDARD. */
                found = true;
                *hassnap = false;
                *snaplen = WTAP_MAX_PACKET_SIZE_STANDARD;
            } else if (*(colonp + 1) == '1') {
                /* {hassnap} is true, so extract {snaplen} */
                if (*(colonp + 2) != '(') {
                    /* Not followed by a parenthesis. Give up. */
                    break;
                }
                if (!ws_strtoi(colonp + 3, &next, &value) ||
                    next == colonp + 3 || *next != ')' || value < 0) {
                    /* Syntax error or range error. Give up. */
                    break;
                }
                found = true;
                *hassnap = true;
                *snaplen = value;
            } else {
                /* Bad {hassnap}. Give up. */
                break;
            }
            break;
        }
    }
    g_strfreev(if_tokens);

    return found;
}

bool
capture_dev_user_pmode_find(const char *if_name, bool *pmode)
{
    int value;

    value = capture_dev_get_if_int_property(prefs.capture_devices_pmode, if_name);
    if (value == -1) {
        /* Not found or bad. */
        return false;
    }
    *pmode = (value != 0);
    return true;
}

char*
capture_dev_user_cfilter_find(const char *if_name)
{
    return capture_dev_get_if_property(prefs.capture_devices_filter, if_name);
}

/*
 * Return as descriptive a name for an interface as we can get.
 * If the user has specified a comment, use that.  Otherwise,
 * if the get_iface_list() method of capture_opts supplies a
 * description, use that, otherwise use the interface name.
 *
 * The result must be g_free()'d when you're done with it.
 *
 * Note: given that this likely calls capture_interface_list(), which
 * attempts to open all adapters it finds in order to check whether
 * they can be captured on, this is an expensive routine to call, so
 * don't call it frequently.
 */
char *
get_interface_descriptive_name(const capture_options *capture_opts, const char *if_name)
{
    char *descr;
    GList *if_list;
    GList *if_entry;
    if_info_t *if_info;
    int err;

    /* Do we have a user-supplied description? */
    descr = capture_dev_user_descr_find(if_name);
    if (descr == NULL) {
        /* No; try to construct a descriptive name. */
        if (strcmp(if_name, "-") == 0) {
            descr = g_strdup("Standard input");
        } else {
            /* No, we don't have a user-supplied description; did we get
               one from the OS or libpcap? */
            /* XXX: Search in capture_opts->ifaces (or all_ifaces) first? */
            if_list = capture_opts->get_iface_list(&err, NULL);
            if (if_list != NULL) {
                if_entry = if_list;
                do {
                    if_info = (if_info_t *)if_entry->data;
                    if (strcmp(if_info->name, if_name) == 0) {
                        if (if_info->friendly_name != NULL) {
                            /* We have a "friendly name"; return a copy of that
                               as the description - when we free the interface
                               list, that'll also free up the strings to which
                               it refers. */
                            descr = g_strdup(if_info->friendly_name);
                        } else if (if_info->vendor_description != NULL) {
                            /* We have no "friendly name", but we have a vendor
                               description; return a copy of that - when we free
                               the interface list, that'll also free up the strings
                               to which it refers. */
                            descr = g_strdup(if_info->vendor_description);
                        }
                        break;
                    }
                } while ((if_entry = g_list_next(if_entry)) != NULL);
            }
            free_interface_list(if_list);

            if (descr == NULL) {
                /* The interface name is all we have, so just return a copy of that. */
                descr = g_strdup(if_name);
            }
        }
    }

    return descr;
}

GList *
build_capture_combo_list(GList *if_list, bool do_hide)
{
    GList *combo_list;
    GList *if_entry;
    if_info_t *if_info;
    char *if_string;
    char *descr;

    combo_list = NULL;
    if (if_list != NULL) {
        /* Scan through the list and build a list of strings to display. */
        for (if_entry = if_list; if_entry != NULL;
                if_entry = g_list_next(if_entry)) {
            if_info = (if_info_t *)if_entry->data;

            /* Is this interface hidden and, if so, should we include it
               anyway? */
            if (!prefs_is_capture_device_hidden(if_info->name) || !do_hide) {
                /* It's not hidden, or it is but we should include it in the list. */

                /* Do we have a user-supplied description? */
                descr = capture_dev_user_descr_find(if_info->name);
                if (descr != NULL) {
                    /* Yes, we have a user-supplied description; use it. */
                    if_string = ws_strdup_printf("%s: %s", descr, if_info->name);
                    g_free(descr);
                } else {
                    /* No, we don't have a user-supplied description; did we get
                       one from the OS or libpcap? */
                    if (if_info->vendor_description != NULL) {
                        /* Yes - use it. */
                        if_string = ws_strdup_printf("%s: %s",
                                if_info->vendor_description,
                                if_info->name);
                    } else {
                        /* No. */
                        if_string = g_strdup(if_info->name);
                    }
                }
                combo_list = g_list_prepend(combo_list, if_string);
            }
        }/*for*/
        if(combo_list){
            combo_list = g_list_reverse(combo_list);
        }
    }
    return combo_list;
}

static void
free_if_string(void *data, void *user_data _U_)
{
    g_free(data);
}

void
free_capture_combo_list(GList *combo_list)
{
    if (combo_list != NULL) {
        g_list_foreach(combo_list, free_if_string, NULL);
        g_list_free(combo_list);
    }
}

/*
 * Given text that contains an interface name possibly prefixed by an
 * interface description, extract the interface name.
 */
const char *
get_if_name(const char *if_text)
{
    const char *if_name;

#ifdef _WIN32
    /*
     * We cannot assume that the interface name doesn't contain a space;
     * some names on Windows OT do.
     *
     * We also can't assume it begins with "\Device\", either, as, on
     * Windows OT, WinPcap doesn't put "\Device\" in front of the name.
     *
     * XXX - we don't support Windows OT any more; do we need to worry
     * about this?
     *
     * As I remember, we can't assume that the interface description
     * doesn't contain a colon, either; I think some do.
     *
     * We can probably assume that the interface *name* doesn't contain
     * a colon, however; if any interface name does contain a colon on
     * Windows, it'll be time to just get rid of the damn interface
     * descriptions in the drop-down list, have just the names in the
     * drop-down list, and have a "Browse..." button to browse for interfaces,
     * with names, descriptions, IP addresses, blah blah blah available when
     * possible.
     *
     * So we search backwards for a colon.  If we don't find it, just
     * return the entire string; otherwise, skip the colon and any blanks
     * after it, and return that string.
     */
    if_name = if_text + strlen(if_text);
    for (;;) {
        if (if_name == if_text) {
            /* We're at the beginning of the string; return it. */
            break;
        }
        if_name--;
        if (*if_name == ':') {
            /*
             * We've found a colon.
             * Unfortunately, a colon is used in the string "rpcap://",
             * which is used in case of a remote capture.
             * So we'll check to make sure the colon isn't followed by "//";
             * it'll be followed by a blank if it separates the description
             * and the interface name.  (We don't wire in "rpcap", in case we
             * support other protocols in the same syntax.)
             * Unfortunately, another colon can be used in "rpcap://host:port/"
             * before port. Check if colon is followed by digit.
             */
            if ((strncmp(if_name, "://", 3) != 0) && !g_ascii_isdigit(if_name[1])) {
                /*
                 * OK, we've found a colon followed neither by "//" nor by digit.
                 * Skip blanks following it.
                 */
                if_name++;
                while (*if_name == ' ')
                    if_name++;
                break;
            }
        }
        /* Keep looking for a colon not followed by "//". */
    }
#else
    /*
     * There's a space between the interface description and name, and
     * the interface name shouldn't have a space in it (it doesn't, on
     * UNIX systems); look backwards in the string for a space.
     *
     * (An interface name might, however, contain a colon in it, which
     * is why we don't use the colon search on UNIX.)
     */
    if_name = strrchr(if_text, ' ');
    if (if_name == NULL) {
        if_name = if_text;
    } else {
        if_name++;
    }
#endif
    return if_name;
}

/*
 * Set the active DLT for a device appropriately.
 */
void
set_active_dlt(interface_t *device, int global_default_dlt)
{
    GList    *list;
    bool      found_active_dlt;
    link_row *link;

    /*
     * If there's a preference for the link-layer header type for
     * this interface, use it.  If not, use the all-interface
     * default; if that's not set on the command line, that will
     * be -1, meaning "use per-interface defaults", otherwise
     * we'll fail if it's not one of the types the interface
     * supports.
     */
    if ((device->active_dlt = capture_dev_user_linktype_find(device->name)) == -1) {
        device->active_dlt = global_default_dlt;
    }

    /*
     * Is that one of the supported link-layer header types?
     * If not, set it to -1, so we'll fall back on the first supported
     * link-layer header type.
     */
    found_active_dlt = false;
    for (list = device->links; list != NULL; list = g_list_next(list)) {
        link = (link_row *)(list->data);
        if (link->dlt != -1 && link->dlt == device->active_dlt) {
            found_active_dlt = true;
            break;
        }
    }
    if (!found_active_dlt) {
        device->active_dlt = -1;
    }
    if (device->active_dlt == -1) {
        /* Fall back on the first supported DLT, if we have one. */
        for (list = device->links; list != NULL; list = g_list_next(list)) {
            link = (link_row *)(list->data);
            if (link->dlt != -1) {
                device->active_dlt = link->dlt;
                break;
            }
        }
    }
}

GString *
get_iface_list_string(capture_options *capture_opts, uint32_t style)
{
    GString *iface_list_string = g_string_new("");
    unsigned i;

    /*
     * If we have a descriptive name for the interface, show that,
     * rather than its raw name.  On NT 5.x (2K/XP/Server2K3), the
     * interface name is something like "\Device\NPF_{242423..."
     * which is pretty useless to the normal user.  On other platforms,
     * it might be less cryptic, but if a more descriptive name is
     * available, we should still use that.
     */
#ifdef _WIN32
    if (capture_opts->ifaces->len < 2) {
#else
    if (capture_opts->ifaces->len < 4) {
#endif
        for (i = 0; i < capture_opts->ifaces->len; i++) {
            if (i > 0) {
                if (capture_opts->ifaces->len > 2) {
                    g_string_append_printf(iface_list_string, ",");
                }
                g_string_append_printf(iface_list_string, " ");
                if (i == capture_opts->ifaces->len - 1) {
                    g_string_append_printf(iface_list_string, "and ");
                }
            }

            interface_options *interface_opts = &g_array_index(capture_opts->ifaces, interface_options, i);

            if (style & IFLIST_QUOTE_IF_DESCRIPTION)
                g_string_append_printf(iface_list_string, "'");
            /* If we have a special user-supplied description (via the prefs
             * or the documented "-X stdin_descr" option for stdin), make sure
             * we're using it.
             */
            char *user_descr = capture_dev_user_descr_find(interface_opts->name);
            if (user_descr != NULL) {
                if (g_strcmp0(interface_opts->descr, user_descr) != 0) {
                    g_free(interface_opts->descr);
                    interface_opts->descr = user_descr;
                    g_free(interface_opts->display_name);
                    interface_opts->display_name = g_strdup(interface_opts->descr);
                } else {
                    g_free(user_descr);
                }
            }
            if (interface_opts->display_name == NULL) {
                /*
                 * We don't have a display name; generate one.
                 * fill_in_interface_opts_from_finfo and
                 * capture_opts_add_iface_opt always fill in
                 * the display name, so this shouldn't be necessary.
                 */
                if (interface_opts->descr == NULL) {
                    if (interface_opts->name != NULL)
                        interface_opts->descr = get_interface_descriptive_name(capture_opts, interface_opts->name);
                    else
                        interface_opts->descr = g_strdup("(Unknown)");
                }
                interface_opts->display_name = g_strdup(interface_opts->descr);
            }
            g_string_append_printf(iface_list_string, "%s", interface_opts->display_name);
            if (style & IFLIST_QUOTE_IF_DESCRIPTION)
                g_string_append_printf(iface_list_string, "'");
            if (style & IFLIST_SHOW_FILTER) {
                if (interface_opts->cfilter != NULL &&
                        strlen(interface_opts->cfilter) > 0) {
                    g_string_append_printf(iface_list_string, " (%s)", interface_opts->cfilter);
                }
            }
        }
    } else {
        g_string_append_printf(iface_list_string, "%u interfaces", capture_opts->ifaces->len);
    }
    return iface_list_string;
}
#endif /* HAVE_LIBPCAP */