hostap/wpa_supplicant/scan.c

/*
 * WPA Supplicant - Scanning
 * Copyright (c) 2003-2008, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"

#include "common.h"
#include "eloop.h"
#include "config.h"
#include "wpa_supplicant_i.h"
#include "driver_i.h"
#include "mlme.h"
#include "wps_supplicant.h"


static void wpa_supplicant_gen_assoc_event(struct wpa_supplicant *wpa_s)
{
	struct wpa_ssid *ssid;
	union wpa_event_data data;

	ssid = wpa_supplicant_get_ssid(wpa_s);
	if (ssid == NULL)
		return;

	if (wpa_s->current_ssid == NULL)
		wpa_s->current_ssid = ssid;
	wpa_supplicant_initiate_eapol(wpa_s);
	wpa_printf(MSG_DEBUG, "Already associated with a configured network - "
		   "generating associated event");
	os_memset(&data, 0, sizeof(data));
	wpa_supplicant_event(wpa_s, EVENT_ASSOC, &data);
}


#ifdef CONFIG_WPS
static int wpas_wps_in_use(struct wpa_config *conf,
			   enum wps_request_type *req_type)
{
	struct wpa_ssid *ssid;
	int wps = 0;

	for (ssid = conf->ssid; ssid; ssid = ssid->next) {
		if (!(ssid->key_mgmt & WPA_KEY_MGMT_WPS))
			continue;

		wps = 1;
		*req_type = wpas_wps_get_req_type(ssid);
		if (!ssid->eap.phase1)
			continue;

		if (os_strstr(ssid->eap.phase1, "pbc=1"))
			return 2;
	}

	return wps;
}
#endif /* CONFIG_WPS */


static int wpa_supplicant_enabled_networks(struct wpa_config *conf)
{
	struct wpa_ssid *ssid = conf->ssid;
	while (ssid) {
		if (!ssid->disabled)
			return 1;
		ssid = ssid->next;
	}
	return 0;
}


static void wpa_supplicant_assoc_try(struct wpa_supplicant *wpa_s,
				     struct wpa_ssid *ssid)
{
	while (ssid) {
		if (!ssid->disabled)
			break;
		ssid = ssid->next;
	}

	/* ap_scan=2 mode - try to associate with each SSID. */
	if (ssid == NULL) {
		wpa_printf(MSG_DEBUG, "wpa_supplicant_scan: Reached "
			   "end of scan list - go back to beginning");
		wpa_s->prev_scan_ssid = WILDCARD_SSID_SCAN;
		wpa_supplicant_req_scan(wpa_s, 0, 0);
		return;
	}
	if (ssid->next) {
		/* Continue from the next SSID on the next attempt. */
		wpa_s->prev_scan_ssid = ssid;
	} else {
		/* Start from the beginning of the SSID list. */
		wpa_s->prev_scan_ssid = WILDCARD_SSID_SCAN;
	}
	wpa_supplicant_associate(wpa_s, NULL, ssid);
}


static int int_array_len(const int *a)
{
	int i;
	for (i = 0; a && a[i]; i++)
		;
	return i;
}


static void int_array_concat(int **res, const int *a)
{
	int reslen, alen, i;
	int *n;

	reslen = int_array_len(*res);
	alen = int_array_len(a);

	n = os_realloc(*res, (reslen + alen + 1) * sizeof(int));
	if (n == NULL) {
		os_free(*res);
		*res = NULL;
	}
	for (i = 0; i <= alen; i++)
		n[reslen + i] = a[i];
	*res = n;
}


static int freq_cmp(const void *a, const void *b)
{
	int _a = *(int *) a;
	int _b = *(int *) b;

	if (_a == 0)
		return 1;
	if (_b == 0)
		return -1;
	return _a - _b;
}


static void int_array_sort_unique(int *a)
{
	int alen;
	int i, j;

	if (a == NULL)
		return;

	alen = int_array_len(a);
	qsort(a, alen, sizeof(int), freq_cmp);

	i = 0;
	j = 1;
	while (a[i] && a[j]) {
		if (a[i] == a[j]) {
			j++;
			continue;
		}
		a[++i] = a[j++];
	}
	if (a[i])
		i++;
	a[i] = 0;
}


static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
{
	struct wpa_supplicant *wpa_s = eloop_ctx;
	struct wpa_ssid *ssid;
	int scan_req = 0, ret;
	struct wpabuf *wps_ie = NULL;
	int wps = 0;
#ifdef CONFIG_WPS
	enum wps_request_type req_type = WPS_REQ_ENROLLEE_INFO;
#endif /* CONFIG_WPS */
	struct wpa_driver_scan_params params;
	size_t max_ssids;

	if (wpa_s->disconnected && !wpa_s->scan_req)
		return;

	if (!wpa_supplicant_enabled_networks(wpa_s->conf) &&
	    !wpa_s->scan_req) {
		wpa_printf(MSG_DEBUG, "No enabled networks - do not scan");
		wpa_supplicant_set_state(wpa_s, WPA_INACTIVE);
		return;
	}

	if (wpa_s->conf->ap_scan != 0 &&
	    (wpa_s->drv_flags & WPA_DRIVER_FLAGS_WIRED)) {
		wpa_printf(MSG_DEBUG, "Using wired authentication - "
			   "overriding ap_scan configuration");
		wpa_s->conf->ap_scan = 0;
	}

	if (wpa_s->conf->ap_scan == 0) {
		wpa_supplicant_gen_assoc_event(wpa_s);
		return;
	}

	if ((wpa_s->drv_flags & WPA_DRIVER_FLAGS_USER_SPACE_MLME) ||
	    wpa_s->conf->ap_scan == 2)
		max_ssids = 1;
	else {
		max_ssids = wpa_s->max_scan_ssids;
		if (max_ssids > WPAS_MAX_SCAN_SSIDS)
			max_ssids = WPAS_MAX_SCAN_SSIDS;
	}

#ifdef CONFIG_WPS
	wps = wpas_wps_in_use(wpa_s->conf, &req_type);
#endif /* CONFIG_WPS */

	if (wpa_s->scan_res_tried == 0 && wpa_s->conf->ap_scan == 1 &&
	    !(wpa_s->drv_flags & WPA_DRIVER_FLAGS_USER_SPACE_MLME) &&
	    wps != 2) {
		wpa_s->scan_res_tried++;
		wpa_printf(MSG_DEBUG, "Trying to get current scan results "
			   "first without requesting a new scan to speed up "
			   "initial association");
		wpa_supplicant_event(wpa_s, EVENT_SCAN_RESULTS, NULL);
		return;
	}

	scan_req = wpa_s->scan_req;
	wpa_s->scan_req = 0;

	os_memset(&params, 0, sizeof(params));

	if (wpa_s->wpa_state == WPA_DISCONNECTED ||
	    wpa_s->wpa_state == WPA_INACTIVE)
		wpa_supplicant_set_state(wpa_s, WPA_SCANNING);

	/* Find the starting point from which to continue scanning */
	ssid = wpa_s->conf->ssid;
	if (wpa_s->prev_scan_ssid != WILDCARD_SSID_SCAN) {
		while (ssid) {
			if (ssid == wpa_s->prev_scan_ssid) {
				ssid = ssid->next;
				break;
			}
			ssid = ssid->next;
		}
	}

	if (scan_req != 2 && wpa_s->conf->ap_scan == 2) {
		wpa_supplicant_assoc_try(wpa_s, ssid);
		return;
	} else if (wpa_s->conf->ap_scan == 2) {
		/*
		 * User-initiated scan request in ap_scan == 2; scan with
		 * wildcard SSID.
		 */
		ssid = NULL;
	} else {
		struct wpa_ssid *start = ssid;
		int freqs_set = 0;
		if (ssid == NULL && max_ssids > 1)
			ssid = wpa_s->conf->ssid;
		while (ssid) {
			if (!ssid->disabled && ssid->scan_ssid) {
				wpa_hexdump_ascii(MSG_DEBUG, "Scan SSID",
						  ssid->ssid, ssid->ssid_len);
				params.ssids[params.num_ssids].ssid =
					ssid->ssid;
				params.ssids[params.num_ssids].ssid_len =
					ssid->ssid_len;
				params.num_ssids++;
				if (params.num_ssids + 1 >= max_ssids)
					break;
			}
			ssid = ssid->next;
			if (ssid == start)
				break;
			if (ssid == NULL && max_ssids > 1 &&
			    start != wpa_s->conf->ssid)
				ssid = wpa_s->conf->ssid;
		}

		for (ssid = wpa_s->conf->ssid; ssid; ssid = ssid->next) {
			if (ssid->disabled)
				continue;
			if ((params.freqs || !freqs_set) && ssid->scan_freq) {
				int_array_concat(&params.freqs,
						 ssid->scan_freq);
			} else {
				os_free(params.freqs);
				params.freqs = NULL;
			}
			freqs_set = 1;
		}
		int_array_sort_unique(params.freqs);
	}

	if (ssid) {
		wpa_s->prev_scan_ssid = ssid;
		if (max_ssids > 1) {
			wpa_printf(MSG_DEBUG, "Include wildcard SSID in the "
				   "scan request");
			params.num_ssids++;
		}
		wpa_printf(MSG_DEBUG, "Starting AP scan for specific SSID(s)");
	} else {
		wpa_s->prev_scan_ssid = WILDCARD_SSID_SCAN;
		params.num_ssids++;
		wpa_printf(MSG_DEBUG, "Starting AP scan for wildcard SSID");
	}

#ifdef CONFIG_WPS
	if (wps) {
		wps_ie = wps_build_probe_req_ie(wps == 2, &wpa_s->wps->dev,
						wpa_s->wps->uuid, req_type);
		if (wps_ie) {
			params.extra_ies = wpabuf_head(wps_ie);
			params.extra_ies_len = wpabuf_len(wps_ie);
		}
	}
#endif /* CONFIG_WPS */

	if (wpa_s->drv_flags & WPA_DRIVER_FLAGS_USER_SPACE_MLME) {
		ieee80211_sta_set_probe_req_ie(wpa_s, params.extra_ies,
					       params.extra_ies_len);
		ret = ieee80211_sta_req_scan(wpa_s, params.ssids[0].ssid,
					     params.ssids[0].ssid_len);
	} else {
		wpa_drv_set_probe_req_ie(wpa_s, params.extra_ies,
					 params.extra_ies_len);
		ret = wpa_drv_scan(wpa_s, &params);
	}

	wpabuf_free(wps_ie);
	os_free(params.freqs);

	if (ret) {
		wpa_printf(MSG_WARNING, "Failed to initiate AP scan.");
		wpa_supplicant_req_scan(wpa_s, 10, 0);
	} else
		wpa_s->scan_runs++;
}


/**
 * wpa_supplicant_req_scan - Schedule a scan for neighboring access points
 * @wpa_s: Pointer to wpa_supplicant data
 * @sec: Number of seconds after which to scan
 * @usec: Number of microseconds after which to scan
 *
 * This function is used to schedule a scan for neighboring access points after
 * the specified time.
 */
void wpa_supplicant_req_scan(struct wpa_supplicant *wpa_s, int sec, int usec)
{
	/* If there's at least one network that should be specifically scanned
	 * then don't cancel the scan and reschedule.  Some drivers do
	 * background scanning which generates frequent scan results, and that
	 * causes the specific SSID scan to get continually pushed back and
	 * never happen, which causes hidden APs to never get probe-scanned.
	 */
	if (eloop_is_timeout_registered(wpa_supplicant_scan, wpa_s, NULL) &&
	    wpa_s->conf->ap_scan == 1) {
		struct wpa_ssid *ssid = wpa_s->conf->ssid;

		while (ssid) {
			if (!ssid->disabled && ssid->scan_ssid)
				break;
			ssid = ssid->next;
		}
		if (ssid) {
			wpa_msg(wpa_s, MSG_DEBUG, "Not rescheduling scan to "
			        "ensure that specific SSID scans occur");
			return;
		}
	}

	wpa_msg(wpa_s, MSG_DEBUG, "Setting scan request: %d sec %d usec",
		sec, usec);
	eloop_cancel_timeout(wpa_supplicant_scan, wpa_s, NULL);
	eloop_register_timeout(sec, usec, wpa_supplicant_scan, wpa_s, NULL);
}


/**
 * wpa_supplicant_cancel_scan - Cancel a scheduled scan request
 * @wpa_s: Pointer to wpa_supplicant data
 *
 * This function is used to cancel a scan request scheduled with
 * wpa_supplicant_req_scan().
 */
void wpa_supplicant_cancel_scan(struct wpa_supplicant *wpa_s)
{
	wpa_msg(wpa_s, MSG_DEBUG, "Cancelling scan request");
	eloop_cancel_timeout(wpa_supplicant_scan, wpa_s, NULL);
}