hostap/wpa_supplicant/scan.c
Jouni Malinen 17a4734dc4 Optimize post-WPS scan based on channel used during provisioning
Scan only the frequency that was used during provisioning during the
first five scans for the connection. This speeds up connection in the
most likely case where the AP remains on the same channel. If the AP is
not found after these initial scans, all channels will be scanned.
2010-04-11 19:06:42 +03:00

699 lines
16 KiB
C

/*
* WPA Supplicant - Scanning
* Copyright (c) 2003-2010, 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 "utils/includes.h"
#include "utils/common.h"
#include "utils/eloop.h"
#include "common/ieee802_11_defs.h"
#include "config.h"
#include "wpa_supplicant_i.h"
#include "driver_i.h"
#include "mlme.h"
#include "wps_supplicant.h"
#include "notify.h"
#include "bss.h"
#include "scan.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;
if (wpa_s->current_ssid != NULL)
wpas_notify_network_changed(wpa_s);
}
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 */
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;
return;
}
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;
}
int wpa_supplicant_trigger_scan(struct wpa_supplicant *wpa_s,
struct wpa_driver_scan_params *params)
{
int ret;
wpa_supplicant_notify_scanning(wpa_s, 1);
if (wpa_s->drv_flags & WPA_DRIVER_FLAGS_USER_SPACE_MLME)
ret = ieee80211_sta_req_scan(wpa_s, params);
else
ret = wpa_drv_scan(wpa_s, params);
if (ret) {
wpa_supplicant_notify_scanning(wpa_s, 0);
wpas_notify_scan_done(wpa_s, 0);
} else
wpa_s->scan_runs++;
return ret;
}
static struct wpa_driver_scan_filter *
wpa_supplicant_build_filter_ssids(struct wpa_config *conf, size_t *num_ssids)
{
struct wpa_driver_scan_filter *ssids;
struct wpa_ssid *ssid;
size_t count;
*num_ssids = 0;
if (!conf->filter_ssids)
return NULL;
for (count = 0, ssid = conf->ssid; ssid; ssid = ssid->next) {
if (ssid->ssid && ssid->ssid_len)
count++;
}
if (count == 0)
return NULL;
ssids = os_zalloc(count * sizeof(struct wpa_driver_scan_filter));
if (ssids == NULL)
return NULL;
for (ssid = conf->ssid; ssid; ssid = ssid->next) {
if (!ssid->ssid || !ssid->ssid_len)
continue;
os_memcpy(ssids[*num_ssids].ssid, ssid->ssid, ssid->ssid_len);
ssids[*num_ssids].ssid_len = ssid->ssid_len;
(*num_ssids)++;
}
return ssids;
}
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;
enum wpa_states prev_state;
if (wpa_s->disconnected && !wpa_s->scan_req) {
wpa_supplicant_set_state(wpa_s, WPA_DISCONNECTED);
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;
wpas_notify_ap_scan_changed(wpa_s);
}
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->conf->filter_ssids) {
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));
prev_state = wpa_s->wpa_state;
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, *tssid;
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 (tssid = wpa_s->conf->ssid; tssid; tssid = tssid->next) {
if (tssid->disabled)
continue;
if ((params.freqs || !freqs_set) && tssid->scan_freq) {
int_array_concat(&params.freqs,
tssid->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 (params.freqs == NULL && wpa_s->after_wps && wpa_s->wps_freq) {
/*
* Optimize post-provisioning scan based on channel used
* during provisioning.
*/
wpa_printf(MSG_DEBUG, "WPS: Scan only frequency %u MHz that "
"was used during provisioning", wpa_s->wps_freq);
params.freqs = os_zalloc(2 * sizeof(int));
if (params.freqs)
params.freqs[0] = wpa_s->wps_freq;
wpa_s->after_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 */
params.filter_ssids = wpa_supplicant_build_filter_ssids(
wpa_s->conf, &params.num_filter_ssids);
ret = wpa_supplicant_trigger_scan(wpa_s, &params);
wpabuf_free(wps_ie);
os_free(params.freqs);
os_free(params.filter_ssids);
if (ret) {
wpa_printf(MSG_WARNING, "Failed to initiate AP scan.");
if (prev_state != wpa_s->wpa_state)
wpa_supplicant_set_state(wpa_s, prev_state);
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);
}
void wpa_supplicant_notify_scanning(struct wpa_supplicant *wpa_s,
int scanning)
{
if (wpa_s->scanning != scanning) {
wpa_s->scanning = scanning;
wpas_notify_scanning(wpa_s);
}
}
static int wpa_scan_get_max_rate(const struct wpa_scan_res *res)
{
int rate = 0;
const u8 *ie;
int i;
ie = wpa_scan_get_ie(res, WLAN_EID_SUPP_RATES);
for (i = 0; ie && i < ie[1]; i++) {
if ((ie[i + 2] & 0x7f) > rate)
rate = ie[i + 2] & 0x7f;
}
ie = wpa_scan_get_ie(res, WLAN_EID_EXT_SUPP_RATES);
for (i = 0; ie && i < ie[1]; i++) {
if ((ie[i + 2] & 0x7f) > rate)
rate = ie[i + 2] & 0x7f;
}
return rate;
}
const u8 * wpa_scan_get_ie(const struct wpa_scan_res *res, u8 ie)
{
const u8 *end, *pos;
pos = (const u8 *) (res + 1);
end = pos + res->ie_len;
while (pos + 1 < end) {
if (pos + 2 + pos[1] > end)
break;
if (pos[0] == ie)
return pos;
pos += 2 + pos[1];
}
return NULL;
}
const u8 * wpa_scan_get_vendor_ie(const struct wpa_scan_res *res,
u32 vendor_type)
{
const u8 *end, *pos;
pos = (const u8 *) (res + 1);
end = pos + res->ie_len;
while (pos + 1 < end) {
if (pos + 2 + pos[1] > end)
break;
if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
vendor_type == WPA_GET_BE32(&pos[2]))
return pos;
pos += 2 + pos[1];
}
return NULL;
}
struct wpabuf * wpa_scan_get_vendor_ie_multi(const struct wpa_scan_res *res,
u32 vendor_type)
{
struct wpabuf *buf;
const u8 *end, *pos;
buf = wpabuf_alloc(res->ie_len);
if (buf == NULL)
return NULL;
pos = (const u8 *) (res + 1);
end = pos + res->ie_len;
while (pos + 1 < end) {
if (pos + 2 + pos[1] > end)
break;
if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
vendor_type == WPA_GET_BE32(&pos[2]))
wpabuf_put_data(buf, pos + 2 + 4, pos[1] - 4);
pos += 2 + pos[1];
}
if (wpabuf_len(buf) == 0) {
wpabuf_free(buf);
buf = NULL;
}
return buf;
}
/* Compare function for sorting scan results. Return >0 if @b is considered
* better. */
static int wpa_scan_result_compar(const void *a, const void *b)
{
struct wpa_scan_res **_wa = (void *) a;
struct wpa_scan_res **_wb = (void *) b;
struct wpa_scan_res *wa = *_wa;
struct wpa_scan_res *wb = *_wb;
int wpa_a, wpa_b, maxrate_a, maxrate_b;
/* WPA/WPA2 support preferred */
wpa_a = wpa_scan_get_vendor_ie(wa, WPA_IE_VENDOR_TYPE) != NULL ||
wpa_scan_get_ie(wa, WLAN_EID_RSN) != NULL;
wpa_b = wpa_scan_get_vendor_ie(wb, WPA_IE_VENDOR_TYPE) != NULL ||
wpa_scan_get_ie(wb, WLAN_EID_RSN) != NULL;
if (wpa_b && !wpa_a)
return 1;
if (!wpa_b && wpa_a)
return -1;
/* privacy support preferred */
if ((wa->caps & IEEE80211_CAP_PRIVACY) == 0 &&
(wb->caps & IEEE80211_CAP_PRIVACY))
return 1;
if ((wa->caps & IEEE80211_CAP_PRIVACY) &&
(wb->caps & IEEE80211_CAP_PRIVACY) == 0)
return -1;
/* best/max rate preferred if signal level close enough XXX */
if ((wa->level && wb->level && abs(wb->level - wa->level) < 5) ||
(wa->qual && wb->qual && abs(wb->qual - wa->qual) < 10)) {
maxrate_a = wpa_scan_get_max_rate(wa);
maxrate_b = wpa_scan_get_max_rate(wb);
if (maxrate_a != maxrate_b)
return maxrate_b - maxrate_a;
}
/* use freq for channel preference */
/* all things being equal, use signal level; if signal levels are
* identical, use quality values since some drivers may only report
* that value and leave the signal level zero */
if (wb->level == wa->level)
return wb->qual - wa->qual;
return wb->level - wa->level;
}
/**
* wpa_supplicant_get_scan_results - Get scan results
* @wpa_s: Pointer to wpa_supplicant data
* @info: Information about what was scanned or %NULL if not available
* @new_scan: Whether a new scan was performed
* Returns: Scan results, %NULL on failure
*
* This function request the current scan results from the driver and updates
* the local BSS list wpa_s->bss. The caller is responsible for freeing the
* results with wpa_scan_results_free().
*/
struct wpa_scan_results *
wpa_supplicant_get_scan_results(struct wpa_supplicant *wpa_s,
struct scan_info *info, int new_scan)
{
struct wpa_scan_results *scan_res;
size_t i;
if (wpa_s->drv_flags & WPA_DRIVER_FLAGS_USER_SPACE_MLME)
scan_res = ieee80211_sta_get_scan_results(wpa_s);
else
scan_res = wpa_drv_get_scan_results2(wpa_s);
if (scan_res == NULL) {
wpa_printf(MSG_DEBUG, "Failed to get scan results");
return NULL;
}
qsort(scan_res->res, scan_res->num, sizeof(struct wpa_scan_res *),
wpa_scan_result_compar);
wpa_bss_update_start(wpa_s);
for (i = 0; i < scan_res->num; i++)
wpa_bss_update_scan_res(wpa_s, scan_res->res[i]);
wpa_bss_update_end(wpa_s, info, new_scan);
return scan_res;
}
int wpa_supplicant_update_scan_results(struct wpa_supplicant *wpa_s)
{
struct wpa_scan_results *scan_res;
scan_res = wpa_supplicant_get_scan_results(wpa_s, NULL, 0);
if (scan_res == NULL)
return -1;
wpa_scan_results_free(scan_res);
return 0;
}
void wpa_scan_results_free(struct wpa_scan_results *res)
{
size_t i;
if (res == NULL)
return;
for (i = 0; i < res->num; i++)
os_free(res->res[i]);
os_free(res->res);
os_free(res);
}