hostap/wpa_supplicant/scan.c

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/*
* 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 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) {
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->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, *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 (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 */
ret = wpa_supplicant_trigger_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);
}
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);
}