hostap/wpa_supplicant/bgscan_learn.c

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/*
* WPA Supplicant - background scan and roaming module: learn
* Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
#include "includes.h"
#include "common.h"
#include "eloop.h"
#include "list.h"
#include "common/ieee802_11_defs.h"
#include "drivers/driver.h"
#include "config_ssid.h"
#include "wpa_supplicant_i.h"
#include "driver_i.h"
#include "scan.h"
#include "bgscan.h"
struct bgscan_learn_bss {
struct dl_list list;
u8 bssid[ETH_ALEN];
int freq;
u8 *neigh; /* num_neigh * ETH_ALEN buffer */
size_t num_neigh;
};
struct bgscan_learn_data {
struct wpa_supplicant *wpa_s;
const struct wpa_ssid *ssid;
int scan_interval;
int signal_threshold;
int short_interval; /* use if signal < threshold */
int long_interval; /* use if signal > threshold */
struct os_time last_bgscan;
char *fname;
struct dl_list bss;
int *supp_freqs;
int probe_idx;
};
static void bss_free(struct bgscan_learn_bss *bss)
{
os_free(bss->neigh);
os_free(bss);
}
static int bssid_in_array(u8 *array, size_t array_len, const u8 *bssid)
{
size_t i;
if (array == NULL || array_len == 0)
return 0;
for (i = 0; i < array_len; i++) {
if (os_memcmp(array + i * ETH_ALEN, bssid, ETH_ALEN) == 0)
return 1;
}
return 0;
}
static void bgscan_learn_add_neighbor(struct bgscan_learn_bss *bss,
const u8 *bssid)
{
u8 *n;
if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
return;
if (bssid_in_array(bss->neigh, bss->num_neigh, bssid))
return;
n = os_realloc_array(bss->neigh, bss->num_neigh + 1, ETH_ALEN);
if (n == NULL)
return;
os_memcpy(n + bss->num_neigh * ETH_ALEN, bssid, ETH_ALEN);
bss->neigh = n;
bss->num_neigh++;
}
static struct bgscan_learn_bss * bgscan_learn_get_bss(
struct bgscan_learn_data *data, const u8 *bssid)
{
struct bgscan_learn_bss *bss;
dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
return bss;
}
return NULL;
}
static int bgscan_learn_load(struct bgscan_learn_data *data)
{
FILE *f;
char buf[128];
struct bgscan_learn_bss *bss;
if (data->fname == NULL)
return 0;
f = fopen(data->fname, "r");
if (f == NULL)
return 0;
wpa_printf(MSG_DEBUG, "bgscan learn: Loading data from %s",
data->fname);
if (fgets(buf, sizeof(buf), f) == NULL ||
os_strncmp(buf, "wpa_supplicant-bgscan-learn\n", 28) != 0) {
wpa_printf(MSG_INFO, "bgscan learn: Invalid data file %s",
data->fname);
fclose(f);
return -1;
}
while (fgets(buf, sizeof(buf), f)) {
if (os_strncmp(buf, "BSS ", 4) == 0) {
bss = os_zalloc(sizeof(*bss));
if (!bss)
continue;
if (hwaddr_aton(buf + 4, bss->bssid) < 0) {
bss_free(bss);
continue;
}
bss->freq = atoi(buf + 4 + 18);
dl_list_add(&data->bss, &bss->list);
wpa_printf(MSG_DEBUG, "bgscan learn: Loaded BSS "
"entry: " MACSTR " freq=%d",
MAC2STR(bss->bssid), bss->freq);
}
if (os_strncmp(buf, "NEIGHBOR ", 9) == 0) {
u8 addr[ETH_ALEN];
if (hwaddr_aton(buf + 9, addr) < 0)
continue;
bss = bgscan_learn_get_bss(data, addr);
if (bss == NULL)
continue;
if (hwaddr_aton(buf + 9 + 18, addr) < 0)
continue;
bgscan_learn_add_neighbor(bss, addr);
}
}
fclose(f);
return 0;
}
static void bgscan_learn_save(struct bgscan_learn_data *data)
{
FILE *f;
struct bgscan_learn_bss *bss;
if (data->fname == NULL)
return;
wpa_printf(MSG_DEBUG, "bgscan learn: Saving data to %s",
data->fname);
f = fopen(data->fname, "w");
if (f == NULL)
return;
fprintf(f, "wpa_supplicant-bgscan-learn\n");
dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
fprintf(f, "BSS " MACSTR " %d\n",
MAC2STR(bss->bssid), bss->freq);
}
dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
size_t i;
for (i = 0; i < bss->num_neigh; i++) {
fprintf(f, "NEIGHBOR " MACSTR " " MACSTR "\n",
MAC2STR(bss->bssid),
MAC2STR(bss->neigh + i * ETH_ALEN));
}
}
fclose(f);
}
static int in_array(int *array, int val)
{
int i;
if (array == NULL)
return 0;
for (i = 0; array[i]; i++) {
if (array[i] == val)
return 1;
}
return 0;
}
static int * bgscan_learn_get_freqs(struct bgscan_learn_data *data,
size_t *count)
{
struct bgscan_learn_bss *bss;
int *freqs = NULL, *n;
*count = 0;
dl_list_for_each(bss, &data->bss, struct bgscan_learn_bss, list) {
if (in_array(freqs, bss->freq))
continue;
n = os_realloc_array(freqs, *count + 2, sizeof(int));
if (n == NULL)
return freqs;
freqs = n;
freqs[*count] = bss->freq;
(*count)++;
freqs[*count] = 0;
}
return freqs;
}
static int * bgscan_learn_get_probe_freq(struct bgscan_learn_data *data,
int *freqs, size_t count)
{
int idx, *n;
if (data->supp_freqs == NULL)
return freqs;
idx = data->probe_idx + 1;
while (idx != data->probe_idx) {
if (data->supp_freqs[idx] == 0) {
if (data->probe_idx == 0)
break;
idx = 0;
}
if (!in_array(freqs, data->supp_freqs[idx])) {
wpa_printf(MSG_DEBUG, "bgscan learn: Probe new freq "
"%u", data->supp_freqs[idx]);
data->probe_idx = idx;
n = os_realloc_array(freqs, count + 2, sizeof(int));
if (n == NULL)
return freqs;
freqs = n;
freqs[count] = data->supp_freqs[idx];
count++;
freqs[count] = 0;
break;
}
idx++;
}
return freqs;
}
static void bgscan_learn_timeout(void *eloop_ctx, void *timeout_ctx)
{
struct bgscan_learn_data *data = eloop_ctx;
struct wpa_supplicant *wpa_s = data->wpa_s;
struct wpa_driver_scan_params params;
int *freqs = NULL;
size_t count, i;
char msg[100], *pos;
os_memset(&params, 0, sizeof(params));
params.num_ssids = 1;
params.ssids[0].ssid = data->ssid->ssid;
params.ssids[0].ssid_len = data->ssid->ssid_len;
if (data->ssid->scan_freq)
params.freqs = data->ssid->scan_freq;
else {
freqs = bgscan_learn_get_freqs(data, &count);
wpa_printf(MSG_DEBUG, "bgscan learn: BSSes in this ESS have "
"been seen on %u channels", (unsigned int) count);
freqs = bgscan_learn_get_probe_freq(data, freqs, count);
msg[0] = '\0';
pos = msg;
for (i = 0; freqs && freqs[i]; i++) {
int ret;
ret = os_snprintf(pos, msg + sizeof(msg) - pos, " %d",
freqs[i]);
if (ret < 0 || ret >= msg + sizeof(msg) - pos)
break;
pos += ret;
}
pos[0] = '\0';
wpa_printf(MSG_DEBUG, "bgscan learn: Scanning frequencies:%s",
msg);
params.freqs = freqs;
}
wpa_printf(MSG_DEBUG, "bgscan learn: Request a background scan");
if (wpa_supplicant_trigger_scan(wpa_s, &params)) {
wpa_printf(MSG_DEBUG, "bgscan learn: Failed to trigger scan");
eloop_register_timeout(data->scan_interval, 0,
bgscan_learn_timeout, data, NULL);
} else
os_get_time(&data->last_bgscan);
os_free(freqs);
}
static int bgscan_learn_get_params(struct bgscan_learn_data *data,
const char *params)
{
const char *pos;
if (params == NULL)
return 0;
data->short_interval = atoi(params);
pos = os_strchr(params, ':');
if (pos == NULL)
return 0;
pos++;
data->signal_threshold = atoi(pos);
pos = os_strchr(pos, ':');
if (pos == NULL) {
wpa_printf(MSG_ERROR, "bgscan learn: Missing scan interval "
"for high signal");
return -1;
}
pos++;
data->long_interval = atoi(pos);
pos = os_strchr(pos, ':');
if (pos) {
pos++;
data->fname = os_strdup(pos);
}
return 0;
}
static int * bgscan_learn_get_supp_freqs(struct wpa_supplicant *wpa_s)
{
struct hostapd_hw_modes *modes;
int i, j, *freqs = NULL, *n;
size_t count = 0;
modes = wpa_s->hw.modes;
if (modes == NULL)
return NULL;
for (i = 0; i < wpa_s->hw.num_modes; i++) {
for (j = 0; j < modes[i].num_channels; j++) {
if (modes[i].channels[j].flag & HOSTAPD_CHAN_DISABLED)
continue;
/* some hw modes (e.g. 11b & 11g) contain same freqs */
if (in_array(freqs, modes[i].channels[j].freq))
continue;
n = os_realloc_array(freqs, count + 2, sizeof(int));
if (n == NULL)
continue;
freqs = n;
freqs[count] = modes[i].channels[j].freq;
count++;
freqs[count] = 0;
}
}
return freqs;
}
static void * bgscan_learn_init(struct wpa_supplicant *wpa_s,
const char *params,
const struct wpa_ssid *ssid)
{
struct bgscan_learn_data *data;
data = os_zalloc(sizeof(*data));
if (data == NULL)
return NULL;
dl_list_init(&data->bss);
data->wpa_s = wpa_s;
data->ssid = ssid;
if (bgscan_learn_get_params(data, params) < 0) {
os_free(data->fname);
os_free(data);
return NULL;
}
if (data->short_interval <= 0)
data->short_interval = 30;
if (data->long_interval <= 0)
data->long_interval = 30;
if (bgscan_learn_load(data) < 0) {
os_free(data->fname);
os_free(data);
return NULL;
}
wpa_printf(MSG_DEBUG, "bgscan learn: Signal strength threshold %d "
"Short bgscan interval %d Long bgscan interval %d",
data->signal_threshold, data->short_interval,
data->long_interval);
if (data->signal_threshold &&
wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) {
wpa_printf(MSG_ERROR, "bgscan learn: Failed to enable "
"signal strength monitoring");
}
data->supp_freqs = bgscan_learn_get_supp_freqs(wpa_s);
data->scan_interval = data->short_interval;
eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout,
data, NULL);
/*
* This function is called immediately after an association, so it is
* reasonable to assume that a scan was completed recently. This makes
* us skip an immediate new scan in cases where the current signal
* level is below the bgscan threshold.
*/
os_get_time(&data->last_bgscan);
return data;
}
static void bgscan_learn_deinit(void *priv)
{
struct bgscan_learn_data *data = priv;
struct bgscan_learn_bss *bss, *n;
bgscan_learn_save(data);
eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
if (data->signal_threshold)
wpa_drv_signal_monitor(data->wpa_s, 0, 0);
os_free(data->fname);
dl_list_for_each_safe(bss, n, &data->bss, struct bgscan_learn_bss,
list) {
dl_list_del(&bss->list);
bss_free(bss);
}
os_free(data->supp_freqs);
os_free(data);
}
static int bgscan_learn_bss_match(struct bgscan_learn_data *data,
struct wpa_scan_res *bss)
{
const u8 *ie;
ie = wpa_scan_get_ie(bss, WLAN_EID_SSID);
if (ie == NULL)
return 0;
if (data->ssid->ssid_len != ie[1] ||
os_memcmp(data->ssid->ssid, ie + 2, ie[1]) != 0)
return 0; /* SSID mismatch */
return 1;
}
static int bgscan_learn_notify_scan(void *priv,
struct wpa_scan_results *scan_res)
{
struct bgscan_learn_data *data = priv;
size_t i, j;
#define MAX_BSS 50
u8 bssid[MAX_BSS * ETH_ALEN];
size_t num_bssid = 0;
wpa_printf(MSG_DEBUG, "bgscan learn: scan result notification");
eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
eloop_register_timeout(data->scan_interval, 0, bgscan_learn_timeout,
data, NULL);
for (i = 0; i < scan_res->num; i++) {
struct wpa_scan_res *res = scan_res->res[i];
if (!bgscan_learn_bss_match(data, res))
continue;
if (num_bssid < MAX_BSS) {
os_memcpy(bssid + num_bssid * ETH_ALEN, res->bssid,
ETH_ALEN);
num_bssid++;
}
}
wpa_printf(MSG_DEBUG, "bgscan learn: %u matching BSSes in scan "
"results", (unsigned int) num_bssid);
for (i = 0; i < scan_res->num; i++) {
struct wpa_scan_res *res = scan_res->res[i];
struct bgscan_learn_bss *bss;
if (!bgscan_learn_bss_match(data, res))
continue;
bss = bgscan_learn_get_bss(data, res->bssid);
if (bss && bss->freq != res->freq) {
wpa_printf(MSG_DEBUG, "bgscan learn: Update BSS "
MACSTR " freq %d -> %d",
MAC2STR(res->bssid), bss->freq, res->freq);
bss->freq = res->freq;
} else if (!bss) {
wpa_printf(MSG_DEBUG, "bgscan learn: Add BSS " MACSTR
" freq=%d", MAC2STR(res->bssid), res->freq);
bss = os_zalloc(sizeof(*bss));
if (!bss)
continue;
os_memcpy(bss->bssid, res->bssid, ETH_ALEN);
bss->freq = res->freq;
dl_list_add(&data->bss, &bss->list);
}
for (j = 0; j < num_bssid; j++) {
u8 *addr = bssid + j * ETH_ALEN;
bgscan_learn_add_neighbor(bss, addr);
}
}
/*
* A more advanced bgscan could process scan results internally, select
* the BSS and request roam if needed. This sample uses the existing
* BSS/ESS selection routine. Change this to return 1 if selection is
* done inside the bgscan module.
*/
return 0;
}
static void bgscan_learn_notify_beacon_loss(void *priv)
{
wpa_printf(MSG_DEBUG, "bgscan learn: beacon loss");
/* TODO: speed up background scanning */
}
static void bgscan_learn_notify_signal_change(void *priv, int above,
int current_signal,
int current_noise,
int current_txrate)
{
struct bgscan_learn_data *data = priv;
int scan = 0;
struct os_time now;
if (data->short_interval == data->long_interval ||
data->signal_threshold == 0)
return;
wpa_printf(MSG_DEBUG, "bgscan learn: signal level changed "
"(above=%d current_signal=%d current_noise=%d "
"current_txrate=%d)", above, current_signal,
current_noise, current_txrate);
if (data->scan_interval == data->long_interval && !above) {
wpa_printf(MSG_DEBUG, "bgscan learn: Start using short bgscan "
"interval");
data->scan_interval = data->short_interval;
os_get_time(&now);
if (now.sec > data->last_bgscan.sec + 1)
scan = 1;
} else if (data->scan_interval == data->short_interval && above) {
wpa_printf(MSG_DEBUG, "bgscan learn: Start using long bgscan "
"interval");
data->scan_interval = data->long_interval;
eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
eloop_register_timeout(data->scan_interval, 0,
bgscan_learn_timeout, data, NULL);
} else if (!above) {
/*
* Signal dropped further 4 dB. Request a new scan if we have
* not yet scanned in a while.
*/
os_get_time(&now);
if (now.sec > data->last_bgscan.sec + 10)
scan = 1;
}
if (scan) {
wpa_printf(MSG_DEBUG, "bgscan learn: Trigger immediate scan");
eloop_cancel_timeout(bgscan_learn_timeout, data, NULL);
eloop_register_timeout(0, 0, bgscan_learn_timeout, data, NULL);
}
}
const struct bgscan_ops bgscan_learn_ops = {
.name = "learn",
.init = bgscan_learn_init,
.deinit = bgscan_learn_deinit,
.notify_scan = bgscan_learn_notify_scan,
.notify_beacon_loss = bgscan_learn_notify_beacon_loss,
.notify_signal_change = bgscan_learn_notify_signal_change,
};