hostapd/wpa_supplicant/bss.c
Jouni Malinen 83922c2d34 Add BSS table to track scan results without dropping information
Collect information from scan results into a BSS table that will not
expire information as quickly as scan results where every new scan,
no matter for how limited set of channels/SSIDs, clears all old
information.

For now, this is only used for D-Bus BSS added/removed notifications,
but this will likely be extended to be used internally instead of the
scan results to better support partial scans.
2009-12-27 21:07:47 +02:00

262 lines
6.9 KiB
C

/*
* BSS table
* Copyright (c) 2009, 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 "drivers/driver.h"
#include "wpa_supplicant_i.h"
#include "notify.h"
#include "bss.h"
#ifndef WPA_BSS_MAX_COUNT
#define WPA_BSS_MAX_COUNT 200
#endif /* WPA_BSS_MAX_COUNT */
/**
* WPA_BSS_EXPIRATION_PERIOD - Period of expiration run in seconds
*/
#define WPA_BSS_EXPIRATION_PERIOD 10
/**
* WPA_BSS_EXPIRATION_AGE - BSS entry age after which it can be expired
*
* This value control the time in seconds after which a BSS entry gets removed
* if it has not been updated or is not in use.
*/
#define WPA_BSS_EXPIRATION_AGE 180
/**
* WPA_BSS_EXPIRATION_SCAN_COUNT - Expire BSS after number of scans
*
* If the BSS entry has not been seen in this many scans, it will be removed.
* Value 1 means that the entry is removed after the first scan without the
* BSSID being seen. Larger values can be used to avoid BSS entries
* disappearing if they are not visible in every scan (e.g., low signal quality
* or interference).
*/
#define WPA_BSS_EXPIRATION_SCAN_COUNT 2
static void wpa_bss_remove(struct wpa_supplicant *wpa_s, struct wpa_bss *bss)
{
dl_list_del(&bss->list);
wpa_s->num_bss--;
wpa_printf(MSG_DEBUG, "BSS: Remove id %u BSSID " MACSTR " SSID '%s'",
bss->id, MAC2STR(bss->bssid),
wpa_ssid_txt(bss->ssid, bss->ssid_len));
wpas_notify_bss_removed(wpa_s, bss->bssid);
os_free(bss);
}
static struct wpa_bss * wpa_bss_get(struct wpa_supplicant *wpa_s,
const u8 *bssid, const u8 *ssid,
size_t ssid_len)
{
struct wpa_bss *bss;
dl_list_for_each(bss, &wpa_s->bss, struct wpa_bss, list) {
if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0 &&
bss->ssid_len == ssid_len &&
os_memcmp(bss->ssid, ssid, ssid_len) == 0)
return bss;
}
return NULL;
}
static void wpa_bss_copy_res(struct wpa_bss *dst, struct wpa_scan_res *src)
{
os_time_t usec;
dst->flags = src->flags;
os_memcpy(dst->bssid, src->bssid, ETH_ALEN);
dst->freq = src->freq;
dst->beacon_int = src->beacon_int;
dst->caps = src->caps;
dst->qual = src->qual;
dst->noise = src->noise;
dst->level = src->level;
dst->tsf = src->tsf;
os_get_time(&dst->last_update);
dst->last_update.sec -= src->age / 1000;
usec = (src->age % 1000) * 1000;
if (dst->last_update.usec < usec) {
dst->last_update.sec--;
dst->last_update.usec += 1000000;
}
dst->last_update.usec -= usec;
}
static void wpa_bss_add(struct wpa_supplicant *wpa_s,
const u8 *ssid, size_t ssid_len,
struct wpa_scan_res *res)
{
struct wpa_bss *bss;
bss = os_zalloc(sizeof(*bss) + res->ie_len);
if (bss == NULL)
return;
bss->id = wpa_s->bss_next_id++;
bss->last_update_idx = wpa_s->bss_update_idx;
wpa_bss_copy_res(bss, res);
os_memcpy(bss->ssid, ssid, ssid_len);
bss->ssid_len = ssid_len;
bss->ie_len = res->ie_len;
os_memcpy(bss + 1, res + 1, res->ie_len);
dl_list_add_tail(&wpa_s->bss, &bss->list);
wpa_s->num_bss++;
wpa_printf(MSG_DEBUG, "BSS: Add new id %u BSSID " MACSTR " SSID '%s'",
bss->id, MAC2STR(bss->bssid), wpa_ssid_txt(ssid, ssid_len));
wpas_notify_bss_added(wpa_s, res->bssid);
if (wpa_s->num_bss > WPA_BSS_MAX_COUNT) {
/* Remove the oldest entry */
wpa_bss_remove(wpa_s, dl_list_first(&wpa_s->bss,
struct wpa_bss, list));
}
}
static void wpa_bss_update(struct wpa_supplicant *wpa_s, struct wpa_bss *bss,
struct wpa_scan_res *res)
{
bss->scan_miss_count = 0;
bss->last_update_idx = wpa_s->bss_update_idx;
wpa_bss_copy_res(bss, res);
/* Move the entry to the end of the list */
dl_list_del(&bss->list);
if (bss->ie_len >= res->ie_len) {
os_memcpy(bss + 1, res + 1, res->ie_len);
bss->ie_len = res->ie_len;
} else {
struct wpa_bss *nbss;
nbss = os_realloc(bss, sizeof(*bss) + res->ie_len);
if (nbss) {
bss = nbss;
os_memcpy(bss + 1, res + 1, res->ie_len);
bss->ie_len = res->ie_len;
}
}
dl_list_add_tail(&wpa_s->bss, &bss->list);
}
void wpa_bss_update_start(struct wpa_supplicant *wpa_s)
{
wpa_s->bss_update_idx++;
wpa_printf(MSG_DEBUG, "BSS: Start scan result update %u",
wpa_s->bss_update_idx);
}
void wpa_bss_update_scan_res(struct wpa_supplicant *wpa_s,
struct wpa_scan_res *res)
{
const u8 *ssid;
struct wpa_bss *bss;
ssid = wpa_scan_get_ie(res, WLAN_EID_SSID);
if (ssid == NULL) {
wpa_printf(MSG_DEBUG, "BSS: No SSID IE included for " MACSTR,
MAC2STR(res->bssid));
return;
}
if (ssid[1] > 32) {
wpa_printf(MSG_DEBUG, "BSS: Too long SSID IE included for "
MACSTR, MAC2STR(res->bssid));
return;
}
/* TODO: add option for ignoring BSSes we are not interested in
* (to save memory) */
bss = wpa_bss_get(wpa_s, res->bssid, ssid + 2, ssid[1]);
if (bss == NULL)
wpa_bss_add(wpa_s, ssid + 2, ssid[1], res);
else
wpa_bss_update(wpa_s, bss, res);
}
void wpa_bss_update_end(struct wpa_supplicant *wpa_s)
{
struct wpa_bss *bss, *n;
/* TODO: expire only entries that were on the scanned frequencies/SSIDs
* list; need to get info from driver about scanned frequencies and
* SSIDs to be able to figure out which entries should be expired based
* on this */
dl_list_for_each_safe(bss, n, &wpa_s->bss, struct wpa_bss, list) {
if (bss->last_update_idx < wpa_s->bss_update_idx)
bss->scan_miss_count++;
if (bss->scan_miss_count >= WPA_BSS_EXPIRATION_SCAN_COUNT) {
wpa_printf(MSG_DEBUG, "BSS: Expire BSS %u due to no "
"match in scan", bss->id);
wpa_bss_remove(wpa_s, bss);
}
}
}
static void wpa_bss_timeout(void *eloop_ctx, void *timeout_ctx)
{
struct wpa_supplicant *wpa_s = eloop_ctx;
struct wpa_bss *bss, *n;
struct os_time t;
if (dl_list_empty(&wpa_s->bss))
return;
os_get_time(&t);
t.sec -= WPA_BSS_EXPIRATION_AGE;
dl_list_for_each_safe(bss, n, &wpa_s->bss, struct wpa_bss, list) {
if (os_memcmp(bss->bssid, wpa_s->bssid, ETH_ALEN) == 0 ||
os_memcmp(bss->bssid, wpa_s->pending_bssid, ETH_ALEN) == 0)
continue; /* do not expire BSSes that are in use */
if (os_time_before(&bss->last_update, &t)) {
wpa_printf(MSG_DEBUG, "BSS: Expire BSS %u due to age",
bss->id);
wpa_bss_remove(wpa_s, bss);
} else
break;
}
eloop_register_timeout(WPA_BSS_EXPIRATION_PERIOD, 0,
wpa_bss_timeout, wpa_s, NULL);
}
int wpa_bss_init(struct wpa_supplicant *wpa_s)
{
dl_list_init(&wpa_s->bss);
eloop_register_timeout(WPA_BSS_EXPIRATION_PERIOD, 0,
wpa_bss_timeout, wpa_s, NULL);
return 0;
}
void wpa_bss_deinit(struct wpa_supplicant *wpa_s)
{
struct wpa_bss *bss, *n;
eloop_cancel_timeout(wpa_bss_timeout, wpa_s, NULL);
dl_list_for_each_safe(bss, n, &wpa_s->bss, struct wpa_bss, list)
wpa_bss_remove(wpa_s, bss);
}