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60b94c98 JM |
1 | /* |
2 | * WPA Supplicant - background scan and roaming module: simple | |
e2f74005 | 3 | * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi> |
60b94c98 | 4 | * |
0f3d578e JM |
5 | * This software may be distributed under the terms of the BSD license. |
6 | * See README for more details. | |
60b94c98 JM |
7 | */ |
8 | ||
9 | #include "includes.h" | |
10 | ||
11 | #include "common.h" | |
12 | #include "eloop.h" | |
13 | #include "drivers/driver.h" | |
14 | #include "config_ssid.h" | |
15 | #include "wpa_supplicant_i.h" | |
e2f74005 | 16 | #include "driver_i.h" |
9ba9fa07 | 17 | #include "scan.h" |
60b94c98 JM |
18 | #include "bgscan.h" |
19 | ||
20 | struct bgscan_simple_data { | |
21 | struct wpa_supplicant *wpa_s; | |
22 | const struct wpa_ssid *ssid; | |
23 | int scan_interval; | |
e2f74005 | 24 | int signal_threshold; |
6d21d411 | 25 | int short_scan_count; /* counter for scans using short scan interval */ |
87343c20 | 26 | int max_short_scans; /* maximum times we short-scan before back-off */ |
e2f74005 JM |
27 | int short_interval; /* use if signal < threshold */ |
28 | int long_interval; /* use if signal > threshold */ | |
e72a001b | 29 | struct os_reltime last_bgscan; |
60b94c98 JM |
30 | }; |
31 | ||
32 | ||
33 | static void bgscan_simple_timeout(void *eloop_ctx, void *timeout_ctx) | |
34 | { | |
35 | struct bgscan_simple_data *data = eloop_ctx; | |
36 | struct wpa_supplicant *wpa_s = data->wpa_s; | |
37 | struct wpa_driver_scan_params params; | |
38 | ||
39 | os_memset(¶ms, 0, sizeof(params)); | |
40 | params.num_ssids = 1; | |
41 | params.ssids[0].ssid = data->ssid->ssid; | |
42 | params.ssids[0].ssid_len = data->ssid->ssid_len; | |
43 | params.freqs = data->ssid->scan_freq; | |
44 | ||
45 | /* | |
46 | * A more advanced bgscan module would learn about most like channels | |
47 | * over time and request scans only for some channels (probing others | |
48 | * every now and then) to reduce effect on the data connection. | |
49 | */ | |
50 | ||
51 | wpa_printf(MSG_DEBUG, "bgscan simple: Request a background scan"); | |
52 | if (wpa_supplicant_trigger_scan(wpa_s, ¶ms)) { | |
53 | wpa_printf(MSG_DEBUG, "bgscan simple: Failed to trigger scan"); | |
54 | eloop_register_timeout(data->scan_interval, 0, | |
55 | bgscan_simple_timeout, data, NULL); | |
6d21d411 PS |
56 | } else { |
57 | if (data->scan_interval == data->short_interval) { | |
58 | data->short_scan_count++; | |
59 | /* | |
60 | * Spend at most the duration of a long scan interval | |
61 | * scanning at the short scan interval. After that, | |
62 | * revert to the long scan interval. | |
63 | */ | |
87343c20 | 64 | if (data->short_scan_count > data->max_short_scans) { |
6d21d411 PS |
65 | data->scan_interval = data->long_interval; |
66 | wpa_printf(MSG_DEBUG, "bgscan simple: Backing " | |
67 | "off to long scan interval"); | |
68 | } | |
87343c20 PS |
69 | } else if (data->short_scan_count > 0) { |
70 | /* | |
71 | * If we lasted a long scan interval without any | |
72 | * CQM triggers, decrease the short-scan count, | |
73 | * which allows 1 more short-scan interval to | |
74 | * occur in the future when CQM triggers. | |
75 | */ | |
76 | data->short_scan_count--; | |
6d21d411 | 77 | } |
e72a001b | 78 | os_get_reltime(&data->last_bgscan); |
6d21d411 | 79 | } |
e2f74005 JM |
80 | } |
81 | ||
82 | ||
83 | static int bgscan_simple_get_params(struct bgscan_simple_data *data, | |
84 | const char *params) | |
85 | { | |
86 | const char *pos; | |
87 | ||
88 | if (params == NULL) | |
89 | return 0; | |
90 | ||
91 | data->short_interval = atoi(params); | |
92 | ||
93 | pos = os_strchr(params, ':'); | |
94 | if (pos == NULL) | |
95 | return 0; | |
96 | pos++; | |
97 | data->signal_threshold = atoi(pos); | |
98 | pos = os_strchr(pos, ':'); | |
99 | if (pos == NULL) { | |
100 | wpa_printf(MSG_ERROR, "bgscan simple: Missing scan interval " | |
101 | "for high signal"); | |
102 | return -1; | |
60b94c98 | 103 | } |
e2f74005 JM |
104 | pos++; |
105 | data->long_interval = atoi(pos); | |
106 | ||
107 | return 0; | |
60b94c98 JM |
108 | } |
109 | ||
110 | ||
111 | static void * bgscan_simple_init(struct wpa_supplicant *wpa_s, | |
112 | const char *params, | |
113 | const struct wpa_ssid *ssid) | |
114 | { | |
115 | struct bgscan_simple_data *data; | |
116 | ||
117 | data = os_zalloc(sizeof(*data)); | |
118 | if (data == NULL) | |
119 | return NULL; | |
120 | data->wpa_s = wpa_s; | |
121 | data->ssid = ssid; | |
e2f74005 JM |
122 | if (bgscan_simple_get_params(data, params) < 0) { |
123 | os_free(data); | |
124 | return NULL; | |
125 | } | |
126 | if (data->short_interval <= 0) | |
127 | data->short_interval = 30; | |
128 | if (data->long_interval <= 0) | |
129 | data->long_interval = 30; | |
130 | ||
131 | wpa_printf(MSG_DEBUG, "bgscan simple: Signal strength threshold %d " | |
132 | "Short bgscan interval %d Long bgscan interval %d", | |
133 | data->signal_threshold, data->short_interval, | |
134 | data->long_interval); | |
135 | ||
136 | if (data->signal_threshold && | |
137 | wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) { | |
138 | wpa_printf(MSG_ERROR, "bgscan simple: Failed to enable " | |
139 | "signal strength monitoring"); | |
140 | } | |
141 | ||
142 | data->scan_interval = data->short_interval; | |
87343c20 | 143 | data->max_short_scans = data->long_interval / data->short_interval + 1; |
db03ddac PS |
144 | if (data->signal_threshold) { |
145 | /* Poll for signal info to set initial scan interval */ | |
146 | struct wpa_signal_info siginfo; | |
147 | if (wpa_drv_signal_poll(wpa_s, &siginfo) == 0 && | |
148 | siginfo.current_signal >= data->signal_threshold) | |
149 | data->scan_interval = data->long_interval; | |
150 | } | |
151 | wpa_printf(MSG_DEBUG, "bgscan simple: Init scan interval: %d", | |
152 | data->scan_interval); | |
60b94c98 JM |
153 | eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout, |
154 | data, NULL); | |
1e6ef645 JM |
155 | |
156 | /* | |
157 | * This function is called immediately after an association, so it is | |
158 | * reasonable to assume that a scan was completed recently. This makes | |
159 | * us skip an immediate new scan in cases where the current signal | |
160 | * level is below the bgscan threshold. | |
161 | */ | |
e72a001b | 162 | os_get_reltime(&data->last_bgscan); |
1e6ef645 | 163 | |
60b94c98 JM |
164 | return data; |
165 | } | |
166 | ||
167 | ||
168 | static void bgscan_simple_deinit(void *priv) | |
169 | { | |
170 | struct bgscan_simple_data *data = priv; | |
171 | eloop_cancel_timeout(bgscan_simple_timeout, data, NULL); | |
e2f74005 JM |
172 | if (data->signal_threshold) |
173 | wpa_drv_signal_monitor(data->wpa_s, 0, 0); | |
60b94c98 JM |
174 | os_free(data); |
175 | } | |
176 | ||
177 | ||
c2594c36 JM |
178 | static int bgscan_simple_notify_scan(void *priv, |
179 | struct wpa_scan_results *scan_res) | |
60b94c98 JM |
180 | { |
181 | struct bgscan_simple_data *data = priv; | |
182 | ||
183 | wpa_printf(MSG_DEBUG, "bgscan simple: scan result notification"); | |
184 | ||
185 | eloop_cancel_timeout(bgscan_simple_timeout, data, NULL); | |
186 | eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout, | |
187 | data, NULL); | |
188 | ||
189 | /* | |
190 | * A more advanced bgscan could process scan results internally, select | |
191 | * the BSS and request roam if needed. This sample uses the existing | |
192 | * BSS/ESS selection routine. Change this to return 1 if selection is | |
193 | * done inside the bgscan module. | |
194 | */ | |
195 | ||
196 | return 0; | |
197 | } | |
198 | ||
199 | ||
200 | static void bgscan_simple_notify_beacon_loss(void *priv) | |
201 | { | |
202 | wpa_printf(MSG_DEBUG, "bgscan simple: beacon loss"); | |
203 | /* TODO: speed up background scanning */ | |
204 | } | |
205 | ||
206 | ||
60a972a6 | 207 | static void bgscan_simple_notify_signal_change(void *priv, int above, |
174fa789 PS |
208 | int current_signal, |
209 | int current_noise, | |
210 | int current_txrate) | |
60b94c98 | 211 | { |
e2f74005 | 212 | struct bgscan_simple_data *data = priv; |
1e6ef645 | 213 | int scan = 0; |
e72a001b | 214 | struct os_reltime now; |
e2f74005 JM |
215 | |
216 | if (data->short_interval == data->long_interval || | |
217 | data->signal_threshold == 0) | |
218 | return; | |
219 | ||
220 | wpa_printf(MSG_DEBUG, "bgscan simple: signal level changed " | |
174fa789 PS |
221 | "(above=%d current_signal=%d current_noise=%d " |
222 | "current_txrate=%d))", above, current_signal, | |
223 | current_noise, current_txrate); | |
e2f74005 | 224 | if (data->scan_interval == data->long_interval && !above) { |
1e6ef645 JM |
225 | wpa_printf(MSG_DEBUG, "bgscan simple: Start using short " |
226 | "bgscan interval"); | |
e2f74005 | 227 | data->scan_interval = data->short_interval; |
e72a001b | 228 | os_get_reltime(&now); |
87343c20 PS |
229 | if (now.sec > data->last_bgscan.sec + 1 && |
230 | data->short_scan_count <= data->max_short_scans) | |
231 | /* | |
232 | * If we haven't just previously (<1 second ago) | |
233 | * performed a scan, and we haven't depleted our | |
234 | * budget for short-scans, perform a scan | |
235 | * immediately. | |
236 | */ | |
1e6ef645 | 237 | scan = 1; |
439efd1e PS |
238 | else if (data->last_bgscan.sec + data->long_interval > |
239 | now.sec + data->scan_interval) { | |
240 | /* | |
241 | * Restart scan interval timer if currently scheduled | |
242 | * scan is too far in the future. | |
243 | */ | |
244 | eloop_cancel_timeout(bgscan_simple_timeout, data, | |
245 | NULL); | |
246 | eloop_register_timeout(data->scan_interval, 0, | |
247 | bgscan_simple_timeout, data, | |
248 | NULL); | |
249 | } | |
e2f74005 JM |
250 | } else if (data->scan_interval == data->short_interval && above) { |
251 | wpa_printf(MSG_DEBUG, "bgscan simple: Start using long bgscan " | |
252 | "interval"); | |
253 | data->scan_interval = data->long_interval; | |
254 | eloop_cancel_timeout(bgscan_simple_timeout, data, NULL); | |
255 | eloop_register_timeout(data->scan_interval, 0, | |
256 | bgscan_simple_timeout, data, NULL); | |
257 | } else if (!above) { | |
e2f74005 JM |
258 | /* |
259 | * Signal dropped further 4 dB. Request a new scan if we have | |
260 | * not yet scanned in a while. | |
261 | */ | |
e72a001b | 262 | os_get_reltime(&now); |
1e6ef645 JM |
263 | if (now.sec > data->last_bgscan.sec + 10) |
264 | scan = 1; | |
265 | } | |
266 | ||
267 | if (scan) { | |
268 | wpa_printf(MSG_DEBUG, "bgscan simple: Trigger immediate scan"); | |
269 | eloop_cancel_timeout(bgscan_simple_timeout, data, NULL); | |
270 | eloop_register_timeout(0, 0, bgscan_simple_timeout, data, | |
271 | NULL); | |
e2f74005 | 272 | } |
60b94c98 JM |
273 | } |
274 | ||
275 | ||
276 | const struct bgscan_ops bgscan_simple_ops = { | |
277 | .name = "simple", | |
278 | .init = bgscan_simple_init, | |
279 | .deinit = bgscan_simple_deinit, | |
280 | .notify_scan = bgscan_simple_notify_scan, | |
281 | .notify_beacon_loss = bgscan_simple_notify_beacon_loss, | |
282 | .notify_signal_change = bgscan_simple_notify_signal_change, | |
283 | }; |