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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++; | |
e72faadb | 59 | if (data->short_scan_count >= data->max_short_scans) { |
6d21d411 PS |
60 | data->scan_interval = data->long_interval; |
61 | wpa_printf(MSG_DEBUG, "bgscan simple: Backing " | |
62 | "off to long scan interval"); | |
63 | } | |
87343c20 PS |
64 | } else if (data->short_scan_count > 0) { |
65 | /* | |
66 | * If we lasted a long scan interval without any | |
67 | * CQM triggers, decrease the short-scan count, | |
68 | * which allows 1 more short-scan interval to | |
69 | * occur in the future when CQM triggers. | |
70 | */ | |
71 | data->short_scan_count--; | |
6d21d411 | 72 | } |
e72a001b | 73 | os_get_reltime(&data->last_bgscan); |
6d21d411 | 74 | } |
e2f74005 JM |
75 | } |
76 | ||
77 | ||
78 | static int bgscan_simple_get_params(struct bgscan_simple_data *data, | |
79 | const char *params) | |
80 | { | |
81 | const char *pos; | |
82 | ||
e2f74005 JM |
83 | data->short_interval = atoi(params); |
84 | ||
85 | pos = os_strchr(params, ':'); | |
86 | if (pos == NULL) | |
87 | return 0; | |
88 | pos++; | |
89 | data->signal_threshold = atoi(pos); | |
90 | pos = os_strchr(pos, ':'); | |
91 | if (pos == NULL) { | |
92 | wpa_printf(MSG_ERROR, "bgscan simple: Missing scan interval " | |
93 | "for high signal"); | |
94 | return -1; | |
60b94c98 | 95 | } |
e2f74005 JM |
96 | pos++; |
97 | data->long_interval = atoi(pos); | |
98 | ||
99 | return 0; | |
60b94c98 JM |
100 | } |
101 | ||
102 | ||
103 | static void * bgscan_simple_init(struct wpa_supplicant *wpa_s, | |
104 | const char *params, | |
105 | const struct wpa_ssid *ssid) | |
106 | { | |
107 | struct bgscan_simple_data *data; | |
108 | ||
109 | data = os_zalloc(sizeof(*data)); | |
110 | if (data == NULL) | |
111 | return NULL; | |
112 | data->wpa_s = wpa_s; | |
113 | data->ssid = ssid; | |
e2f74005 JM |
114 | if (bgscan_simple_get_params(data, params) < 0) { |
115 | os_free(data); | |
116 | return NULL; | |
117 | } | |
118 | if (data->short_interval <= 0) | |
119 | data->short_interval = 30; | |
120 | if (data->long_interval <= 0) | |
121 | data->long_interval = 30; | |
122 | ||
123 | wpa_printf(MSG_DEBUG, "bgscan simple: Signal strength threshold %d " | |
124 | "Short bgscan interval %d Long bgscan interval %d", | |
125 | data->signal_threshold, data->short_interval, | |
126 | data->long_interval); | |
127 | ||
128 | if (data->signal_threshold && | |
129 | wpa_drv_signal_monitor(wpa_s, data->signal_threshold, 4) < 0) { | |
130 | wpa_printf(MSG_ERROR, "bgscan simple: Failed to enable " | |
131 | "signal strength monitoring"); | |
132 | } | |
133 | ||
134 | data->scan_interval = data->short_interval; | |
87343c20 | 135 | data->max_short_scans = data->long_interval / data->short_interval + 1; |
db03ddac PS |
136 | if (data->signal_threshold) { |
137 | /* Poll for signal info to set initial scan interval */ | |
138 | struct wpa_signal_info siginfo; | |
139 | if (wpa_drv_signal_poll(wpa_s, &siginfo) == 0 && | |
140 | siginfo.current_signal >= data->signal_threshold) | |
141 | data->scan_interval = data->long_interval; | |
142 | } | |
143 | wpa_printf(MSG_DEBUG, "bgscan simple: Init scan interval: %d", | |
144 | data->scan_interval); | |
60b94c98 JM |
145 | eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout, |
146 | data, NULL); | |
1e6ef645 JM |
147 | |
148 | /* | |
149 | * This function is called immediately after an association, so it is | |
150 | * reasonable to assume that a scan was completed recently. This makes | |
151 | * us skip an immediate new scan in cases where the current signal | |
152 | * level is below the bgscan threshold. | |
153 | */ | |
e72a001b | 154 | os_get_reltime(&data->last_bgscan); |
1e6ef645 | 155 | |
60b94c98 JM |
156 | return data; |
157 | } | |
158 | ||
159 | ||
160 | static void bgscan_simple_deinit(void *priv) | |
161 | { | |
162 | struct bgscan_simple_data *data = priv; | |
163 | eloop_cancel_timeout(bgscan_simple_timeout, data, NULL); | |
e2f74005 JM |
164 | if (data->signal_threshold) |
165 | wpa_drv_signal_monitor(data->wpa_s, 0, 0); | |
60b94c98 JM |
166 | os_free(data); |
167 | } | |
168 | ||
169 | ||
c2594c36 JM |
170 | static int bgscan_simple_notify_scan(void *priv, |
171 | struct wpa_scan_results *scan_res) | |
60b94c98 JM |
172 | { |
173 | struct bgscan_simple_data *data = priv; | |
174 | ||
175 | wpa_printf(MSG_DEBUG, "bgscan simple: scan result notification"); | |
176 | ||
177 | eloop_cancel_timeout(bgscan_simple_timeout, data, NULL); | |
178 | eloop_register_timeout(data->scan_interval, 0, bgscan_simple_timeout, | |
179 | data, NULL); | |
180 | ||
181 | /* | |
182 | * A more advanced bgscan could process scan results internally, select | |
183 | * the BSS and request roam if needed. This sample uses the existing | |
184 | * BSS/ESS selection routine. Change this to return 1 if selection is | |
185 | * done inside the bgscan module. | |
186 | */ | |
187 | ||
188 | return 0; | |
189 | } | |
190 | ||
191 | ||
192 | static void bgscan_simple_notify_beacon_loss(void *priv) | |
193 | { | |
194 | wpa_printf(MSG_DEBUG, "bgscan simple: beacon loss"); | |
195 | /* TODO: speed up background scanning */ | |
196 | } | |
197 | ||
198 | ||
60a972a6 | 199 | static void bgscan_simple_notify_signal_change(void *priv, int above, |
174fa789 PS |
200 | int current_signal, |
201 | int current_noise, | |
202 | int current_txrate) | |
60b94c98 | 203 | { |
e2f74005 | 204 | struct bgscan_simple_data *data = priv; |
1e6ef645 | 205 | int scan = 0; |
e72a001b | 206 | struct os_reltime now; |
e2f74005 JM |
207 | |
208 | if (data->short_interval == data->long_interval || | |
209 | data->signal_threshold == 0) | |
210 | return; | |
211 | ||
212 | wpa_printf(MSG_DEBUG, "bgscan simple: signal level changed " | |
174fa789 PS |
213 | "(above=%d current_signal=%d current_noise=%d " |
214 | "current_txrate=%d))", above, current_signal, | |
215 | current_noise, current_txrate); | |
e2f74005 | 216 | if (data->scan_interval == data->long_interval && !above) { |
1e6ef645 JM |
217 | wpa_printf(MSG_DEBUG, "bgscan simple: Start using short " |
218 | "bgscan interval"); | |
e2f74005 | 219 | data->scan_interval = data->short_interval; |
e72a001b | 220 | os_get_reltime(&now); |
87343c20 PS |
221 | if (now.sec > data->last_bgscan.sec + 1 && |
222 | data->short_scan_count <= data->max_short_scans) | |
223 | /* | |
224 | * If we haven't just previously (<1 second ago) | |
225 | * performed a scan, and we haven't depleted our | |
226 | * budget for short-scans, perform a scan | |
227 | * immediately. | |
228 | */ | |
1e6ef645 | 229 | scan = 1; |
439efd1e PS |
230 | else if (data->last_bgscan.sec + data->long_interval > |
231 | now.sec + data->scan_interval) { | |
232 | /* | |
233 | * Restart scan interval timer if currently scheduled | |
234 | * scan is too far in the future. | |
235 | */ | |
236 | eloop_cancel_timeout(bgscan_simple_timeout, data, | |
237 | NULL); | |
238 | eloop_register_timeout(data->scan_interval, 0, | |
239 | bgscan_simple_timeout, data, | |
240 | NULL); | |
241 | } | |
e2f74005 JM |
242 | } else if (data->scan_interval == data->short_interval && above) { |
243 | wpa_printf(MSG_DEBUG, "bgscan simple: Start using long bgscan " | |
244 | "interval"); | |
245 | data->scan_interval = data->long_interval; | |
246 | eloop_cancel_timeout(bgscan_simple_timeout, data, NULL); | |
247 | eloop_register_timeout(data->scan_interval, 0, | |
248 | bgscan_simple_timeout, data, NULL); | |
249 | } else if (!above) { | |
e2f74005 JM |
250 | /* |
251 | * Signal dropped further 4 dB. Request a new scan if we have | |
252 | * not yet scanned in a while. | |
253 | */ | |
e72a001b | 254 | os_get_reltime(&now); |
1e6ef645 JM |
255 | if (now.sec > data->last_bgscan.sec + 10) |
256 | scan = 1; | |
257 | } | |
258 | ||
259 | if (scan) { | |
260 | wpa_printf(MSG_DEBUG, "bgscan simple: Trigger immediate scan"); | |
261 | eloop_cancel_timeout(bgscan_simple_timeout, data, NULL); | |
262 | eloop_register_timeout(0, 0, bgscan_simple_timeout, data, | |
263 | NULL); | |
e2f74005 | 264 | } |
60b94c98 JM |
265 | } |
266 | ||
267 | ||
268 | const struct bgscan_ops bgscan_simple_ops = { | |
269 | .name = "simple", | |
270 | .init = bgscan_simple_init, | |
271 | .deinit = bgscan_simple_deinit, | |
272 | .notify_scan = bgscan_simple_notify_scan, | |
273 | .notify_beacon_loss = bgscan_simple_notify_beacon_loss, | |
274 | .notify_signal_change = bgscan_simple_notify_signal_change, | |
275 | }; |