1 /*
2 * Generic advertisement service (GAS) server
3 * Copyright (c) 2017, Qualcomm Atheros, Inc.
4 *
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
7 */
8
9 #include "includes.h"
10
11 #include "utils/common.h"
12 #include "utils/list.h"
13 #include "utils/eloop.h"
14 #include "ieee802_11_defs.h"
15 #include "gas.h"
16 #include "gas_server.h"
17
18
19 #define MAX_ADV_PROTO_ID_LEN 10
20 #define GAS_QUERY_TIMEOUT 10
21
22 struct gas_server_handler {
23 struct dl_list list;
24 u8 adv_proto_id[MAX_ADV_PROTO_ID_LEN];
25 u8 adv_proto_id_len;
26 struct wpabuf * (*req_cb)(void *ctx, const u8 *sa,
27 const u8 *query, size_t query_len);
28 void (*status_cb)(void *ctx, struct wpabuf *resp, int ok);
29 void *ctx;
30 struct gas_server *gas;
31 };
32
33 struct gas_server_response {
34 struct dl_list list;
35 size_t offset;
36 u8 frag_id;
37 struct wpabuf *resp;
38 int freq;
39 u8 dst[ETH_ALEN];
40 u8 dialog_token;
41 struct gas_server_handler *handler;
42 };
43
44 struct gas_server {
45 struct dl_list handlers; /* struct gas_server_handler::list */
46 struct dl_list responses; /* struct gas_server_response::list */
47 void (*tx)(void *ctx, int freq, const u8 *da, struct wpabuf *resp,
48 unsigned int wait_time);
49 void *ctx;
50 };
51
52 static void gas_server_free_response(struct gas_server_response *response);
53
54
gas_server_response_timeout(void * eloop_ctx,void * user_ctx)55 static void gas_server_response_timeout(void *eloop_ctx, void *user_ctx)
56 {
57 struct gas_server_response *response = eloop_ctx;
58
59 wpa_printf(MSG_DEBUG, "GAS: Response @%p timeout for " MACSTR
60 " (dialog_token=%u freq=%d frag_id=%u sent=%lu/%lu) - drop pending data",
61 response, MAC2STR(response->dst), response->dialog_token,
62 response->freq, response->frag_id,
63 (unsigned long) response->offset,
64 (unsigned long) wpabuf_len(response->resp));
65 response->handler->status_cb(response->handler->ctx,
66 response->resp, 0);
67 response->resp = NULL;
68 dl_list_del(&response->list);
69 gas_server_free_response(response);
70 }
71
72
gas_server_free_response(struct gas_server_response * response)73 static void gas_server_free_response(struct gas_server_response *response)
74 {
75 if (!response)
76 return;
77 wpa_printf(MSG_DEBUG, "DPP: Free GAS response @%p", response);
78 eloop_cancel_timeout(gas_server_response_timeout, response, NULL);
79 wpabuf_free(response->resp);
80 os_free(response);
81 }
82
83
84 static void
gas_server_send_resp(struct gas_server * gas,struct gas_server_handler * handler,const u8 * da,int freq,u8 dialog_token,struct wpabuf * query_resp)85 gas_server_send_resp(struct gas_server *gas, struct gas_server_handler *handler,
86 const u8 *da, int freq, u8 dialog_token,
87 struct wpabuf *query_resp)
88 {
89 size_t max_len = (freq > 56160) ? 928 : 1400;
90 size_t hdr_len = 24 + 2 + 5 + 3 + handler->adv_proto_id_len + 2;
91 size_t resp_frag_len;
92 struct wpabuf *resp;
93 u16 comeback_delay;
94 struct gas_server_response *response;
95
96 if (!query_resp)
97 return;
98
99 response = os_zalloc(sizeof(*response));
100 if (!response) {
101 wpabuf_free(query_resp);
102 return;
103 }
104 wpa_printf(MSG_DEBUG, "DPP: Allocated GAS response @%p", response);
105 response->freq = freq;
106 response->handler = handler;
107 os_memcpy(response->dst, da, ETH_ALEN);
108 response->dialog_token = dialog_token;
109 if (hdr_len + wpabuf_len(query_resp) > max_len) {
110 /* Need to use comeback to initiate fragmentation */
111 comeback_delay = 1;
112 resp_frag_len = 0;
113 } else {
114 /* Full response fits into the initial response */
115 comeback_delay = 0;
116 resp_frag_len = wpabuf_len(query_resp);
117 }
118
119 resp = gas_build_initial_resp(dialog_token, WLAN_STATUS_SUCCESS,
120 comeback_delay,
121 handler->adv_proto_id_len +
122 resp_frag_len);
123 if (!resp) {
124 wpabuf_free(query_resp);
125 gas_server_free_response(response);
126 return;
127 }
128
129 /* Advertisement Protocol element */
130 wpabuf_put_u8(resp, WLAN_EID_ADV_PROTO);
131 wpabuf_put_u8(resp, 1 + handler->adv_proto_id_len); /* Length */
132 wpabuf_put_u8(resp, 0x7f);
133 /* Advertisement Protocol ID */
134 wpabuf_put_data(resp, handler->adv_proto_id, handler->adv_proto_id_len);
135
136 /* Query Response Length */
137 wpabuf_put_le16(resp, resp_frag_len);
138 if (!comeback_delay)
139 wpabuf_put_buf(resp, query_resp);
140
141 if (comeback_delay) {
142 wpa_printf(MSG_DEBUG,
143 "GAS: Need to fragment query response");
144 } else {
145 wpa_printf(MSG_DEBUG,
146 "GAS: Full query response fits in the GAS Initial Response frame");
147 }
148 response->offset = resp_frag_len;
149 response->resp = query_resp;
150 dl_list_add(&gas->responses, &response->list);
151 gas->tx(gas->ctx, freq, da, resp, comeback_delay ? 2000 : 0);
152 wpabuf_free(resp);
153 eloop_register_timeout(GAS_QUERY_TIMEOUT, 0,
154 gas_server_response_timeout, response, NULL);
155 }
156
157
158 static int
gas_server_rx_initial_req(struct gas_server * gas,const u8 * da,const u8 * sa,const u8 * bssid,int freq,u8 dialog_token,const u8 * data,size_t len)159 gas_server_rx_initial_req(struct gas_server *gas, const u8 *da, const u8 *sa,
160 const u8 *bssid, int freq, u8 dialog_token,
161 const u8 *data, size_t len)
162 {
163 const u8 *pos, *end, *adv_proto, *query_req;
164 u8 adv_proto_len;
165 u16 query_req_len;
166 struct gas_server_handler *handler;
167 struct wpabuf *resp;
168
169 wpa_hexdump(MSG_MSGDUMP, "GAS: Received GAS Initial Request frame",
170 data, len);
171 pos = data;
172 end = data + len;
173
174 if (end - pos < 2 || pos[0] != WLAN_EID_ADV_PROTO) {
175 wpa_printf(MSG_DEBUG,
176 "GAS: No Advertisement Protocol element found");
177 return -1;
178 }
179 pos++;
180 adv_proto_len = *pos++;
181 if (end - pos < adv_proto_len || adv_proto_len < 2) {
182 wpa_printf(MSG_DEBUG,
183 "GAS: Truncated Advertisement Protocol element");
184 return -1;
185 }
186
187 adv_proto = pos;
188 pos += adv_proto_len;
189 wpa_hexdump(MSG_MSGDUMP, "GAS: Advertisement Protocol element",
190 adv_proto, adv_proto_len);
191
192 if (end - pos < 2) {
193 wpa_printf(MSG_DEBUG, "GAS: No Query Request Length field");
194 return -1;
195 }
196 query_req_len = WPA_GET_LE16(pos);
197 pos += 2;
198 if (end - pos < query_req_len) {
199 wpa_printf(MSG_DEBUG, "GAS: Truncated Query Request field");
200 return -1;
201 }
202 query_req = pos;
203 pos += query_req_len;
204 wpa_hexdump(MSG_MSGDUMP, "GAS: Query Request",
205 query_req, query_req_len);
206
207 if (pos < end) {
208 wpa_hexdump(MSG_MSGDUMP,
209 "GAS: Ignored extra data after Query Request field",
210 pos, end - pos);
211 }
212
213 dl_list_for_each(handler, &gas->handlers, struct gas_server_handler,
214 list) {
215 if (adv_proto_len < 1 + handler->adv_proto_id_len ||
216 os_memcmp(adv_proto + 1, handler->adv_proto_id,
217 handler->adv_proto_id_len) != 0)
218 continue;
219
220 wpa_printf(MSG_DEBUG,
221 "GAS: Calling handler for the requested Advertisement Protocol ID");
222 resp = handler->req_cb(handler->ctx, sa, query_req,
223 query_req_len);
224 wpa_hexdump_buf(MSG_MSGDUMP, "GAS: Response from the handler",
225 resp);
226 gas_server_send_resp(gas, handler, sa, freq, dialog_token,
227 resp);
228 return 0;
229 }
230
231 wpa_printf(MSG_DEBUG,
232 "GAS: No registered handler for the requested Advertisement Protocol ID");
233 return -1;
234 }
235
236
237 static void
gas_server_handle_rx_comeback_req(struct gas_server_response * response)238 gas_server_handle_rx_comeback_req(struct gas_server_response *response)
239 {
240 struct gas_server_handler *handler = response->handler;
241 struct gas_server *gas = handler->gas;
242 size_t max_len = (response->freq > 56160) ? 928 : 1400;
243 size_t hdr_len = 24 + 2 + 6 + 3 + handler->adv_proto_id_len + 2;
244 size_t remaining, resp_frag_len;
245 struct wpabuf *resp;
246
247 remaining = wpabuf_len(response->resp) - response->offset;
248 if (hdr_len + remaining > max_len)
249 resp_frag_len = max_len - hdr_len;
250 else
251 resp_frag_len = remaining;
252 wpa_printf(MSG_DEBUG,
253 "GAS: Sending out %u/%u remaining Query Response octets",
254 (unsigned int) resp_frag_len, (unsigned int) remaining);
255
256 resp = gas_build_comeback_resp(response->dialog_token,
257 WLAN_STATUS_SUCCESS,
258 response->frag_id++,
259 resp_frag_len < remaining, 0,
260 handler->adv_proto_id_len +
261 resp_frag_len);
262 if (!resp) {
263 dl_list_del(&response->list);
264 gas_server_free_response(response);
265 return;
266 }
267
268 /* Advertisement Protocol element */
269 wpabuf_put_u8(resp, WLAN_EID_ADV_PROTO);
270 wpabuf_put_u8(resp, 1 + handler->adv_proto_id_len); /* Length */
271 wpabuf_put_u8(resp, 0x7f);
272 /* Advertisement Protocol ID */
273 wpabuf_put_data(resp, handler->adv_proto_id, handler->adv_proto_id_len);
274
275 /* Query Response Length */
276 wpabuf_put_le16(resp, resp_frag_len);
277 wpabuf_put_data(resp, wpabuf_head_u8(response->resp) + response->offset,
278 resp_frag_len);
279
280 response->offset += resp_frag_len;
281
282 gas->tx(gas->ctx, response->freq, response->dst, resp,
283 remaining > resp_frag_len ? 2000 : 0);
284 wpabuf_free(resp);
285 }
286
287
288 static int
gas_server_rx_comeback_req(struct gas_server * gas,const u8 * da,const u8 * sa,const u8 * bssid,int freq,u8 dialog_token)289 gas_server_rx_comeback_req(struct gas_server *gas, const u8 *da, const u8 *sa,
290 const u8 *bssid, int freq, u8 dialog_token)
291 {
292 struct gas_server_response *response;
293
294 dl_list_for_each(response, &gas->responses, struct gas_server_response,
295 list) {
296 if (response->dialog_token != dialog_token ||
297 os_memcmp(sa, response->dst, ETH_ALEN) != 0)
298 continue;
299 gas_server_handle_rx_comeback_req(response);
300 return 0;
301 }
302
303 wpa_printf(MSG_DEBUG, "GAS: No pending GAS response for " MACSTR
304 " (dialog token %u)", MAC2STR(sa), dialog_token);
305 return -1;
306 }
307
308
309 /**
310 * gas_query_rx - Indicate reception of a Public Action or Protected Dual frame
311 * @gas: GAS query data from gas_server_init()
312 * @da: Destination MAC address of the Action frame
313 * @sa: Source MAC address of the Action frame
314 * @bssid: BSSID of the Action frame
315 * @categ: Category of the Action frame
316 * @data: Payload of the Action frame
317 * @len: Length of @data
318 * @freq: Frequency (in MHz) on which the frame was received
319 * Returns: 0 if the Public Action frame was a GAS request frame or -1 if not
320 */
gas_server_rx(struct gas_server * gas,const u8 * da,const u8 * sa,const u8 * bssid,u8 categ,const u8 * data,size_t len,int freq)321 int gas_server_rx(struct gas_server *gas, const u8 *da, const u8 *sa,
322 const u8 *bssid, u8 categ, const u8 *data, size_t len,
323 int freq)
324 {
325 u8 action, dialog_token;
326 const u8 *pos, *end;
327
328 if (!gas || len < 2)
329 return -1;
330
331 if (categ == WLAN_ACTION_PROTECTED_DUAL)
332 return -1; /* Not supported for now */
333
334 pos = data;
335 end = data + len;
336 action = *pos++;
337 dialog_token = *pos++;
338
339 if (action != WLAN_PA_GAS_INITIAL_REQ &&
340 action != WLAN_PA_GAS_COMEBACK_REQ)
341 return -1; /* Not a GAS request */
342
343 wpa_printf(MSG_DEBUG, "GAS: Received GAS %s Request frame DA=" MACSTR
344 " SA=" MACSTR " BSSID=" MACSTR
345 " freq=%d dialog_token=%u len=%u",
346 action == WLAN_PA_GAS_INITIAL_REQ ? "Initial" : "Comeback",
347 MAC2STR(da), MAC2STR(sa), MAC2STR(bssid), freq, dialog_token,
348 (unsigned int) len);
349
350 if (action == WLAN_PA_GAS_INITIAL_REQ)
351 return gas_server_rx_initial_req(gas, da, sa, bssid,
352 freq, dialog_token,
353 pos, end - pos);
354 return gas_server_rx_comeback_req(gas, da, sa, bssid,
355 freq, dialog_token);
356 }
357
358
gas_server_handle_tx_status(struct gas_server_response * response,int ack)359 static void gas_server_handle_tx_status(struct gas_server_response *response,
360 int ack)
361 {
362 if (ack && response->offset < wpabuf_len(response->resp)) {
363 wpa_printf(MSG_DEBUG,
364 "GAS: More fragments remaining - keep pending entry");
365 return;
366 }
367
368 if (!ack)
369 wpa_printf(MSG_DEBUG,
370 "GAS: No ACK received - drop pending entry");
371 else
372 wpa_printf(MSG_DEBUG,
373 "GAS: Last fragment of the response sent out - drop pending entry");
374
375 response->handler->status_cb(response->handler->ctx,
376 response->resp, ack);
377 response->resp = NULL;
378 dl_list_del(&response->list);
379 gas_server_free_response(response);
380 }
381
382
gas_server_tx_status(struct gas_server * gas,const u8 * dst,const u8 * data,size_t data_len,int ack)383 void gas_server_tx_status(struct gas_server *gas, const u8 *dst, const u8 *data,
384 size_t data_len, int ack)
385 {
386 const u8 *pos;
387 u8 action, code, dialog_token;
388 struct gas_server_response *response;
389
390 if (data_len < 24 + 3)
391 return;
392 pos = data + 24;
393 action = *pos++;
394 code = *pos++;
395 dialog_token = *pos++;
396 if (action != WLAN_ACTION_PUBLIC ||
397 (code != WLAN_PA_GAS_INITIAL_RESP &&
398 code != WLAN_PA_GAS_COMEBACK_RESP))
399 return;
400 wpa_printf(MSG_DEBUG, "GAS: TX status dst=" MACSTR
401 " ack=%d %s dialog_token=%u",
402 MAC2STR(dst), ack,
403 code == WLAN_PA_GAS_INITIAL_RESP ? "initial" : "comeback",
404 dialog_token);
405 dl_list_for_each(response, &gas->responses, struct gas_server_response,
406 list) {
407 if (response->dialog_token != dialog_token ||
408 os_memcmp(dst, response->dst, ETH_ALEN) != 0)
409 continue;
410 gas_server_handle_tx_status(response, ack);
411 return;
412 }
413
414 wpa_printf(MSG_DEBUG, "GAS: No pending response matches TX status");
415 }
416
417
gas_server_init(void * ctx,void (* tx)(void * ctx,int freq,const u8 * da,struct wpabuf * buf,unsigned int wait_time))418 struct gas_server * gas_server_init(void *ctx,
419 void (*tx)(void *ctx, int freq,
420 const u8 *da,
421 struct wpabuf *buf,
422 unsigned int wait_time))
423 {
424 struct gas_server *gas;
425
426 gas = os_zalloc(sizeof(*gas));
427 if (!gas)
428 return NULL;
429 gas->ctx = ctx;
430 gas->tx = tx;
431 dl_list_init(&gas->handlers);
432 dl_list_init(&gas->responses);
433 return gas;
434 }
435
436
gas_server_deinit(struct gas_server * gas)437 void gas_server_deinit(struct gas_server *gas)
438 {
439 struct gas_server_handler *handler, *tmp;
440 struct gas_server_response *response, *tmp_r;
441
442 if (!gas)
443 return;
444
445 dl_list_for_each_safe(handler, tmp, &gas->handlers,
446 struct gas_server_handler, list) {
447 dl_list_del(&handler->list);
448 os_free(handler);
449 }
450
451 dl_list_for_each_safe(response, tmp_r, &gas->responses,
452 struct gas_server_response, list) {
453 dl_list_del(&response->list);
454 gas_server_free_response(response);
455 }
456
457 os_free(gas);
458 }
459
460
gas_server_register(struct gas_server * gas,const u8 * adv_proto_id,u8 adv_proto_id_len,struct wpabuf * (* req_cb)(void * ctx,const u8 * sa,const u8 * query,size_t query_len),void (* status_cb)(void * ctx,struct wpabuf * resp,int ok),void * ctx)461 int gas_server_register(struct gas_server *gas,
462 const u8 *adv_proto_id, u8 adv_proto_id_len,
463 struct wpabuf *
464 (*req_cb)(void *ctx, const u8 *sa,
465 const u8 *query, size_t query_len),
466 void (*status_cb)(void *ctx, struct wpabuf *resp,
467 int ok),
468 void *ctx)
469 {
470 struct gas_server_handler *handler;
471
472 if (!gas || adv_proto_id_len > MAX_ADV_PROTO_ID_LEN)
473 return -1;
474 handler = os_zalloc(sizeof(*handler));
475 if (!handler)
476 return -1;
477
478 os_memcpy(handler->adv_proto_id, adv_proto_id, adv_proto_id_len);
479 handler->adv_proto_id_len = adv_proto_id_len;
480 handler->req_cb = req_cb;
481 handler->status_cb = status_cb;
482 handler->ctx = ctx;
483 handler->gas = gas;
484 dl_list_add(&gas->handlers, &handler->list);
485
486 return 0;
487 }
488