gas.c revision 1f69aa52ea2e0a73ac502565df8c666ee49cab6a 
1/*
2 * Generic advertisement service (GAS) (IEEE 802.11u)
3 * Copyright (c) 2009, Atheros Communications
4 * Copyright (c) 2011, Qualcomm Atheros
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Alternatively, this software may be distributed under the terms of BSD
11 * license.
12 *
13 * See README and COPYING for more details.
14 */
15
16#include "includes.h"
17
18#include "common.h"
19#include "ieee802_11_defs.h"
20#include "gas.h"
21
22
23static struct wpabuf *
24gas_build_req(u8 action, u8 dialog_token, size_t size)
25{
26	struct wpabuf *buf;
27
28	buf = wpabuf_alloc(100 + size);
29	if (buf == NULL)
30		return NULL;
31
32	wpabuf_put_u8(buf, WLAN_ACTION_PUBLIC);
33	wpabuf_put_u8(buf, action);
34	wpabuf_put_u8(buf, dialog_token);
35
36	return buf;
37}
38
39
40static struct wpabuf * gas_build_initial_req(u8 dialog_token, size_t size)
41{
42	return gas_build_req(WLAN_PA_GAS_INITIAL_REQ, dialog_token,
43			     size);
44}
45
46
47struct wpabuf * gas_build_comeback_req(u8 dialog_token)
48{
49	return gas_build_req(WLAN_PA_GAS_COMEBACK_REQ, dialog_token, 0);
50}
51
52
53static struct wpabuf *
54gas_build_resp(u8 action, u8 dialog_token, u16 status_code, u8 frag_id,
55	       u8 more, u16 comeback_delay, size_t size)
56{
57	struct wpabuf *buf;
58
59	buf = wpabuf_alloc(100 + size);
60	if (buf == NULL)
61		return NULL;
62
63	wpabuf_put_u8(buf, WLAN_ACTION_PUBLIC);
64	wpabuf_put_u8(buf, action);
65	wpabuf_put_u8(buf, dialog_token);
66	wpabuf_put_le16(buf, status_code);
67	if (action == WLAN_PA_GAS_COMEBACK_RESP)
68		wpabuf_put_u8(buf, frag_id | (more ? 0x80 : 0));
69	wpabuf_put_le16(buf, comeback_delay);
70
71	return buf;
72}
73
74
75struct wpabuf *
76gas_build_initial_resp(u8 dialog_token, u16 status_code, u16 comeback_delay,
77		       size_t size)
78{
79	return gas_build_resp(WLAN_PA_GAS_INITIAL_RESP, dialog_token,
80			      status_code, 0, 0, comeback_delay, size);
81}
82
83
84static struct wpabuf *
85gas_build_comeback_resp(u8 dialog_token, u16 status_code, u8 frag_id, u8 more,
86			u16 comeback_delay, size_t size)
87{
88	return gas_build_resp(WLAN_PA_GAS_COMEBACK_RESP, dialog_token,
89			      status_code, frag_id, more, comeback_delay,
90			      size);
91}
92
93
94/**
95 * gas_add_adv_proto_anqp - Add an Advertisement Protocol element
96 * @buf: Buffer to which the element is added
97 * @query_resp_len_limit: Query Response Length Limit in units of 256 octets
98 * @pame_bi: Pre-Association Message Exchange BSSID Independent (0/1)
99 *
100 *
101 * @query_resp_len_limit is 0 for request and 1-0x7f for response. 0x7f means
102 * that the maximum limit is determined by the maximum allowable number of
103 * fragments in the GAS Query Response Fragment ID.
104 */
105static void gas_add_adv_proto_anqp(struct wpabuf *buf, u8 query_resp_len_limit,
106				   u8 pame_bi)
107{
108	/* Advertisement Protocol IE */
109	wpabuf_put_u8(buf, WLAN_EID_ADV_PROTO);
110	wpabuf_put_u8(buf, 2); /* Length */
111	wpabuf_put_u8(buf, (query_resp_len_limit & 0x7f) |
112		      (pame_bi ? 0x80 : 0));
113	/* Advertisement Protocol */
114	wpabuf_put_u8(buf, ACCESS_NETWORK_QUERY_PROTOCOL);
115}
116
117
118struct wpabuf * gas_anqp_build_initial_req(u8 dialog_token, size_t size)
119{
120	struct wpabuf *buf;
121
122	buf = gas_build_initial_req(dialog_token, 4 + size);
123	if (buf == NULL)
124		return NULL;
125
126	gas_add_adv_proto_anqp(buf, 0, 0);
127
128	wpabuf_put(buf, 2); /* Query Request Length to be filled */
129
130	return buf;
131}
132
133
134struct wpabuf * gas_anqp_build_initial_resp(u8 dialog_token, u16 status_code,
135					    u16 comeback_delay, size_t size)
136{
137	struct wpabuf *buf;
138
139	buf = gas_build_initial_resp(dialog_token, status_code, comeback_delay,
140				     4 + size);
141	if (buf == NULL)
142		return NULL;
143
144	gas_add_adv_proto_anqp(buf, 0x7f, 0);
145
146	wpabuf_put(buf, 2); /* Query Response Length to be filled */
147
148	return buf;
149}
150
151
152struct wpabuf * gas_anqp_build_initial_resp_buf(u8 dialog_token,
153						u16 status_code,
154						u16 comeback_delay,
155						struct wpabuf *payload)
156{
157	struct wpabuf *buf;
158
159	buf = gas_anqp_build_initial_resp(dialog_token, status_code,
160					  comeback_delay,
161					  payload ? wpabuf_len(payload) : 0);
162	if (buf == NULL)
163		return NULL;
164
165	if (payload)
166		wpabuf_put_buf(buf, payload);
167
168	gas_anqp_set_len(buf);
169
170	return buf;
171}
172
173
174struct wpabuf * gas_anqp_build_comeback_resp(u8 dialog_token, u16 status_code,
175					     u8 frag_id, u8 more,
176					     u16 comeback_delay, size_t size)
177{
178	struct wpabuf *buf;
179
180	buf = gas_build_comeback_resp(dialog_token, status_code,
181				      frag_id, more, comeback_delay, 4 + size);
182	if (buf == NULL)
183		return NULL;
184
185	gas_add_adv_proto_anqp(buf, 0x7f, 0);
186
187	wpabuf_put(buf, 2); /* Query Response Length to be filled */
188
189	return buf;
190}
191
192
193struct wpabuf * gas_anqp_build_comeback_resp_buf(u8 dialog_token,
194						 u16 status_code,
195						 u8 frag_id, u8 more,
196						 u16 comeback_delay,
197						 struct wpabuf *payload)
198{
199	struct wpabuf *buf;
200
201	buf = gas_anqp_build_comeback_resp(dialog_token, status_code, frag_id,
202					   more, comeback_delay,
203					   payload ? wpabuf_len(payload) : 0);
204	if (buf == NULL)
205		return NULL;
206
207	if (payload)
208		wpabuf_put_buf(buf, payload);
209
210	gas_anqp_set_len(buf);
211
212	return buf;
213}
214
215
216/**
217 * gas_anqp_set_len - Set Query Request/Response Length
218 * @buf: GAS message
219 *
220 * This function is used to update the Query Request/Response Length field once
221 * the payload has been filled.
222 */
223void gas_anqp_set_len(struct wpabuf *buf)
224{
225	u8 action;
226	size_t offset;
227	u8 *len;
228
229	if (buf == NULL || wpabuf_len(buf) < 2)
230		return;
231
232	action = *(wpabuf_head_u8(buf) + 1);
233	switch (action) {
234	case WLAN_PA_GAS_INITIAL_REQ:
235		offset = 3 + 4;
236		break;
237	case WLAN_PA_GAS_INITIAL_RESP:
238		offset = 7 + 4;
239		break;
240	case WLAN_PA_GAS_COMEBACK_RESP:
241		offset = 8 + 4;
242		break;
243	default:
244		return;
245	}
246
247	if (wpabuf_len(buf) < offset + 2)
248		return;
249
250	len = wpabuf_mhead_u8(buf) + offset;
251	WPA_PUT_LE16(len, (u8 *) wpabuf_put(buf, 0) - len - 2);
252}
253
254
255/**
256 * gas_anqp_add_element - Add ANQP element header
257 * @buf: GAS message
258 * @info_id: ANQP Info ID
259 * Returns: Pointer to the Length field for gas_anqp_set_element_len()
260 */
261u8 * gas_anqp_add_element(struct wpabuf *buf, u16 info_id)
262{
263	wpabuf_put_le16(buf, info_id);
264	return wpabuf_put(buf, 2); /* Length to be filled */
265}
266
267
268/**
269 * gas_anqp_set_element_len - Update ANQP element Length field
270 * @buf: GAS message
271 * @len_pos: Length field position from gas_anqp_add_element()
272 *
273 * This function is called after the ANQP element payload has been added to the
274 * buffer.
275 */
276void gas_anqp_set_element_len(struct wpabuf *buf, u8 *len_pos)
277{
278	WPA_PUT_LE16(len_pos, (u8 *) wpabuf_put(buf, 0) - len_pos - 2);
279}
280