1 /*
2 * NDEF(NFC Data Exchange Format) routines for Wi-Fi Protected Setup
3 * Reference is "NFCForum-TS-NDEF_1.0 2006-07-24".
4 * Copyright (c) 2009-2012, Masashi Honma <masashi.honma@gmail.com>
5 *
6 * This software may be distributed under the terms of the BSD license.
7 * See README for more details.
8 */
9
10 #include "includes.h"
11 #include "common.h"
12 #include "wps/wps.h"
13
14 #define FLAG_MESSAGE_BEGIN (1 << 7)
15 #define FLAG_MESSAGE_END (1 << 6)
16 #define FLAG_CHUNK (1 << 5)
17 #define FLAG_SHORT_RECORD (1 << 4)
18 #define FLAG_ID_LENGTH_PRESENT (1 << 3)
19 #define FLAG_TNF_NFC_FORUM (0x01)
20 #define FLAG_TNF_RFC2046 (0x02)
21
22 struct ndef_record {
23 const u8 *type;
24 const u8 *id;
25 const u8 *payload;
26 u8 type_length;
27 u8 id_length;
28 u32 payload_length;
29 u32 total_length;
30 };
31
32 static char wifi_handover_type[] = "application/vnd.wfa.wsc";
33
ndef_parse_record(const u8 * data,u32 size,struct ndef_record * record)34 static int ndef_parse_record(const u8 *data, u32 size,
35 struct ndef_record *record)
36 {
37 const u8 *pos = data + 1;
38
39 if (size < 2)
40 return -1;
41 record->type_length = *pos++;
42 if (data[0] & FLAG_SHORT_RECORD) {
43 if (size < 3)
44 return -1;
45 record->payload_length = *pos++;
46 } else {
47 if (size < 6)
48 return -1;
49 record->payload_length = ntohl(*(u32 *)pos);
50 pos += sizeof(u32);
51 }
52
53 if (data[0] & FLAG_ID_LENGTH_PRESENT) {
54 if ((int) size < pos - data + 1)
55 return -1;
56 record->id_length = *pos++;
57 } else
58 record->id_length = 0;
59
60 record->type = record->type_length == 0 ? NULL : pos;
61 pos += record->type_length;
62
63 record->id = record->id_length == 0 ? NULL : pos;
64 pos += record->id_length;
65
66 record->payload = record->payload_length == 0 ? NULL : pos;
67 pos += record->payload_length;
68
69 record->total_length = pos - data;
70 if (record->total_length > size)
71 return -1;
72 return 0;
73 }
74
75
ndef_parse_records(const struct wpabuf * buf,int (* filter)(struct ndef_record *))76 static struct wpabuf * ndef_parse_records(const struct wpabuf *buf,
77 int (*filter)(struct ndef_record *))
78 {
79 struct ndef_record record;
80 int len = wpabuf_len(buf);
81 const u8 *data = wpabuf_head(buf);
82
83 while (len > 0) {
84 if (ndef_parse_record(data, len, &record) < 0) {
85 wpa_printf(MSG_ERROR, "NDEF : Failed to parse");
86 return NULL;
87 }
88 if (filter == NULL || filter(&record))
89 return wpabuf_alloc_copy(record.payload,
90 record.payload_length);
91 data += record.total_length;
92 len -= record.total_length;
93 }
94 wpa_printf(MSG_ERROR, "NDEF : Record not found");
95 return NULL;
96 }
97
98
ndef_build_record(u8 flags,void * type,u8 type_length,void * id,u8 id_length,const struct wpabuf * payload)99 static struct wpabuf * ndef_build_record(u8 flags, void *type,
100 u8 type_length, void *id,
101 u8 id_length,
102 const struct wpabuf *payload)
103 {
104 struct wpabuf *record;
105 size_t total_len;
106 int short_record;
107 u8 local_flag;
108 size_t payload_length = wpabuf_len(payload);
109
110 short_record = payload_length < 256 ? 1 : 0;
111
112 total_len = 2; /* flag + type length */
113 /* payload length */
114 total_len += short_record ? sizeof(u8) : sizeof(u32);
115 if (id_length > 0)
116 total_len += 1;
117 total_len += type_length + id_length + payload_length;
118 record = wpabuf_alloc(total_len);
119 if (record == NULL) {
120 wpa_printf(MSG_ERROR, "NDEF : Failed to allocate "
121 "record for build");
122 return NULL;
123 }
124
125 local_flag = flags;
126 if (id_length > 0)
127 local_flag |= FLAG_ID_LENGTH_PRESENT;
128 if (short_record)
129 local_flag |= FLAG_SHORT_RECORD;
130 wpabuf_put_u8(record, local_flag);
131
132 wpabuf_put_u8(record, type_length);
133
134 if (short_record)
135 wpabuf_put_u8(record, payload_length);
136 else
137 wpabuf_put_be32(record, payload_length);
138
139 if (id_length > 0)
140 wpabuf_put_u8(record, id_length);
141 wpabuf_put_data(record, type, type_length);
142 wpabuf_put_data(record, id, id_length);
143 wpabuf_put_buf(record, payload);
144 return record;
145 }
146
147
wifi_filter(struct ndef_record * record)148 static int wifi_filter(struct ndef_record *record)
149 {
150 if (record->type_length != os_strlen(wifi_handover_type))
151 return 0;
152 if (os_memcmp(record->type, wifi_handover_type,
153 os_strlen(wifi_handover_type)) != 0)
154 return 0;
155 return 1;
156 }
157
158
ndef_parse_wifi(const struct wpabuf * buf)159 struct wpabuf * ndef_parse_wifi(const struct wpabuf *buf)
160 {
161 return ndef_parse_records(buf, wifi_filter);
162 }
163
164
ndef_build_wifi(const struct wpabuf * buf)165 struct wpabuf * ndef_build_wifi(const struct wpabuf *buf)
166 {
167 return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END |
168 FLAG_TNF_RFC2046, wifi_handover_type,
169 os_strlen(wifi_handover_type), NULL, 0, buf);
170 }
171
172
ndef_build_wifi_hc(int begin)173 struct wpabuf * ndef_build_wifi_hc(int begin)
174 {
175 struct wpabuf *hc, *carrier;
176
177 carrier = wpabuf_alloc(2 + os_strlen(wifi_handover_type));
178 if (carrier == NULL)
179 return NULL;
180 wpabuf_put_u8(carrier, 0x02); /* Carrier Type Format */
181 wpabuf_put_u8(carrier, os_strlen(wifi_handover_type));
182 wpabuf_put_str(carrier, wifi_handover_type);
183
184 hc = ndef_build_record((begin ? FLAG_MESSAGE_BEGIN : 0) |
185 FLAG_MESSAGE_END | FLAG_TNF_NFC_FORUM, "Hc", 2,
186 "0", 1, carrier);
187 wpabuf_free(carrier);
188
189 return hc;
190 }
191
192
ndef_build_wifi_hr(void)193 struct wpabuf * ndef_build_wifi_hr(void)
194 {
195 struct wpabuf *rn, *cr, *ac_payload, *ac, *hr_payload, *hr;
196 struct wpabuf *hc;
197
198 rn = wpabuf_alloc(2);
199 if (rn == NULL)
200 return NULL;
201 wpabuf_put_be16(rn, os_random() & 0xffff);
202
203 cr = ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_TNF_NFC_FORUM, "cr", 2,
204 NULL, 0, rn);
205 wpabuf_free(rn);
206
207 if (cr == NULL)
208 return NULL;
209
210 ac_payload = wpabuf_alloc(4);
211 if (ac_payload == NULL) {
212 wpabuf_free(cr);
213 return NULL;
214 }
215 wpabuf_put_u8(ac_payload, 0x01); /* Carrier Flags: CRS=1 "active" */
216 wpabuf_put_u8(ac_payload, 0x01); /* Carrier Data Reference Length */
217 wpabuf_put_u8(ac_payload, '0'); /* Carrier Data Reference: "0" */
218 wpabuf_put_u8(ac_payload, 0); /* Aux Data Reference Count */
219
220 ac = ndef_build_record(FLAG_MESSAGE_END | FLAG_TNF_NFC_FORUM, "ac", 2,
221 NULL, 0, ac_payload);
222 wpabuf_free(ac_payload);
223 if (ac == NULL) {
224 wpabuf_free(cr);
225 return NULL;
226 }
227
228 hr_payload = wpabuf_alloc(1 + wpabuf_len(cr) + wpabuf_len(ac));
229 if (hr_payload == NULL) {
230 wpabuf_free(cr);
231 wpabuf_free(ac);
232 return NULL;
233 }
234
235 wpabuf_put_u8(hr_payload, 0x12); /* Connection Handover Version 1.2 */
236 wpabuf_put_buf(hr_payload, cr);
237 wpabuf_put_buf(hr_payload, ac);
238 wpabuf_free(cr);
239 wpabuf_free(ac);
240
241 hr = ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_TNF_NFC_FORUM, "Hr", 2,
242 NULL, 0, hr_payload);
243 wpabuf_free(hr_payload);
244 if (hr == NULL)
245 return NULL;
246
247 hc = ndef_build_wifi_hc(0);
248 if (hc == NULL) {
249 wpabuf_free(hr);
250 return NULL;
251 }
252
253 return wpabuf_concat(hr, hc);
254 }
255