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 const char wifi_handover_type[] = "application/vnd.wfa.wsc";
33 static const char p2p_handover_type[] = "application/vnd.wfa.p2p";
34
ndef_parse_record(const u8 * data,u32 size,struct ndef_record * record)35 static int ndef_parse_record(const u8 *data, u32 size,
36 struct ndef_record *record)
37 {
38 const u8 *pos = data + 1;
39
40 if (size < 2)
41 return -1;
42 record->type_length = *pos++;
43 if (data[0] & FLAG_SHORT_RECORD) {
44 if (size < 3)
45 return -1;
46 record->payload_length = *pos++;
47 } else {
48 u32 len;
49
50 if (size < 6)
51 return -1;
52 len = WPA_GET_BE32(pos);
53 if (len > size - 6 || len > 20000)
54 return -1;
55 record->payload_length = len;
56 pos += sizeof(u32);
57 }
58
59 if (data[0] & FLAG_ID_LENGTH_PRESENT) {
60 if ((int) size < pos - data + 1)
61 return -1;
62 record->id_length = *pos++;
63 } else
64 record->id_length = 0;
65
66 record->type = record->type_length == 0 ? NULL : pos;
67 pos += record->type_length;
68
69 record->id = record->id_length == 0 ? NULL : pos;
70 pos += record->id_length;
71
72 record->payload = record->payload_length == 0 ? NULL : pos;
73 pos += record->payload_length;
74
75 record->total_length = pos - data;
76 if (record->total_length > size ||
77 record->total_length < record->payload_length)
78 return -1;
79 return 0;
80 }
81
82
ndef_parse_records(const struct wpabuf * buf,int (* filter)(struct ndef_record *))83 static struct wpabuf * ndef_parse_records(const struct wpabuf *buf,
84 int (*filter)(struct ndef_record *))
85 {
86 struct ndef_record record;
87 int len = wpabuf_len(buf);
88 const u8 *data = wpabuf_head(buf);
89
90 while (len > 0) {
91 if (ndef_parse_record(data, len, &record) < 0) {
92 wpa_printf(MSG_ERROR, "NDEF : Failed to parse");
93 return NULL;
94 }
95 if (filter == NULL || filter(&record))
96 return wpabuf_alloc_copy(record.payload,
97 record.payload_length);
98 data += record.total_length;
99 len -= record.total_length;
100 }
101 wpa_printf(MSG_ERROR, "NDEF : Record not found");
102 return NULL;
103 }
104
105
ndef_build_record(u8 flags,const void * type,u8 type_length,void * id,u8 id_length,const struct wpabuf * payload)106 static struct wpabuf * ndef_build_record(u8 flags, const void *type,
107 u8 type_length, void *id,
108 u8 id_length,
109 const struct wpabuf *payload)
110 {
111 struct wpabuf *record;
112 size_t total_len;
113 int short_record;
114 u8 local_flag;
115 size_t payload_length = wpabuf_len(payload);
116
117 short_record = payload_length < 256 ? 1 : 0;
118
119 total_len = 2; /* flag + type length */
120 /* payload length */
121 total_len += short_record ? sizeof(u8) : sizeof(u32);
122 if (id_length > 0)
123 total_len += 1;
124 total_len += type_length + id_length + payload_length;
125 record = wpabuf_alloc(total_len);
126 if (record == NULL) {
127 wpa_printf(MSG_ERROR, "NDEF : Failed to allocate "
128 "record for build");
129 return NULL;
130 }
131
132 local_flag = flags;
133 if (id_length > 0)
134 local_flag |= FLAG_ID_LENGTH_PRESENT;
135 if (short_record)
136 local_flag |= FLAG_SHORT_RECORD;
137 wpabuf_put_u8(record, local_flag);
138
139 wpabuf_put_u8(record, type_length);
140
141 if (short_record)
142 wpabuf_put_u8(record, payload_length);
143 else
144 wpabuf_put_be32(record, payload_length);
145
146 if (id_length > 0)
147 wpabuf_put_u8(record, id_length);
148 wpabuf_put_data(record, type, type_length);
149 wpabuf_put_data(record, id, id_length);
150 wpabuf_put_buf(record, payload);
151 return record;
152 }
153
154
wifi_filter(struct ndef_record * record)155 static int wifi_filter(struct ndef_record *record)
156 {
157 if (record->type == NULL ||
158 record->type_length != os_strlen(wifi_handover_type))
159 return 0;
160 if (os_memcmp(record->type, wifi_handover_type,
161 os_strlen(wifi_handover_type)) != 0)
162 return 0;
163 return 1;
164 }
165
166
ndef_parse_wifi(const struct wpabuf * buf)167 struct wpabuf * ndef_parse_wifi(const struct wpabuf *buf)
168 {
169 return ndef_parse_records(buf, wifi_filter);
170 }
171
172
ndef_build_wifi(const struct wpabuf * buf)173 struct wpabuf * ndef_build_wifi(const struct wpabuf *buf)
174 {
175 return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END |
176 FLAG_TNF_RFC2046, wifi_handover_type,
177 os_strlen(wifi_handover_type), NULL, 0, buf);
178 }
179
180
p2p_filter(struct ndef_record * record)181 static int p2p_filter(struct ndef_record *record)
182 {
183 if (record->type == NULL ||
184 record->type_length != os_strlen(p2p_handover_type))
185 return 0;
186 if (os_memcmp(record->type, p2p_handover_type,
187 os_strlen(p2p_handover_type)) != 0)
188 return 0;
189 return 1;
190 }
191
192
ndef_parse_p2p(const struct wpabuf * buf)193 struct wpabuf * ndef_parse_p2p(const struct wpabuf *buf)
194 {
195 return ndef_parse_records(buf, p2p_filter);
196 }
197
198
ndef_build_p2p(const struct wpabuf * buf)199 struct wpabuf * ndef_build_p2p(const struct wpabuf *buf)
200 {
201 return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END |
202 FLAG_TNF_RFC2046, p2p_handover_type,
203 os_strlen(p2p_handover_type), NULL, 0, buf);
204 }
205