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 if (record->type_length > data + size - pos)
67 return -1;
68 record->type = record->type_length == 0 ? NULL : pos;
69 pos += record->type_length;
70
71 if (record->id_length > data + size - pos)
72 return -1;
73 record->id = record->id_length == 0 ? NULL : pos;
74 pos += record->id_length;
75
76 if (record->payload_length > (size_t) (data + size - pos))
77 return -1;
78 record->payload = record->payload_length == 0 ? NULL : pos;
79 pos += record->payload_length;
80
81 record->total_length = pos - data;
82 if (record->total_length > size ||
83 record->total_length < record->payload_length)
84 return -1;
85 return 0;
86 }
87
88
ndef_parse_records(const struct wpabuf * buf,int (* filter)(struct ndef_record *))89 static struct wpabuf * ndef_parse_records(const struct wpabuf *buf,
90 int (*filter)(struct ndef_record *))
91 {
92 struct ndef_record record;
93 int len = wpabuf_len(buf);
94 const u8 *data = wpabuf_head(buf);
95
96 while (len > 0) {
97 if (ndef_parse_record(data, len, &record) < 0) {
98 wpa_printf(MSG_ERROR, "NDEF : Failed to parse");
99 return NULL;
100 }
101 if (filter == NULL || filter(&record))
102 return wpabuf_alloc_copy(record.payload,
103 record.payload_length);
104 data += record.total_length;
105 len -= record.total_length;
106 }
107 wpa_printf(MSG_ERROR, "NDEF : Record not found");
108 return NULL;
109 }
110
111
ndef_build_record(u8 flags,const void * type,u8 type_length,void * id,u8 id_length,const struct wpabuf * payload)112 static struct wpabuf * ndef_build_record(u8 flags, const void *type,
113 u8 type_length, void *id,
114 u8 id_length,
115 const struct wpabuf *payload)
116 {
117 struct wpabuf *record;
118 size_t total_len;
119 int short_record;
120 u8 local_flag;
121 size_t payload_length = wpabuf_len(payload);
122
123 short_record = payload_length < 256 ? 1 : 0;
124
125 total_len = 2; /* flag + type length */
126 /* payload length */
127 total_len += short_record ? sizeof(u8) : sizeof(u32);
128 if (id_length > 0)
129 total_len += 1;
130 total_len += type_length + id_length + payload_length;
131 record = wpabuf_alloc(total_len);
132 if (record == NULL) {
133 wpa_printf(MSG_ERROR, "NDEF : Failed to allocate "
134 "record for build");
135 return NULL;
136 }
137
138 local_flag = flags;
139 if (id_length > 0)
140 local_flag |= FLAG_ID_LENGTH_PRESENT;
141 if (short_record)
142 local_flag |= FLAG_SHORT_RECORD;
143 wpabuf_put_u8(record, local_flag);
144
145 wpabuf_put_u8(record, type_length);
146
147 if (short_record)
148 wpabuf_put_u8(record, payload_length);
149 else
150 wpabuf_put_be32(record, payload_length);
151
152 if (id_length > 0)
153 wpabuf_put_u8(record, id_length);
154 wpabuf_put_data(record, type, type_length);
155 wpabuf_put_data(record, id, id_length);
156 wpabuf_put_buf(record, payload);
157 return record;
158 }
159
160
wifi_filter(struct ndef_record * record)161 static int wifi_filter(struct ndef_record *record)
162 {
163 if (record->type == NULL ||
164 record->type_length != os_strlen(wifi_handover_type))
165 return 0;
166 if (os_memcmp(record->type, wifi_handover_type,
167 os_strlen(wifi_handover_type)) != 0)
168 return 0;
169 return 1;
170 }
171
172
ndef_parse_wifi(const struct wpabuf * buf)173 struct wpabuf * ndef_parse_wifi(const struct wpabuf *buf)
174 {
175 return ndef_parse_records(buf, wifi_filter);
176 }
177
178
ndef_build_wifi(const struct wpabuf * buf)179 struct wpabuf * ndef_build_wifi(const struct wpabuf *buf)
180 {
181 return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END |
182 FLAG_TNF_RFC2046, wifi_handover_type,
183 os_strlen(wifi_handover_type), NULL, 0, buf);
184 }
185
186
p2p_filter(struct ndef_record * record)187 static int p2p_filter(struct ndef_record *record)
188 {
189 if (record->type == NULL ||
190 record->type_length != os_strlen(p2p_handover_type))
191 return 0;
192 if (os_memcmp(record->type, p2p_handover_type,
193 os_strlen(p2p_handover_type)) != 0)
194 return 0;
195 return 1;
196 }
197
198
ndef_parse_p2p(const struct wpabuf * buf)199 struct wpabuf * ndef_parse_p2p(const struct wpabuf *buf)
200 {
201 return ndef_parse_records(buf, p2p_filter);
202 }
203
204
ndef_build_p2p(const struct wpabuf * buf)205 struct wpabuf * ndef_build_p2p(const struct wpabuf *buf)
206 {
207 return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END |
208 FLAG_TNF_RFC2046, p2p_handover_type,
209 os_strlen(p2p_handover_type), NULL, 0, buf);
210 }
211