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, Masashi Honma <honma@ictec.co.jp>
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 #include "common.h"
18 #include "wps/wps.h"
19 #include "wps/wps_i.h"
20
21 #define FLAG_MESSAGE_BEGIN (1 << 7)
22 #define FLAG_MESSAGE_END (1 << 6)
23 #define FLAG_CHUNK (1 << 5)
24 #define FLAG_SHORT_RECORD (1 << 4)
25 #define FLAG_ID_LENGTH_PRESENT (1 << 3)
26 #define FLAG_TNF_RFC2046 (0x02)
27
28 struct ndef_record {
29 u8 *type;
30 u8 *id;
31 u8 *payload;
32 u8 type_length;
33 u8 id_length;
34 u32 payload_length;
35 u32 total_length;
36 };
37
38 static char wifi_handover_type[] = "application/vnd.wfa.wsc";
39
ndef_parse_record(u8 * data,u32 size,struct ndef_record * record)40 static int ndef_parse_record(u8 *data, u32 size, struct ndef_record *record)
41 {
42 u8 *pos = data + 1;
43
44 if (size < 2)
45 return -1;
46 record->type_length = *pos++;
47 if (data[0] & FLAG_SHORT_RECORD) {
48 if (size < 3)
49 return -1;
50 record->payload_length = *pos++;
51 } else {
52 if (size < 6)
53 return -1;
54 record->payload_length = ntohl(*(u32 *)pos);
55 pos += sizeof(u32);
56 }
57
58 if (data[0] & FLAG_ID_LENGTH_PRESENT) {
59 if ((int) size < pos - data + 1)
60 return -1;
61 record->id_length = *pos++;
62 } else
63 record->id_length = 0;
64
65 record->type = record->type_length == 0 ? NULL : pos;
66 pos += record->type_length;
67
68 record->id = record->id_length == 0 ? NULL : pos;
69 pos += record->id_length;
70
71 record->payload = record->payload_length == 0 ? NULL : pos;
72 pos += record->payload_length;
73
74 record->total_length = pos - data;
75 if (record->total_length > size)
76 return -1;
77 return 0;
78 }
79
80
ndef_parse_records(struct wpabuf * buf,int (* filter)(struct ndef_record *))81 static struct wpabuf * ndef_parse_records(struct wpabuf *buf,
82 int (*filter)(struct ndef_record *))
83 {
84 struct ndef_record record;
85 int len = wpabuf_len(buf);
86 u8 *data = wpabuf_mhead(buf);
87
88 while (len > 0) {
89 if (ndef_parse_record(data, len, &record) < 0) {
90 wpa_printf(MSG_ERROR, "NDEF : Failed to parse");
91 return NULL;
92 }
93 if (filter == NULL || filter(&record))
94 return wpabuf_alloc_copy(record.payload,
95 record.payload_length);
96 data += record.total_length;
97 len -= record.total_length;
98 }
99 wpa_printf(MSG_ERROR, "NDEF : Record not found");
100 return NULL;
101 }
102
103
ndef_build_record(u8 flags,void * type,u8 type_length,void * id,u8 id_length,void * payload,u32 payload_length)104 static struct wpabuf * ndef_build_record(u8 flags, void *type,
105 u8 type_length, void *id,
106 u8 id_length, void *payload,
107 u32 payload_length)
108 {
109 struct wpabuf *record;
110 size_t total_len;
111 int short_record;
112 u8 local_flag;
113
114 short_record = payload_length < 256 ? 1 : 0;
115
116 total_len = 2; /* flag + type length */
117 /* payload length */
118 total_len += short_record ? sizeof(u8) : sizeof(u32);
119 if (id_length > 0)
120 total_len += 1;
121 total_len += type_length + id_length + payload_length;
122 record = wpabuf_alloc(total_len);
123 if (record == NULL) {
124 wpa_printf(MSG_ERROR, "NDEF : Failed to allocate "
125 "record for build");
126 return NULL;
127 }
128
129 local_flag = flags;
130 if (id_length > 0)
131 local_flag |= FLAG_ID_LENGTH_PRESENT;
132 if (short_record)
133 local_flag |= FLAG_SHORT_RECORD;
134 wpabuf_put_u8(record, local_flag);
135
136 wpabuf_put_u8(record, type_length);
137
138 if (short_record)
139 wpabuf_put_u8(record, payload_length);
140 else
141 wpabuf_put_be32(record, payload_length);
142
143 if (id_length > 0)
144 wpabuf_put_u8(record, id_length);
145 wpabuf_put_data(record, type, type_length);
146 wpabuf_put_data(record, id, id_length);
147 wpabuf_put_data(record, payload, payload_length);
148 return record;
149 }
150
151
wifi_filter(struct ndef_record * record)152 static int wifi_filter(struct ndef_record *record)
153 {
154 if (record->type_length != os_strlen(wifi_handover_type))
155 return 0;
156 if (os_memcmp(record->type, wifi_handover_type,
157 os_strlen(wifi_handover_type)) != 0)
158 return 0;
159 return 1;
160 }
161
162
ndef_parse_wifi(struct wpabuf * buf)163 struct wpabuf * ndef_parse_wifi(struct wpabuf *buf)
164 {
165 return ndef_parse_records(buf, wifi_filter);
166 }
167
168
ndef_build_wifi(struct wpabuf * buf)169 struct wpabuf * ndef_build_wifi(struct wpabuf *buf)
170 {
171 return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END |
172 FLAG_TNF_RFC2046, wifi_handover_type,
173 os_strlen(wifi_handover_type), NULL, 0,
174 wpabuf_mhead(buf), wpabuf_len(buf));
175 }
176