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
22struct 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
32static const char wifi_handover_type[] = "application/vnd.wfa.wsc";
33static const char p2p_handover_type[] = "application/vnd.wfa.p2p";
34
35static 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
83static 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
106static 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
155static 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
167struct wpabuf * ndef_parse_wifi(const struct wpabuf *buf)
168{
169	return ndef_parse_records(buf, wifi_filter);
170}
171
172
173struct 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
181static 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
193struct wpabuf * ndef_parse_p2p(const struct wpabuf *buf)
194{
195	return ndef_parse_records(buf, p2p_filter);
196}
197
198
199struct 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