libeap/src/wps/ndef.c

   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
  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
  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
 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
 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
 167 struct wpabuf * ndef_parse_wifi(const struct wpabuf *buf)
 168 {
 169         return ndef_parse_records(buf, wifi_filter);
 170 }
 171
 172
 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
 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
 193 struct wpabuf * ndef_parse_p2p(const struct wpabuf *buf)
 194 {
 195         return ndef_parse_records(buf, p2p_filter);
 196 }
 197
 198
 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 }