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