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 #include "wps/wps_i.h"
  14
  15 #define FLAG_MESSAGE_BEGIN (1 << 7)
  16 #define FLAG_MESSAGE_END (1 << 6)
  17 #define FLAG_CHUNK (1 << 5)
  18 #define FLAG_SHORT_RECORD (1 << 4)
  19 #define FLAG_ID_LENGTH_PRESENT (1 << 3)
  20 #define FLAG_TNF_RFC2046 (0x02)
  21
  22 struct ndef_record {
  23         u8 *type;
  24         u8 *id;
  25         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
  34 static int ndef_parse_record(u8 *data, u32 size, struct ndef_record *record)
  35 {
  36         u8 *pos = data + 1;
  37
  38         if (size < 2)
  39                 return -1;
  40         record->type_length = *pos++;
  41         if (data[0] & FLAG_SHORT_RECORD) {
  42                 if (size < 3)
  43                         return -1;
  44                 record->payload_length = *pos++;
  45         } else {
  46                 if (size < 6)
  47                         return -1;
  48                 record->payload_length = ntohl(*(u32 *)pos);
  49                 pos += sizeof(u32);
  50         }
  51
  52         if (data[0] & FLAG_ID_LENGTH_PRESENT) {
  53                 if ((int) size < pos - data + 1)
  54                         return -1;
  55                 record->id_length = *pos++;
  56         } else
  57                 record->id_length = 0;
  58
  59         record->type = record->type_length == 0 ? NULL : pos;
  60         pos += record->type_length;
  61
  62         record->id = record->id_length == 0 ? NULL : pos;
  63         pos += record->id_length;
  64
  65         record->payload = record->payload_length == 0 ? NULL : pos;
  66         pos += record->payload_length;
  67
  68         record->total_length = pos - data;
  69         if (record->total_length > size)
  70                 return -1;
  71         return 0;
  72 }
  73
  74
  75 static struct wpabuf * ndef_parse_records(struct wpabuf *buf,
  76                                           int (*filter)(struct ndef_record *))
  77 {
  78         struct ndef_record record;
  79         int len = wpabuf_len(buf);
  80         u8 *data = wpabuf_mhead(buf);
  81
  82         while (len > 0) {
  83                 if (ndef_parse_record(data, len, &record) < 0) {
  84                         wpa_printf(MSG_ERROR, "NDEF : Failed to parse");
  85                         return NULL;
  86                 }
  87                 if (filter == NULL || filter(&record))
  88                         return wpabuf_alloc_copy(record.payload,
  89                                                  record.payload_length);
  90                 data += record.total_length;
  91                 len -= record.total_length;
  92         }
  93         wpa_printf(MSG_ERROR, "NDEF : Record not found");
  94         return NULL;
  95 }
  96
  97
  98 static struct wpabuf * ndef_build_record(u8 flags, void *type,
  99                                          u8 type_length, void *id,
 100                                          u8 id_length, void *payload,
 101                                          u32 payload_length)
 102 {
 103         struct wpabuf *record;
 104         size_t total_len;
 105         int short_record;
 106         u8 local_flag;
 107
 108         short_record = payload_length < 256 ? 1 : 0;
 109
 110         total_len = 2; /* flag + type length */
 111         /* payload length */
 112         total_len += short_record ? sizeof(u8) : sizeof(u32);
 113         if (id_length > 0)
 114                 total_len += 1;
 115         total_len += type_length + id_length + payload_length;
 116         record = wpabuf_alloc(total_len);
 117         if (record == NULL) {
 118                 wpa_printf(MSG_ERROR, "NDEF : Failed to allocate "
 119                            "record for build");
 120                 return NULL;
 121         }
 122
 123         local_flag = flags;
 124         if (id_length > 0)
 125                 local_flag |= FLAG_ID_LENGTH_PRESENT;
 126         if (short_record)
 127                 local_flag |= FLAG_SHORT_RECORD;
 128         wpabuf_put_u8(record, local_flag);
 129
 130         wpabuf_put_u8(record, type_length);
 131
 132         if (short_record)
 133                 wpabuf_put_u8(record, payload_length);
 134         else
 135                 wpabuf_put_be32(record, payload_length);
 136
 137         if (id_length > 0)
 138                 wpabuf_put_u8(record, id_length);
 139         wpabuf_put_data(record, type, type_length);
 140         wpabuf_put_data(record, id, id_length);
 141         wpabuf_put_data(record, payload, payload_length);
 142         return record;
 143 }
 144
 145
 146 static int wifi_filter(struct ndef_record *record)
 147 {
 148         if (record->type_length != os_strlen(wifi_handover_type))
 149                 return 0;
 150         if (os_memcmp(record->type, wifi_handover_type,
 151                       os_strlen(wifi_handover_type)) != 0)
 152                 return 0;
 153         return 1;
 154 }
 155
 156
 157 struct wpabuf * ndef_parse_wifi(struct wpabuf *buf)
 158 {
 159         return ndef_parse_records(buf, wifi_filter);
 160 }
 161
 162
 163 struct wpabuf * ndef_build_wifi(struct wpabuf *buf)
 164 {
 165         return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END |
 166                                  FLAG_TNF_RFC2046, wifi_handover_type,
 167                                  os_strlen(wifi_handover_type), NULL, 0,
 168                                  wpabuf_mhead(buf), wpabuf_len(buf));
 169 }