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 if (record->type_length > data + size - pos) 67 return -1; 68 record->type = record->type_length == 0 ? NULL : pos; 69 pos += record->type_length; 70 71 if (record->id_length > data + size - pos) 72 return -1; 73 record->id = record->id_length == 0 ? NULL : pos; 74 pos += record->id_length; 75 76 if (record->payload_length > (size_t) (data + size - pos)) 77 return -1; 78 record->payload = record->payload_length == 0 ? NULL : pos; 79 pos += record->payload_length; 80 81 record->total_length = pos - data; 82 if (record->total_length > size || 83 record->total_length < record->payload_length) 84 return -1; 85 return 0; 86 } 87 88 89 static struct wpabuf * ndef_parse_records(const struct wpabuf *buf, 90 int (*filter)(struct ndef_record *)) 91 { 92 struct ndef_record record; 93 int len = wpabuf_len(buf); 94 const u8 *data = wpabuf_head(buf); 95 96 while (len > 0) { 97 if (ndef_parse_record(data, len, &record) < 0) { 98 wpa_printf(MSG_ERROR, "NDEF : Failed to parse"); 99 return NULL; 100 } 101 if (filter == NULL || filter(&record)) 102 return wpabuf_alloc_copy(record.payload, 103 record.payload_length); 104 data += record.total_length; 105 len -= record.total_length; 106 } 107 wpa_printf(MSG_ERROR, "NDEF : Record not found"); 108 return NULL; 109 } 110 111 112 static struct wpabuf * ndef_build_record(u8 flags, const void *type, 113 u8 type_length, void *id, 114 u8 id_length, 115 const struct wpabuf *payload) 116 { 117 struct wpabuf *record; 118 size_t total_len; 119 int short_record; 120 u8 local_flag; 121 size_t payload_length = wpabuf_len(payload); 122 123 short_record = payload_length < 256 ? 1 : 0; 124 125 total_len = 2; /* flag + type length */ 126 /* payload length */ 127 total_len += short_record ? sizeof(u8) : sizeof(u32); 128 if (id_length > 0) 129 total_len += 1; 130 total_len += type_length + id_length + payload_length; 131 record = wpabuf_alloc(total_len); 132 if (record == NULL) { 133 wpa_printf(MSG_ERROR, "NDEF : Failed to allocate " 134 "record for build"); 135 return NULL; 136 } 137 138 local_flag = flags; 139 if (id_length > 0) 140 local_flag |= FLAG_ID_LENGTH_PRESENT; 141 if (short_record) 142 local_flag |= FLAG_SHORT_RECORD; 143 wpabuf_put_u8(record, local_flag); 144 145 wpabuf_put_u8(record, type_length); 146 147 if (short_record) 148 wpabuf_put_u8(record, payload_length); 149 else 150 wpabuf_put_be32(record, payload_length); 151 152 if (id_length > 0) 153 wpabuf_put_u8(record, id_length); 154 wpabuf_put_data(record, type, type_length); 155 wpabuf_put_data(record, id, id_length); 156 wpabuf_put_buf(record, payload); 157 return record; 158 } 159 160 161 static int wifi_filter(struct ndef_record *record) 162 { 163 if (record->type == NULL || 164 record->type_length != os_strlen(wifi_handover_type)) 165 return 0; 166 if (os_memcmp(record->type, wifi_handover_type, 167 os_strlen(wifi_handover_type)) != 0) 168 return 0; 169 return 1; 170 } 171 172 173 struct wpabuf * ndef_parse_wifi(const struct wpabuf *buf) 174 { 175 return ndef_parse_records(buf, wifi_filter); 176 } 177 178 179 struct wpabuf * ndef_build_wifi(const struct wpabuf *buf) 180 { 181 return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END | 182 FLAG_TNF_RFC2046, wifi_handover_type, 183 os_strlen(wifi_handover_type), NULL, 0, buf); 184 } 185 186 187 static int p2p_filter(struct ndef_record *record) 188 { 189 if (record->type == NULL || 190 record->type_length != os_strlen(p2p_handover_type)) 191 return 0; 192 if (os_memcmp(record->type, p2p_handover_type, 193 os_strlen(p2p_handover_type)) != 0) 194 return 0; 195 return 1; 196 } 197 198 199 struct wpabuf * ndef_parse_p2p(const struct wpabuf *buf) 200 { 201 return ndef_parse_records(buf, p2p_filter); 202 } 203 204 205 struct wpabuf * ndef_build_p2p(const struct wpabuf *buf) 206 { 207 return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END | 208 FLAG_TNF_RFC2046, p2p_handover_type, 209 os_strlen(p2p_handover_type), NULL, 0, buf); 210 } 211