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 (at) 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 == NULL || 152 record->type_length != os_strlen(wifi_handover_type)) 153 return 0; 154 if (os_memcmp(record->type, wifi_handover_type, 155 os_strlen(wifi_handover_type)) != 0) 156 return 0; 157 return 1; 158 } 159 160 161 struct wpabuf * ndef_parse_wifi(const struct wpabuf *buf) 162 { 163 return ndef_parse_records(buf, wifi_filter); 164 } 165 166 167 struct wpabuf * ndef_build_wifi(const struct wpabuf *buf) 168 { 169 return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END | 170 FLAG_TNF_RFC2046, wifi_handover_type, 171 os_strlen(wifi_handover_type), NULL, 0, buf); 172 } 173 174 175 static int p2p_filter(struct ndef_record *record) 176 { 177 if (record->type == NULL || 178 record->type_length != os_strlen(p2p_handover_type)) 179 return 0; 180 if (os_memcmp(record->type, p2p_handover_type, 181 os_strlen(p2p_handover_type)) != 0) 182 return 0; 183 return 1; 184 } 185 186 187 struct wpabuf * ndef_parse_p2p(const struct wpabuf *buf) 188 { 189 return ndef_parse_records(buf, p2p_filter); 190 } 191 192 193 struct wpabuf * ndef_build_p2p(const struct wpabuf *buf) 194 { 195 return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END | 196 FLAG_TNF_RFC2046, p2p_handover_type, 197 os_strlen(p2p_handover_type), NULL, 0, buf); 198 } 199
