fragattacks/src/wps/ndef.c
Jouni Malinen 8a13732f83 NDEF: Mark input data const when it is not modified
Signed-hostap: Jouni Malinen <j@w1.fi>
2012-06-27 21:22:12 +03:00

171 lines
4.0 KiB
C

/*
* NDEF(NFC Data Exchange Format) routines for Wi-Fi Protected Setup
* Reference is "NFCForum-TS-NDEF_1.0 2006-07-24".
* Copyright (c) 2009-2012, Masashi Honma <masashi.honma@gmail.com>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
#include "includes.h"
#include "common.h"
#include "wps/wps.h"
#include "wps/wps_i.h"
#define FLAG_MESSAGE_BEGIN (1 << 7)
#define FLAG_MESSAGE_END (1 << 6)
#define FLAG_CHUNK (1 << 5)
#define FLAG_SHORT_RECORD (1 << 4)
#define FLAG_ID_LENGTH_PRESENT (1 << 3)
#define FLAG_TNF_RFC2046 (0x02)
struct ndef_record {
const u8 *type;
const u8 *id;
const u8 *payload;
u8 type_length;
u8 id_length;
u32 payload_length;
u32 total_length;
};
static char wifi_handover_type[] = "application/vnd.wfa.wsc";
static int ndef_parse_record(const u8 *data, u32 size,
struct ndef_record *record)
{
const u8 *pos = data + 1;
if (size < 2)
return -1;
record->type_length = *pos++;
if (data[0] & FLAG_SHORT_RECORD) {
if (size < 3)
return -1;
record->payload_length = *pos++;
} else {
if (size < 6)
return -1;
record->payload_length = ntohl(*(u32 *)pos);
pos += sizeof(u32);
}
if (data[0] & FLAG_ID_LENGTH_PRESENT) {
if ((int) size < pos - data + 1)
return -1;
record->id_length = *pos++;
} else
record->id_length = 0;
record->type = record->type_length == 0 ? NULL : pos;
pos += record->type_length;
record->id = record->id_length == 0 ? NULL : pos;
pos += record->id_length;
record->payload = record->payload_length == 0 ? NULL : pos;
pos += record->payload_length;
record->total_length = pos - data;
if (record->total_length > size)
return -1;
return 0;
}
static struct wpabuf * ndef_parse_records(const struct wpabuf *buf,
int (*filter)(struct ndef_record *))
{
struct ndef_record record;
int len = wpabuf_len(buf);
const u8 *data = wpabuf_head(buf);
while (len > 0) {
if (ndef_parse_record(data, len, &record) < 0) {
wpa_printf(MSG_ERROR, "NDEF : Failed to parse");
return NULL;
}
if (filter == NULL || filter(&record))
return wpabuf_alloc_copy(record.payload,
record.payload_length);
data += record.total_length;
len -= record.total_length;
}
wpa_printf(MSG_ERROR, "NDEF : Record not found");
return NULL;
}
static struct wpabuf * ndef_build_record(u8 flags, void *type,
u8 type_length, void *id,
u8 id_length,
const struct wpabuf *payload)
{
struct wpabuf *record;
size_t total_len;
int short_record;
u8 local_flag;
size_t payload_length = wpabuf_len(payload);
short_record = payload_length < 256 ? 1 : 0;
total_len = 2; /* flag + type length */
/* payload length */
total_len += short_record ? sizeof(u8) : sizeof(u32);
if (id_length > 0)
total_len += 1;
total_len += type_length + id_length + payload_length;
record = wpabuf_alloc(total_len);
if (record == NULL) {
wpa_printf(MSG_ERROR, "NDEF : Failed to allocate "
"record for build");
return NULL;
}
local_flag = flags;
if (id_length > 0)
local_flag |= FLAG_ID_LENGTH_PRESENT;
if (short_record)
local_flag |= FLAG_SHORT_RECORD;
wpabuf_put_u8(record, local_flag);
wpabuf_put_u8(record, type_length);
if (short_record)
wpabuf_put_u8(record, payload_length);
else
wpabuf_put_be32(record, payload_length);
if (id_length > 0)
wpabuf_put_u8(record, id_length);
wpabuf_put_data(record, type, type_length);
wpabuf_put_data(record, id, id_length);
wpabuf_put_buf(record, payload);
return record;
}
static int wifi_filter(struct ndef_record *record)
{
if (record->type_length != os_strlen(wifi_handover_type))
return 0;
if (os_memcmp(record->type, wifi_handover_type,
os_strlen(wifi_handover_type)) != 0)
return 0;
return 1;
}
struct wpabuf * ndef_parse_wifi(const struct wpabuf *buf)
{
return ndef_parse_records(buf, wifi_filter);
}
struct wpabuf * ndef_build_wifi(const struct wpabuf *buf)
{
return ndef_build_record(FLAG_MESSAGE_BEGIN | FLAG_MESSAGE_END |
FLAG_TNF_RFC2046, wifi_handover_type,
os_strlen(wifi_handover_type), NULL, 0, buf);
}