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/*
* Copyright © 2011 Keith Packard <keithp@keithp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*/
#include <ao.h>
#include <ao_radio_cmac.h>
static __xdata uint8_t ao_radio_cmac_mutex;
__pdata int8_t ao_radio_cmac_rssi;
static __xdata uint8_t cmac_data[AO_CMAC_MAX_LEN + AO_CMAC_KEY_LEN + 2 + AO_CMAC_KEY_LEN];
static uint8_t
round_len(uint8_t len)
{
uint8_t rem;
/* Make sure we transfer at least one packet, and
* then make sure every packet is full. Note that
* there is no length encoded, and that the receiver
* must deal with any extra bytes in the packet
*/
if (len < AO_CMAC_KEY_LEN)
len = AO_CMAC_KEY_LEN;
rem = len % AO_CMAC_KEY_LEN;
if (rem != 0)
len += (AO_CMAC_KEY_LEN - rem);
return len;
}
/*
* Sign and deliver the data sitting in the cmac buffer
*/
static void
radio_cmac_send(uint8_t len) __reentrant
{
uint8_t i;
len = round_len(len);
/* Make sure the AES key is loaded */
ao_config_get();
#if HAS_MONITOR
ao_monitor_set(0);
#endif
ao_mutex_get(&ao_aes_mutex);
ao_aes_set_mode(ao_aes_mode_cbc_mac);
ao_aes_set_key(ao_config.aes_key);
ao_aes_zero_iv();
for (i = 0; i < len; i += AO_CMAC_KEY_LEN) {
if (i + AO_CMAC_KEY_LEN < len)
ao_aes_run(&cmac_data[i], NULL);
else
ao_aes_run(&cmac_data[i], &cmac_data[len]);
}
ao_mutex_put(&ao_aes_mutex);
ao_radio_send(cmac_data, len + AO_CMAC_KEY_LEN);
}
/*
* Receive and validate an incoming packet
*/
static int8_t
radio_cmac_recv(uint8_t len, uint16_t timeout) __reentrant
{
uint8_t i;
len = round_len(len);
#if HAS_MONITOR
ao_monitor_set(0);
#endif
i = ao_radio_recv(cmac_data, len + AO_CMAC_KEY_LEN + 2, timeout);
if (!i) {
ao_radio_cmac_rssi = 0;
return AO_RADIO_CMAC_TIMEOUT;
}
if (!(cmac_data[len + AO_CMAC_KEY_LEN +1] & AO_RADIO_STATUS_CRC_OK))
return AO_RADIO_CMAC_CRC_ERROR;
ao_config_get();
/* Compute the packet signature
*/
ao_mutex_get(&ao_aes_mutex);
ao_aes_set_mode(ao_aes_mode_cbc_mac);
ao_aes_set_key(ao_config.aes_key);
ao_aes_zero_iv();
for (i = 0; i < len; i += AO_CMAC_KEY_LEN) {
if (i + AO_CMAC_KEY_LEN < len)
ao_aes_run(&cmac_data[i], NULL);
else
ao_aes_run(&cmac_data[i], &cmac_data[len + AO_CMAC_KEY_LEN + 2]);
}
ao_mutex_put(&ao_aes_mutex);
/* Check the packet signature against the signature provided
* over the link
*/
if (memcmp(&cmac_data[len],
&cmac_data[len + AO_CMAC_KEY_LEN + 2],
AO_CMAC_KEY_LEN) != 0) {
return AO_RADIO_CMAC_MAC_ERROR;
}
ao_radio_cmac_rssi = ao_radio_rssi;
return AO_RADIO_CMAC_OK;
}
int8_t
ao_radio_cmac_send(__xdata void *packet, uint8_t len) __reentrant
{
if (len > AO_CMAC_MAX_LEN)
return AO_RADIO_CMAC_LEN_ERROR;
ao_mutex_get(&ao_radio_cmac_mutex);
ao_xmemcpy(cmac_data, packet, len);
#if AO_LED_TX
ao_led_on(AO_LED_TX);
#endif
radio_cmac_send(len);
#if AO_LED_TX
ao_led_off(AO_LED_TX);
#endif
ao_mutex_put(&ao_radio_cmac_mutex);
return AO_RADIO_CMAC_OK;
}
int8_t
ao_radio_cmac_recv(__xdata void *packet, uint8_t len, uint16_t timeout) __reentrant
{
int8_t i;
if (len > AO_CMAC_MAX_LEN)
return AO_RADIO_CMAC_LEN_ERROR;
ao_mutex_get(&ao_radio_cmac_mutex);
#if AO_LED_RX
ao_led_on(AO_LED_RX);
#endif
i = radio_cmac_recv(len, timeout);
#if AO_LED_RX
ao_led_off(AO_LED_RX);
#endif
if (i == AO_RADIO_CMAC_OK)
ao_xmemcpy(packet, cmac_data, len);
ao_mutex_put(&ao_radio_cmac_mutex);
return i;
}
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