diff options
Diffstat (limited to 'src/kernel/ao_radio_cmac.c')
| -rw-r--r-- | src/kernel/ao_radio_cmac.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/src/kernel/ao_radio_cmac.c b/src/kernel/ao_radio_cmac.c new file mode 100644 index 00000000..bff848f6 --- /dev/null +++ b/src/kernel/ao_radio_cmac.c @@ -0,0 +1,164 @@ +/* + * 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; version 2 of the License. + * + * 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; + } + + ao_radio_cmac_rssi = ao_radio_rssi; + 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; + } + + 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; +} + |