Move payload CRC to layer 2
Layer 1 only does decoding of the FEC, but the CRC check for data integrity is done in layer 2 now.
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@ -16,7 +16,7 @@
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#define PAYLOAD_CHANNEL_CODE LIQUID_FEC_CONV_V27P34
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#define PAYLOAD_MODULATION LIQUID_MODEM_QAM16
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#define HEADER_CHANNEL_CODE LIQUID_FEC_HAMMING84
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#define HEADER_CHANNEL_CODE LIQUID_FEC_HAMMING128
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#define HEADER_MODULATION LIQUID_MODEM_QPSK
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#define PAYLOAD_CRC_SCHEME LIQUID_CRC_16
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@ -81,7 +81,6 @@ result_t packet_mod_set_data(packet_mod_ctx_t *ctx, const unsigned char *data, s
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memcpy(ctx->pkt_bytes, data, length);
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ctx->length = length;
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ctx->raw_data_crc = crc_generate_key(PAYLOAD_CRC_SCHEME, (unsigned char *)data, length);
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ctx->raw_data_len = length;
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ctx->state = DATA_RAW;
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@ -173,18 +172,12 @@ result_t packet_mod_add_header(packet_mod_ctx_t *ctx)
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}
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// build the header. All field are transferred in network byte order (big endian).
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uint8_t header[5];
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uint8_t header[2];
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// set length
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header[0] = (ctx->raw_data_len >> 8) & 0x07;
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header[0] |= ctx->modcod << 3;
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header[1] = (ctx->raw_data_len >> 0) & 0xFF;
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// set raw data CRC
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header[2] = (ctx->raw_data_crc >> 8) & 0xFF;
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header[3] = (ctx->raw_data_crc >> 0) & 0xFF;
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// append an 8-bit CRC to the header
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crc_append_key(LIQUID_CRC_8, header, 4);
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// note: the header is coded and modulated differently than the data.
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@ -30,7 +30,6 @@ typedef struct
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modem hdr_modem;
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fec hdr_fec;
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uint16_t raw_data_crc;
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uint16_t raw_data_len;
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uint8_t modcod;
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@ -20,7 +20,7 @@
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#define SYMBOL_BUFFER_SIZE 16384
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#define HEADER_SIZE_BYTES 5 // including CRC
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#define HEADER_SIZE_BYTES 2
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#define FREQ_EST_L 24
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#define AGC_BW_ACQUISITION 5e-2f
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@ -370,18 +370,7 @@ result_t layer1_rx_process(layer1_rx_t *rx, const float complex *samples, size_t
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break;
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}
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// CRC check
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if(crc_check_key(LIQUID_CRC_8, header, HEADER_SIZE_BYTES) != LIQUID_OK) {
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uint8_t expected_crc = crc_generate_key(LIQUID_CRC_8, header, 4);
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LOG(LVL_WARN, "@%zu: Header CRC check failed! Expected: 0x%02x, received: 0x%02x",
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rx->sample_index, expected_crc, header[4]);
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rx->state = RX_STATE_ACQUISITION;
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rx->callback(RX_EVT_HEADER_ERROR, rx, NULL, 0);
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break;
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}
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rx->payload_len_bytes = (((uint16_t)header[0] << 8) | header[1]) & 0x07FF;
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rx->payload_crc = ((uint16_t)header[2] << 8) | header[3];
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rx->modcod = header[0] >> 3;
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// check the received information
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@ -417,7 +406,6 @@ result_t layer1_rx_process(layer1_rx_t *rx, const float complex *samples, size_t
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LOG(LVL_DUMP, "=== DECODED HEADER @%zu ===", rx->sample_index);
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LOG(LVL_DUMP, "Payload length: %u symbols, %u bytes encoded, %u bytes decoded", rx->payload_len_symbols, rx->payload_len_enc_bytes, rx->payload_len_bytes);
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LOG(LVL_DUMP, "CRC16: 0x%04x", rx->payload_crc);
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LOG(LVL_DUMP, "======================");
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//dump_array_cf(symbols_cpx, symbol_counter, 1.0f, "/tmp/hdr.cpx");
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@ -461,22 +449,25 @@ result_t layer1_rx_process(layer1_rx_t *rx, const float complex *samples, size_t
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payload_enc, 8, sizeof(payload_enc), &nsyms));
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fec payload_fec = modcod_create_fec(rx->modcod);
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fec_decode(payload_fec, rx->payload_len_bytes, payload_enc, payload);
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result_t res = fec_decode(payload_fec, rx->payload_len_bytes, payload_enc, payload);
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fec_destroy(payload_fec);
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if(res != LIQUID_OK) {
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LOG(LVL_WARN, "@%zu: Payload decoding failed!", rx->sample_index);
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rx->state = RX_STATE_ACQUISITION;
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rx->callback(RX_EVT_DECODE_FAILED, rx, NULL, 0);
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break;
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}
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// de-whiten the data
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whitening_apply_in_place(payload, rx->payload_len_bytes);
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int valid = crc_validate_message(PAYLOAD_CRC_SCHEME, payload, rx->payload_len_bytes, rx->payload_crc);
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// note: CRC is included in data and checked in layer 2
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payload[rx->payload_len_bytes] = '\0';
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//dump_array_cf(symbols_cpx, symbol_counter, 1.0f, "/tmp/payload.cpx");
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if(valid) {
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rx->callback(RX_EVT_PACKET_RECEIVED, rx, payload, rx->payload_len_bytes);
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} else {
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rx->callback(RX_EVT_CHECKSUM_ERROR, rx, payload, rx->payload_len_bytes);
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}
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rx->callback(RX_EVT_PACKET_RECEIVED, rx, payload, rx->payload_len_bytes);
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modem_destroy(rx->payload_demod);
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rx->state = RX_STATE_ACQUISITION;
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@ -20,7 +20,7 @@ typedef enum {
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RX_EVT_PACKET_RECEIVED,
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RX_EVT_PREAMBLE_FOUND,
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RX_EVT_HEADER_ERROR,
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RX_EVT_CHECKSUM_ERROR,
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RX_EVT_DECODE_FAILED,
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RX_EVT_PACKET_DEBUG_INFO_COMPLETE,
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} rx_evt_t;
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@ -69,7 +69,6 @@ typedef struct layer1_rx_s
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// Information from the decoded header
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uint16_t payload_len_symbols;
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uint16_t payload_len_bytes;
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uint16_t payload_crc;
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uint16_t payload_len_enc_bytes;
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modcod_t modcod;
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@ -116,7 +116,7 @@ void cb_rx(rx_evt_t evt, const struct layer1_rx_s *rx, uint8_t *packet_data, siz
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switch(evt)
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{
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case RX_EVT_CHECKSUM_ERROR:
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case RX_EVT_DECODE_FAILED:
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//LOG(LVL_WARN, "Received a message of %zu bytes, but decoding failed.", packet_len);
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//LOG(LVL_INFO, "=== FAILED PAYLOAD ===");
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//hexdump(packet_data, packet_len);
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@ -138,7 +138,15 @@ void cb_rx(rx_evt_t evt, const struct layer1_rx_s *rx, uint8_t *packet_data, siz
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block_tx_for(TX_SWITCH_BACKOFF_END_OF_PACKET_MS);
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ret = write(m_tunfd, packet_data, packet_len);
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unsigned int data_size = packet_len - crc_sizeof_key(PAYLOAD_CRC_SCHEME);
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// FIXME: move to layer 2
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if(!crc_check_key(PAYLOAD_CRC_SCHEME, packet_data, data_size)) {
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LOG(LVL_WARN, "payload CRC check failed!");
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break;
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}
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ret = write(m_tunfd, packet_data, data_size);
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if(ret < 0) {
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LOG(LVL_ERR, "write: %s", strerror(errno));
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}
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@ -278,6 +286,16 @@ int main(int argc, char **argv)
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break;
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}
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/* append CRC to packet */
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unsigned int crc_size = crc_sizeof_key(PAYLOAD_CRC_SCHEME);
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if((unsigned)ret > sizeof(packetbuf) - crc_size) {
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LOG(LVL_ERR, "Packet is too large to append CRC! %i bytes.", ret);
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break;
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}
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crc_append_key(PAYLOAD_CRC_SCHEME, packetbuf, ret);
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LOG(LVL_DEBUG, "Transmitting packet with %d bytes.", ret);
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RESULT_CHECK(layer1_tx_reset(&tx));
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@ -12,6 +12,7 @@
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#include "logger.h"
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#include "utils.h"
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#include "config.h"
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#define RESULT_CHECK(stmt) { \
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result_t res = stmt; \
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@ -77,9 +78,11 @@ void cb_rx(rx_evt_t evt, const layer1_rx_t *rx, uint8_t *packet_data, size_t pac
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{
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(void)rx;
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unsigned int data_size;
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switch(evt)
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{
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case RX_EVT_CHECKSUM_ERROR:
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case RX_EVT_DECODE_FAILED:
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LOG(LVL_ERR, "Received a message of %zu bytes, but decoding failed.", packet_len);
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LOG(LVL_INFO, "=== FAILED PAYLOAD ===");
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hexdump(packet_data, packet_len);
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@ -87,10 +90,19 @@ void cb_rx(rx_evt_t evt, const layer1_rx_t *rx, uint8_t *packet_data, size_t pac
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break;
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case RX_EVT_PACKET_RECEIVED:
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LOG(LVL_INFO, "A message of %zu bytes was decoded successfully.", packet_len);
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data_size = packet_len - crc_sizeof_key(PAYLOAD_CRC_SCHEME);
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LOG(LVL_INFO, "=== DECODED PAYLOAD (%4zu bytes) ===", packet_len);
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hexdump(packet_data, packet_len < 64 ? packet_len : 64);
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hexdump(packet_data, packet_len);
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LOG(LVL_INFO, "====================================");
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// FIXME: move to layer 2
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if(!crc_check_key(PAYLOAD_CRC_SCHEME, packet_data, data_size)) {
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LOG(LVL_WARN, "payload CRC check failed!");
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break;
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}
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LOG(LVL_INFO, "A message of %zu bytes was decoded successfully.", packet_len);
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break;
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case RX_EVT_HEADER_ERROR:
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@ -127,19 +139,24 @@ int main(void)
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RESULT_CHECK(layer1_tx_reset(&tx));
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uint8_t packetbuf1[] = "Hello World! 1234567890";
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size_t l = sizeof(packetbuf1);
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uint8_t packetbuf1[64] = "Hello World! 1234567890";
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size_t crc_size = crc_sizeof_key(PAYLOAD_CRC_SCHEME);
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size_t l = strlen((char*)packetbuf1);
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LOG(LVL_INFO, "Transmitting packet with %zd bytes.", l);
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crc_append_key(PAYLOAD_CRC_SCHEME, packetbuf1, l);
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RESULT_CHECK(layer1_tx_add_packet_to_burst(&tx, packetbuf1, l));
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LOG(LVL_INFO, "Transmitting packet with %zd bytes.", l + crc_size);
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uint8_t packetbuf2[] = "This is just a test message. Just writing some stuff here to create a longer packet.";
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l = sizeof(packetbuf2);
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RESULT_CHECK(layer1_tx_add_packet_to_burst(&tx, packetbuf1, l + crc_size));
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LOG(LVL_INFO, "Transmitting packet with %zd bytes.", l);
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uint8_t packetbuf2[128] = "This is just a test message. Just writing some stuff here to create a longer packet.";
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l = strlen((char*)packetbuf2);
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RESULT_CHECK(layer1_tx_add_packet_to_burst(&tx, packetbuf2, l));
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crc_append_key(PAYLOAD_CRC_SCHEME, packetbuf2, l);
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LOG(LVL_INFO, "Transmitting packet with %zd bytes.", l + crc_size);
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RESULT_CHECK(layer1_tx_add_packet_to_burst(&tx, packetbuf2, l + crc_size));
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RESULT_CHECK(layer1_tx_finalize_burst(&tx));
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@ -150,7 +167,7 @@ int main(void)
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// ** Simulate channel effects **
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channel_cccf ch = channel_cccf_create();
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channel_cccf_add_awgn(ch, -30, 10);
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channel_cccf_add_awgn(ch, -30, 30);
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//channel_cccf_add_carrier_offset(ch, 0.05f, 1.23f);
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float complex whole_burst_ch[burst_len];
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@ -64,9 +64,11 @@ void cb_rx(rx_evt_t evt, const layer1_rx_t *rx, uint8_t *packet_data, size_t pac
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(void)packet_len;
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(void)rx;
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unsigned int data_size;
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switch(evt)
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{
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case RX_EVT_CHECKSUM_ERROR:
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case RX_EVT_DECODE_FAILED:
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//LOG(LVL_WARN, "Received a message of %zu bytes, but decoding failed.", packet_len);
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//LOG(LVL_INFO, "=== FAILED PAYLOAD ===");
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//hexdump(packet_data, packet_len);
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@ -84,6 +86,14 @@ void cb_rx(rx_evt_t evt, const layer1_rx_t *rx, uint8_t *packet_data, size_t pac
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//hexdump(packet_data, packet_len < 64 ? packet_len : 64);
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//LOG(LVL_INFO, "====================================");
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data_size = packet_len - crc_sizeof_key(PAYLOAD_CRC_SCHEME);
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// FIXME: move to layer 2
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if(!crc_check_key(PAYLOAD_CRC_SCHEME, packet_data, data_size)) {
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LOG(LVL_WARN, "payload CRC check failed!");
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break;
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}
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m_rx_stats.successful_decodes++;
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break;
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