unsigned int CGatewayProtocolHandler::readHeader(unsigned char* buffer, unsigned int length)
{
if (m_type != NETWORK_HEADER)
return 0U;
// If the checksum is 0xFFFF then we accept the header without testing the checksum
if (m_buffer[47U] == 0xFFU && m_buffer[48U] == 0xFFU) {
::memcpy(buffer, m_buffer + 8U, RADIO_HEADER_LENGTH_BYTES);
return RADIO_HEADER_LENGTH_BYTES;
}
// Get the checksum for the header
CCCITTChecksumReverse csum;
csum.update(m_buffer + 8U, RADIO_HEADER_LENGTH_BYTES - 2U);
bool check = csum.check(m_buffer + 8U + RADIO_HEADER_LENGTH_BYTES - 2U);
if (!check) {
CUtils::dump(wxT("Header checksum failure from the Repeater"), m_buffer + 8U, RADIO_HEADER_LENGTH_BYTES);
return 0U;
}
::memcpy(buffer, m_buffer + 8U, RADIO_HEADER_LENGTH_BYTES);
return RADIO_HEADER_LENGTH_BYTES;
}
bool CSplitRepeaterHeaderData::setRepeaterData(const unsigned char *data, unsigned int length, bool check, const in_addr& address, unsigned int port)
{
wxASSERT(data != NULL);
wxASSERT(length >= 49U);
m_id = data[5U] * 256U + data[6U];
m_errors = data[7U];
m_flag1 = data[8U];
m_flag2 = data[9U];
m_flag3 = data[10U];
::memcpy(m_rptCall2, data + 11U, LONG_CALLSIGN_LENGTH);
::memcpy(m_rptCall1, data + 19U, LONG_CALLSIGN_LENGTH);
::memcpy(m_yourCall, data + 27U, LONG_CALLSIGN_LENGTH);
::memcpy(m_myCall1, data + 35U, LONG_CALLSIGN_LENGTH);
::memcpy(m_myCall2, data + 43U, SHORT_CALLSIGN_LENGTH);
m_address = address;
m_port = port;
if (check) {
CCCITTChecksumReverse cksum;
cksum.update(data + 8U, RADIO_HEADER_LENGTH_BYTES - 2U);
bool valid = cksum.check(data + 8U + RADIO_HEADER_LENGTH_BYTES - 2U);
return valid;
} else {
return true;
}
}
bool CSplitRepeaterHeaderData::setData(const unsigned char *data, unsigned int length)
{
wxASSERT(data != NULL);
wxASSERT(length >= RADIO_HEADER_LENGTH_BYTES);
m_flag1 = data[0U];
m_flag2 = data[1U];
m_flag3 = data[2U];
::memcpy(m_rptCall2, data + 3U, LONG_CALLSIGN_LENGTH);
::memcpy(m_rptCall1, data + 11U, LONG_CALLSIGN_LENGTH);
::memcpy(m_yourCall, data + 19U, LONG_CALLSIGN_LENGTH);
::memcpy(m_myCall1, data + 27U, LONG_CALLSIGN_LENGTH);
::memcpy(m_myCall2, data + 35U, SHORT_CALLSIGN_LENGTH);
CCCITTChecksumReverse cksum;
cksum.update(data, RADIO_HEADER_LENGTH_BYTES - 2U);
return cksum.check(data + RADIO_HEADER_LENGTH_BYTES - 2U);
}
bool CSlowDataDecoder::processHeader(const unsigned char* bytes)
{
unsigned char buffer[RADIO_HEADER_LENGTH_BYTES];
// Clean up the header data
for (unsigned int n = 0U; n < RADIO_HEADER_LENGTH_BYTES; n++) {
switch (n) {
case 0U: // Flag 1
// Only allow BK and EMR bits and always assert the repeater bit
buffer[n] = (bytes[n] & (INTERRUPTED_MASK | URGENT_MASK)) | REPEATER_MASK;
break;
case 1U: // Flag 2
case 2U: // Flag 3
// Always 0x00 in current implementations
buffer[n] = 0x00;
break;
case 39U: // Checksum 1
case 40U: // Checksum 2
// These bytes can be any value
buffer[n] = bytes[n];
break;
default: // Callsign text
// Only ASCII text so MSB is always clear
buffer[n] = bytes[n] & 0x7F;
break;
}
}
CCCITTChecksumReverse cksum;
cksum.update(buffer, RADIO_HEADER_LENGTH_BYTES - 2U);
bool valid = cksum.check(buffer + RADIO_HEADER_LENGTH_BYTES - 2U);
if (!valid)
return false;
// The checksum has already been checked
m_header = new CHeaderData(buffer, RADIO_HEADER_LENGTH_BYTES, false);
return true;
}
