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Settings: Better handling of the checksum

pull/35/head
Paul Hollinsky 2021-05-05 02:20:36 -04:00
parent 0006f31844
commit 82113f1a67
2 changed files with 57 additions and 32 deletions
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87
device/idevicesettings.cpp
View File

@ -4,14 +4,14 @@
using namespace icsneo;
uint16_t IDeviceSettings::CalculateGSChecksum(const std::vector<uint8_t>& settings) {
uint16_t gs_crc = 0;
const uint16_t* p = (const uint16_t*)settings.data();
size_t words = settings.size();
optional<uint16_t> IDeviceSettings::CalculateGSChecksum(const std::vector<uint8_t>& settings, optional<size_t> knownSize) {
const uint16_t* p = reinterpret_cast<const uint16_t*>(settings.data());
size_t words = std::min(knownSize.value_or(0), settings.size());
if(words % 2 == 1)
return 0xFFFF; // Somehow settings is not word aligned
return nullopt; // Somehow settings is not word aligned
words /= 2;
uint16_t gsCrc = 0;
while(words--) {
uint16_t temp = *p;
@ -20,7 +20,7 @@ uint16_t IDeviceSettings::CalculateGSChecksum(const std::vector<uint8_t>& settin
int iCrcNxt;
//CRCNXT = NXTBIT EXOR CRC_RG(15);
if (gs_crc & (1 << 15))
if (gsCrc & (1 << 15))
iCrcNxt = iBit ^ 1;
else
iCrcNxt = iBit;
@ -28,18 +28,18 @@ uint16_t IDeviceSettings::CalculateGSChecksum(const std::vector<uint8_t>& settin
// CRC_RG(15:1) = CRC_RG(14:0); // shift left by
gs_crc = gs_crc << 1;
gs_crc = gs_crc & 0xFFFE;// clear first bit
gsCrc = gsCrc << 1;
gsCrc = gsCrc & 0xFFFE;// clear first bit
if (iCrcNxt)//CRC_RG(14:0) = CRC_RG(14:0) EXOR (4599hex);
gs_crc = gs_crc ^ 0xa001;
gsCrc = gsCrc ^ 0xa001;
temp >>= 1;
}
p++;
}
return gs_crc;
return gsCrc;
}
CANBaudrate IDeviceSettings::GetEnumValueForBaudrate(int64_t baudrate) {
@ -144,30 +144,40 @@ bool IDeviceSettings::refresh(bool ignoreChecksum) {
return false;
}
if(rxSettings.size() < 6) { // We need to at least have the header of GLOBAL_SETTINGS
constexpr size_t GsSize = 3 * sizeof(uint16_t);
if(rxSettings.size() < GsSize) { // We need to at least have the header of GLOBAL_SETTINGS
report(APIEvent::Type::SettingsReadError, APIEvent::Severity::Error);
return false;
}
constexpr size_t gs_size = 3 * sizeof(uint16_t);
size_t rxLen = rxSettings.size() - gs_size;
// The length of the settings structure sent to us
// This is the length the firmware thinks the current version of the structure is
const size_t rxLen = rxSettings.size() - GsSize;
uint16_t gs_version = rxSettings[0] | (rxSettings[1] << 8);
uint16_t gs_len = rxSettings[2] | (rxSettings[3] << 8);
uint16_t gs_chksum = rxSettings[4] | (rxSettings[5] << 8);
rxSettings.erase(rxSettings.begin(), rxSettings.begin() + gs_size);
const uint16_t gsVersion = rxSettings[0] | (rxSettings[1] << 8);
if(gs_version != 5) {
// The length of the settings last saved
// If the firmware is updated, it will have either extended (with zeros) or truncated
// the structure, but this value will continue to be set to the last saved value
const uint16_t gsLen = rxSettings[2] | (rxSettings[3] << 8);
const uint16_t gsChecksum = rxSettings[4] | (rxSettings[5] << 8);
rxSettings.erase(rxSettings.begin(), rxSettings.begin() + GsSize);
if(gsVersion != GS_VERSION) {
report(APIEvent::Type::SettingsVersionError, APIEvent::Severity::Error);
return false;
}
if(rxLen != gs_len) {
report(APIEvent::Type::SettingsLengthError, APIEvent::Severity::Error);
return false;
if(rxLen < gsLen) {
// We got less data, i.e. the firmware thinks the strucure is smaller than what
// was last saved. Usually this is due to a firmware downgrade. We'll ignore the
// checksum for now, because it will definitely be wrong.
ignoreChecksum = true;
}
if(!ignoreChecksum && gs_chksum != CalculateGSChecksum(rxSettings)) {
// We check the checksum against the data last saved
if(!ignoreChecksum && gsChecksum != CalculateGSChecksum(rxSettings, gsLen)) {
report(APIEvent::Type::SettingsChecksumError, APIEvent::Severity::Error);
return false;
}
@ -205,9 +215,14 @@ bool IDeviceSettings::apply(bool temporary) {
bytestream[2] = GS_VERSION >> 8;
bytestream[3] = (uint8_t)settings.size();
bytestream[4] = (uint8_t)(settings.size() >> 8);
uint16_t gs_checksum = CalculateGSChecksum(settings);
bytestream[5] = (uint8_t)gs_checksum;
bytestream[6] = (uint8_t)(gs_checksum >> 8);
optional<uint16_t> gsChecksum = CalculateGSChecksum(settings);
if(!gsChecksum) {
// Could not calculate the checksum for some reason
report(APIEvent::Type::SettingsChecksumError, APIEvent::Severity::Error);
return false;
}
bytestream[5] = (uint8_t)*gsChecksum;
bytestream[6] = (uint8_t)(*gsChecksum >> 8);
memcpy(bytestream.data() + 7, getMutableRawStructurePointer(), settings.size());
// Pause I/O with the device while the settings are applied
@ -229,9 +244,14 @@ bool IDeviceSettings::apply(bool temporary) {
refresh(true); // Refresh ignoring checksum
// The device might modify the settings once they are applied, however in this case it does not update the checksum
// We refresh to get these updates, update the checksum, and send it back so it's all in sync
gs_checksum = CalculateGSChecksum(settings);
bytestream[5] = (uint8_t)gs_checksum;
bytestream[6] = (uint8_t)(gs_checksum >> 8);
gsChecksum = CalculateGSChecksum(settings);
if(!gsChecksum) {
// Could not calculate the checksum for some reason
report(APIEvent::Type::SettingsChecksumError, APIEvent::Severity::Error);
return false;
}
bytestream[5] = (uint8_t)*gsChecksum;
bytestream[6] = (uint8_t)(*gsChecksum >> 8);
memcpy(bytestream.data() + 7, getMutableRawStructurePointer(), settings.size());
msg = com->waitForMessageSync([this, &bytestream]() {
@ -301,9 +321,14 @@ bool IDeviceSettings::applyDefaults(bool temporary) {
bytestream[2] = GS_VERSION >> 8;
bytestream[3] = (uint8_t)settings.size();
bytestream[4] = (uint8_t)(settings.size() >> 8);
uint16_t gs_checksum = CalculateGSChecksum(settings);
bytestream[5] = (uint8_t)gs_checksum;
bytestream[6] = (uint8_t)(gs_checksum >> 8);
const optional<uint16_t> gsChecksum = CalculateGSChecksum(settings);
if(!gsChecksum) {
// Could not calculate the checksum for some reason
report(APIEvent::Type::SettingsChecksumError, APIEvent::Severity::Error);
return false;
}
bytestream[5] = (uint8_t)*gsChecksum;
bytestream[6] = (uint8_t)(*gsChecksum >> 8);
memcpy(bytestream.data() + 7, getMutableRawStructurePointer(), settings.size());
msg = com->waitForMessageSync([this, &bytestream]() {

2
include/icsneo/device/idevicesettings.h
View File

@ -591,7 +591,7 @@ public:
using TerminationGroup = std::vector<Network>;
static constexpr uint16_t GS_VERSION = 5;
static uint16_t CalculateGSChecksum(const std::vector<uint8_t>& settings);
static optional<uint16_t> CalculateGSChecksum(const std::vector<uint8_t>& settings, optional<size_t> knownSize = nullopt);
static CANBaudrate GetEnumValueForBaudrate(int64_t baudrate);
static int64_t GetBaudrateValueForEnum(CANBaudrate enumValue);