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Fix CRC error during DSMR chunked message reading (#2622)

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* DSMR chunk size from 50 to 500

* Still a few CRC errors with 500, upping to 1024.

* Adding timers to measure how long processing DSMR takes

* Handle chunked output from smart meter.

* Cleaning up and commenting the new chunk handling code

* Remove debug code.

* Fixing clang-tidy issues.

* Implementing chunked reading support for encrypted telegrams.

* Remove redundant extra delay for encrypted reader

* Beware not to flush crypted telegram headers

* Use insane data timeout for testing

* Improve logging

* Make clang-tidy happy

Co-authored-by: Maurice Makaay <mmakaay1@xs4all.net>
Co-authored-by: Maurice Makaay <account-github@makaay.nl>
This commit is contained in:
Maurice Makaay 2021-11-06 22:52:04 +01:00 committed by GitHub
parent d536509a63
commit b450d4c734
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
2 changed files with 71 additions and 47 deletions
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104
esphome/components/dsmr/dsmr.cpp
View file

@ -19,14 +19,30 @@ void Dsmr::loop() {
this->receive_encrypted_();
}
bool Dsmr::available_within_timeout_() {
uint8_t tries = READ_TIMEOUT_MS / 5;
while (tries--) {
delay(5);
if (available()) {
return true;
}
}
return false;
}
void Dsmr::receive_telegram_() {
int count = MAX_BYTES_PER_LOOP;
while (available() && count-- > 0) {
while (true) {
if (!available()) {
if (!header_found_ || !available_within_timeout_()) {
return;
}
}
const char c = read();
// Find a new telegram header, i.e. forward slash.
if (c == '/') {
ESP_LOGV(TAG, "Header found");
ESP_LOGV(TAG, "Header of telegram found");
header_found_ = true;
footer_found_ = false;
telegram_len_ = 0;
@ -38,7 +54,7 @@ void Dsmr::receive_telegram_() {
if (telegram_len_ >= MAX_TELEGRAM_LENGTH) {
header_found_ = false;
footer_found_ = false;
ESP_LOGE(TAG, "Error: Message larger than buffer");
ESP_LOGE(TAG, "Error: telegram larger than buffer (%d bytes)", MAX_TELEGRAM_LENGTH);
return;
}
@ -54,7 +70,7 @@ void Dsmr::receive_telegram_() {
// Check for a footer, i.e. exlamation mark, followed by a hex checksum.
if (c == '!') {
ESP_LOGV(TAG, "Footer found");
ESP_LOGV(TAG, "Footer of telegram found");
footer_found_ = true;
continue;
}
@ -62,8 +78,8 @@ void Dsmr::receive_telegram_() {
if (footer_found_ && c == '\n') {
header_found_ = false;
// Parse the telegram and publish sensor values.
if (parse_telegram())
return;
parse_telegram();
return;
}
}
}
@ -72,41 +88,46 @@ void Dsmr::receive_encrypted_() {
// Encrypted buffer
uint8_t buffer[MAX_TELEGRAM_LENGTH];
size_t buffer_length = 0;
size_t packet_size = 0;
while (available()) {
const char c = read();
if (!header_found_) {
if ((uint8_t) c == 0xdb) {
ESP_LOGV(TAG, "Start byte 0xDB found");
header_found_ = true;
while (true) {
if (!available()) {
if (!header_found_) {
return;
}
if (!available_within_timeout_()) {
ESP_LOGW(TAG, "Timeout while reading data for encrypted telegram");
return;
}
}
// Sanity check
if (!header_found_ || buffer_length >= MAX_TELEGRAM_LENGTH) {
if (buffer_length == 0) {
ESP_LOGE(TAG, "First byte of encrypted telegram should be 0xDB, aborting.");
} else {
ESP_LOGW(TAG, "Unexpected data");
const char c = read();
// Find a new telegram start byte.
if (!header_found_) {
if ((uint8_t) c == 0xDB) {
ESP_LOGV(TAG, "Start byte 0xDB of encrypted telegram found");
header_found_ = true;
}
this->status_momentary_warning("unexpected_data");
this->flush();
while (available())
read();
continue;
}
// Check for buffer overflow.
if (buffer_length >= MAX_TELEGRAM_LENGTH) {
header_found_ = false;
ESP_LOGE(TAG, "Error: encrypted telegram larger than buffer (%d bytes)", MAX_TELEGRAM_LENGTH);
return;
}
buffer[buffer_length++] = c;
if (packet_size == 0 && buffer_length > 20) {
// Complete header + a few bytes of data
packet_size = buffer[11] << 8 | buffer[12];
// Complete header + data bytes
packet_size = 13 + (buffer[11] << 8 | buffer[12]);
ESP_LOGV(TAG, "Encrypted telegram size: %d bytes", packet_size);
}
if (buffer_length == packet_size + 13 && packet_size > 0) {
ESP_LOGV(TAG, "Encrypted data: %d bytes", buffer_length);
if (buffer_length == packet_size && packet_size > 0) {
ESP_LOGV(TAG, "End of encrypted telegram found");
GCM<AES128> *gcmaes128{new GCM<AES128>()};
gcmaes128->setKey(this->decryption_key_.data(), gcmaes128->keySize());
// the iv is 8 bytes of the system title + 4 bytes frame counter
@ -123,28 +144,21 @@ void Dsmr::receive_encrypted_() {
delete gcmaes128; // NOLINT(cppcoreguidelines-owning-memory)
telegram_len_ = strnlen(this->telegram_, sizeof(this->telegram_));
ESP_LOGV(TAG, "Decrypted data length: %d", telegram_len_);
ESP_LOGVV(TAG, "Decrypted data %s", this->telegram_);
ESP_LOGV(TAG, "Decrypted telegram size: %d bytes", telegram_len_);
ESP_LOGVV(TAG, "Decrypted telegram: %s", this->telegram_);
header_found_ = false;
telegram_len_ = 0;
parse_telegram();
telegram_len_ = 0;
return;
}
if (!available()) {
// baud rate is 115200 for encrypted data, this means a few byte should arrive every time
// program runs faster than buffer loading then available() might return false in the middle
delay(4); // Wait for data
}
}
if (buffer_length > 0) {
ESP_LOGW(TAG, "Timeout while waiting for encrypted data or invalid data received.");
}
}
bool Dsmr::parse_telegram() {
MyData data;
ESP_LOGV(TAG, "Trying to parse");
ESP_LOGV(TAG, "Trying to parse telegram");
::dsmr::ParseResult<void> res =
::dsmr::P1Parser::parse(&data, telegram_, telegram_len_, false,
this->crc_check_); // Parse telegram according to data definition. Ignore unknown values.
@ -161,7 +175,7 @@ bool Dsmr::parse_telegram() {
}
void Dsmr::dump_config() {
ESP_LOGCONFIG(TAG, "dsmr:");
ESP_LOGCONFIG(TAG, "DSMR:");
#define DSMR_LOG_SENSOR(s) LOG_SENSOR(" ", #s, this->s_##s##_);
DSMR_SENSOR_LIST(DSMR_LOG_SENSOR, )
@ -178,12 +192,12 @@ void Dsmr::set_decryption_key(const std::string &decryption_key) {
}
if (decryption_key.length() != 32) {
ESP_LOGE(TAG, "Error, decryption key must be 32 character long.");
ESP_LOGE(TAG, "Error, decryption key must be 32 character long");
return;
}
this->decryption_key_.clear();
ESP_LOGI(TAG, "Decryption key is set.");
ESP_LOGI(TAG, "Decryption key is set");
// Verbose level prints decryption key
ESP_LOGV(TAG, "Using decryption key: %s", decryption_key.c_str());

14
esphome/components/dsmr/dsmr.h
View file

@ -17,8 +17,7 @@ namespace esphome {
namespace dsmr {
static constexpr uint32_t MAX_TELEGRAM_LENGTH = 1500;
static constexpr uint32_t MAX_BYTES_PER_LOOP = 50;
static constexpr uint32_t POLL_TIMEOUT = 1000;
static constexpr uint32_t READ_TIMEOUT_MS = 200;
using namespace ::dsmr::fields;
@ -86,6 +85,17 @@ class Dsmr : public Component, public uart::UARTDevice {
void receive_telegram_();
void receive_encrypted_();
/// Wait for UART data to become available within the read timeout.
///
/// The smart meter might provide data in chunks, causing available() to
/// return 0. When we're already reading a telegram, then we don't return
/// right away (to handle further data in an upcoming loop) but wait a
/// little while using this method to see if more data are incoming.
/// By not returning, we prevent other components from taking so much
/// time that the UART RX buffer overflows and bytes of the telegram get
/// lost in the process.
bool available_within_timeout_();
// Telegram buffer
char telegram_[MAX_TELEGRAM_LENGTH];
int telegram_len_{0};