[vbus] Discard P1 telegrams after a frame checksum error (#21045)

esphome/components/vbus/vbus.cpp

@@ -90,6 +90,7 @@ void VBus::loop() {
       this->fbcount_ = 0;
       if (!checksum(this->fbytes_, 0, 6)) {
         ESP_LOGE(TAG, "frame checksum failed");
+        this->state_ = 0;
         return;
       }
       septet_spread(this->fbytes_, 0, 4, this->fbytes_[4]);

tests/components/vbus/vbus_test.cpp

@@ -0,0 +1,159 @@
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include <algorithm>
+#include <array>
+#include <vector>
+
+#include "esphome/components/vbus/vbus.h"
+
+namespace esphome::vbus::testing {
+namespace {
+
+class MockUART : public uart::UARTComponent {
+ public:
+  void inject(const std::vector<uint8_t> &bytes) { this->rx_.insert(this->rx_.end(), bytes.begin(), bytes.end()); }
+  size_t available() override { return this->rx_.size() - this->position_; }
+  bool read_array(uint8_t *data, size_t size) override {
+    if (size > this->available())
+      return false;
+    std::copy_n(this->rx_.data() + this->position_, size, data);
+    this->position_ += size;
+    return true;
+  }
+  bool peek_byte(uint8_t *data) override {
+    if (!this->available())
+      return false;
+    *data = this->rx_[this->position_];
+    return true;
+  }
+  MOCK_METHOD(void, write_array, (const uint8_t *data, size_t size), (override));
+  uart::UARTFlushResult flush() override { return uart::UARTFlushResult::UART_FLUSH_RESULT_ASSUMED_SUCCESS; }
+  void check_logger_conflict() override {}
+#if defined(USE_ESP8266) || defined(USE_ESP32)
+  void load_settings(bool dump_config) override {}
+#endif
+
+ protected:
+  std::vector<uint8_t> rx_;
+  size_t position_{0};
+};
+
+class RecordingListener : public VBusListener {
+ public:
+  std::vector<std::vector<uint8_t>> messages;
+
+ protected:
+  void handle_message(std::vector<uint8_t> &message) override { this->messages.push_back(message); }
+};
+
+// P1 command 0x0100, source 0x2211, destination 0x0010, two frames.
+const std::vector<uint8_t> HEADER = {0xaa, 0x10, 0x00, 0x11, 0x22, 0x10, 0x00, 0x01, 0x02, 0x29};
+const std::array<std::vector<uint8_t>, 3> FRAMES = {{
+    {0x01, 0x02, 0x03, 0x04, 0x00, 0x75},
+    {0x10, 0x20, 0x30, 0x40, 0x0f, 0x50},
+    {0x05, 0x06, 0x07, 0x08, 0x00, 0x65},
+}};
+const std::vector<uint8_t> PAYLOAD = {0x01, 0x02, 0x03, 0x04, 0x90, 0xa0, 0xb0, 0xc0};
+
+class VBusTest : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    this->bus_.set_uart_parent(&this->uart_);
+    this->listener_.set_command(0x0100);
+    this->listener_.set_source(0x2211);
+    this->listener_.set_dest(0x0010);
+    this->bus_.register_listener(&this->listener_);
+    EXPECT_CALL(this->uart_, write_array(::testing::_, ::testing::_)).Times(0);
+  }
+  void feed_(const std::vector<uint8_t> &bytes) {
+    this->uart_.inject(bytes);
+    this->bus_.loop();
+  }
+  void valid_packet_() {
+    this->feed_(HEADER);
+    this->feed_(FRAMES[0]);
+    this->feed_(FRAMES[1]);
+  }
+
+  MockUART uart_;
+  VBus bus_{};
+  RecordingListener listener_;
+};
+
+TEST_F(VBusTest, DecodesValidPacketAndSeptets) {
+  this->valid_packet_();
+  ASSERT_EQ(this->listener_.messages.size(), 1u);
+  EXPECT_EQ(this->listener_.messages[0], PAYLOAD);
+}
+
+TEST_F(VBusTest, PreservesPartialHeaderAndFrameAcrossLoopCalls) {
+  this->feed_({HEADER.begin(), HEADER.begin() + 5});
+  this->feed_({HEADER.begin() + 5, HEADER.end()});
+  this->feed_({FRAMES[0].begin(), FRAMES[0].begin() + 3});
+  this->feed_({FRAMES[0].begin() + 3, FRAMES[0].end()});
+  EXPECT_TRUE(this->listener_.messages.empty());
+  this->feed_(FRAMES[1]);
+  ASSERT_EQ(this->listener_.messages.size(), 1u);
+  EXPECT_EQ(this->listener_.messages[0], PAYLOAD);
+}
+
+TEST_F(VBusTest, RejectsBadHeaderChecksumAndRecoversAtNextSync) {
+  auto bad_header = HEADER;
+  bad_header.back() ^= 0x01;
+  this->feed_(bad_header);
+  this->feed_(FRAMES[0]);
+  this->feed_(FRAMES[1]);
+  EXPECT_TRUE(this->listener_.messages.empty());
+  this->valid_packet_();
+  ASSERT_EQ(this->listener_.messages.size(), 1u);
+  EXPECT_EQ(this->listener_.messages[0], PAYLOAD);
+}
+
+class VBusBadFrameTest : public VBusTest, public ::testing::WithParamInterface<size_t> {};
+
+TEST_P(VBusBadFrameTest, DiscardsWholePacketUntilNextSync) {
+  auto header = HEADER;
+  header[8] = 0x03;
+  header[9] = 0x28;
+  this->feed_(header);
+  for (size_t i = 0; i < FRAMES.size(); ++i) {
+    auto frame = FRAMES[i];
+    if (i == GetParam())
+      frame.back() ^= 0x01;
+    this->feed_(frame);
+  }
+  // Checksum-valid trailing data must not replace the rejected frame.
+  this->feed_(FRAMES[0]);
+  EXPECT_TRUE(this->listener_.messages.empty());
+
+  this->valid_packet_();
+  ASSERT_EQ(this->listener_.messages.size(), 1u);
+  EXPECT_EQ(this->listener_.messages[0], PAYLOAD);
+}
+
+INSTANTIATE_TEST_SUITE_P(FirstMiddleLast, VBusBadFrameTest, ::testing::Values(0u, 1u, 2u));
+
+TEST_F(VBusTest, RecoversWithinTheSameUartBatch) {
+  auto bad_frame = FRAMES[0];
+  bad_frame.back() ^= 0x01;
+  for (const auto &bytes : {HEADER, bad_frame, FRAMES[0], FRAMES[1], HEADER, FRAMES[0], FRAMES[1]})
+    this->uart_.inject(bytes);
+  this->bus_.loop();
+  ASSERT_EQ(this->listener_.messages.size(), 1u);
+  EXPECT_EQ(this->listener_.messages[0], PAYLOAD);
+}
+
+TEST_F(VBusTest, AcceptsMaximumFrameCount) {
+  this->feed_({0xaa, 0x10, 0x00, 0x11, 0x22, 0x10, 0x00, 0x01, 0x7f, 0x2c});
+  std::vector<uint8_t> expected;
+  for (size_t i = 0; i < 127; ++i) {
+    this->feed_(FRAMES[0]);
+    expected.insert(expected.end(), {0x01, 0x02, 0x03, 0x04});
+  }
+  ASSERT_EQ(this->listener_.messages.size(), 1u);
+  EXPECT_EQ(this->listener_.messages[0], expected);
+}
+
+}  // namespace
+}  // namespace esphome::vbus::testing