fix: make end of telegram char optional

nozols · nozols · commit 9cebe94e052b · 2025-04-24T15:27:44.000+02:00
Some ISK MT382 meters don't send the last line of the DSMR telegram (which is "!\r\n"). I've added support for this, it is not ideal as we just try to parse the telegram after the timeout was reached, or when a new start of frame was received.
diff --git a/src/parsers/stream-unencrypted.ts b/src/parsers/stream-unencrypted.ts
@@ -95,38 +95,43 @@ export class UnencryptedDSMRStreamParser implements DSMRStreamParser {
 
     const eofRegexResult = this.eofRegex.exec(this.telegram.toString(this.encoding));
 
-    // End of telegram has not been reached, wait for more data to arrive.
-    if (!eofRegexResult) return;
-
-    const endOfFrameIndex = eofRegexResult.index + eofRegexResult[0].length;
-
-    // Clear the full frame required timeout. The full frame
-    // has been received and the data buffer will be cleared.
-    clearTimeout(this.fullFrameRequiredTimeout);
-
-    try {
-      const result = DSMRParser({
-        telegram: this.telegram.subarray(0, endOfFrameIndex),
-        newLineChars: this.options.newLineChars,
-      });
-
-      this.options.callback(null, result);
-    } catch (error) {
-      if (error instanceof DSMRError) {
-        error.withRawTelegram(this.telegram);
+    // End of telegram has not been reached.
+    if (!eofRegexResult) {
+      // Check if we've received another start of frame.
+      // Some variants of the MT382 meters don't send an eof.
+      // We skip the first byte, as this is already the sof of the current frame.
+      // Note: add 1 to the index, as we skip the first byte when doing indexOf.
+      const sofIndex = this.telegram.subarray(1).indexOf('/') + 1;
+
+      if (sofIndex === 0) return;
+
+      // Check if the characters before the sof char are newlines. Otherwise the sof
+      // can be part of a text message element of a telegram.
+      if (this.options.newLineChars === '\n' && sofIndex > 1) {
+        const bytesBeforeSof = this.telegram.subarray(sofIndex - 1, sofIndex);
+
+        // 0x0a is a newline character.
+        if (bytesBeforeSof[0] !== 0x0a) {
+          return;
+        }
+      } else if (sofIndex > 2) {
+        const bytesBeforeSof = this.telegram.subarray(sofIndex - 2, sofIndex);
+
+        // 0x0d is a carriage return and 0x0a is a newline character.
+        if (bytesBeforeSof[0] !== 0x0d || bytesBeforeSof[1] !== 0x0a) {
+          return;
+        }
       }
 
-      this.options.callback(error, undefined);
+      // Try to parse the data up to the start of the next frame.
+      this.tryParseTelegram(sofIndex);
+
+      return;
     }
 
-    const remainingData = this.telegram.subarray(endOfFrameIndex, this.telegram.length);
-    this.hasStartOfFrame = false;
-    this.telegram = Buffer.alloc(0);
+    const endOfFrameIndex = eofRegexResult.index + eofRegexResult[0].length;
 
-    // There might be more data in the buffer for the next telegram.
-    if (remainingData.length > 0) {
-      this.onData(remainingData);
-    }
+    this.tryParseTelegram(endOfFrameIndex);
   }
 
   private checkEncryption() {
@@ -156,10 +161,39 @@ export class UnencryptedDSMRStreamParser implements DSMRStreamParser {
     };
   }
 
+  private tryParseTelegram(frameLength: number, overrideError?: Error) {
+    // Clear the full frame required timeout. The full frame
+    // has been received and the data buffer will be cleared.
+    clearTimeout(this.fullFrameRequiredTimeout);
+
+    try {
+      const result = DSMRParser({
+        telegram: this.telegram.subarray(0, frameLength),
+        newLineChars: this.options.newLineChars,
+      });
+
+      this.options.callback(null, result);
+    } catch (err) {
+      const error = overrideError ?? err;
+      if (error instanceof DSMRError) {
+        error.withRawTelegram(this.telegram);
+      }
+
+      this.options.callback(error, undefined);
+    }
+
+    const remainingData = this.telegram.subarray(frameLength, this.telegram.length);
+    this.hasStartOfFrame = false;
+    this.telegram = Buffer.alloc(0);
+
+    // There might be more data in the buffer for the next telegram.
+    if (remainingData.length > 0) {
+      this.onData(remainingData);
+    }
+  }
+
   private onFullFrameRequiredTimeout() {
-    const error = new DSMRTimeoutError();
-    error.withRawTelegram(this.telegram);
-    this.options.callback(error, undefined);
+    this.tryParseTelegram(this.telegram.length, new DSMRTimeoutError());
 
     // Reset the entire state here, as the full frame was not received.
     this.clear();
diff --git a/tests/stream.spec.ts b/tests/stream.spec.ts
@@ -17,6 +17,7 @@ import {
   DSMRTimeoutError,
   DSMRDecryptionError,
   DSMRParserResult,
+  DSMRParserError,
 } from '../src/index.js';
 import { ENCRYPTED_DSMR_HEADER_LEN, ENCRYPTED_DSMR_TELEGRAM_SOF } from '../src/util/encryption.js';
 
@@ -233,6 +234,128 @@ describe('DSMRStreamParser', () => {
 
       instance.destroy();
     });
+
+    it('Parses when the CRC line is missing', async (context) => {
+      context.mock.timers.enable();
+
+      const { input, output } = await readTelegramFromFiles('tests/telegrams/iskra-mt-382-no-crc');
+
+      const stream = new PassThrough();
+      const callback = mock.fn();
+
+      const instance = DSMR.createStreamParser({
+        stream,
+        callback,
+        fullFrameRequiredWithinMs: 1000,
+      });
+
+      stream.write(input);
+
+      context.mock.timers.tick(1000);
+
+      stream.end();
+      instance.destroy();
+
+      assert.deepStrictEqual(callback.mock.calls.length, 1);
+      assert.deepStrictEqual(callback.mock.calls[0].arguments[0], null);
+      assert.deepStrictEqual(callback.mock.calls[0].arguments[1], output);
+    });
+
+    it('Immediately parses when CRC is missing and a 2nd telegram is received', async (context) => {
+      context.mock.timers.enable();
+
+      const { input, output } = await readTelegramFromFiles(
+        'tests/telegrams/iskra-mt-382-no-crc',
+        true,
+      );
+
+      const stream = new PassThrough();
+      const callback = mock.fn();
+
+      const instance = DSMR.createStreamParser({
+        stream,
+        callback,
+        fullFrameRequiredWithinMs: 1000,
+      });
+
+      stream.write(input);
+      stream.write(input);
+
+      assert.deepStrictEqual(callback.mock.calls.length, 1);
+      assert.deepStrictEqual(callback.mock.calls[0].arguments[0], null);
+      assert.deepStrictEqual(callback.mock.calls[0].arguments[1], output);
+
+      context.mock.timers.tick(1000);
+
+      stream.end();
+      instance.destroy();
+
+      assert.deepStrictEqual(callback.mock.calls.length, 2);
+      assert.deepStrictEqual(callback.mock.calls[1].arguments[0], null);
+      assert.deepStrictEqual(callback.mock.calls[1].arguments[1], output);
+    });
+
+    it('Immediately parses when CRC is missing and a three telegrams are received', async (context) => {
+      context.mock.timers.enable();
+
+      const { input, output } = await readTelegramFromFiles('tests/telegrams/iskra-mt-382-no-crc');
+
+      const stream = new PassThrough();
+      const callback = mock.fn();
+
+      const instance = DSMR.createStreamParser({
+        stream,
+        callback,
+        fullFrameRequiredWithinMs: 1000,
+      });
+
+      stream.write(input);
+      stream.write(input);
+      stream.write(input);
+
+      assert.deepStrictEqual(callback.mock.calls.length, 2);
+      assert.deepStrictEqual(callback.mock.calls[0].arguments[0], null);
+      assert.deepStrictEqual(callback.mock.calls[0].arguments[1], output);
+      assert.deepStrictEqual(callback.mock.calls[1].arguments[0], null);
+      assert.deepStrictEqual(callback.mock.calls[1].arguments[1], output);
+
+      context.mock.timers.tick(1000);
+
+      stream.end();
+      instance.destroy();
+
+      assert.deepStrictEqual(callback.mock.calls.length, 3);
+      assert.deepStrictEqual(callback.mock.calls[2].arguments[0], null);
+      assert.deepStrictEqual(callback.mock.calls[2].arguments[1], output);
+    });
+
+    it('Handles text messages', async (context) => {
+      context.mock.timers.enable();
+
+      const { input, output } = await readTelegramFromFiles(
+        'tests/telegrams/iskra-mt-382-no-crc-with-text-message',
+      );
+
+      const stream = new PassThrough();
+      const callback = mock.fn();
+
+      const instance = DSMR.createStreamParser({
+        stream,
+        callback,
+        fullFrameRequiredWithinMs: 1000,
+      });
+
+      stream.write(input);
+
+      context.mock.timers.tick(1000);
+
+      assert.deepStrictEqual(callback.mock.calls.length, 1);
+      assert.deepStrictEqual(callback.mock.calls[0].arguments[0], null);
+      assert.deepStrictEqual(callback.mock.calls[0].arguments[1], output);
+
+      stream.end();
+      instance.destroy();
+    });
   });
 
   describe('Encrypted', () => {
@@ -404,7 +527,10 @@ describe('DSMRStreamParser', () => {
       // it should be able to detect that it is an encrypted frame.
       for (let index = 1; index < callback.mock.calls.length; index++) {
         const error = callback.mock.calls[index].arguments[0] as unknown;
-        assert.ok(error instanceof DSMRDecodeError && !(error instanceof DSMRDecryptionRequired));
+        assert.ok(
+          (error instanceof DSMRDecodeError && !(error instanceof DSMRDecryptionRequired)) ||
+            error instanceof DSMRParserError,
+        );
         assert.deepStrictEqual(callback.mock.calls[index].arguments[1], undefined);
       }
     });
diff --git a/tests/telegrams/iskra-mt-382-no-crc-with-text-message.json b/tests/telegrams/iskra-mt-382-no-crc-with-text-message.json
@@ -0,0 +1,44 @@
+{
+  "raw": "/ISk5\\2MT382-1003\r\n\r\n0-0:96.1.1(00112233445566778899aabbccddeeff)\r\n1-0:1.8.1(39837.604*kWh)\r\n1-0:1.8.2(30477.225*kWh)\r\n1-0:2.8.1(05174.479*kWh)\r\n1-0:2.8.2(11772.946*kWh)\r\n0-0:96.14.0(0002)\r\n1-0:1.7.0(0000.00*kW)\r\n1-0:2.7.0(0000.14*kW)\r\n0-0:17.0.0(0999.00*kW)\r\n0-0:96.3.10(1)\r\n0-0:96.13.1()\r\n0-0:96.13.0(test-/-test)\r\n0-1:24.1.0(3)\r\n0-1:96.1.0(0011223344556677889900112233445566)\r\n0-1:24.3.0(250423090000)(00)(60)(1)(0-1:24.2.1)(m3)\r\n(13032.850)\r\n0-1:24.4.0(1)\r\n",
+  "header": {
+    "identifier": "\\2MT382-1003",
+    "xxx": "ISk",
+    "z": "5"
+  },
+  "metadata": {
+    "equipmentId": "00112233445566778899aabbccddeeff",
+    "unknownLines": [
+      "0-0:17.0.0(0999.00*kW)",
+      "0-0:96.3.10(1)",
+      "(13032.850)",
+      "0-1:24.4.0(1)"
+    ],
+    "numericMessage": 0,
+    "textMessage": "test-/-test"
+  },
+  "electricity": {
+    "tariffs": {
+      "1": {
+        "received": 39837.604,
+        "returned": 5174.479
+      },
+      "2": {
+        "received": 30477.225,
+        "returned": 11772.946
+      }
+    },
+    "currentTariff": 2,
+    "powerReceivedTotal": 0,
+    "powerReturnedTotal": 0.14
+  },
+  "mBus": {
+    "1": {
+      "deviceType": 3,
+      "equipmentId": "0011223344556677889900112233445566",
+      "timestamp": "250423090000",
+      "value": 13032.85,
+      "unit": "m3",
+      "recordingPeriodMinutes": 60
+    }
+  }
+}
diff --git a/tests/telegrams/iskra-mt-382-no-crc-with-text-message.txt b/tests/telegrams/iskra-mt-382-no-crc-with-text-message.txt
@@ -0,0 +1,19 @@
+/ISk5\2MT382-1003
+
+0-0:96.1.1(00112233445566778899aabbccddeeff)
+1-0:1.8.1(39837.604*kWh)
+1-0:1.8.2(30477.225*kWh)
+1-0:2.8.1(05174.479*kWh)
+1-0:2.8.2(11772.946*kWh)
+0-0:96.14.0(0002)
+1-0:1.7.0(0000.00*kW)
+1-0:2.7.0(0000.14*kW)
+0-0:17.0.0(0999.00*kW)
+0-0:96.3.10(1)
+0-0:96.13.1()
+0-0:96.13.0(test-/-test)
+0-1:24.1.0(3)
+0-1:96.1.0(0011223344556677889900112233445566)
+0-1:24.3.0(250423090000)(00)(60)(1)(0-1:24.2.1)(m3)
+(13032.850)
+0-1:24.4.0(1)
diff --git a/tests/telegrams/iskra-mt-382-no-crc.json b/tests/telegrams/iskra-mt-382-no-crc.json
@@ -0,0 +1,44 @@
+{
+  "raw": "/ISk5\\2MT382-1003\r\n\r\n0-0:96.1.1(00112233445566778899aabbccddeeff)\r\n1-0:1.8.1(39837.604*kWh)\r\n1-0:1.8.2(30477.225*kWh)\r\n1-0:2.8.1(05174.479*kWh)\r\n1-0:2.8.2(11772.946*kWh)\r\n0-0:96.14.0(0002)\r\n1-0:1.7.0(0000.00*kW)\r\n1-0:2.7.0(0000.14*kW)\r\n0-0:17.0.0(0999.00*kW)\r\n0-0:96.3.10(1)\r\n0-0:96.13.1()\r\n0-0:96.13.0()\r\n0-1:24.1.0(3)\r\n0-1:96.1.0(0011223344556677889900112233445566)\r\n0-1:24.3.0(250423090000)(00)(60)(1)(0-1:24.2.1)(m3)\r\n(13032.850)\r\n0-1:24.4.0(1)\r\n",
+  "header": {
+    "identifier": "\\2MT382-1003",
+    "xxx": "ISk",
+    "z": "5"
+  },
+  "metadata": {
+    "equipmentId": "00112233445566778899aabbccddeeff",
+    "unknownLines": [
+      "0-0:17.0.0(0999.00*kW)",
+      "0-0:96.3.10(1)",
+      "(13032.850)",
+      "0-1:24.4.0(1)"
+    ],
+    "numericMessage": 0,
+    "textMessage": ""
+  },
+  "electricity": {
+    "tariffs": {
+      "1": {
+        "received": 39837.604,
+        "returned": 5174.479
+      },
+      "2": {
+        "received": 30477.225,
+        "returned": 11772.946
+      }
+    },
+    "currentTariff": 2,
+    "powerReceivedTotal": 0,
+    "powerReturnedTotal": 0.14
+  },
+  "mBus": {
+    "1": {
+      "deviceType": 3,
+      "equipmentId": "0011223344556677889900112233445566",
+      "timestamp": "250423090000",
+      "value": 13032.85,
+      "unit": "m3",
+      "recordingPeriodMinutes": 60
+    }
+  }
+}
diff --git a/tests/telegrams/iskra-mt-382-no-crc.txt b/tests/telegrams/iskra-mt-382-no-crc.txt
@@ -0,0 +1,19 @@
+/ISk5\2MT382-1003
+
+0-0:96.1.1(00112233445566778899aabbccddeeff)
+1-0:1.8.1(39837.604*kWh)
+1-0:1.8.2(30477.225*kWh)
+1-0:2.8.1(05174.479*kWh)
+1-0:2.8.2(11772.946*kWh)
+0-0:96.14.0(0002)
+1-0:1.7.0(0000.00*kW)
+1-0:2.7.0(0000.14*kW)
+0-0:17.0.0(0999.00*kW)
+0-0:96.3.10(1)
+0-0:96.13.1()
+0-0:96.13.0()
+0-1:24.1.0(3)
+0-1:96.1.0(0011223344556677889900112233445566)
+0-1:24.3.0(250423090000)(00)(60)(1)(0-1:24.2.1)(m3)
+(13032.850)
+0-1:24.4.0(1)
