fix TLV Parser BER long-form length parsing (#2289)

src/core/lib/TLVParser.mjs

@@ -33,20 +33,29 @@ export default class TLVParser {
      * @returns {number}
      */
     getLength() {
+        let bytesInLength = this.bytesInLength;
+        let bigEndian = false;
+
         if (this.basicEncodingRules) {
-            const bit = this.input[this.location];
+            const firstLengthByte = this.input[this.location];
-            if (bit & 0x80) {
+            this.location++;
-                this.bytesInLength = bit & ~0x80;
+
+            if (firstLengthByte & 0x80) {
+                bytesInLength = firstLengthByte & ~0x80;
+                bigEndian = true;
             } else {
-                this.location++;
+                return firstLengthByte & ~0x80;
-                return bit & ~0x80;
             }
         }
 
         let length = 0;
 
-        for (let i = 0; i < this.bytesInLength; i++) {
+        for (let i = 0; i < bytesInLength; i++) {
-            length += this.input[this.location] * Math.pow(Math.pow(2, 8), i);
+            if (bigEndian) {
+                length = (length << 8) + this.input[this.location];
+            } else {
+                length += this.input[this.location] * Math.pow(Math.pow(2, 8), i);
+            }
             this.location++;
         }
 

tests/operations/tests/ParseTLV.mjs

@@ -52,5 +52,46 @@ TestRegister.addTests([
                 "args": [1, 4, true] // length value is patently wrong, should be ignored by BER.
             }
         ]
+    },
+    {
+        name: "Parse TLV: BER long-form length (two-byte length encoding)",
+        input: "\x01\x82\x01\x00" + "A".repeat(256) + "\x02\x03\x41\x42\x43",
+        expectedOutput: JSON.stringify([
+            {"key": [1], "length": 256, "value": Array(256).fill(65)},
+            {"key": [2], "length": 3, "value": [65, 66, 67]}
+        ], null, 4),
+        recipeConfig: [
+            {
+                "op": "Parse TLV",
+                "args": [1, 1, true]
+            }
+        ]
+    },
+    {
+        name: "Parse TLV: BER long-form length (one-byte length encoding)",
+        input: "\x01\x81\x80" + "B".repeat(128),
+        expectedOutput: JSON.stringify([
+            {"key": [1], "length": 128, "value": Array(128).fill(66)}
+        ], null, 4),
+        recipeConfig: [
+            {
+                "op": "Parse TLV",
+                "args": [1, 1, true]
+            }
+        ]
+    },
+    {
+        name: "Parse TLV: BER multiple entries with mixed short and long-form lengths",
+        input: "\x01\x05\x48\x65\x6c\x6c\x6f\x02\x81\x05\x57\x6f\x72\x6c\x64",
+        expectedOutput: JSON.stringify([
+            {"key": [1], "length": 5, "value": [72, 101, 108, 108, 111]},
+            {"key": [2], "length": 5, "value": [87, 111, 114, 108, 100]}
+        ], null, 4),
+        recipeConfig: [
+            {
+                "op": "Parse TLV",
+                "args": [1, 1, true]
+            }
+        ]
     }
 ]);