Merge branch 'master' into strip_ipv4_header

src/core/operations/StripTCPHeader.mjs

@@ -0,0 +1,60 @@
+/**
+ * @author c65722 []
+ * @copyright Crown Copyright 2024
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+import OperationError from "../errors/OperationError.mjs";
+import Stream from "../lib/Stream.mjs";
+
+/**
+ * Strip TCP header operation
+ */
+class StripTCPHeader extends Operation {
+
+    /**
+     * StripTCPHeader constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Strip TCP header";
+        this.module = "Default";
+        this.description = "Strips the TCP header from a TCP segment, outputting the payload.";
+        this.infoURL = "https://wikipedia.org/wiki/Transmission_Control_Protocol";
+        this.inputType = "ArrayBuffer";
+        this.outputType = "ArrayBuffer";
+        this.args = [];
+    }
+
+    /**
+     * @param {ArrayBuffer} input
+     * @param {Object[]} args
+     * @returns {ArrayBuffer}
+     */
+    run(input, args) {
+        const MIN_HEADER_LEN = 20;
+        const DATA_OFFSET_OFFSET = 12;
+        const DATA_OFFSET_LEN_BITS = 4;
+
+        const s = new Stream(new Uint8Array(input));
+        if (s.length < MIN_HEADER_LEN) {
+            throw new OperationError("Need at least 20 bytes for a TCP Header");
+        }
+
+        s.moveTo(DATA_OFFSET_OFFSET);
+        const dataOffsetWords = s.readBits(DATA_OFFSET_LEN_BITS);
+        const dataOffsetBytes = dataOffsetWords * 4;
+        if (s.length < dataOffsetBytes) {
+            throw new OperationError("Input length is less than data offset");
+        }
+
+        s.moveTo(dataOffsetBytes);
+
+        return s.getBytes().buffer;
+    }
+
+}
+
+export default StripTCPHeader;