WebSocket

src/core/config/Categories.json

@@ -74,7 +74,8 @@
  "CBOR Decode",
  "Caret/M-decode",
  "Rison Encode",
- "Rison Decode"
+ "Rison Decode",
+ "WebSocket Decode"
  ]
  },
  {

src/core/lib/WebSocket.mjs

@@ -0,0 +1,9 @@
+/**
+ * WebSocket operation resources.
+ *
+ * @author cod [[email protected]]
+ * @copyright Crown Copyright 2024
+ * @license Apache-2.0
+ */
+
+export const WEBSOCKET_OPCODE = ["continuation frame", "text frame", "binary frame", "rsv3", "rsv4", "rsv5", "rsv6", "rsv7", "ping", "pong", "rsvb", "rsvc", "rsvd", "rsve", "rsvf"];

src/core/operations/WebSocketDecode.mjs

@@ -0,0 +1,116 @@
+/**
+ * @author cod [[email protected]]
+ * @copyright Crown Copyright 2024
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+import OperationError from "../errors/OperationError.mjs";
+import { WEBSOCKET_OPCODE } from "../lib/WebSocket.mjs";
+
+/** WebSocket */
+class WebSocketDecode extends Operation {
+
+ /**
+ * Default constructor
+ */
+ constructor() {
+ super();
+
+ this.name = "WebSocket Decode";
+ this.module = "Code";
+ this.description = "Converts a WebSocket encoded to JSON. WebSocket is computer communitions protocol, providing simultaneous two-way communication channels";
+ this.infoURL = "https://wikipedia.org/wiki/WebSocket";
+ this.inputType = "ArrayBuffer";
+ this.outputType = "JSON";
+ this.args = [];
+ }
+
+ /**
+ * @param {ArrayBuffer} input
+ * @param {Object[]} args
+ * @returns {JSON}
+ */
+ run(input, args) {
+ try {
+ let pos = 0;
+ const buf = Buffer.from(new Uint8Array(input));
+
+ if (buf.length < 2) {
+ throw new OperationError("Expected size: 2 bytes");
+ }
+
+ const b0 = buf[0];
+ const b1 = buf[1];
+
+ const fin = (b0 & 0x80) === 0x80 ? true : false;
+ const opcode = WEBSOCKET_OPCODE[b0 & 0x7f];
+ let payloadLength = (b1 & 0x7f);
+
+ pos = 2;
+ const mask = (b1 & 0x80) === 0x80 ? true : false;
+ const maskSize = (mask) ? 4 : 0;
+
+ if (payloadLength < 126) {
+ /** payload is less of 126 bytes */
+ if (buf.length < (pos + payloadLength + maskSize))
+ throw new OperationError(`Expected size: ${(pos + payloadLength + maskSize)}`);
+ } else if (payloadLength === 126) {
+ /** payload is 2 bytes */
+ pos += 2;
+ payloadLength = buf.readUInt16BE(2);
+
+ if (buf.length < (pos + payloadLength + maskSize))
+ throw new OperationError(`Expected size: ${(pos + payloadLength + maskSize)}`);
+
+ } else if (payloadLength === 127) {
+ pos += 8;
+ payloadLength = buf.readUInt64BE(2);
+
+ if (buf.length < (pos + payloadLength + maskSize))
+ throw new OperationError(`Expected size: ${(pos + payloadLength + maskSize)}`);
+ }
+
+ const maskBytes = Buffer.alloc(4);
+
+ if (mask) {
+ maskBytes[0] = buf[pos];
+ maskBytes[1] = buf[pos+1];
+ maskBytes[2] = buf[pos+2];
+ maskBytes[3] = buf[pos+3];
+ pos += 4;
+ }
+
+ const payload = buf.slice(pos, buf.length);
+
+ if (mask) {
+ for (let i = 0; i < payload.length; i++) {
+ payload[i] = payload[i] ^ maskBytes[i % 4];
+ }
+ }
+
+ let content;
+
+ if ((b0 & 1) === 1) {
+ content = payload.toString();
+ } else {
+ content = payload.toString("hex");
+ }
+
+ const ws = {
+ fin: fin,
+ opcode: opcode,
+ maskPresent: mask,
+ mask: maskBytes.toString("hex"),
+ payloadLength: payloadLength,
+ payload: content
+ };
+
+ return ws;
+ } catch (err) {
+ throw new OperationError(`Could not decode WebSocket to JSON: ${err}`);
+ }
+ }
+}
+
+export default WebSocketDecode;