initial commit

packages/acn/src/pdu/index.ts

@@ -0,0 +1,4 @@
+import rlp from './rlp';
+export default {
+  rlp,
+};

packages/acn/src/pdu/rlp.ts

@@ -0,0 +1,61 @@
+import { RootLayerPDU } from '../models';
+
+function decode(bytes: Uint8Array): RootLayerPDU {
+  const view = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
+  const flags = view.getUint8(0) >> 4;
+  const lengthFlag = ((flags >> 3) & 0x1) === 1;
+  const vectorFlag = ((flags >> 2) & 0x1) === 1;
+
+  if (!vectorFlag) {
+    throw new Error('Root Layer PDU must have a vector');
+  }
+
+  const headerFlag = ((flags >> 1) & 0x1) === 1;
+
+  if (!headerFlag) {
+    throw new Error('Root Layer PDU must have a header');
+  }
+
+  const dataFlag = (flags & 0x1) === 1;
+
+  if (!dataFlag) {
+    // TODO(jwetzell): idk know if this is true
+    throw new Error('Root Layer PDU must have data');
+  }
+
+  const lengthH = view.getUint8(0) & 0x0f;
+  let lengthOffset = 1;
+  const lengthL = view.getUint8(lengthOffset);
+
+  let length = (lengthH << 8) + lengthL;
+
+  if (lengthFlag) {
+    lengthOffset += 1;
+    const lengthX = view.getUint8(lengthOffset);
+    length = (lengthH << 16) + (lengthL << 8) + lengthX;
+  }
+  let vectorOffset = lengthOffset + 1;
+
+  if (lengthFlag) {
+    vectorOffset += 1;
+  }
+
+  const vector = view.getUint32(vectorOffset);
+  const headerOffset = vectorOffset + 4;
+
+  const header = bytes.subarray(headerOffset, headerOffset + 16);
+  const dataOffset = headerOffset + 16;
+  // NOTE(jwetzell): flags/lengthH + lengthL + lengthX + vector + header
+  const dataLength = length - (1 + 1 + (lengthFlag ? 1 : 0) + 4 + 16);
+  const data = bytes.subarray(dataOffset, dataOffset + dataLength);
+
+  return {
+    vector,
+    header,
+    data,
+  };
+}
+
+export default {
+  decode,
+};