feat: 🎸 add encoding for auth packet

src/packets/__tests__/auth.spec.ts

@@ -0,0 +1,49 @@
+import {PACKET_TYPE, PROPERTY} from '../../enums';
+import {PacketAuth} from '../auth';
+import {MqttDecoder} from '../../MqttDecoder';
+
+test('can create a packet', () => {
+  const packet = PacketAuth.create(12, {});
+  expect(packet.b >> 4).toBe(PACKET_TYPE.AUTH);
+  expect(packet.l).toBe(0);
+  expect(packet.c).toBe(12);
+  expect(packet.p).toEqual({});
+});
+
+test('can serialize basic packet MQTT 5.0', () => {
+  const packet = PacketAuth.create(3, {});
+  expect(packet instanceof PacketAuth).toBe(true);
+  const buf = packet.toBuffer();
+  expect(buf).toEqual(Buffer.from([
+    PACKET_TYPE.AUTH << 4,   // Header
+    0x01,   // Remaining length
+    0x03,   // Reason code
+  ]));
+});
+
+test('can serialize packet and deserialize it back with props', () => {
+  const packet1 = PacketAuth.create(1, {
+    [PROPERTY.UserProperty]: ['test', 'test'],
+  });
+  const decoder = new MqttDecoder();
+  decoder.version = 5;
+  decoder.push(packet1.toBuffer());
+  const packet2 = decoder.parse()! as PacketAuth;
+  expect(packet2).toEqual(packet1);
+  expect(packet2.c).toEqual(1);
+  expect(packet2.p).toEqual({
+    [PROPERTY.UserProperty]: ['test', 'test'],
+  });
+});
+
+test('can serialize packet and deserialize it back without props', () => {
+  const packet1 = PacketAuth.create(5, {});
+  const decoder = new MqttDecoder();
+  decoder.version = 5;
+  const buf = packet1.toBuffer();
+  decoder.push(buf);
+  const packet2 = decoder.parse()! as PacketAuth;
+  expect(packet2).toEqual(packet1);
+  expect(packet2.c).toEqual(5);
+  expect(packet2.p).toEqual({});
+});

src/packets/auth/encodeAuth.ts

@@ -0,0 +1,44 @@
+import {PacketAuthData} from '.';
+import {genProps} from '../../util/genProps';
+
+export const encodeDisconnect = (packet: PacketAuthData): Buffer => {
+  const {b, c, p} = packet;
+  const props = genProps(p);
+  const propsLength = props.length;
+  const remainingLength: number = 1 + propsLength;
+  const remainingLengthSize = remainingLength < 128 ? 1 : remainingLength < 16_384 ? 2 : remainingLength < 2_097_152 ? 3 : 4;
+  const bufferLength = 1 + remainingLengthSize + remainingLength;
+  const buf = Buffer.allocUnsafe(bufferLength);
+
+  packet.l = remainingLength;
+
+  buf.writeUInt8(b, 0);
+
+  let offset = 1;
+
+  switch (remainingLengthSize) {
+    case 1:
+      buf.writeUInt8(remainingLength, 1);
+      offset = 2;
+      break;
+    case 2:
+      buf.writeUInt16LE(((remainingLength & 0b011111110000000) << 1) | (0b10000000 | (remainingLength & 0b01111111)), 1);
+      offset = 3;
+      break;
+    case 3:
+      buf.writeUInt16LE(((0b100000000000000 | (remainingLength & 0b011111110000000)) << 1) | (0b10000000 | (remainingLength & 0b01111111)), 1);
+      buf.writeUInt8((remainingLength >> 14) & 0b01111111, 3);
+      offset = 4;
+      break;
+    case 4:
+      buf.writeUInt32LE((((((remainingLength >> 21) & 0b01111111) << 8) | (0b10000000 | ((remainingLength >> 14) & 0b01111111))) << 16) |
+        ((0b100000000000000 | (remainingLength & 0b011111110000000)) << 1) | (0b10000000 | (remainingLength & 0b01111111)), 1);
+      offset = 5;
+      break;
+  }
+
+  buf.writeUInt8(c, offset);
+  props!.copy(buf, offset + 1);
+
+  return buf;
+}

src/packets/auth/index.ts

@@ -0,0 +1,42 @@
+import {PACKET_TYPE} from '../../enums';
+import {Packet, PacketHeaderData} from '../../packet';
+import {BufferLike, Properties} from '../../types';
+import {parseProps} from '../../util/parseProps';
+import {encodeDisconnect} from '../disconnect/encodeDisconnect';
+
+export interface PacketAuthData extends PacketHeaderData {
+  /** Authenticate Reason Code. */
+  c: number;
+  /** Properties. */
+  p: Properties;
+}
+
+export class PacketAuth extends Packet implements PacketAuthData {
+  /**
+   * @param c Authenticate Reason Code
+   * @param p Properties
+   */
+  static create(c: number, p: Properties): PacketAuth {
+    return new PacketAuth(PACKET_TYPE.AUTH << 4, 0, c, p);
+  }
+
+  constructor(
+    b: number,
+    l: number,
+    public c: number,
+    public p: Properties,
+  ) {
+    super(b, l);
+  }
+
+  public toBuffer(): Buffer {
+    return encodeDisconnect(this, 5);
+  }
+}
+
+export const parseAuth = (b: number, l: number, buf: BufferLike, version: number): PacketAuth => {
+  const c: number = buf.readUInt8(0);
+  let p: Properties = {};
+  if (l > 1) [p] = parseProps(buf, 1);
+  return new PacketAuth(b, l, c, p);
+};