feat: 🎸 add suback packet

Author: streamich

src/MqttDecoder.ts

@@ -8,6 +8,7 @@ import {PacketPubrec, parsePubrec} from './packets/pubrec';
 import {PacketPubrel, parsePubrel} from './packets/pubrel';
 import {PacketPubcomp, parsePubcomp} from './packets/pubcomp';
 import {PacketSubscribe, parseSubscribe} from './packets/subscribe';
+import {PacketSuback, parseSuback} from './packets/suback';
 
 export class MqttDecoder {
   public state: DECODER_STATE = DECODER_STATE.HEADER;
@@ -35,7 +36,7 @@ export class MqttDecoder {
     this.list = new BufferList();
   }
 
-  public parse(): null | PacketConnect | PacketConnack | PacketPublish | PacketPuback | PacketPubrec | PacketPubrel | PacketPubcomp | PacketSubscribe {
+  public parse(): null | PacketConnect | PacketConnack | PacketPublish | PacketPuback | PacketPubrec | PacketPubrel | PacketPubcomp | PacketSubscribe | PacketSuback {
     this.parseFixedHeader();
     const data = this.parseVariableData();
     if (!data) return null;
@@ -50,9 +51,6 @@ export class MqttDecoder {
       case PACKET_TYPE.CONNACK: {
         return parseConnack(b, l, data, this.version);
       }
-      case PACKET_TYPE.SUBACK: {
-        return null;
-      }
       case PACKET_TYPE.PUBLISH: {
         const packet = parsePublish(b, l, data, this.version);
         return packet;
@@ -77,6 +75,10 @@ export class MqttDecoder {
         const packet = parseSubscribe(b, l, data, this.version);
         return packet;
       }
+      case PACKET_TYPE.SUBACK: {
+        const packet = parseSuback(b, l, data, this.version);
+        return packet;
+      }
       default: {
         return null;
       }

src/__tests__/MqttDecoder.spec.ts

@@ -7,6 +7,7 @@ import {PacketPublish} from '../packets/publish';
 import {PacketPuback} from '../packets/puback';
 import {PacketPubrec} from '../packets/pubrec';
 import {PacketSubscribe} from '../packets/subscribe';
+import { PacketSuback } from '../packets/suback';
 
 it('can instantiate', () => {
   const decoder = new MqttDecoder();
@@ -479,3 +480,44 @@ describe('SUBSCRIBE', () => {
     expect(packet.s[2].retainHandling()).toBe(0);
   });
 });
+
+describe('SUBACK', () => {
+  it('parses MQTT 3.1.1 packet', () => {
+    const decoder = new MqttDecoder();
+    decoder.push(Buffer.from([
+      144, 6, // Header
+      0, 6, // Message ID
+      0, 1, 2, 128 // Granted qos (0, 1, 2) and a rejected being 0x80
+    ]));
+    const packet: PacketSuback = decoder.parse() as PacketSuback;
+    expect(packet.b).toBe(144);
+    expect(packet.l).toBe(6);
+    expect(packet.i).toBe(6);
+    expect(packet.p).toEqual({});
+    expect(packet.s).toEqual([0, 1, 2, 128]);
+  });
+
+  it('parses MQTT 5.0 packet', () => {
+    const decoder = new MqttDecoder();
+    decoder.version = 5;
+    decoder.push(Buffer.from([
+      144, 27, // Header
+      0, 6, // Message ID
+      20, // properties length
+      31, 0, 4, 116, 101, 115, 116, // reasonString
+      38, 0, 4, 116, 101, 115, 116, 0, 4, 116, 101, 115, 116, // userProperties
+      0, 1, 2, 1 // Granted qos (0, 1, 2) and a rejected being 0x80
+    ]));
+    const packet: PacketSuback = decoder.parse() as PacketSuback;
+    expect(packet.b).toBe(144);
+    expect(packet.l).toBe(27);
+    expect(packet.i).toBe(6);
+    expect(packet.p).toEqual({
+      [PROPERTY.ReasonString]: 'test',
+      [PROPERTY.UserProperty]: [
+        ['test', 'test'],
+      ],
+    });
+    expect(packet.s).toEqual([0, 1, 2, 1]);
+  });
+});

src/packets/suback.ts

@@ -0,0 +1,42 @@
+import BufferList from 'bl';
+import {Packet, PacketHeaderData} from '../packet';
+import {Properties} from '../types';
+import {parseProps} from '../util/parse';
+
+export interface PacketSubackData extends PacketHeaderData {
+  /** Packet Identifier. */
+  i: number;
+  /** Properties. */
+  p: Properties;
+  /** SUBACK Payload. */
+  s: number[];
+}
+
+export class PacketSuback extends Packet implements PacketSubackData {
+  constructor(
+    b: number,
+    l: number,
+    public i: number,
+    public p: Properties,
+    public s: number[],
+  ) {
+    super(b, l);
+  }
+}
+
+export const parseSuback = (b: number, l: number, data: BufferList, version: number): PacketSuback => {
+  const i = data.readUInt16BE(0);
+  let offset = 2;
+  let p: Properties = {};
+  if (version === 5) {
+    const [props, size] = parseProps(data, offset);
+      p = props;
+      offset += size;
+  }
+  const len = data.length;
+  const s: number[] = [];
+  while (offset < len) {
+    s.push(data.readUInt8(offset++));
+  }
+  return new PacketSuback(b, l, i, p, s);
+};