715367b9ea
Add ParsePub, ParseSubsOrUnsubs, ProcessPub (QoS 0), ProcessSubs, ProcessUnsubs, EnqueueSubAck, and EnqueueUnsubAck to MqttPacketHandlers. Wire PUB/SUB/UNSUB dispatch cases in MqttParser. Add ReadSlice to MqttReader for raw payload extraction. 18 new unit tests covering parsing, flags, error cases, QoS downgrade, and full flow. 1 new integration test verifying SUBSCRIBE handshake over TCP.
304 lines
11 KiB
C#
304 lines
11 KiB
C#
// Copyright 2020-2026 The NATS Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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using Shouldly;
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using ZB.MOM.NatsNet.Server;
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using ZB.MOM.NatsNet.Server.Internal;
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using ZB.MOM.NatsNet.Server.Mqtt;
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namespace ZB.MOM.NatsNet.Server.Tests.Mqtt;
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/// <summary>
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/// Unit tests for <see cref="MqttParser"/> — validates packet type extraction,
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/// remaining length decoding, CONNECT-first enforcement, partial packet handling,
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/// and PINGREQ dispatch.
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/// </summary>
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public sealed class MqttParserTests
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{
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/// <summary>
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/// Creates a minimal ClientConnection with MQTT handler for testing.
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/// </summary>
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private static ClientConnection CreateMqttClient()
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{
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var c = new ClientConnection(ClientKind.Client, nc: new MemoryStream());
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c.InitMqtt(new MqttHandler());
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return c;
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}
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// =========================================================================
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// CONNECT-first enforcement
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// =========================================================================
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[Fact]
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public void Parse_NonConnectFirst_ShouldReturnError()
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{
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var c = CreateMqttClient();
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// PINGREQ before CONNECT → error
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var buf = new byte[] { MqttPacket.Ping, 0x00 };
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var err = MqttParser.Parse(c, buf, buf.Length);
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err.ShouldNotBeNull();
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err.Message.ShouldContain("first packet should be a CONNECT");
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}
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[Fact]
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public void Parse_PublishBeforeConnect_ShouldReturnError()
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{
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var c = CreateMqttClient();
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// PUBLISH QoS 0 before CONNECT
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var buf = new byte[] { MqttPacket.Pub, 0x05, 0x00, 0x01, (byte)'t', 0x68, 0x69 };
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var err = MqttParser.Parse(c, buf, buf.Length);
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err.ShouldNotBeNull();
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err.Message.ShouldContain("first packet should be a CONNECT");
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}
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[Fact]
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public void Parse_ConnectFirst_ShouldAcceptConnect()
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{
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var c = CreateMqttClient();
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// Use a MemoryStream so CONNACK can be written.
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typeof(ClientConnection)
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.GetField("_nc", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance)!
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.SetValue(c, new MemoryStream());
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// Build a valid CONNECT packet.
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var payload = new List<byte>();
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payload.AddRange(new byte[] { 0x00, 0x04 }); // protocol name length
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payload.AddRange(System.Text.Encoding.UTF8.GetBytes("MQTT"));
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payload.Add(0x04); // level
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payload.Add(0x02); // flags: clean session
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payload.AddRange(new byte[] { 0x00, 0x3C }); // keep alive = 60
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payload.AddRange(new byte[] { 0x00, 0x04 }); // client id length
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payload.AddRange(System.Text.Encoding.UTF8.GetBytes("test"));
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var buf = new List<byte> { MqttPacket.Connect };
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// Remaining length
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var remLen = payload.Count;
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do
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{
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var b = (byte)(remLen & 0x7F);
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remLen >>= 7;
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if (remLen > 0) b |= 0x80;
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buf.Add(b);
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} while (remLen > 0);
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buf.AddRange(payload);
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var err = MqttParser.Parse(c, buf.ToArray(), buf.Count);
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err.ShouldBeNull("CONNECT should be accepted, not rejected as non-CONNECT");
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(c.Flags & ClientFlags.ConnectReceived).ShouldNotBe((ClientFlags)0);
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}
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[Fact]
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public void Parse_SecondConnect_ShouldReturnError()
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{
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var c = CreateMqttClient();
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// Simulate that CONNECT was already received.
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c.Flags |= ClientFlags.ConnectReceived;
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var buf = new byte[] { MqttPacket.Connect, 0x00 };
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var err = MqttParser.Parse(c, buf, buf.Length);
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err.ShouldNotBeNull();
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err.Message.ShouldContain("second CONNECT");
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}
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// =========================================================================
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// PINGREQ dispatch
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// =========================================================================
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[Fact]
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public void Parse_PingReq_ShouldEnqueuePingResp()
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{
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var c = CreateMqttClient();
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// Mark as connected so ping is accepted.
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c.Flags |= ClientFlags.ConnectReceived;
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// Use a memory stream to capture EnqueueProto output.
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var ms = new MemoryStream();
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// Set up the connection's network stream.
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typeof(ClientConnection)
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.GetField("_nc", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance)!
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.SetValue(c, ms);
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var buf = new byte[] { MqttPacket.Ping, 0x00 };
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var err = MqttParser.Parse(c, buf, buf.Length);
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err.ShouldBeNull();
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// Verify PINGRESP was written.
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var written = ms.ToArray();
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written.Length.ShouldBe(2);
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written[0].ShouldBe(MqttPacket.PingResp);
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written[1].ShouldBe((byte)0x00);
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}
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[Fact]
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public void Parse_MultiplePings_ShouldSucceed()
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{
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var c = CreateMqttClient();
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c.Flags |= ClientFlags.ConnectReceived;
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var ms = new MemoryStream();
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typeof(ClientConnection)
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.GetField("_nc", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance)!
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.SetValue(c, ms);
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// Two PINGREQ packets in the same buffer.
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var buf = new byte[] { MqttPacket.Ping, 0x00, MqttPacket.Ping, 0x00 };
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var err = MqttParser.Parse(c, buf, buf.Length);
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err.ShouldBeNull();
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// Two PINGRESP packets should have been written.
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var written = ms.ToArray();
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written.Length.ShouldBe(4);
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written[0].ShouldBe(MqttPacket.PingResp);
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written[1].ShouldBe((byte)0x00);
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written[2].ShouldBe(MqttPacket.PingResp);
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written[3].ShouldBe((byte)0x00);
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}
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// =========================================================================
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// Remaining length decoding
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// =========================================================================
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[Fact]
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public void Parse_SingleByteRemainingLength_ShouldWork()
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{
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// SUBSCRIBE with remaining length = 6 (single byte < 128).
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// Proves single-byte remaining length decoding works.
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var c = CreateMqttClient();
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c.Flags |= ClientFlags.ConnectReceived;
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// SUBSCRIBE: type=0x82, remlen=6, PI=1, filter="t" (len=1), QoS=0
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var buf = new byte[] { 0x82, 0x06, 0x00, 0x01, 0x00, 0x01, (byte)'t', 0x00 };
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var err = MqttParser.Parse(c, buf, buf.Length);
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err.ShouldBeNull();
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}
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[Fact]
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public void Parse_TwoByteRemainingLength_ShouldWork()
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{
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// PUBLISH QoS 0 with remaining length = 200 → encoded as [0xC8, 0x01].
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// Proves two-byte remaining length decoding works.
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var c = CreateMqttClient();
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c.Flags |= ClientFlags.ConnectReceived;
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// type(1) + remlen(2) + payload(200) = 203 bytes total.
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var buf = new byte[203];
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buf[0] = MqttPacket.Pub; // 0x30, QoS 0
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buf[1] = 0xC8;
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buf[2] = 0x01;
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// Topic "t": length prefix (2 bytes) + 1 byte.
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buf[3] = 0x00;
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buf[4] = 0x01;
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buf[5] = (byte)'t';
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// Bytes 6..202 are zero (197-byte payload).
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var err = MqttParser.Parse(c, buf, buf.Length);
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err.ShouldBeNull();
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}
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// =========================================================================
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// Partial packet handling
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// =========================================================================
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[Fact]
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public void Parse_PartialPacket_ShouldSaveState()
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{
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var c = CreateMqttClient();
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c.Flags |= ClientFlags.ConnectReceived;
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// Send only the first byte of a PING packet (missing the 0x00 remaining length).
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var buf = new byte[] { MqttPacket.Ping };
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var err = MqttParser.Parse(c, buf, buf.Length);
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// Should succeed (partial packet saved) — no error because it just stops.
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// Actually, the ReadByte for packet type succeeds, then ReadPacketLen has no data,
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// so it returns (0, false) — incomplete, state saved.
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err.ShouldBeNull();
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// Now send the remaining length byte.
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var buf2 = new byte[] { 0x00 };
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// The reader's pending buffer should have the first byte saved.
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var ms = new MemoryStream();
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typeof(ClientConnection)
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.GetField("_nc", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance)!
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.SetValue(c, ms);
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err = MqttParser.Parse(c, buf2, buf2.Length);
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err.ShouldBeNull();
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// PINGRESP should have been written.
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var written = ms.ToArray();
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written.Length.ShouldBe(2);
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written[0].ShouldBe(MqttPacket.PingResp);
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}
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[Fact]
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public void Parse_PartialPayload_ShouldSaveState()
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{
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var c = CreateMqttClient();
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c.Flags |= ClientFlags.ConnectReceived;
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// SUBSCRIBE packet: type=0x82, remaining length=10, but only send 5 payload bytes.
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var buf = new byte[] { 0x82, 0x0A, 0x01, 0x02, 0x03, 0x04, 0x05 };
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// remaining length = 10, but only 5 bytes of payload present → partial.
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var err = MqttParser.Parse(c, buf, buf.Length);
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// Should save state and return null (needs more data).
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err.ShouldBeNull();
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}
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// =========================================================================
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// Unknown packet type
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// =========================================================================
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[Fact]
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public void Parse_UnknownPacketType_ShouldReturnError()
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{
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var c = CreateMqttClient();
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c.Flags |= ClientFlags.ConnectReceived;
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// Packet type 0x00 is reserved/invalid.
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var buf = new byte[] { 0x00, 0x00 };
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var err = MqttParser.Parse(c, buf, buf.Length);
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err.ShouldNotBeNull();
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err.Message.ShouldContain("unknown MQTT packet type");
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}
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// =========================================================================
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// Empty buffer
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// =========================================================================
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[Fact]
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public void Parse_EmptyBuffer_ShouldSucceed()
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{
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var c = CreateMqttClient();
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var buf = Array.Empty<byte>();
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var err = MqttParser.Parse(c, buf, 0);
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err.ShouldBeNull(); // Nothing to parse.
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}
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// =========================================================================
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// Buffer length parameter
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// =========================================================================
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[Fact]
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public void Parse_LenSmallerThanBuffer_ShouldOnlyParseLenBytes()
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{
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var c = CreateMqttClient();
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c.Flags |= ClientFlags.ConnectReceived;
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var ms = new MemoryStream();
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typeof(ClientConnection)
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.GetField("_nc", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance)!
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.SetValue(c, ms);
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// Buffer has two PING packets, but len says only the first one.
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var buf = new byte[] { MqttPacket.Ping, 0x00, MqttPacket.Ping, 0x00 };
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var err = MqttParser.Parse(c, buf, 2); // Only first 2 bytes.
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err.ShouldBeNull();
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var written = ms.ToArray();
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written.Length.ShouldBe(2); // Only one PINGRESP.
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}
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}
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