Issue #22: implement pipe client and frame protocol

2026-04-26 17:16:49 -04:00
parent 0b0be7098e
commit d5a982152b
15 changed files with 1148 additions and 3 deletions
@@ -0,0 +1,93 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using Google.Protobuf;
+using MxGateway.Contracts.Proto;
+
+namespace MxGateway.Worker.Ipc;
+
+public sealed class WorkerFrameReader
+{
+    private readonly WorkerFrameProtocolOptions _options;
+    private readonly Stream _stream;
+
+    public WorkerFrameReader(
+        Stream stream,
+        WorkerFrameProtocolOptions options)
+    {
+        _stream = stream ?? throw new ArgumentNullException(nameof(stream));
+        _options = options ?? throw new ArgumentNullException(nameof(options));
+    }
+
+    public async Task<WorkerEnvelope> ReadAsync(CancellationToken cancellationToken = default)
+    {
+        byte[] lengthPrefix = new byte[sizeof(uint)];
+        await ReadExactlyOrThrowAsync(lengthPrefix, cancellationToken).ConfigureAwait(false);
+
+        uint payloadLength = ReadUInt32LittleEndian(lengthPrefix);
+        if (payloadLength == 0)
+        {
+            throw new WorkerFrameProtocolException(
+                WorkerFrameProtocolErrorCode.MalformedLength,
+                "Worker frame payload length must be greater than zero.");
+        }
+
+        if (payloadLength > _options.MaxMessageBytes)
+        {
+            throw new WorkerFrameProtocolException(
+                WorkerFrameProtocolErrorCode.MessageTooLarge,
+                $"Worker frame payload length {payloadLength} exceeds the configured maximum of {_options.MaxMessageBytes} bytes.");
+        }
+
+        byte[] payload = new byte[payloadLength];
+        await ReadExactlyOrThrowAsync(payload, cancellationToken).ConfigureAwait(false);
+
+        WorkerEnvelope envelope;
+        try
+        {
+            envelope = WorkerEnvelope.Parser.ParseFrom(payload);
+        }
+        catch (InvalidProtocolBufferException exception)
+        {
+            throw new WorkerFrameProtocolException(
+                WorkerFrameProtocolErrorCode.InvalidEnvelope,
+                "Worker frame payload is not a valid WorkerEnvelope protobuf message.",
+                exception);
+        }
+
+        WorkerEnvelopeValidator.Validate(envelope, _options);
+
+        return envelope;
+    }
+
+    private static uint ReadUInt32LittleEndian(byte[] buffer)
+    {
+        return (uint)buffer[0]
+            | ((uint)buffer[1] << 8)
+            | ((uint)buffer[2] << 16)
+            | ((uint)buffer[3] << 24);
+    }
+
+    private async Task ReadExactlyOrThrowAsync(
+        byte[] buffer,
+        CancellationToken cancellationToken)
+    {
+        int offset = 0;
+        while (offset < buffer.Length)
+        {
+            int bytesRead = await _stream
+                .ReadAsync(buffer, offset, buffer.Length - offset, cancellationToken)
+                .ConfigureAwait(false);
+
+            if (bytesRead == 0)
+            {
+                throw new WorkerFrameProtocolException(
+                    WorkerFrameProtocolErrorCode.EndOfStream,
+                    "Worker frame ended before the expected number of bytes were read.");
+            }
+
+            offset += bytesRead;
+        }
+    }
+}