initial commit, 4.5 stable

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/Client.cs

@@ -0,0 +1,363 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Collections.Generic;
+using System.IO;
+using System.Net;
+using System.Net.Sockets;
+using Newtonsoft.Json;
+using System.Threading;
+using System.Threading.Tasks;
+using GodotTools.IdeMessaging.Requests;
+using GodotTools.IdeMessaging.Utils;
+
+namespace GodotTools.IdeMessaging
+{
+    // ReSharper disable once UnusedType.Global
+    public sealed class Client : IDisposable
+    {
+        private readonly ILogger logger;
+
+        private readonly string identity;
+
+        private string MetaFilePath { get; }
+        private DateTime? metaFileModifiedTime;
+        private GodotIdeMetadata godotIdeMetadata;
+        private readonly FileSystemWatcher fsWatcher;
+
+        public string GodotEditorExecutablePath => godotIdeMetadata.EditorExecutablePath;
+
+        private readonly IMessageHandler messageHandler;
+
+        private Peer? peer;
+        private readonly SemaphoreSlim connectionSem = new SemaphoreSlim(1);
+
+        private readonly Queue<NotifyAwaiter<bool>> clientConnectedAwaiters = new Queue<NotifyAwaiter<bool>>();
+        private readonly Queue<NotifyAwaiter<bool>> clientDisconnectedAwaiters = new Queue<NotifyAwaiter<bool>>();
+
+        // ReSharper disable once UnusedMember.Global
+        public async Task<bool> AwaitConnected()
+        {
+            var awaiter = new NotifyAwaiter<bool>();
+            clientConnectedAwaiters.Enqueue(awaiter);
+            return await awaiter;
+        }
+
+        // ReSharper disable once UnusedMember.Global
+        public async Task<bool> AwaitDisconnected()
+        {
+            var awaiter = new NotifyAwaiter<bool>();
+            clientDisconnectedAwaiters.Enqueue(awaiter);
+            return await awaiter;
+        }
+
+        // ReSharper disable once MemberCanBePrivate.Global
+        public bool IsDisposed { get; private set; }
+
+        // ReSharper disable once MemberCanBePrivate.Global
+        [MemberNotNullWhen(true, "peer")]
+        public bool IsConnected => peer != null && !peer.IsDisposed && peer.IsTcpClientConnected;
+
+        // ReSharper disable once EventNeverSubscribedTo.Global
+        public event Action Connected
+        {
+            add
+            {
+                if (peer != null && !peer.IsDisposed)
+                    peer.Connected += value;
+            }
+            remove
+            {
+                if (peer != null && !peer.IsDisposed)
+                    peer.Connected -= value;
+            }
+        }
+
+        // ReSharper disable once EventNeverSubscribedTo.Global
+        public event Action Disconnected
+        {
+            add
+            {
+                if (peer != null && !peer.IsDisposed)
+                    peer.Disconnected += value;
+            }
+            remove
+            {
+                if (peer != null && !peer.IsDisposed)
+                    peer.Disconnected -= value;
+            }
+        }
+
+        ~Client()
+        {
+            Dispose(disposing: false);
+        }
+
+        public async void Dispose()
+        {
+            if (IsDisposed)
+                return;
+
+            using (await connectionSem.UseAsync())
+            {
+                if (IsDisposed) // lock may not be fair
+                    return;
+                IsDisposed = true;
+            }
+
+            Dispose(disposing: true);
+            GC.SuppressFinalize(this);
+        }
+
+        private void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                peer?.Dispose();
+                fsWatcher.Dispose();
+            }
+        }
+
+        public Client(string identity, string godotProjectDir, IMessageHandler messageHandler, ILogger logger)
+        {
+            this.identity = identity;
+            this.messageHandler = messageHandler;
+            this.logger = logger;
+
+            string projectMetadataDir = Path.Combine(godotProjectDir, ".godot", "mono", "metadata");
+            // FileSystemWatcher requires an existing directory
+            if (!Directory.Exists(projectMetadataDir))
+            {
+                // Check if the non hidden version exists
+                string nonHiddenProjectMetadataDir = Path.Combine(godotProjectDir, "godot", "mono", "metadata");
+                if (Directory.Exists(nonHiddenProjectMetadataDir))
+                {
+                    projectMetadataDir = nonHiddenProjectMetadataDir;
+                }
+                else
+                {
+                    Directory.CreateDirectory(projectMetadataDir);
+                }
+            }
+
+            MetaFilePath = Path.Combine(projectMetadataDir, GodotIdeMetadata.DefaultFileName);
+
+            fsWatcher = new FileSystemWatcher(projectMetadataDir, GodotIdeMetadata.DefaultFileName);
+        }
+
+        private async void OnMetaFileChanged(object sender, FileSystemEventArgs e)
+        {
+            if (IsDisposed)
+                return;
+
+            using (await connectionSem.UseAsync())
+            {
+                if (IsDisposed)
+                    return;
+
+                if (!File.Exists(MetaFilePath))
+                    return;
+
+                var lastWriteTime = File.GetLastWriteTime(MetaFilePath);
+
+                if (lastWriteTime == metaFileModifiedTime)
+                    return;
+
+                metaFileModifiedTime = lastWriteTime;
+
+                var metadata = ReadMetadataFile();
+
+                if (metadata != null && metadata != godotIdeMetadata)
+                {
+                    godotIdeMetadata = metadata.Value;
+                    _ = Task.Run(ConnectToServer);
+                }
+            }
+        }
+
+        private async void OnMetaFileDeleted(object sender, FileSystemEventArgs e)
+        {
+            if (IsDisposed)
+                return;
+
+            if (IsConnected)
+            {
+                using (await connectionSem.UseAsync())
+                    peer?.Dispose();
+            }
+
+            // The file may have been re-created
+
+            using (await connectionSem.UseAsync())
+            {
+                if (IsDisposed)
+                    return;
+
+                if (IsConnected || !File.Exists(MetaFilePath))
+                    return;
+
+                var lastWriteTime = File.GetLastWriteTime(MetaFilePath);
+
+                if (lastWriteTime == metaFileModifiedTime)
+                    return;
+
+                metaFileModifiedTime = lastWriteTime;
+
+                var metadata = ReadMetadataFile();
+
+                if (metadata != null)
+                {
+                    godotIdeMetadata = metadata.Value;
+                    _ = Task.Run(ConnectToServer);
+                }
+            }
+        }
+
+        private GodotIdeMetadata? ReadMetadataFile()
+        {
+            using (var fileStream = new FileStream(MetaFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
+            using (var reader = new StreamReader(fileStream))
+            {
+                string? portStr = reader.ReadLine();
+
+                if (portStr == null)
+                    return null;
+
+                string? editorExecutablePath = reader.ReadLine();
+
+                if (editorExecutablePath == null)
+                    return null;
+
+                if (!int.TryParse(portStr, out int port))
+                    return null;
+
+                return new GodotIdeMetadata(port, editorExecutablePath);
+            }
+        }
+
+        private async Task AcceptClient(TcpClient tcpClient)
+        {
+            logger.LogDebug("Accept client...");
+
+            using (peer = new Peer(tcpClient, new ClientHandshake(), messageHandler, logger))
+            {
+                // ReSharper disable AccessToDisposedClosure
+                peer.Connected += () =>
+                {
+                    logger.LogInfo("Connection open with Ide Client");
+
+                    while (clientConnectedAwaiters.Count > 0)
+                        clientConnectedAwaiters.Dequeue().SetResult(true);
+                };
+
+                peer.Disconnected += () =>
+                {
+                    while (clientDisconnectedAwaiters.Count > 0)
+                        clientDisconnectedAwaiters.Dequeue().SetResult(true);
+                };
+                // ReSharper restore AccessToDisposedClosure
+
+                try
+                {
+                    if (!await peer.DoHandshake(identity))
+                    {
+                        logger.LogError("Handshake failed");
+                        return;
+                    }
+                }
+                catch (Exception e)
+                {
+                    logger.LogError("Handshake failed with unhandled exception: ", e);
+                    return;
+                }
+
+                await peer.Process();
+
+                logger.LogInfo("Connection closed with Ide Client");
+            }
+        }
+
+        private async Task ConnectToServer()
+        {
+            var tcpClient = new TcpClient();
+
+            try
+            {
+                logger.LogInfo("Connecting to Godot Ide Server");
+
+                await tcpClient.ConnectAsync(IPAddress.Loopback, godotIdeMetadata.Port);
+
+                logger.LogInfo("Connection open with Godot Ide Server");
+
+                await AcceptClient(tcpClient);
+            }
+            catch (SocketException e)
+            {
+                if (e.SocketErrorCode == SocketError.ConnectionRefused)
+                    logger.LogError("The connection to the Godot Ide Server was refused");
+                else
+                    throw;
+            }
+        }
+
+        // ReSharper disable once UnusedMember.Global
+        public async void Start()
+        {
+            fsWatcher.Created += OnMetaFileChanged;
+            fsWatcher.Changed += OnMetaFileChanged;
+            fsWatcher.Deleted += OnMetaFileDeleted;
+            fsWatcher.EnableRaisingEvents = true;
+
+            using (await connectionSem.UseAsync())
+            {
+                if (IsDisposed)
+                    return;
+
+                if (IsConnected)
+                    return;
+
+                if (!File.Exists(MetaFilePath))
+                {
+                    logger.LogInfo("There is no Godot Ide Server running");
+                    return;
+                }
+
+                var metadata = ReadMetadataFile();
+
+                if (metadata != null)
+                {
+                    godotIdeMetadata = metadata.Value;
+                    _ = Task.Run(ConnectToServer);
+                }
+                else
+                {
+                    logger.LogError("Failed to read Godot Ide metadata file");
+                }
+            }
+        }
+
+        public async Task<TResponse?> SendRequest<TResponse>(Request request)
+            where TResponse : Response, new()
+        {
+            if (!IsConnected)
+            {
+                logger.LogError("Cannot write request. Not connected to the Godot Ide Server.");
+                return null;
+            }
+
+            string body = JsonConvert.SerializeObject(request);
+            return await peer.SendRequest<TResponse>(request.Id, body);
+        }
+
+        public async Task<TResponse?> SendRequest<TResponse>(string id, string body)
+            where TResponse : Response, new()
+        {
+            if (!IsConnected)
+            {
+                logger.LogError("Cannot write request. Not connected to the Godot Ide Server.");
+                return null;
+            }
+
+            return await peer.SendRequest<TResponse>(id, body);
+        }
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/ClientHandshake.cs

@@ -0,0 +1,45 @@
+using System.Diagnostics.CodeAnalysis;
+using System.Text.RegularExpressions;
+
+namespace GodotTools.IdeMessaging
+{
+    public class ClientHandshake : IHandshake
+    {
+        private static readonly string ClientHandshakeBase = $"{Peer.ClientHandshakeName},Version={Peer.ProtocolVersionMajor}.{Peer.ProtocolVersionMinor}.{Peer.ProtocolVersionRevision}";
+        private static readonly string ServerHandshakePattern = $@"{Regex.Escape(Peer.ServerHandshakeName)},Version=([0-9]+)\.([0-9]+)\.([0-9]+),([_a-zA-Z][_a-zA-Z0-9]{{0,63}})";
+
+        public string GetHandshakeLine(string identity) => $"{ClientHandshakeBase},{identity}";
+
+        public bool IsValidPeerHandshake(string handshake, [NotNullWhen(true)] out string? identity, ILogger logger)
+        {
+            identity = null;
+
+            var match = Regex.Match(handshake, ServerHandshakePattern);
+
+            if (!match.Success)
+                return false;
+
+            if (!uint.TryParse(match.Groups[1].Value, out uint serverMajor) || Peer.ProtocolVersionMajor != serverMajor)
+            {
+                logger.LogDebug("Incompatible major version: " + match.Groups[1].Value);
+                return false;
+            }
+
+            if (!uint.TryParse(match.Groups[2].Value, out uint serverMinor) || Peer.ProtocolVersionMinor < serverMinor)
+            {
+                logger.LogDebug("Incompatible minor version: " + match.Groups[2].Value);
+                return false;
+            }
+
+            if (!uint.TryParse(match.Groups[3].Value, out uint _)) // Revision
+            {
+                logger.LogDebug("Incompatible revision build: " + match.Groups[3].Value);
+                return false;
+            }
+
+            identity = match.Groups[4].Value;
+
+            return true;
+        }
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/ClientMessageHandler.cs

@@ -0,0 +1,52 @@
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using GodotTools.IdeMessaging.Requests;
+using Newtonsoft.Json;
+
+namespace GodotTools.IdeMessaging
+{
+    // ReSharper disable once UnusedType.Global
+    public abstract class ClientMessageHandler : IMessageHandler
+    {
+        private readonly Dictionary<string, Peer.RequestHandler> requestHandlers;
+
+        protected ClientMessageHandler()
+        {
+            requestHandlers = InitializeRequestHandlers();
+        }
+
+        public async Task<MessageContent> HandleRequest(Peer peer, string id, MessageContent content, ILogger logger)
+        {
+            if (!requestHandlers.TryGetValue(id, out var handler))
+            {
+                logger.LogError($"Received unknown request: {id}");
+                return new MessageContent(MessageStatus.RequestNotSupported, "null");
+            }
+
+            try
+            {
+                var response = await handler(peer, content);
+                return new MessageContent(response.Status, JsonConvert.SerializeObject(response));
+            }
+            catch (JsonException)
+            {
+                logger.LogError($"Received request with invalid body: {id}");
+                return new MessageContent(MessageStatus.InvalidRequestBody, "null");
+            }
+        }
+
+        private Dictionary<string, Peer.RequestHandler> InitializeRequestHandlers()
+        {
+            return new Dictionary<string, Peer.RequestHandler>
+            {
+                [OpenFileRequest.Id] = async (peer, content) =>
+                {
+                    var request = JsonConvert.DeserializeObject<OpenFileRequest>(content.Body);
+                    return await HandleOpenFile(request!);
+                }
+            };
+        }
+
+        protected abstract Task<Response> HandleOpenFile(OpenFileRequest request);
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/CodeAnalysisAttributes.cs

@@ -0,0 +1,142 @@
+// ReSharper disable once CheckNamespace
+namespace System.Diagnostics.CodeAnalysis
+{
+    /// <summary>Specifies that null is allowed as an input even if the corresponding type disallows it.</summary>
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property, Inherited = false)]
+    internal sealed class AllowNullAttribute : Attribute
+    { }
+
+    /// <summary>Specifies that null is disallowed as an input even if the corresponding type allows it.</summary>
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property, Inherited = false)]
+    internal sealed class DisallowNullAttribute : Attribute
+    { }
+
+    /// <summary>Specifies that an output may be null even if the corresponding type disallows it.</summary>
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, Inherited = false)]
+    internal sealed class MaybeNullAttribute : Attribute
+    { }
+
+    /// <summary>Specifies that an output will not be null even if the corresponding type allows it. Specifies that an input argument was not null when the call returns.</summary>
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, Inherited = false)]
+    internal sealed class NotNullAttribute : Attribute
+    { }
+
+    /// <summary>Specifies that when a method returns <see cref="ReturnValue"/>, the parameter may be null even if the corresponding type disallows it.</summary>
+    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+    internal sealed class MaybeNullWhenAttribute : Attribute
+    {
+        /// <summary>Initializes the attribute with the specified return value condition.</summary>
+        /// <param name="returnValue">
+        /// The return value condition. If the method returns this value, the associated parameter may be null.
+        /// </param>
+        public MaybeNullWhenAttribute(bool returnValue) => ReturnValue = returnValue;
+
+        /// <summary>Gets the return value condition.</summary>
+        public bool ReturnValue { get; }
+    }
+
+    /// <summary>Specifies that when a method returns <see cref="ReturnValue"/>, the parameter will not be null even if the corresponding type allows it.</summary>
+    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+    internal sealed class NotNullWhenAttribute : Attribute
+    {
+        /// <summary>Initializes the attribute with the specified return value condition.</summary>
+        /// <param name="returnValue">
+        /// The return value condition. If the method returns this value, the associated parameter will not be null.
+        /// </param>
+        public NotNullWhenAttribute(bool returnValue) => ReturnValue = returnValue;
+
+        /// <summary>Gets the return value condition.</summary>
+        public bool ReturnValue { get; }
+    }
+
+    /// <summary>Specifies that the output will be non-null if the named parameter is non-null.</summary>
+    [AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue, AllowMultiple = true, Inherited = false)]
+    internal sealed class NotNullIfNotNullAttribute : Attribute
+    {
+        /// <summary>Initializes the attribute with the associated parameter name.</summary>
+        /// <param name="parameterName">
+        /// The associated parameter name.  The output will be non-null if the argument to the parameter specified is non-null.
+        /// </param>
+        public NotNullIfNotNullAttribute(string parameterName) => ParameterName = parameterName;
+
+        /// <summary>Gets the associated parameter name.</summary>
+        public string ParameterName { get; }
+    }
+
+    /// <summary>Applied to a method that will never return under any circumstance.</summary>
+    [AttributeUsage(AttributeTargets.Method, Inherited = false)]
+    internal sealed class DoesNotReturnAttribute : Attribute
+    { }
+
+    /// <summary>Specifies that the method will not return if the associated Boolean parameter is passed the specified value.</summary>
+    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+    internal sealed class DoesNotReturnIfAttribute : Attribute
+    {
+        /// <summary>Initializes the attribute with the specified parameter value.</summary>
+        /// <param name="parameterValue">
+        /// The condition parameter value. Code after the method will be considered unreachable by diagnostics if the argument to
+        /// the associated parameter matches this value.
+        /// </param>
+        public DoesNotReturnIfAttribute(bool parameterValue) => ParameterValue = parameterValue;
+
+        /// <summary>Gets the condition parameter value.</summary>
+        public bool ParameterValue { get; }
+    }
+
+    /// <summary>Specifies that the method or property will ensure that the listed field and property members have not-null values.</summary>
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
+    internal sealed class MemberNotNullAttribute : Attribute
+    {
+        /// <summary>Initializes the attribute with a field or property member.</summary>
+        /// <param name="member">
+        /// The field or property member that is promised to be not-null.
+        /// </param>
+        public MemberNotNullAttribute(string member) => Members = new[] { member };
+
+        /// <summary>Initializes the attribute with the list of field and property members.</summary>
+        /// <param name="members">
+        /// The list of field and property members that are promised to be not-null.
+        /// </param>
+        public MemberNotNullAttribute(params string[] members) => Members = members;
+
+        /// <summary>Gets field or property member names.</summary>
+        public string[] Members { get; }
+    }
+
+    /// <summary>Specifies that the method or property will ensure that the listed field and property members have not-null values when returning with the specified return value condition.</summary>
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Property, Inherited = false, AllowMultiple = true)]
+    internal sealed class MemberNotNullWhenAttribute : Attribute
+    {
+        /// <summary>Initializes the attribute with the specified return value condition and a field or property member.</summary>
+        /// <param name="returnValue">
+        /// The return value condition. If the method returns this value, the associated parameter will not be null.
+        /// </param>
+        /// <param name="member">
+        /// The field or property member that is promised to be not-null.
+        /// </param>
+        public MemberNotNullWhenAttribute(bool returnValue, string member)
+        {
+            ReturnValue = returnValue;
+            Members = new[] { member };
+        }
+
+        /// <summary>Initializes the attribute with the specified return value condition and list of field and property members.</summary>
+        /// <param name="returnValue">
+        /// The return value condition. If the method returns this value, the associated parameter will not be null.
+        /// </param>
+        /// <param name="members">
+        /// The list of field and property members that are promised to be not-null.
+        /// </param>
+        public MemberNotNullWhenAttribute(bool returnValue, params string[] members)
+        {
+            ReturnValue = returnValue;
+            Members = members;
+        }
+
+        /// <summary>Gets the return value condition.</summary>
+        public bool ReturnValue { get; }
+
+        /// <summary>Gets field or property member names.</summary>
+        public string[] Members { get; }
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/GodotIdeMetadata.cs

@@ -0,0 +1,46 @@
+using System.Diagnostics.CodeAnalysis;
+
+namespace GodotTools.IdeMessaging
+{
+    public readonly struct GodotIdeMetadata
+    {
+        public int Port { get; }
+        public string EditorExecutablePath { get; }
+
+        public const string DefaultFileName = "ide_messaging_meta.txt";
+
+        public GodotIdeMetadata(int port, string editorExecutablePath)
+        {
+            Port = port;
+            EditorExecutablePath = editorExecutablePath;
+        }
+
+        public static bool operator ==(GodotIdeMetadata a, GodotIdeMetadata b)
+        {
+            return a.Port == b.Port && a.EditorExecutablePath == b.EditorExecutablePath;
+        }
+
+        public static bool operator !=(GodotIdeMetadata a, GodotIdeMetadata b)
+        {
+            return !(a == b);
+        }
+
+        public override bool Equals([NotNullWhen(true)] object? obj)
+        {
+            return obj is GodotIdeMetadata metadata && metadata == this;
+        }
+
+        public bool Equals(GodotIdeMetadata other)
+        {
+            return Port == other.Port && EditorExecutablePath == other.EditorExecutablePath;
+        }
+
+        public override int GetHashCode()
+        {
+            unchecked
+            {
+                return (Port * 397) ^ (EditorExecutablePath != null ? EditorExecutablePath.GetHashCode() : 0);
+            }
+        }
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/GodotTools.IdeMessaging.csproj

@@ -0,0 +1,26 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <ProjectGuid>{92600954-25F0-4291-8E11-1FEE9FC4BE20}</ProjectGuid>
+    <TargetFramework>netstandard2.0</TargetFramework>
+    <LangVersion>9</LangVersion>
+    <Nullable>enable</Nullable>
+    <PackageId>GodotTools.IdeMessaging</PackageId>
+    <Version>1.1.2</Version>
+    <AssemblyVersion>$(Version)</AssemblyVersion>
+    <Authors>Godot Engine contributors</Authors>
+    <Company />
+    <PackageTags>godot</PackageTags>
+    <RepositoryUrl>https://github.com/godotengine/godot/tree/master/modules/mono/editor/GodotTools/GodotTools.IdeMessaging</RepositoryUrl>
+    <PackageLicenseExpression>MIT</PackageLicenseExpression>
+    <Copyright>Copyright (c) Godot Engine contributors</Copyright>
+    <Description>
+This library enables communication with the Godot Engine editor (the version with .NET support).
+It's intended for use in IDEs/editors plugins for a better experience working with Godot C# projects.
+
+A client using this library is only compatible with servers of the same major version and of a lower or equal minor version.
+    </Description>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
+  </ItemGroup>
+</Project>

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/IHandshake.cs

@@ -0,0 +1,10 @@
+using System.Diagnostics.CodeAnalysis;
+
+namespace GodotTools.IdeMessaging
+{
+    public interface IHandshake
+    {
+        string GetHandshakeLine(string identity);
+        bool IsValidPeerHandshake(string handshake, [NotNullWhen(true)] out string? identity, ILogger logger);
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/ILogger.cs

@@ -0,0 +1,13 @@
+using System;
+
+namespace GodotTools.IdeMessaging
+{
+    public interface ILogger
+    {
+        void LogDebug(string message);
+        void LogInfo(string message);
+        void LogWarning(string message);
+        void LogError(string message);
+        void LogError(string message, Exception e);
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/IMessageHandler.cs

@@ -0,0 +1,9 @@
+using System.Threading.Tasks;
+
+namespace GodotTools.IdeMessaging
+{
+    public interface IMessageHandler
+    {
+        Task<MessageContent> HandleRequest(Peer peer, string id, MessageContent content, ILogger logger);
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/Message.cs

@@ -0,0 +1,52 @@
+namespace GodotTools.IdeMessaging
+{
+    public class Message
+    {
+        public MessageKind Kind { get; }
+        public string Id { get; }
+        public MessageContent Content { get; }
+
+        public Message(MessageKind kind, string id, MessageContent content)
+        {
+            Kind = kind;
+            Id = id;
+            Content = content;
+        }
+
+        public override string ToString()
+        {
+            return $"{Kind} | {Id}";
+        }
+    }
+
+    public enum MessageKind
+    {
+        Request,
+        Response
+    }
+
+    public enum MessageStatus
+    {
+        Ok,
+        RequestNotSupported,
+        InvalidRequestBody
+    }
+
+    public readonly struct MessageContent
+    {
+        public MessageStatus Status { get; }
+        public string Body { get; }
+
+        public MessageContent(string body)
+        {
+            Status = MessageStatus.Ok;
+            Body = body;
+        }
+
+        public MessageContent(MessageStatus status, string body)
+        {
+            Status = status;
+            Body = body;
+        }
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/MessageDecoder.cs

@@ -0,0 +1,100 @@
+using System;
+using System.Text;
+
+namespace GodotTools.IdeMessaging
+{
+    public class MessageDecoder
+    {
+        private class DecodedMessage
+        {
+            public MessageKind? Kind;
+            public string? Id;
+            public MessageStatus? Status;
+            public readonly StringBuilder Body = new StringBuilder();
+            public uint? PendingBodyLines;
+
+            public void Clear()
+            {
+                Kind = null;
+                Id = null;
+                Status = null;
+                Body.Clear();
+                PendingBodyLines = null;
+            }
+
+            public Message ToMessage()
+            {
+                if (!Kind.HasValue || Id == null || !Status.HasValue ||
+                    !PendingBodyLines.HasValue || PendingBodyLines.Value > 0)
+                    throw new InvalidOperationException();
+
+                return new Message(Kind.Value, Id, new MessageContent(Status.Value, Body.ToString()));
+            }
+        }
+
+        public enum State
+        {
+            Decoding,
+            Decoded,
+            Errored
+        }
+
+        private readonly DecodedMessage decodingMessage = new DecodedMessage();
+
+        public State Decode(string messageLine, out Message? decodedMessage)
+        {
+            decodedMessage = null;
+
+            if (!decodingMessage.Kind.HasValue)
+            {
+                if (!Enum.TryParse(messageLine, ignoreCase: true, out MessageKind kind))
+                {
+                    decodingMessage.Clear();
+                    return State.Errored;
+                }
+
+                decodingMessage.Kind = kind;
+            }
+            else if (decodingMessage.Id == null)
+            {
+                decodingMessage.Id = messageLine;
+            }
+            else if (decodingMessage.Status == null)
+            {
+                if (!Enum.TryParse(messageLine, ignoreCase: true, out MessageStatus status))
+                {
+                    decodingMessage.Clear();
+                    return State.Errored;
+                }
+
+                decodingMessage.Status = status;
+            }
+            else if (decodingMessage.PendingBodyLines == null)
+            {
+                if (!uint.TryParse(messageLine, out uint pendingBodyLines))
+                {
+                    decodingMessage.Clear();
+                    return State.Errored;
+                }
+
+                decodingMessage.PendingBodyLines = pendingBodyLines;
+            }
+            else
+            {
+                if (decodingMessage.PendingBodyLines > 0)
+                {
+                    decodingMessage.Body.AppendLine(messageLine);
+                    decodingMessage.PendingBodyLines -= 1;
+                }
+                else
+                {
+                    decodedMessage = decodingMessage.ToMessage();
+                    decodingMessage.Clear();
+                    return State.Decoded;
+                }
+            }
+
+            return State.Decoding;
+        }
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/Peer.cs

@@ -0,0 +1,298 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net.Sockets;
+using System.Reflection;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using GodotTools.IdeMessaging.Requests;
+using GodotTools.IdeMessaging.Utils;
+
+namespace GodotTools.IdeMessaging
+{
+    public sealed class Peer : IDisposable
+    {
+        /// <summary>
+        /// Major version.
+        /// There is no forward nor backward compatibility between different major versions.
+        /// Connection is refused if client and server have different major versions.
+        /// </summary>
+        public static readonly int ProtocolVersionMajor = Assembly.GetAssembly(typeof(Peer)).GetName().Version.Major;
+
+        /// <summary>
+        /// Minor version, which clients must be backward compatible with.
+        /// Connection is refused if the client's minor version is lower than the server's.
+        /// </summary>
+        public static readonly int ProtocolVersionMinor = Assembly.GetAssembly(typeof(Peer)).GetName().Version.Minor;
+
+        /// <summary>
+        /// Revision, which doesn't affect compatibility.
+        /// </summary>
+        public static readonly int ProtocolVersionRevision = Assembly.GetAssembly(typeof(Peer)).GetName().Version.Revision;
+
+        public const string ClientHandshakeName = "GodotIdeClient";
+        public const string ServerHandshakeName = "GodotIdeServer";
+
+        private const int ClientWriteTimeout = 8000;
+
+        public delegate Task<Response> RequestHandler(Peer peer, MessageContent content);
+
+        private readonly TcpClient tcpClient;
+
+        private readonly TextReader clientReader;
+        private readonly TextWriter clientWriter;
+
+        private readonly SemaphoreSlim writeSem = new SemaphoreSlim(1);
+
+        private string? remoteIdentity;
+        public string RemoteIdentity => remoteIdentity ??= string.Empty;
+
+        public event Action? Connected;
+        public event Action? Disconnected;
+
+        private ILogger Logger { get; }
+
+        public bool IsDisposed { get; private set; }
+
+        public bool IsTcpClientConnected => tcpClient.Client != null && tcpClient.Client.Connected;
+
+        private bool IsConnected { get; set; }
+
+        private readonly IHandshake handshake;
+        private readonly IMessageHandler messageHandler;
+
+        private readonly Dictionary<string, Queue<ResponseAwaiter>> requestAwaiterQueues = new Dictionary<string, Queue<ResponseAwaiter>>();
+        private readonly SemaphoreSlim requestsSem = new SemaphoreSlim(1);
+
+        public Peer(TcpClient tcpClient, IHandshake handshake, IMessageHandler messageHandler, ILogger logger)
+        {
+            this.tcpClient = tcpClient;
+            this.handshake = handshake;
+            this.messageHandler = messageHandler;
+
+            Logger = logger;
+
+            NetworkStream clientStream = tcpClient.GetStream();
+            clientStream.WriteTimeout = ClientWriteTimeout;
+
+            clientReader = new StreamReader(clientStream, Encoding.UTF8);
+            clientWriter = new StreamWriter(clientStream, Encoding.UTF8) { NewLine = "\n" };
+        }
+
+        public async Task Process()
+        {
+            try
+            {
+                var decoder = new MessageDecoder();
+
+                string? messageLine;
+                while ((messageLine = await ReadLine()) != null)
+                {
+                    var state = decoder.Decode(messageLine, out var msg);
+
+                    if (state == MessageDecoder.State.Decoding)
+                        continue; // Not finished decoding yet
+
+                    if (state == MessageDecoder.State.Errored)
+                    {
+                        Logger.LogError($"Received message line with invalid format: {messageLine}");
+                        continue;
+                    }
+
+                    Logger.LogDebug($"Received message: {msg}");
+
+                    try
+                    {
+                        if (msg!.Kind == MessageKind.Request)
+                        {
+                            var responseContent = await messageHandler.HandleRequest(this, msg.Id, msg.Content, Logger);
+                            await WriteMessage(new Message(MessageKind.Response, msg.Id, responseContent));
+                        }
+                        else if (msg.Kind == MessageKind.Response)
+                        {
+                            ResponseAwaiter responseAwaiter;
+
+                            using (await requestsSem.UseAsync())
+                            {
+                                if (!requestAwaiterQueues.TryGetValue(msg.Id, out var queue) || queue.Count <= 0)
+                                {
+                                    Logger.LogError($"Received unexpected response: {msg.Id}");
+                                    return;
+                                }
+
+                                responseAwaiter = queue.Dequeue();
+                            }
+
+                            responseAwaiter.SetResult(msg.Content);
+                        }
+                        else
+                        {
+                            throw new IndexOutOfRangeException($"Invalid message kind {msg.Kind}");
+                        }
+                    }
+                    catch (Exception e)
+                    {
+                        Logger.LogError($"Message handler for '{msg}' failed with exception", e);
+                    }
+                }
+            }
+            catch (Exception e)
+            {
+                if (!IsDisposed || !(e is SocketException || e.InnerException is SocketException))
+                {
+                    Logger.LogError("Unhandled exception in the peer loop", e);
+                }
+            }
+        }
+
+        public async Task<bool> DoHandshake(string identity)
+        {
+            if (!await WriteLine(handshake.GetHandshakeLine(identity)))
+            {
+                Logger.LogError("Could not write handshake");
+                return false;
+            }
+
+            var readHandshakeTask = ReadLine();
+
+            if (await Task.WhenAny(readHandshakeTask, Task.Delay(8000)) != readHandshakeTask)
+            {
+                Logger.LogError("Timeout waiting for the client handshake");
+                return false;
+            }
+
+            string? peerHandshake = await readHandshakeTask;
+
+            if (peerHandshake == null || !handshake.IsValidPeerHandshake(peerHandshake, out remoteIdentity, Logger))
+            {
+                Logger.LogError("Received invalid handshake: " + peerHandshake);
+                return false;
+            }
+
+            IsConnected = true;
+            Connected?.Invoke();
+
+            Logger.LogInfo("Peer connection started");
+
+            return true;
+        }
+
+        private async Task<string?> ReadLine()
+        {
+            try
+            {
+                return await clientReader.ReadLineAsync();
+            }
+            catch (Exception e)
+            {
+                if (IsDisposed)
+                {
+                    var se = e as SocketException ?? e.InnerException as SocketException;
+                    if (se != null && se.SocketErrorCode == SocketError.Interrupted)
+                        return null;
+                }
+
+                throw;
+            }
+        }
+
+        private Task<bool> WriteMessage(Message message)
+        {
+            Logger.LogDebug($"Sending message: {message}");
+            int bodyLineCount = message.Content.Body.Count(c => c == '\n');
+
+            bodyLineCount += 1; // Extra line break at the end
+
+            var builder = new StringBuilder();
+
+            builder.AppendLine(message.Kind.ToString());
+            builder.AppendLine(message.Id);
+            builder.AppendLine(message.Content.Status.ToString());
+            builder.AppendLine(bodyLineCount.ToString());
+            builder.AppendLine(message.Content.Body);
+
+            return WriteLine(builder.ToString());
+        }
+
+        public async Task<TResponse?> SendRequest<TResponse>(string id, string body)
+            where TResponse : Response, new()
+        {
+            ResponseAwaiter responseAwaiter;
+
+            using (await requestsSem.UseAsync())
+            {
+                bool written = await WriteMessage(new Message(MessageKind.Request, id, new MessageContent(body)));
+
+                if (!written)
+                    return null;
+
+                if (!requestAwaiterQueues.TryGetValue(id, out var queue))
+                {
+                    queue = new Queue<ResponseAwaiter>();
+                    requestAwaiterQueues.Add(id, queue);
+                }
+
+                responseAwaiter = new ResponseAwaiter<TResponse>();
+                queue.Enqueue(responseAwaiter);
+            }
+
+            return (TResponse)await responseAwaiter;
+        }
+
+        private async Task<bool> WriteLine(string text)
+        {
+            if (IsDisposed || !IsTcpClientConnected)
+                return false;
+
+            using (await writeSem.UseAsync())
+            {
+                try
+                {
+                    await clientWriter.WriteLineAsync(text);
+                    await clientWriter.FlushAsync();
+                }
+                catch (Exception e)
+                {
+                    if (!IsDisposed)
+                    {
+                        var se = e as SocketException ?? e.InnerException as SocketException;
+                        if (se != null && se.SocketErrorCode == SocketError.Shutdown)
+                            Logger.LogInfo("Client disconnected ungracefully");
+                        else
+                            Logger.LogError("Exception thrown when trying to write to client", e);
+
+                        Dispose();
+                    }
+                }
+            }
+
+            return true;
+        }
+
+        // ReSharper disable once UnusedMember.Global
+        public void ShutdownSocketSend()
+        {
+            tcpClient.Client.Shutdown(SocketShutdown.Send);
+        }
+
+        public void Dispose()
+        {
+            if (IsDisposed)
+                return;
+
+            IsDisposed = true;
+
+            if (IsTcpClientConnected)
+            {
+                if (IsConnected)
+                    Disconnected?.Invoke();
+            }
+
+            clientReader.Dispose();
+            clientWriter.Dispose();
+            ((IDisposable)tcpClient).Dispose();
+        }
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/Requests/Requests.cs

@@ -0,0 +1,130 @@
+// ReSharper disable ClassNeverInstantiated.Global
+// ReSharper disable UnusedMember.Global
+// ReSharper disable UnusedAutoPropertyAccessor.Global
+
+using System;
+using Newtonsoft.Json;
+
+namespace GodotTools.IdeMessaging.Requests
+{
+    public abstract class Request
+    {
+        [JsonIgnore] public string Id { get; }
+
+        protected Request(string id)
+        {
+            Id = id;
+        }
+    }
+
+    public abstract class Response
+    {
+        [JsonIgnore] public MessageStatus Status { get; set; } = MessageStatus.Ok;
+    }
+
+    public sealed class CodeCompletionRequest : Request
+    {
+        public enum CompletionKind
+        {
+            InputActions = 0,
+            NodePaths,
+            ResourcePaths,
+            ScenePaths,
+            ShaderParams,
+            Signals,
+            ThemeColors,
+            ThemeConstants,
+            ThemeFonts,
+            ThemeStyles
+        }
+
+        public CompletionKind Kind { get; set; }
+        public string ScriptFile { get; set; } = string.Empty;
+
+        public new const string Id = "CodeCompletion";
+
+        public CodeCompletionRequest() : base(Id)
+        {
+        }
+    }
+
+    public sealed class CodeCompletionResponse : Response
+    {
+        public CodeCompletionRequest.CompletionKind Kind;
+        public string ScriptFile { get; set; } = string.Empty;
+        public string[] Suggestions { get; set; } = Array.Empty<string>();
+    }
+
+    public sealed class PlayRequest : Request
+    {
+        public new const string Id = "Play";
+
+        public PlayRequest() : base(Id)
+        {
+        }
+    }
+
+    public sealed class PlayResponse : Response
+    {
+    }
+
+    public sealed class StopPlayRequest : Request
+    {
+        public new const string Id = "StopPlay";
+
+        public StopPlayRequest() : base(Id)
+        {
+        }
+    }
+
+    public sealed class StopPlayResponse : Response
+    {
+    }
+
+    public sealed class DebugPlayRequest : Request
+    {
+        public string DebuggerHost { get; set; } = string.Empty;
+        public int DebuggerPort { get; set; }
+        public bool? BuildBeforePlaying { get; set; }
+
+        public new const string Id = "DebugPlay";
+
+        public DebugPlayRequest() : base(Id)
+        {
+        }
+    }
+
+    public sealed class DebugPlayResponse : Response
+    {
+    }
+
+    public sealed class OpenFileRequest : Request
+    {
+        public string File { get; set; } = string.Empty;
+        public int? Line { get; set; }
+        public int? Column { get; set; }
+
+        public new const string Id = "OpenFile";
+
+        public OpenFileRequest() : base(Id)
+        {
+        }
+    }
+
+    public sealed class OpenFileResponse : Response
+    {
+    }
+
+    public sealed class ReloadScriptsRequest : Request
+    {
+        public new const string Id = "ReloadScripts";
+
+        public ReloadScriptsRequest() : base(Id)
+        {
+        }
+    }
+
+    public sealed class ReloadScriptsResponse : Response
+    {
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/ResponseAwaiter.cs

@@ -0,0 +1,23 @@
+using GodotTools.IdeMessaging.Requests;
+using GodotTools.IdeMessaging.Utils;
+using Newtonsoft.Json;
+
+namespace GodotTools.IdeMessaging
+{
+    public abstract class ResponseAwaiter : NotifyAwaiter<Response>
+    {
+        public abstract void SetResult(MessageContent content);
+    }
+
+    public class ResponseAwaiter<T> : ResponseAwaiter
+        where T : Response, new()
+    {
+        public override void SetResult(MessageContent content)
+        {
+            if (content.Status == MessageStatus.Ok)
+                SetResult(JsonConvert.DeserializeObject<T>(content.Body)!);
+            else
+                SetResult(new T { Status = content.Status });
+        }
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/Utils/NotifyAwaiter.cs

@@ -0,0 +1,67 @@
+// ReSharper disable ParameterHidesMember
+// ReSharper disable UnusedMember.Global
+
+using System;
+using System.Runtime.CompilerServices;
+
+namespace GodotTools.IdeMessaging.Utils
+{
+    public class NotifyAwaiter<T> : INotifyCompletion
+    {
+        private Action? continuation;
+        private Exception? exception;
+        private T? result;
+
+        public bool IsCompleted { get; private set; }
+
+        public T GetResult()
+        {
+            if (exception != null)
+                throw exception;
+            return result!;
+        }
+
+        public void OnCompleted(Action continuation)
+        {
+            if (this.continuation != null)
+                throw new InvalidOperationException("This awaiter already has a continuation.");
+            this.continuation = continuation;
+        }
+
+        public void SetResult(T result)
+        {
+            if (IsCompleted)
+                throw new InvalidOperationException("This awaiter is already completed.");
+
+            IsCompleted = true;
+            this.result = result;
+
+            continuation?.Invoke();
+        }
+
+        public void SetException(Exception exception)
+        {
+            if (IsCompleted)
+                throw new InvalidOperationException("This awaiter is already completed.");
+
+            IsCompleted = true;
+            this.exception = exception;
+
+            continuation?.Invoke();
+        }
+
+        public NotifyAwaiter<T> Reset()
+        {
+            continuation = null;
+            exception = null;
+            result = default(T);
+            IsCompleted = false;
+            return this;
+        }
+
+        public NotifyAwaiter<T> GetAwaiter()
+        {
+            return this;
+        }
+    }
+}

modules/mono/editor/GodotTools/GodotTools.IdeMessaging/Utils/SemaphoreExtensions.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Runtime.CompilerServices;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace GodotTools.IdeMessaging.Utils
+{
+    public static class SemaphoreExtensions
+    {
+        public static ConfiguredTaskAwaitable<IDisposable> UseAsync(this SemaphoreSlim semaphoreSlim, CancellationToken cancellationToken = default(CancellationToken))
+        {
+            var wrapper = new SemaphoreSlimWaitReleaseWrapper(semaphoreSlim, out Task waitAsyncTask, cancellationToken);
+            return waitAsyncTask.ContinueWith<IDisposable>(t => wrapper, cancellationToken).ConfigureAwait(false);
+        }
+
+        private readonly struct SemaphoreSlimWaitReleaseWrapper : IDisposable
+        {
+            private readonly SemaphoreSlim semaphoreSlim;
+
+            public SemaphoreSlimWaitReleaseWrapper(SemaphoreSlim semaphoreSlim, out Task waitAsyncTask, CancellationToken cancellationToken = default(CancellationToken))
+            {
+                this.semaphoreSlim = semaphoreSlim;
+                waitAsyncTask = this.semaphoreSlim.WaitAsync(cancellationToken);
+            }
+
+            public void Dispose()
+            {
+                semaphoreSlim.Release();
+            }
+        }
+    }
+}