feat: Dalamud RPC service

A draft for a simple RPC service for Dalamud. Enables use of Dalamud URIs, to be added later.

Dalamud.Test/Pipes/DalamudUriTests.cs

@@ -0,0 +1,107 @@
+using System;
+using System.Linq;
+
+using Dalamud.Networking.Pipes;
+using Xunit;
+
+namespace Dalamud.Test.Pipes
+{
+    public class DalamudUriTests
+    {
+        [Theory]
+        [InlineData("https://www.google.com/", false)]
+        [InlineData("dalamud://PluginInstaller/Dalamud.FindAnything", true)]
+        public void ValidatesScheme(string uri, bool valid)
+        {
+            Action act = () => { _ = DalamudUri.FromUri(uri); };
+
+            var ex = Record.Exception(act);
+            if (valid)
+            {
+                Assert.Null(ex);
+            }
+            else
+            {
+                Assert.NotNull(ex);
+                Assert.IsType<ArgumentOutOfRangeException>(ex);
+            }
+        }
+
+        [Theory]
+        [InlineData("dalamud://PluginInstaller/Dalamud.FindAnything", "plugininstaller")]
+        [InlineData("dalamud://Plugin/Dalamud.FindAnything/OpenWindow", "plugin")]
+        [InlineData("dalamud://Test", "test")]
+        public void ExtractsNamespace(string uri, string expectedNamespace)
+        {
+            var dalamudUri = DalamudUri.FromUri(uri);
+            Assert.Equal(expectedNamespace, dalamudUri.Namespace);
+        }
+
+        [Theory]
+        [InlineData("dalamud://foo/bar/baz/qux/?cow=moo", "/bar/baz/qux/")]
+        [InlineData("dalamud://foo/bar/baz/qux?cow=moo", "/bar/baz/qux")]
+        [InlineData("dalamud://foo/bar/baz", "/bar/baz")]
+        [InlineData("dalamud://foo/bar", "/bar")]
+        [InlineData("dalamud://foo/bar/", "/bar/")]
+        [InlineData("dalamud://foo/", "/")]
+        public void ExtractsPath(string uri, string expectedPath)
+        {
+            var dalamudUri = DalamudUri.FromUri(uri);
+            Assert.Equal(expectedPath, dalamudUri.Path);
+        }
+
+        [Theory]
+        [InlineData("dalamud://foo/bar/baz/qux/?cow=moo#frag", "/bar/baz/qux/?cow=moo#frag")]
+        [InlineData("dalamud://foo/bar/baz/qux/?cow=moo", "/bar/baz/qux/?cow=moo")]
+        [InlineData("dalamud://foo/bar/baz/qux?cow=moo", "/bar/baz/qux?cow=moo")]
+        [InlineData("dalamud://foo/bar/baz", "/bar/baz")]
+        [InlineData("dalamud://foo/bar?cow=moo", "/bar?cow=moo")]
+        [InlineData("dalamud://foo/bar", "/bar")]
+        [InlineData("dalamud://foo/bar/?cow=moo", "/bar/?cow=moo")]
+        [InlineData("dalamud://foo/bar/", "/bar/")]
+        [InlineData("dalamud://foo/?cow=moo#chicken", "/?cow=moo#chicken")]
+        [InlineData("dalamud://foo/?cow=moo", "/?cow=moo")]
+        [InlineData("dalamud://foo/", "/")]
+        public void ExtractsData(string uri, string expectedData)
+        {
+            var dalamudUri = DalamudUri.FromUri(uri);
+
+            Assert.Equal(expectedData, dalamudUri.Data);
+        }
+
+        [Theory]
+        [InlineData("dalamud://foo/bar", 0)]
+        [InlineData("dalamud://foo/bar?cow=moo", 1)]
+        [InlineData("dalamud://foo/bar?cow=moo&wolf=awoo", 2)]
+        [InlineData("dalamud://foo/bar?cow=moo&wolf=awoo&cat", 3)]
+        public void ExtractsQueryParams(string uri, int queryCount)
+        {
+            var dalamudUri = DalamudUri.FromUri(uri);
+            Assert.Equal(queryCount, dalamudUri.QueryParams.Count);
+        }
+
+        [Theory]
+        [InlineData("dalamud://foo/bar/baz/qux/meh/?foo=bar", 5, true)]
+        [InlineData("dalamud://foo/bar/baz/qux/meh/", 5, true)]
+        [InlineData("dalamud://foo/bar/baz/qux/meh", 5)]
+        [InlineData("dalamud://foo/bar/baz/qux", 4)]
+        [InlineData("dalamud://foo/bar/baz", 3)]
+        [InlineData("dalamud://foo/bar/", 2)]
+        [InlineData("dalamud://foo/bar", 2)]
+        public void ExtractsSegments(string uri, int segmentCount, bool finalSegmentEndsWithSlash = false)
+        {
+            var dalamudUri = DalamudUri.FromUri(uri);
+            var segments = dalamudUri.Segments;
+
+            // First segment must always be `/`
+            Assert.Equal("/", segments[0]);
+
+            Assert.Equal(segmentCount, segments.Length);
+
+            if (finalSegmentEndsWithSlash)
+            {
+                Assert.EndsWith("/", segments.Last());
+            }
+        }
+    }
+}

Dalamud/Dalamud.csproj

@@ -81,6 +81,7 @@
         <PackageReference Include="Serilog.Sinks.Console" />
         <PackageReference Include="Serilog.Sinks.File" />
         <PackageReference Include="sqlite-net-pcl" />
+        <PackageReference Include="StreamJsonRpc" />
         <PackageReference Include="StyleCop.Analyzers">
             <PrivateAssets>all</PrivateAssets>
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

Dalamud/Networking/Pipes/Api/PluginLinkHandler.cs

@@ -0,0 +1,53 @@
+using System.Linq;
+
+using Dalamud.IoC;
+using Dalamud.IoC.Internal;
+using Dalamud.Networking.Pipes.Internal;
+using Dalamud.Plugin.Internal.Types;
+using Dalamud.Plugin.Services;
+
+namespace Dalamud.Networking.Pipes.Api;
+
+/// <inheritdoc cref="IPluginLinkHandler" />
+[PluginInterface]
+[ServiceManager.ScopedService]
+[ResolveVia<IPluginLinkHandler>]
+public class PluginLinkHandler : IInternalDisposableService, IPluginLinkHandler
+{
+    private readonly LinkHandlerService linkHandler;
+    private readonly LocalPlugin localPlugin;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="PluginLinkHandler"/> class.
+    /// </summary>
+    /// <param name="localPlugin">The plugin to bind this service to.</param>
+    /// <param name="linkHandler">The central link handler.</param>
+    internal PluginLinkHandler(LocalPlugin localPlugin, LinkHandlerService linkHandler)
+    {
+        this.linkHandler = linkHandler;
+        this.localPlugin = localPlugin;
+
+        this.linkHandler.Register("plugin", this.HandleUri);
+    }
+
+    /// <inheritdoc/>
+    public event IPluginLinkHandler.PluginUriReceived? OnUriReceived;
+
+    /// <inheritdoc/>
+    public void DisposeService()
+    {
+        this.OnUriReceived = null;
+        this.linkHandler.Unregister("plugin", this.HandleUri);
+    }
+
+    private void HandleUri(DalamudUri uri)
+    {
+        var target = uri.Path.Split("/").FirstOrDefault();
+        if (target == null || !string.Equals(target, this.localPlugin.InternalName, StringComparison.OrdinalIgnoreCase))
+        {
+            return;
+        }
+
+        this.OnUriReceived?.Invoke(uri);
+    }
+}

Dalamud/Networking/Pipes/DalamudUri.cs

@@ -0,0 +1,102 @@
+using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.Web;
+
+namespace Dalamud.Networking.Pipes;
+
+/// <summary>
+/// A Dalamud Uri, in the format:
+/// <code>dalamud://{NAMESPACE}/{ARBITRARY}</code>
+/// </summary>
+public record DalamudUri
+{
+    private readonly Uri rawUri;
+
+    private DalamudUri(Uri uri)
+    {
+        if (uri.Scheme != "dalamud")
+        {
+            throw new ArgumentOutOfRangeException(nameof(uri), "URI must be of scheme dalamud.");
+        }
+
+        this.rawUri = uri;
+    }
+
+    /// <summary>
+    /// Gets the namespace that this URI should be routed to. Generally a high level component like "PluginInstaller".
+    /// </summary>
+    public string Namespace => this.rawUri.Authority;
+
+    /// <summary>
+    /// Gets the raw (untargeted) path and query params for this URI.
+    /// </summary>
+    public string Data =>
+        this.rawUri.GetComponents(UriComponents.PathAndQuery | UriComponents.Fragment, UriFormat.UriEscaped);
+
+    /// <summary>
+    /// Gets the raw (untargeted) path for this URI.
+    /// </summary>
+    public string Path => this.rawUri.AbsolutePath;
+
+    /// <summary>
+    /// Gets a list of segments based on the provided Data element.
+    /// </summary>
+    public string[] Segments => this.GetDataSegments();
+
+    /// <summary>
+    /// Gets the raw query parameters for this URI, if any.
+    /// </summary>
+    public string Query => this.rawUri.Query;
+
+    /// <summary>
+    /// Gets the query params (as a parsed NameValueCollection) in this URI.
+    /// </summary>
+    public NameValueCollection QueryParams => HttpUtility.ParseQueryString(this.Query);
+
+    /// <summary>
+    /// Gets the fragment (if one is specified) in this URI.
+    /// </summary>
+    public string Fragment => this.rawUri.Fragment;
+
+    /// <inheritdoc/>
+    public override string ToString() => this.rawUri.ToString();
+
+    private string[] GetDataSegments()
+    {
+        // reimplementation of the System.URI#Segments, under MIT license.
+        var path = this.Path;
+
+        var segments = new List<string>();
+        var current = 0;
+        while (current < path.Length)
+        {
+            var next = path.IndexOf('/', current);
+            if (next == -1)
+            {
+                next = path.Length - 1;
+            }
+
+            segments.Add(path.Substring(current, (next - current) + 1));
+            current = next + 1;
+        }
+
+        return segments.ToArray();
+    }
+
+    /// <summary>
+    /// Build a DalamudURI from a given URI.
+    /// </summary>
+    /// <param name="uri">The URI to convert to a Dalamud URI.</param>
+    /// <returns>Returns a DalamudUri.</returns>
+    public static DalamudUri FromUri(Uri uri)
+    {
+        return new DalamudUri(uri);
+    }
+
+    /// <summary>
+    /// Build a DalamudURI from a URI in string format.
+    /// </summary>
+    /// <param name="uri">The URI to convert to a Dalamud URI.</param>
+    /// <returns>Returns a DalamudUri.</returns>
+    public static DalamudUri FromUri(string uri) => FromUri(new Uri(uri));
+}

Dalamud/Networking/Pipes/Internal/ClientHelloService.cs

@@ -0,0 +1,94 @@
+using System.Threading.Tasks;
+
+using Dalamud.Game;
+using Dalamud.Game.ClientState;
+using Dalamud.Networking.Pipes.Rpc;
+using Dalamud.Utility;
+
+namespace Dalamud.Networking.Pipes.Internal;
+
+/// <summary>
+/// A minimal service to respond with information about this client.
+/// </summary>
+[ServiceManager.EarlyLoadedService]
+internal sealed class ClientHelloService : IInternalDisposableService
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ClientHelloService"/> class.
+    /// </summary>
+    /// <param name="rpcHostService">Injected host service.</param>
+    [ServiceManager.ServiceConstructor]
+    public ClientHelloService(RpcHostService rpcHostService)
+    {
+        rpcHostService.AddMethod("hello", this.HandleHello);
+    }
+
+    /// <summary>
+    /// Handle a hello request.
+    /// </summary>
+    /// <param name="request">.</param>
+    /// <returns>Respond with information.</returns>
+    public async Task<ClientHelloResponse> HandleHello(ClientHelloRequest request)
+    {
+        var framework = await Service<Framework>.GetAsync();
+        var dalamud = await Service<Dalamud>.GetAsync();
+        var clientState = await Service<ClientState>.GetAsync();
+
+        var response = await framework.RunOnFrameworkThread(() => new ClientHelloResponse
+        {
+            ApiVersion = "1.0",
+            DalamudVersion = Util.GetScmVersion(),
+            GameVersion = dalamud.StartInfo.GameVersion?.ToString() ?? "Unknown",
+            PlayerName = clientState.IsLoggedIn ? clientState.LocalPlayer?.Name.ToString() ?? "Unknown" : null,
+        });
+
+        return response;
+    }
+
+    /// <inheritdoc/>
+    public void DisposeService()
+    {
+    }
+}
+
+/// <summary>
+/// A request from a client to say hello.
+/// </summary>
+internal record ClientHelloRequest
+{
+    /// <summary>
+    /// Gets the API version this client is expecting.
+    /// </summary>
+    public string ApiVersion { get; init; } = string.Empty;
+
+    /// <summary>
+    /// Gets the user agent of the client.
+    /// </summary>
+    public string UserAgent { get; init; } = string.Empty;
+}
+
+/// <summary>
+/// A response from Dalamud to a hello request.
+/// </summary>
+internal record ClientHelloResponse
+{
+    /// <summary>
+    /// Gets the API version this server has offered.
+    /// </summary>
+    public string? ApiVersion { get; init; }
+
+    /// <summary>
+    /// Gets the current Dalamud version.
+    /// </summary>
+    public string? DalamudVersion { get; init; }
+
+    /// <summary>
+    /// Gets the current game version.
+    /// </summary>
+    public string? GameVersion { get; init; }
+
+    /// <summary>
+    /// Gets or sets the player name, or null if the player isn't logged in.
+    /// </summary>
+    public string? PlayerName { get; set; }
+}

Dalamud/Networking/Pipes/Internal/LinkHandlerService.cs

@@ -0,0 +1,129 @@
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+
+using Dalamud.Logging.Internal;
+using Dalamud.Networking.Pipes.Rpc;
+
+namespace Dalamud.Networking.Pipes.Internal;
+
+/// <summary>
+/// A service responsible for handling Dalamud URIs and dispatching them accordingly.
+/// </summary>
+[ServiceManager.EarlyLoadedService]
+internal class LinkHandlerService : IInternalDisposableService
+{
+    private readonly ModuleLog log = new("LinkHandler");
+
+    // key: namespace (e.g. "plugin" or "PluginInstaller") -> list of handlers
+    private readonly ConcurrentDictionary<string, List<Action<DalamudUri>>> handlers
+        = new(StringComparer.OrdinalIgnoreCase);
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="LinkHandlerService"/> class.
+    /// </summary>
+    /// <param name="rpcHostService">The injected RPC host service.</param>
+    [ServiceManager.ServiceConstructor]
+    public LinkHandlerService(RpcHostService rpcHostService)
+    {
+        rpcHostService.AddMethod("handleLink", this.HandleLinkCall);
+    }
+
+    /// <inheritdoc/>
+    public void DisposeService()
+    {
+    }
+
+    /// <summary>
+    /// Register a handler for a namespace. All URIs with this namespace will be dispatched to the handler.
+    /// </summary>
+    /// <param name="ns">The namespace to use for this subscription.</param>
+    /// <param name="handler">The command handler.</param>
+    public void Register(string ns, Action<DalamudUri> handler)
+    {
+        if (string.IsNullOrWhiteSpace(ns))
+            throw new ArgumentNullException(nameof(ns));
+
+        var list = this.handlers.GetOrAdd(ns, _ => []);
+        lock (list)
+        {
+            list.Add(handler);
+        }
+
+        this.log.Verbose("Registered handler for {Namespace}", ns);
+    }
+
+    /// <summary>
+    /// Unregister a handler.
+    /// </summary>
+    /// <param name="ns">The namespace to use for this subscription.</param>
+    /// <param name="handler">The command handler.</param>
+    public void Unregister(string ns, Action<DalamudUri> handler)
+    {
+        if (string.IsNullOrWhiteSpace(ns))
+            return;
+
+        if (!this.handlers.TryGetValue(ns, out var list))
+            return;
+
+        lock (list)
+        {
+            list.RemoveAll(x => x == handler);
+        }
+
+        if (list.Count == 0)
+            this.handlers.TryRemove(ns, out _);
+
+        this.log.Verbose("Unregistered handler for {Namespace}", ns);
+    }
+
+    /// <summary>
+    /// Dispatch a URI to matching handlers.
+    /// </summary>
+    /// <param name="uri">The URI to parse and dispatch.</param>
+    public void Dispatch(DalamudUri uri)
+    {
+        this.log.Information("Received URI: {Uri}", uri.ToString());
+
+        var ns = uri.Namespace;
+        if (!this.handlers.TryGetValue(ns, out var list))
+            return;
+
+        Action<DalamudUri>[] snapshot;
+        lock (list)
+        {
+            snapshot = list.ToArray();
+        }
+
+        foreach (var h in snapshot)
+        {
+            try
+            {
+                h(uri);
+            }
+            catch (Exception e)
+            {
+                this.log.Warning(e, "Link handler threw for {UriPath}", uri.Path);
+            }
+        }
+    }
+
+    /// <summary>
+    /// The RPC-invokable link handler.
+    /// </summary>
+    /// <param name="uri">A plain-text URI to parse.</param>
+    public void HandleLinkCall(string uri)
+    {
+        if (string.IsNullOrWhiteSpace(uri))
+            return;
+
+        try
+        {
+            var du = DalamudUri.FromUri(uri);
+            this.Dispatch(du);
+        }
+        catch (Exception)
+        {
+            // swallow parse errors; clients shouldn't crash the host
+        }
+    }
+}

Dalamud/Networking/Pipes/Rpc/PipeRpcHost.cs

@@ -0,0 +1,167 @@
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.IO.Pipes;
+using System.Security.AccessControl;
+using System.Security.Principal;
+using System.Threading;
+using System.Threading.Tasks;
+
+using Dalamud.Logging.Internal;
+using Dalamud.Utility;
+
+namespace Dalamud.Networking.Pipes.Rpc;
+
+/// <summary>
+/// Simple multi-client JSON-RPC named pipe host using StreamJsonRpc.
+/// </summary>
+internal class PipeRpcHost : IDisposable
+{
+    private readonly ModuleLog log = new("RPC/Host");
+
+    private readonly RpcServiceRegistry registry = new();
+    private readonly CancellationTokenSource cts = new();
+    private readonly ConcurrentDictionary<Guid, RpcConnection> sessions = new();
+    private Task? acceptLoopTask;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="PipeRpcHost"/> class.
+    /// </summary>
+    /// <param name="pipeName">The pipe name to create.</param>
+    public PipeRpcHost(string? pipeName = null)
+    {
+        // Default pipe name based on current process ID for uniqueness per Dalamud instance.
+        this.PipeName = pipeName ?? $"DalamudRPC.{Environment.ProcessId}";
+    }
+
+    /// <summary>
+    /// Gets the name of the named pipe this RPC host is using.
+    /// </summary>
+    public string PipeName { get; }
+
+    /// <summary>Adds a local object exposing RPC methods callable by clients.</summary>
+    /// <param name="service">An arbitrary service object that will be introspected to add to RPC.</param>
+    public void AddService(object service) => this.registry.AddService(service);
+
+    /// <summary>
+    /// Adds a standalone JSON-RPC method callable by clients.
+    /// </summary>
+    /// <param name="name">The name to add.</param>
+    /// <param name="handler">The delegate that acts as the handler.</param>
+    public void AddMethod(string name, Delegate handler) => this.registry.AddMethod(name, handler);
+
+    /// <summary>Starts accepting client connections.</summary>
+    public void Start()
+    {
+        if (this.acceptLoopTask != null) return;
+        this.acceptLoopTask = Task.Run(this.AcceptLoopAsync);
+    }
+
+    /// <summary>Invoke an RPC request on a specific client expecting a result.</summary>
+    /// <param name="clientId">The client ID to invoke.</param>
+    /// <param name="method">The method to invoke.</param>
+    /// <param name="arguments">Any arguments to invoke.</param>
+    /// <returns>An optional return based on the specified RPC.</returns>
+    /// <typeparam name="T">The expected response type.</typeparam>
+    public Task<T> InvokeClientAsync<T>(Guid clientId, string method, params object[] arguments)
+    {
+        if (!this.sessions.TryGetValue(clientId, out var session))
+            throw new KeyNotFoundException($"No client {clientId}");
+
+        return session.Rpc.InvokeAsync<T>(method, arguments);
+    }
+
+    /// <summary>Send a notification to all connected clients (no response expected).</summary>
+    /// <param name="method">The method name to broadcast.</param>
+    /// <param name="arguments">The arguments to broadcast.</param>
+    /// <returns>Returns a Task when completed.</returns>
+    public Task BroadcastNotifyAsync(string method, params object[] arguments)
+    {
+        var list = this.sessions.Values;
+        var tasks = new List<Task>(list.Count);
+        foreach (var s in list)
+        {
+            tasks.Add(s.Rpc.NotifyAsync(method, arguments));
+        }
+
+        return Task.WhenAll(tasks);
+    }
+
+    /// <summary>
+    /// Gets a list of connected client IDs.
+    /// </summary>
+    /// <returns>Connected client IDs.</returns>
+    public IReadOnlyCollection<Guid> GetClientIds() => this.sessions.Keys.AsReadOnlyCollection();
+
+    /// <inheritdoc/>
+    public void Dispose()
+    {
+        this.cts.Cancel();
+        this.acceptLoopTask?.Wait(1000);
+
+        foreach (var kv in this.sessions)
+        {
+            kv.Value.Dispose();
+        }
+
+        this.sessions.Clear();
+        this.cts.Dispose();
+        this.log.Information("PipeRpcHost disposed ({Pipe})", this.PipeName);
+        GC.SuppressFinalize(this);
+    }
+
+    private PipeSecurity BuildPipeSecurity()
+    {
+        var ps = new PipeSecurity();
+        ps.AddAccessRule(new PipeAccessRule(WindowsIdentity.GetCurrent().User!, PipeAccessRights.FullControl, AccessControlType.Allow));
+
+        return ps;
+    }
+
+    private async Task AcceptLoopAsync()
+    {
+        this.log.Information("PipeRpcHost starting on pipe {Pipe}", this.PipeName);
+        var token = this.cts.Token;
+        var security = this.BuildPipeSecurity();
+
+        while (!token.IsCancellationRequested)
+        {
+            NamedPipeServerStream? server = null;
+            try
+            {
+                server = NamedPipeServerStreamAcl.Create(
+                    this.PipeName,
+                    PipeDirection.InOut,
+                    NamedPipeServerStream.MaxAllowedServerInstances,
+                    PipeTransmissionMode.Message,
+                    PipeOptions.Asynchronous,
+                    65536,
+                    65536,
+                    security);
+
+                await server.WaitForConnectionAsync(token).ConfigureAwait(false);
+
+                var session = new RpcConnection(server, this.registry);
+                this.sessions.TryAdd(session.Id, session);
+
+                this.log.Debug("RPC connection created: {Id}", session.Id);
+
+                _ = session.Completion.ContinueWith(t =>
+                {
+                    this.sessions.TryRemove(session.Id, out _);
+                    this.log.Debug("RPC connection removed: {Id}", session.Id);
+                }, TaskScheduler.Default);
+            }
+            catch (OperationCanceledException)
+            {
+                server?.Dispose();
+                break;
+            }
+            catch (Exception ex)
+            {
+                server?.Dispose();
+                this.log.Error(ex, "Error in pipe accept loop");
+                await Task.Delay(500, token).ConfigureAwait(false);
+            }
+        }
+    }
+}

Dalamud/Networking/Pipes/Rpc/RpcConnection.cs

@@ -0,0 +1,92 @@
+using System.IO.Pipes;
+using System.Threading;
+using System.Threading.Tasks;
+
+using Serilog;
+using StreamJsonRpc;
+
+namespace Dalamud.Networking.Pipes.Rpc;
+
+/// <summary>
+/// A single RPC client session connected via named pipe.
+/// </summary>
+internal class RpcConnection : IDisposable
+{
+    private readonly NamedPipeServerStream pipe;
+    private readonly RpcServiceRegistry registry;
+    private readonly CancellationTokenSource cts = new();
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="RpcConnection"/> class.
+    /// </summary>
+    /// <param name="pipe">The named pipe that this connection will handle.</param>
+    /// <param name="registry">A registry of RPC services.</param>
+    public RpcConnection(NamedPipeServerStream pipe, RpcServiceRegistry registry)
+    {
+        this.Id = Guid.CreateVersion7();
+        this.pipe = pipe;
+        this.registry = registry;
+
+        var formatter = new JsonMessageFormatter();
+        var handler = new HeaderDelimitedMessageHandler(pipe, pipe, formatter);
+
+        this.Rpc = new JsonRpc(handler);
+        this.Rpc.AllowModificationWhileListening = true;
+        this.Rpc.Disconnected += this.OnDisconnected;
+        this.registry.Attach(this.Rpc);
+
+        this.Rpc.StartListening();
+    }
+
+    /// <summary>
+    /// Gets the GUID for this connection.
+    /// </summary>
+    public Guid Id { get; }
+
+    /// <summary>
+    /// Gets the JsonRpc instance for this connection.
+    /// </summary>
+    public JsonRpc Rpc { get; }
+
+    /// <summary>
+    /// Gets a task that's called on RPC completion.
+    /// </summary>
+    public Task Completion => this.Rpc.Completion;
+
+    /// <inheritdoc/>
+    public void Dispose()
+    {
+        if (!this.cts.IsCancellationRequested)
+        {
+            this.cts.Cancel();
+        }
+
+        try
+        {
+            this.Rpc.Dispose();
+        }
+        catch (Exception ex)
+        {
+            Log.Debug(ex, "Error disposing JsonRpc for client {Id}", this.Id);
+        }
+
+        try
+        {
+            this.pipe.Dispose();
+        }
+        catch (Exception ex)
+        {
+            Log.Debug(ex, "Error disposing pipe for client {Id}", this.Id);
+        }
+
+        this.cts.Dispose();
+        GC.SuppressFinalize(this);
+    }
+
+    private void OnDisconnected(object? sender, JsonRpcDisconnectedEventArgs e)
+    {
+        Log.Debug("RPC client {Id} disconnected: {Reason}", this.Id, e.Description);
+        this.registry.Detach(this.Rpc);
+        this.Dispose();
+    }
+}

Dalamud/Networking/Pipes/Rpc/RpcHostService.cs

@@ -0,0 +1,49 @@
+using Dalamud.Logging.Internal;
+
+namespace Dalamud.Networking.Pipes.Rpc;
+
+/// <summary>
+/// The Dalamud service repsonsible for hosting the RPC.
+/// </summary>
+[ServiceManager.EarlyLoadedService]
+internal class RpcHostService : IServiceType, IInternalDisposableService
+{
+    private readonly ModuleLog log = new("RPC");
+    private readonly PipeRpcHost host;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="RpcHostService"/> class.
+    /// </summary>
+    [ServiceManager.ServiceConstructor]
+    public RpcHostService()
+    {
+        this.host = new PipeRpcHost();
+        this.host.Start();
+
+        this.log.Information("RpcHostService started on pipe {Pipe}", this.host.PipeName);
+    }
+
+    /// <summary>
+    /// Gets the RPC host to drill down.
+    /// </summary>
+    public PipeRpcHost Host => this.host;
+
+    /// <summary>
+    /// Add a new service Object to the RPC host.
+    /// </summary>
+    /// <param name="service">The object to add.</param>
+    public void AddService(object service) => this.host.AddService(service);
+
+    /// <summary>
+    /// Add a new standalone method to the RPC host.
+    /// </summary>
+    /// <param name="name">The method name to add.</param>
+    /// <param name="handler">The handler to add.</param>
+    public void AddMethod(string name, Delegate handler) => this.host.AddMethod(name, handler);
+
+    /// <inheritdoc/>
+    public void DisposeService()
+    {
+        this.host.Dispose();
+    }
+}

Dalamud/Networking/Pipes/Rpc/RpcServiceRegistry.cs

@@ -0,0 +1,85 @@
+using System.Collections.Generic;
+using System.Threading;
+
+using StreamJsonRpc;
+
+namespace Dalamud.Networking.Pipes.Rpc;
+
+/// <summary>
+/// Thread-safe registry of local RPC target objects that are exposed to every connected JsonRpc session.
+/// New sessions get all previously registered targets; newly added targets are attached to all active sessions.
+/// </summary>
+internal class RpcServiceRegistry
+{
+    private readonly Lock sync = new();
+    private readonly List<object> targets = [];
+    private readonly List<(string Name, Delegate Handler)> methods = [];
+    private readonly List<JsonRpc> activeRpcs = [];
+
+    /// <summary>
+    /// Registers a new local RPC target object. Its public JSON-RPC methods become callable by clients.
+    /// Adds <paramref name="service"/> to the registry and attaches it to all active RPC sessions.
+    /// </summary>
+    /// <param name="service">The service instance containing JSON-RPC callable methods to expose.</param>
+    public void AddService(object service)
+    {
+        lock (this.sync)
+        {
+            this.targets.Add(service);
+            foreach (var rpc in this.activeRpcs)
+            {
+                rpc.AddLocalRpcTarget(service);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Registers a new standalone JSON-RPC method.
+    /// </summary>
+    /// <param name="name">The name of the method to add.</param>
+    /// <param name="handler">The handler to add.</param>
+    public void AddMethod(string name, Delegate handler)
+    {
+        lock (this.sync)
+        {
+            this.methods.Add((name, handler));
+            foreach (var rpc in this.activeRpcs)
+            {
+                rpc.AddLocalRpcMethod(name, handler);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Attaches a JsonRpc instance <paramref name="rpc"/> to the registry so it receives all existing service targets.
+    /// </summary>
+    /// <param name="rpc">The JsonRpc instance to attach and populate with current targets.</param>
+    internal void Attach(JsonRpc rpc)
+    {
+        lock (this.sync)
+        {
+            this.activeRpcs.Add(rpc);
+            foreach (var t in this.targets)
+            {
+                rpc.AddLocalRpcTarget(t);
+            }
+
+            foreach (var m in this.methods)
+            {
+                rpc.AddLocalRpcMethod(m.Name, m.Handler);
+            }
+        }
+    }
+
+    /// <summary>
+    /// Detaches a JsonRpc instance <paramref name="rpc"/> from the registry (e.g. when a client disconnects).
+    /// </summary>
+    /// <param name="rpc">The JsonRpc instance being detached.</param>
+    internal void Detach(JsonRpc rpc)
+    {
+        lock (this.sync)
+        {
+            this.activeRpcs.Remove(rpc);
+        }
+    }
+}

Dalamud/Plugin/Services/IPluginLinkHandler.cs

@@ -0,0 +1,20 @@
+using Dalamud.Networking.Pipes;
+
+namespace Dalamud.Plugin.Services;
+
+/// <summary>
+/// A service to allow plugins to subscribe to dalamud:// URIs targeting them. Plugins will receive any URI sent to the
+/// <code>dalamud://plugin/{PLUGIN_INTERNAL_NAME}/...</code> namespace.
+/// </summary>
+public interface IPluginLinkHandler
+{
+    /// <summary>
+    /// A delegate containing the received URI.
+    /// </summary>
+    delegate void PluginUriReceived(DalamudUri uri);
+
+    /// <summary>
+    /// The event fired when a URI targeting this plugin is received.
+    /// </summary>
+    event PluginUriReceived OnUriReceived;
+}

Directory.Packages.props

@@ -3,11 +3,13 @@
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
     <CentralPackageVersionOverrideEnabled>false</CentralPackageVersionOverrideEnabled>
   </PropertyGroup>
+
   <ItemGroup>
     <!-- Analyzers -->
     <PackageVersion Include="Microsoft.CodeAnalysis.BannedApiAnalyzers" Version="3.3.4" />
     <PackageVersion Include="StyleCop.Analyzers" Version="1.2.0-beta.556" />
     <PackageVersion Include="JetBrains.Annotations" Version="2025.2.2" />
+
     <!-- Misc Libraries -->
     <PackageVersion Include="BitFaster.Caching" Version="2.4.1" />
     <PackageVersion Include="CheapLoc" Version="1.1.8" />
@@ -22,26 +24,35 @@
     <PackageVersion Include="System.Resources.Extensions" Version="10.0.0" />
     <PackageVersion Include="DotNet.ReproducibleBuilds" Version="1.2.39" />
     <PackageVersion Include="sqlite-net-pcl" Version="1.8.116" />
+
     <!-- DirectX / Win32 -->
     <PackageVersion Include="TerraFX.Interop.Windows" Version="10.0.22621.2" />
     <PackageVersion Include="SharpDX.Direct3D11" Version="4.2.0" />
     <PackageVersion Include="SharpDX.Mathematics" Version="4.2.0" />
     <PackageVersion Include="Microsoft.Windows.CsWin32" Version="0.3.183" />
+
     <!-- Logging -->
     <PackageVersion Include="Serilog" Version="4.0.2" />
     <PackageVersion Include="Serilog.Sinks.Async" Version="2.0.0" />
     <PackageVersion Include="Serilog.Sinks.Console" Version="6.0.0" />
     <PackageVersion Include="Serilog.Sinks.File" Version="6.0.0" />
+
     <!-- Injector Utilities -->
     <PackageVersion Include="Iced" Version="1.17.0" />
     <PackageVersion Include="PeNet" Version="2.6.4" />
+
     <!-- HexaGen -->
     <PackageVersion Include="HexaGen.Runtime" Version="1.1.20" />
+
     <!-- Reloaded -->
     <PackageVersion Include="goatcorp.Reloaded.Hooks" Version="4.2.0-goatcorp7" />
     <PackageVersion Include="goatcorp.Reloaded.Assembler" Version="1.0.14-goatcorp5" />
     <PackageVersion Include="Reloaded.Memory" Version="7.0.0" />
     <PackageVersion Include="Reloaded.Memory.Buffers" Version="2.0.0" />
+
+    <!-- Named Pipes / RPC -->
+    <PackageVersion Include="StreamJsonRpc" Version="2.22.23" />
+
     <!-- Unit Testing -->
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="16.10.0" />
     <PackageVersion Include="xunit" Version="2.4.1" />
@@ -54,4 +65,4 @@
     <PackageVersion Include="xunit.runner.console" Version="2.4.1" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.4.3" />
   </ItemGroup>
-</Project>
+</Project>