Protocol: handle org.freedesktop.DBus.Peer methods. (#221)

tmds · Jan 18, 2024 · 2c9eb4c · 2c9eb4c
1 parent a59736c
commit 2c9eb4c
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Showing 6 changed files with 90 additions and 14 deletions.
diff --git a/src/Tmds.DBus.Protocol/DBusConnection.cs b/src/Tmds.DBus.Protocol/DBusConnection.cs
@@ -6,7 +6,7 @@
 
 namespace Tmds.DBus.Protocol;
 
-class DBusConnection : IDisposable
+class DBusConnection : IDisposable, IMethodHandler
 {
     private delegate void MessageReceivedHandler(Exception? exception, Message message, object? state);
 
@@ -316,7 +316,12 @@ private async void HandleMessages(Exception? exception, Message message)
 
                         if (isMethodCall)
                         {
-                            if (message.PathIsSet)
+                            if (message.InterfaceIsSet &&
+                                message.Interface.SequenceEqual("org.freedesktop.DBus.Peer"u8))
+                            {
+                                methodHandler = this;
+                            }
+                            else if (message.PathIsSet)
                             {
                                 _pathHandlers.TryGetValue(message.PathAsString!, out methodHandler);
                             }
@@ -1255,4 +1260,28 @@ MessageBuffer CreateErrorMessage(Message methodCall, string errorName, string er
             return writer.CreateMessage();
         }
     }
+
+    string IMethodHandler.Path => throw new NotSupportedException();
+
+    ValueTask IMethodHandler.HandleMethodAsync(MethodContext context)
+    {
+        if (context.Request.Interface.SequenceEqual("org.freedesktop.DBus.Peer"u8))
+        {
+            if (context.Request.Member.SequenceEqual("Ping"u8))
+            {
+                using var writer = context.CreateReplyWriter(null);
+                context.Reply(writer.CreateMessage());
+            }
+            else if (context.Request.Member.SequenceEqual("GetMachineId"u8))
+            {
+                using var writer = context.CreateReplyWriter("s");
+                writer.WriteString(DBusEnvironment.MachineId);
+                context.Reply(writer.CreateMessage());
+            }
+        }
+        return default;
+    }
+
+    bool IMethodHandler.RunMethodHandlerSynchronously(Message message)
+        => true;
 }
diff --git a/src/Tmds.DBus.Protocol/DBusEnvironment.cs b/src/Tmds.DBus.Protocol/DBusEnvironment.cs
@@ -21,20 +21,27 @@ static class DBusEnvironment
         }
     }
 
+    private static string? _machineId;
+
     public static string MachineId
     {
         get
         {
-            const string MachineUuidPath = @"/var/lib/dbus/machine-id";
-
-            if (File.Exists(MachineUuidPath))
+            if (_machineId == null)
             {
-                return Guid.Parse(File.ReadAllText(MachineUuidPath).Substring(0, 32)).ToString();
-            }
-            else
-            {
-                return Guid.Empty.ToString();
+                const string MachineUuidPath = @"/var/lib/dbus/machine-id";
+
+                if (File.Exists(MachineUuidPath))
+                {
+                    _machineId = Guid.Parse(File.ReadAllText(MachineUuidPath).Substring(0, 32)).ToString("N");
+                }
+                else
+                {
+                    _machineId = Guid.Empty.ToString("N");
+                }
             }
+
+            return _machineId;
         }
     }
 

diff --git a/src/Tmds.DBus.Protocol/IMethodHandler.cs b/src/Tmds.DBus.Protocol/IMethodHandler.cs
@@ -27,7 +27,7 @@ internal MethodContext(Connection connection, Message request)
 
     public bool NoReplyExpected => (Request.MessageFlags & MessageFlags.NoReplyExpected) != 0;
 
-    public MessageWriter CreateReplyWriter(string signature)
+    public MessageWriter CreateReplyWriter(string? signature)
     {
         var writer = Connection.GetMessageWriter();
         writer.WriteMethodReturnHeader(

diff --git a/src/Tmds.DBus.Protocol/Tmds.DBus.Protocol.csproj b/src/Tmds.DBus.Protocol/Tmds.DBus.Protocol.csproj
@@ -4,7 +4,7 @@
     <TargetFrameworks>netstandard2.0;netstandard2.1;net6.0</TargetFrameworks>
     <Nullable>enable</Nullable>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <LangVersion>10</LangVersion>
+    <LangVersion>11</LangVersion>
   </PropertyGroup>
 
   <PropertyGroup>

diff --git a/src/Tmds.DBus/Environment.cs b/src/Tmds.DBus/Environment.cs
@@ -41,11 +41,11 @@ public static string MachineId
                 }
                 if (File.Exists(MachineUuidPath))
                 {
-                    _machineId = Guid.Parse(File.ReadAllText(MachineUuidPath).Substring(0, 32)).ToString();
+                    _machineId = Guid.Parse(File.ReadAllText(MachineUuidPath).Substring(0, 32)).ToString("N");
                 }
                 else
                 {
-                    _machineId = Guid.Empty.ToString();
+                    _machineId = Guid.Empty.ToString("N");
                 }
                 return _machineId;
             }

diff --git a/test/Tmds.DBus.Protocol.Tests/ConnectionTests.cs b/test/Tmds.DBus.Protocol.Tests/ConnectionTests.cs
@@ -95,6 +95,46 @@ public async Task UnreachableAddressAsync(string address)
             }
         }
 
+        [Fact]
+        public async Task ConnectionRespondsToDBusPeerPing()
+        {
+            var connections = PairedConnection.CreatePair();
+            using var conn1 = connections.Item1;
+            using var conn2 = connections.Item2;
+
+            await conn1.CallMethodAsync(CreateMessage());
+
+            MessageBuffer CreateMessage()
+            {
+                using var writer = conn1.GetMessageWriter();
+                writer.WriteMethodCallHeader(
+                    @interface: "org.freedesktop.DBus.Peer",
+                    member: "Ping");
+                return writer.CreateMessage();
+            }
+        }
+
+        [Fact]
+        public async Task ConnectionRespondsToDBusPeerGetMachineId()
+        {
+            var connections = PairedConnection.CreatePair();
+            using var conn1 = connections.Item1;
+            using var conn2 = connections.Item2;
+
+            string machineId = await conn1.CallMethodAsync(CreateMessage(), (Message m, object? s) => m.GetBodyReader().ReadString(), null);
+            Assert.Equal(32, machineId.Length);
+            Assert.True(Guid.TryParse(machineId, out _));
+
+            MessageBuffer CreateMessage()
+            {
+                using var writer = conn1.GetMessageWriter();
+                writer.WriteMethodCallHeader(
+                    @interface: "org.freedesktop.DBus.Peer",
+                    member: "GetMachineId");
+                return writer.CreateMessage();
+            }
+        }
+
         static class HelloWorldConstants
         {
             public const string Path = "/path";