From 81e2b60d65f57d1642bcc028310455a9e174b0b2 Mon Sep 17 00:00:00 2001
From: sakno <roman.sakno@gmail.com>
Date: Sat, 13 Jan 2024 21:26:25 +0200
Subject: [PATCH] Added support of username

---
 .../ApplicationMaintenanceInterfaceHost.cs    |  7 +--
 .../Principal/LinuxUdsPeerIdentity.cs         | 56 +++++++++++++++++--
 ...ommandLineMaintenanceInterfaceHostTests.cs |  7 ++-
 3 files changed, 56 insertions(+), 14 deletions(-)

diff --git a/src/DotNext.MaintenanceServices/Maintenance/ApplicationMaintenanceInterfaceHost.cs b/src/DotNext.MaintenanceServices/Maintenance/ApplicationMaintenanceInterfaceHost.cs
index abf9fe51b3..249200d797 100644
--- a/src/DotNext.MaintenanceServices/Maintenance/ApplicationMaintenanceInterfaceHost.cs
+++ b/src/DotNext.MaintenanceServices/Maintenance/ApplicationMaintenanceInterfaceHost.cs
@@ -143,12 +143,7 @@ private static IIdentity GetRemotePeerIdentity(Socket socket)
     {
         if (OperatingSystem.IsLinux() && socket.TryGetCredentials(out var processId, out var userId, out var groupId))
         {
-            return new LinuxUdsPeerIdentity()
-            {
-                ProcessId = processId,
-                UserId = userId,
-                GroupId = groupId,
-            };
+            return new LinuxUdsPeerIdentity(processId, userId, groupId);
         }
 
         return AnonymousPrincipal.Instance;
diff --git a/src/DotNext.MaintenanceServices/Security/Principal/LinuxUdsPeerIdentity.cs b/src/DotNext.MaintenanceServices/Security/Principal/LinuxUdsPeerIdentity.cs
index 50c0536bd4..1290ca4745 100644
--- a/src/DotNext.MaintenanceServices/Security/Principal/LinuxUdsPeerIdentity.cs
+++ b/src/DotNext.MaintenanceServices/Security/Principal/LinuxUdsPeerIdentity.cs
@@ -1,5 +1,7 @@
 using System.Runtime.Versioning;
 using System.Security.Principal;
+using System.Runtime.InteropServices;
+using System.Runtime.CompilerServices;
 
 namespace DotNext.Security.Principal;
 
@@ -12,11 +14,35 @@ namespace DotNext.Security.Principal;
 [CLSCompliant(false)]
 public sealed record class LinuxUdsPeerIdentity : IIdentity
 {
+    private static readonly Getpwuid? GetpwuidFunction;
+
+    static LinuxUdsPeerIdentity()
+    {
+        var getpwuid = NativeLibrary.GetExport(NativeLibrary.GetMainProgramHandle(), "getpwuid");
+        GetpwuidFunction = getpwuid is not 0
+            ? Marshal.GetDelegateForFunctionPointer<Getpwuid>(getpwuid)
+            : null;
+    }
+
     [SupportedOSPlatform("linux")]
-    internal LinuxUdsPeerIdentity()
+    internal LinuxUdsPeerIdentity(uint pid, uint uid, uint gid)
     {
         if (!OperatingSystem.IsLinux())
             throw new PlatformNotSupportedException();
+
+        ProcessId = pid;
+        UserId = uid;
+        GroupId = gid;
+
+        if (GetpwuidFunction is not null)
+        {
+            ref var passwd = ref GetpwuidFunction(uid);
+            if (!Unsafe.IsNullRef(ref passwd))
+            {
+                Name = Marshal.PtrToStringAnsi(passwd.Name);
+                DisplayName = Marshal.PtrToStringAnsi(passwd.UserInfo);
+            }
+        }
     }
 
     /// <summary>
@@ -27,21 +53,41 @@ internal LinuxUdsPeerIdentity()
     /// <summary>
     /// Gets calling process ID.
     /// </summary>
-    public uint ProcessId { get; internal init; }
+    public uint ProcessId { get; }
 
     /// <summary>
     /// Gets user ID of the process identified by <see cref="ProcessId"/>.
     /// </summary>
-    public uint UserId { get; internal init; }
+    public uint UserId { get; }
 
     /// <summary>
     /// Gets group ID of the process identified by <see cref="ProcessId"/>.
     /// </summary>
-    public uint GroupId { get; internal init; }
+    public uint GroupId { get; }
 
     /// <inheritdoc />
     string? IIdentity.AuthenticationType => "ucred";
 
     /// <inheritdoc />
-    string? IIdentity.Name => null;
+    public string? Name { get; }
+
+    /// <summary>
+    /// Gets user information, if available.
+    /// </summary>
+    public string? DisplayName { get; }
+
+    [StructLayout(LayoutKind.Sequential)]
+    private readonly struct Passwd
+    {
+        internal readonly nint Name;
+        internal readonly nint Password;
+        internal readonly uint UserId;
+        internal readonly uint GroupId;
+        internal readonly nint UserInfo;
+        internal readonly nint HomeDirectory;
+        internal readonly nint Shell;
+    }
+
+    [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+    private delegate ref Passwd Getpwuid(uint userId);
 }
\ No newline at end of file
diff --git a/src/DotNext.Tests/Maintenance/CommandLine/CommandLineMaintenanceInterfaceHostTests.cs b/src/DotNext.Tests/Maintenance/CommandLine/CommandLineMaintenanceInterfaceHostTests.cs
index 15720d1519..e19ffda56f 100644
--- a/src/DotNext.Tests/Maintenance/CommandLine/CommandLineMaintenanceInterfaceHostTests.cs
+++ b/src/DotNext.Tests/Maintenance/CommandLine/CommandLineMaintenanceInterfaceHostTests.cs
@@ -56,7 +56,7 @@ public static async Task DefaultCommandsAsync(string request, string response)
         await host.StopAsync();
     }
 
-    [PlatformSpecificFact("linux")]
+    [Fact]
     public static async Task UdsEndpointAuthentication()
     {
         var unixDomainSocketPath = Path.Combine(Path.GetTempPath(), Path.GetRandomFileName());
@@ -71,8 +71,9 @@ public static async Task UdsEndpointAuthentication()
                         command.SetHandler(static session =>
                         {
                             True(session.Identity.IsAuthenticated);
-                            IsType<LinuxUdsPeerIdentity>(session.Identity);
-                            session.ResponseWriter.Write(((LinuxUdsPeerIdentity)session.Identity).ProcessId);
+                            var identity = IsType<LinuxUdsPeerIdentity>(session.Identity);
+                            Equal(Environment.UserName, identity.Name);
+                            session.ResponseWriter.Write(identity.ProcessId);
                         },
                         DefaultBindings.Session);
                     });