Improved LdapService thread safety, fixed user images sometimes not loading

src/Controllers/HomeController.cs

@@ -98,7 +98,6 @@ public class HomeController : Controller
     [ResponseCache(Duration = 3600, Location = ResponseCacheLocation.Any, VaryByQueryKeys = new[] { "uid", "size" })]
     public async Task<IActionResult> UserPhotoAsync(string uid, int? size)
     {
-        Task<AdminSettingsModel> adminSettingsModelTask = _ldap.GetAdminSettingsModelAsync();
         UserModel? user = await _ldap.GetUserByUidAsync(uid, _ldap.UsersAttributes);
         if (user is null || user.JpegPhoto is null || user.JpegPhoto == "")
         {
@@ -110,7 +109,7 @@ public class HomeController : Controller
         }
         if (size is not null)
         {
-            AdminSettingsModel adminSettingsModel = await adminSettingsModelTask;
+            AdminSettingsModel adminSettingsModel = await _ldap.GetAdminSettingsModelAsync();
             size = Math.Min((int)size, adminSettingsModel.MaxDownloadableUserImageSize);
         }
         byte[] encodedFile = ImageHelper.ResizeAndConvertToWebp(user.JpegPhoto, size ?? 32);

src/Services/LdapService.cs

@@ -11,6 +11,7 @@ public partial class LdapService : IDisposable
 {
     private readonly LdapConfig _opts;
     private readonly LdapConnection _conn;
+    private readonly SemaphoreSlim _connLock = new(1, 1);
     private AdminSettingsModel? adminSettingsModel;
     private ILogger _logger;
 
@@ -27,6 +28,9 @@ public partial class LdapService : IDisposable
         int retries = 0;
         while (retries++ < _opts.ConnectionRetryCount)
         {
+            try
+            {
+                await _connLock.WaitAsync();
                 try
                 {
                     if (!_conn.Connected)
@@ -42,6 +46,11 @@ public partial class LdapService : IDisposable
                         }
                     }
                     await _conn.BindAsync(_opts.BindDn, _opts.BindPassword);
+                }
+                finally
+                {
+                    _connLock.Release();
+                }
                 return;
             }
             catch (Exception ex)
@@ -109,7 +118,7 @@ public partial class LdapService : IDisposable
                 LdapModification.Replace,
                 new LdapAttribute("description", targetText)
             );
-            await _conn.ModifyAsync(dn, modification);
+            await ModifyAsync(dn, modification);
         }
         catch (Exception)
         {
@@ -151,7 +160,7 @@ public partial class LdapService : IDisposable
                 LdapModification.Replace,
                 new LdapAttribute("description", targetText)
             );
-            await _conn.ModifyAsync(dn, modification);
+            await ModifyAsync(dn, modification);
         }
         catch (Exception)
         {
@@ -201,7 +210,7 @@ public partial class LdapService : IDisposable
                 LdapModification.Replace,
                 new LdapAttribute("description", targetText)
             );
-            await _conn.ModifyAsync(dn, modification);
+            await ModifyAsync(dn, modification);
         }
         catch (Exception)
         {
@@ -387,16 +396,17 @@ public async Task CreateAsset(LdapAttributeSet attributeSet)
     }
 
     public async Task<IEnumerable<Dictionary<string, string>>> ListObjectBy(string baseDn, string filter, string[] attributes)
-    {
-        return await Task.Run(async () =>
     {
         await ConnectAndBind();
+        await _connLock.WaitAsync();
+        try
+        {
             var search = await _conn.SearchAsync(
                 baseDn,
                 LdapConnection.ScopeSub,
                 $"{filter}",
                 attributes,
-                false);
+                false).ConfigureAwait(false);
             var list = new List<Dictionary<string, string>>();
             while (await search.HasMoreAsync())
             {
@@ -415,7 +425,11 @@ public async Task CreateAsset(LdapAttributeSet attributeSet)
                 catch (LdapException) { }
             }
             return list;
-        });
+        }
+        finally
+        {
+            _connLock.Release();
+        }
     }
 
     public async Task DeleteUserAsync(string uid)
@@ -467,16 +481,24 @@ public async Task CreateAsset(LdapAttributeSet attributeSet)
         await ConnectAndBind();
         string dn = PrependRDN($"{rdnKey}={rdnValue}", baseDn);
         if (attributeName == rdnKey)
+        {
+            await _connLock.WaitAsync();
+            try
             {
                 await _conn.RenameAsync(dn, $"{rdnKey}={attributeValue}", true);
             }
+            finally
+            {
+                _connLock.Release();
+            }
+        }
         else
         {
             var modification = new LdapModification(
                 LdapModification.Replace,
                 new LdapAttribute(attributeName, attributeValue)
             );
-            await _conn.ModifyAsync(dn, modification);
+            await ModifyAsync(dn, modification);
         }
     }
 
@@ -490,24 +512,48 @@ public async Task CreateAsset(LdapAttributeSet attributeSet)
             new LdapAttribute(attributeName)
         );
 
-        await _conn.ModifyAsync(dn, modification);
+        await ModifyAsync(dn, modification);
     }
 
     public async Task DeleteObjectByDnAsync(string dn)
+    {
+        await _connLock.WaitAsync();
+        try
         {
             await _conn.DeleteAsync(dn);
         }
+        finally
+        {
+            _connLock.Release();
+        }
+    }
 
     public async Task CreateObject(string dn, LdapAttributeSet attributeSet)
     {
         await ConnectAndBind();
         LdapEntry ldapEntry = new(dn, attributeSet);
+        await _connLock.WaitAsync();
+        try
+        {
             await _conn.AddAsync(ldapEntry);
         }
-
+        finally
-    public async Task ModifyAsync(string dn, LdapModification ldapModification)
         {
-        await _conn.ModifyAsync(dn, ldapModification);
+            _connLock.Release();
+        }
+    }
+
+    public async Task ModifyAsync(string dn, LdapModification mod, CancellationToken ct = default)
+    {
+        await _connLock.WaitAsync(ct);
+        try
+        {
+            await _conn.ModifyAsync(dn, mod, ct);
+        }
+        finally
+        {
+            _connLock.Release();
+        }
     }
 
     public void Dispose()