fix: Fixes assembly loading. (#759)

* `AssemblyHandler.Assemblies` will now only contain assemblies listed in `assemblies.json`
* `assemblies.json` has been updated to only contain asssemblies directly loaded by the server. Namely, only `UOContent.dll`.
  * Specifically assemblies loaded by assemblies.json are subject to check for `Configure` and `Initialize` methods.
* `modernuo.json` now has a new property called `assemblyDirectories`. This will be automatically set to `Distribution/Assemblies` (absolute path on your machine).
  * You can add more directories to this list.
* All assemblies in assemblies.json _AND_ dependents of any assembly will be searched for in the directories specified by `assemblyDirectories`.

Distribution/Data/assemblies.json

@@ -1,9 +1,3 @@
 [
-  "Argon2.Bindings.dll",
-  "BouncyCastle.Crypto.dll",
-  "MailKit.dll",
-  "MimeKit.dll",
-  "Microsoft.Extensions.FileSystemGlobbing.dll",
-  "Zlib.Bindings.dll",
   "UOContent.dll"
 ]

Projects/Server/AssemblyHandler.cs

@@ -29,13 +29,71 @@ public static class AssemblyHandler
         private static TypeCache m_NullCache;
         public static Assembly[] Assemblies { get; set; }
 
-        public static void LoadScripts(string[] files)
+        internal static Assembly AssemblyResolver(object sender, ResolveEventArgs args) =>
+            LoadAssemblyByAssemblyName(args.Name);
+
+        private static void EnsureAssemblyDirectories()
+        {
+            if (ServerConfiguration.AssemblyDirectories.Count == 0)
+            {
+                ServerConfiguration.AssemblyDirectories.Add(Path.Combine(Core.BaseDirectory, "Assemblies"));
+                ServerConfiguration.Save();
+            }
+        }
+
+        public static Assembly LoadAssemblyByAssemblyName(string fullAssemblyName)
+        {
+            var assemblyName = new AssemblyName(fullAssemblyName);
+            var assemblyFile = $"{assemblyName.Name}.dll";
+
+            EnsureAssemblyDirectories();
+            var assemblyDirectories = ServerConfiguration.AssemblyDirectories;
+
+            foreach (var assemblyDir in assemblyDirectories)
+            {
+                var assemblyPath = Path.Combine(assemblyDir, assemblyFile);
+                if (File.Exists(assemblyPath))
+                {
+                    var assemblyNameCheck = AssemblyName.GetAssemblyName(assemblyPath);
+                    if (assemblyNameCheck.FullName == assemblyName.FullName)
+                    {
+                        return AssemblyLoadContext.Default.LoadFromAssemblyPath(assemblyPath);
+                    }
+                }
+            }
+
+            return null;
+        }
+
+        public static Assembly LoadAssemblyByFileName(string assemblyFile)
+        {
+            EnsureAssemblyDirectories();
+            var assemblyDirectories = ServerConfiguration.AssemblyDirectories;
+
+            foreach (var assemblyDir in assemblyDirectories)
+            {
+                var assemblyPath = Path.Combine(assemblyDir, assemblyFile);
+                if (File.Exists(assemblyPath))
+                {
+                    return AssemblyLoadContext.Default.LoadFromAssemblyPath(assemblyPath);
+                }
+            }
+
+            return null;
+        }
+
+        public static void LoadAssemblies(string[] files)
         {
             var assemblies = new Assembly[files.Length];
 
             for (var i = 0; i < files.Length; i++)
             {
-                assemblies[i] = AssemblyLoadContext.Default.LoadFromAssemblyPath(files[i]);
+                var assembly = LoadAssemblyByFileName(files[i]);
+                if (assembly == null)
+                {
+                    throw new FileNotFoundException($"Could not load {files[i]}");
+                }
+                assemblies[i] = LoadAssemblyByFileName(files[i]);
             }
 
             Assemblies = assemblies;

Projects/Server/Configuration/ServerConfiguration.cs

@@ -32,6 +32,8 @@ public static class ServerConfiguration
         private static ServerSettings m_Settings;
         private static bool m_Mocked;
 
+        public static List<string> AssemblyDirectories => m_Settings.AssemblyDirectories;
+
         public static List<string> DataDirectories => m_Settings.DataDirectories;
 
         public static List<IPEndPoint> Listeners => m_Settings.Listeners;

Projects/Server/Configuration/ServerSettings.cs

@@ -21,6 +21,9 @@ namespace Server
 {
     public class ServerSettings
     {
+        [JsonPropertyName("assemblyDirectories")]
+        public List<string> AssemblyDirectories { get; set; } = new();
+
         [JsonPropertyName("dataDirectories")]
         public List<string> DataDirectories { get; set; } = new();
 

Projects/Server/Main.cs

@@ -365,6 +365,7 @@ public static void Main(string[] args)
         {
             AppDomain.CurrentDomain.UnhandledException += CurrentDomain_UnhandledException;
             AppDomain.CurrentDomain.ProcessExit += CurrentDomain_ProcessExit;
+            AppDomain.CurrentDomain.AssemblyResolve += AssemblyHandler.AssemblyResolver;
 
             LoopContext = new EventLoopContext();
 
@@ -463,7 +464,7 @@ You should have received a copy of the GNU General Public License
                 assemblyFiles[i] = Path.Join(BaseDirectory, "Assemblies", assemblyFiles[i]);
             }
 
-            AssemblyHandler.LoadScripts(assemblyFiles);
+            AssemblyHandler.LoadAssemblies(assemblyFiles);
 
             VerifySerialization();