From e9d0b7329650b23b66e97e1f892cd701a5130c10 Mon Sep 17 00:00:00 2001
From: Sardelka <sardelka9515@gmail.com>
Date: Sat, 9 Jul 2022 09:55:12 +0800
Subject: [PATCH] Add managed and loaded assembly check

---
 RageCoop.Server/Scripting/ServerResource.cs | 63 ++++++++++++++++++++-
 1 file changed, 61 insertions(+), 2 deletions(-)

diff --git a/RageCoop.Server/Scripting/ServerResource.cs b/RageCoop.Server/Scripting/ServerResource.cs
index 12007d4..e05a81c 100644
--- a/RageCoop.Server/Scripting/ServerResource.cs
+++ b/RageCoop.Server/Scripting/ServerResource.cs
@@ -64,9 +64,20 @@ namespace RageCoop.Server.Scripting
 					IsDirectory=false,
 					Name=relativeName
 				};
-				if (file.EndsWith(".dll"))
+				if (file.EndsWith(".dll") && IsManagedAssembly(file))
 				{
-					r.LoadScriptsFromAssembly(rfile, r.LoadAssemblyFromPath(Path.GetFullPath(file)));
+                    try
+                    {
+						r.LoadScriptsFromAssembly(rfile, r.LoadAssemblyFromPath(Path.GetFullPath(file)));
+					}
+					catch(FileLoadException ex)
+                    {
+						if(!ex.Message.EndsWith("Assembly with same name is already loaded"))
+                        {
+							logger?.Warning("Failed to load assembly: "+Path.GetFileName(file));
+							logger?.Trace(ex.Message);
+                        }
+                    }
 				}
 				r.Files.Add(relativeName, rfile);
 			}
@@ -150,6 +161,54 @@ namespace RageCoop.Server.Scripting
 		{
 			base.Dispose();
 		}
+		private static bool IsManagedAssembly(string filename)
+		{
+			try
+			{
+				using (Stream file = new FileStream(filename, FileMode.Open, FileAccess.Read))
+				{
+					if (file.Length < 64)
+						return false;
 
+					using (BinaryReader bin = new BinaryReader(file))
+					{
+						// PE header starts at offset 0x3C (60). Its a 4 byte header.
+						file.Position = 0x3C;
+						uint offset = bin.ReadUInt32();
+						if (offset == 0)
+							offset = 0x80;
+
+						// Ensure there is at least enough room for the following structures:
+						//     24 byte PE Signature & Header
+						//     28 byte Standard Fields         (24 bytes for PE32+)
+						//     68 byte NT Fields               (88 bytes for PE32+)
+						// >= 128 byte Data Dictionary Table
+						if (offset > file.Length - 256)
+							return false;
+
+						// Check the PE signature. Should equal 'PE\0\0'.
+						file.Position = offset;
+						if (bin.ReadUInt32() != 0x00004550)
+							return false;
+
+						// Read PE magic number from Standard Fields to determine format.
+						file.Position += 20;
+						var peFormat = bin.ReadUInt16();
+						if (peFormat != 0x10b /* PE32 */ && peFormat != 0x20b /* PE32Plus */)
+							return false;
+
+						// Read the 15th Data Dictionary RVA field which contains the CLI header RVA.
+						// When this is non-zero then the file contains CLI data otherwise not.
+						file.Position = offset + (peFormat == 0x10b ? 232 : 248);
+						return bin.ReadUInt32() != 0;
+					}
+				}
+			}
+			catch
+			{
+				// This is likely not a valid assembly if any IO exceptions occur during reading
+				return false;
+			}
+		}
 	}
 }