also build for net472, load correct openssl in net472

Author: jogibear9988

src/DriverTest/DriverTest.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFrameworks>net472;net8.0</TargetFrameworks>
     <OutputType>Exe</OutputType>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
   </PropertyGroup>

src/S7CommPlusDriver/OpenSSL/Native.cs

@@ -25,6 +25,22 @@ namespace OpenSsl
 
     public class Native
     {
+#if NET472
+        [DllImport("kernel32.dll")]
+        private static extern IntPtr LoadLibrary(string dllToLoad);
+
+        static Native()
+        {
+            var path = new Uri(typeof(Native).Assembly.CodeBase).LocalPath;
+            var folder = Path.GetDirectoryName(path);
+
+            var is64 = IntPtr.Size == 8;
+            var subfolder = is64 ? "x64" : "x86";
+
+            LoadLibrary(Path.Combine(folder, subfolder, DLLNAME + ".dll"));
+            LoadLibrary(Path.Combine(folder, subfolder, SSLDLLNAME + ".dll"));
+        }
+#else
         static Native()
         {
             NativeLibrary.SetDllImportResolver(Assembly.GetExecutingAssembly(), DllImportResolver);
@@ -43,6 +59,7 @@ private static IntPtr DllImportResolver(string libraryName, Assembly assembly, D
             // Otherwise, fallback to default import resolver.
             return IntPtr.Zero;
         }
+#endif
 
         const string DLLNAME = "libcrypto-3";
         const string SSLDLLNAME = "libssl-3";

src/S7CommPlusDriver/S7CommPlusDriver.csproj

@@ -1,8 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net8.0</TargetFrameworks>
+    <TargetFrameworks>net8.0;net472</TargetFrameworks>
     <OutputType>Library</OutputType>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
+    <LangVersion>9.0</LangVersion>
   </PropertyGroup>
   <PropertyGroup>
     <StartupObject />

src/S7CommPlusGUIBrowser/S7CommPlusGUIBrowser.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFramework>net8.0-windows</TargetFramework>
+    <TargetFrameworks>net472;net8.0-windows</TargetFrameworks>
     <OutputType>WinExe</OutputType>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <UseWindowsForms>true</UseWindowsForms>

src/Zlib.net/Zlib.net.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net8.0</TargetFrameworks>
+    <TargetFrameworks>net8.0;net472</TargetFrameworks>
     <ProjectType>Local</ProjectType>
     <AssemblyKeyContainerName />
     <AssemblyOriginatorKeyFile />
@@ -12,6 +12,7 @@
     <RootNamespace>zlib</RootNamespace>
     <RunPostBuildEvent>OnBuildSuccess</RunPostBuildEvent>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
+    <LangVersion>9.0</LangVersion>
   </PropertyGroup>
   <ItemGroup>
     <Reference Update="System">