Fix NuGet fallback folder packages

- Creates a `Godot.Offline.Config` file to configurate NuGet with
Godot's fallback folder. This is easier because now we can assume we can
override the entire file since user config will likely be in the default
`NuGet.Config` file or an additional `*.config` file.
- Ensure the NuGet fallback folder is created at the same time it is
added to the NuGet configuration so future builds don't fail.
- Add `GodotSharp` and `GodotSharpEditor` packages to the fallback folder.
- Add `.nupkg.metadata` file to packages in fallback folder.
- Refer to `Godot.SourceGenerators` using the specific non-floating version
since floating versions don't seem to work with fallbackPackageFolders.

modules/mono/editor/Godot.NET.Sdk/Godot.NET.Sdk/Sdk/Sdk.targets

@@ -17,7 +17,7 @@
 
   <!-- C# source generators -->
   <ItemGroup Condition=" '$(DisableImplicitGodotGeneratorReferences)' != 'true' ">
-    <PackageReference Include="Godot.SourceGenerators" Version="$(PackageFloatingVersion_Godot)" />
+    <PackageReference Include="Godot.SourceGenerators" Version="$(PackageVersion_Godot_SourceGenerators)" />
   </ItemGroup>
 
   <!-- Godot API references -->

modules/mono/editor/GodotTools/GodotTools.Shared/GenerateGodotNupkgsVersions.targets

@@ -21,10 +21,13 @@
           Outputs="$(GeneratedGodotNupkgsVersionsFile)">
     <PropertyGroup>
       <GenerateGodotNupkgsVersionsCode><![CDATA[
-namespace $(RootNamespace) {
+namespace $(RootNamespace)
-    public class GeneratedGodotNupkgsVersions {
+{
+    public class GeneratedGodotNupkgsVersions
+    {
         public const string GodotNETSdk = "$(PackageVersion_Godot_NET_Sdk)"%3b
         public const string GodotSourceGenerators = "$(PackageVersion_Godot_SourceGenerators)"%3b
+        public const string GodotSharp = "$(PackageVersion_GodotSharp)"%3b
     }
 }
 ]]></GenerateGodotNupkgsVersionsCode>

modules/mono/editor/GodotTools/GodotTools/Build/NuGetUtils.cs

@@ -22,71 +22,13 @@ namespace GodotTools.Build
         public static string GodotFallbackFolderPath
             => Path.Combine(GodotSharpDirs.MonoUserDir, "GodotNuGetFallbackFolder");
 
-        private static void AddFallbackFolderToNuGetConfig(string nuGetConfigPath, string name, string path)
-        {
-            var xmlDoc = new XmlDocument();
-            xmlDoc.Load(nuGetConfigPath);
-
-            const string nuGetConfigRootName = "configuration";
-
-            var rootNode = xmlDoc.DocumentElement;
-
-            if (rootNode == null)
-            {
-                // No root node, create it
-                rootNode = xmlDoc.CreateElement(nuGetConfigRootName);
-                xmlDoc.AppendChild(rootNode);
-
-                // Since this can be considered pretty much a new NuGet.Config, add the default nuget.org source as well
-                XmlElement nugetOrgSourceEntry = xmlDoc.CreateElement("add");
-                nugetOrgSourceEntry.Attributes.Append(xmlDoc.CreateAttribute("key")).Value = "nuget.org";
-                nugetOrgSourceEntry.Attributes.Append(xmlDoc.CreateAttribute("value")).Value =
-                    "https://api.nuget.org/v3/index.json";
-                nugetOrgSourceEntry.Attributes.Append(xmlDoc.CreateAttribute("protocolVersion")).Value = "3";
-                rootNode.AppendChild(xmlDoc.CreateElement("packageSources")).AppendChild(nugetOrgSourceEntry);
-            }
-            else
-            {
-                // Check that the root node is the expected one
-                if (rootNode.Name != nuGetConfigRootName)
-                    throw new FormatException("Invalid root Xml node for NuGet.Config. " +
-                                        $"Expected '{nuGetConfigRootName}' got '{rootNode.Name}'.");
-            }
-
-            var fallbackFoldersNode = rootNode["fallbackPackageFolders"] ??
-                                      rootNode.AppendChild(xmlDoc.CreateElement("fallbackPackageFolders"));
-
-            // Check if it already has our fallback package folder
-            for (var xmlNode = fallbackFoldersNode.FirstChild; xmlNode != null; xmlNode = xmlNode.NextSibling)
-            {
-                if (xmlNode.NodeType != XmlNodeType.Element)
-                    continue;
-
-                var xmlElement = (XmlElement)xmlNode;
-                if (xmlElement.Name == "add" &&
-                    xmlElement.Attributes["key"]?.Value == name &&
-                    xmlElement.Attributes["value"]?.Value == path)
-                {
-                    return;
-                }
-            }
-
-            XmlElement newEntry = xmlDoc.CreateElement("add");
-            newEntry.Attributes.Append(xmlDoc.CreateAttribute("key")).Value = name;
-            newEntry.Attributes.Append(xmlDoc.CreateAttribute("value")).Value = path;
-
-            fallbackFoldersNode.AppendChild(newEntry);
-
-            xmlDoc.Save(nuGetConfigPath);
-        }
-
         /// <summary>
-        /// Returns all the paths where the user NuGet.Config files can be found.
+        /// Returns all the paths where the Godot.Offline.Config files can be found.
         /// Does not determine whether the returned files exist or not.
         /// </summary>
-        private static string[] GetAllUserNuGetConfigFilePaths()
+        private static string[] GetAllGodotNuGetConfigFilePaths()
         {
-            // Where to find 'NuGet/NuGet.Config':
+            // Where to find 'NuGet/config/Godot.Offline.Config':
             //
             // - Mono/.NETFramework (standalone NuGet):
             //     Uses Environment.SpecialFolder.ApplicationData
@@ -98,10 +40,12 @@ namespace GodotTools.Build
 
             string applicationData = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
 
+            const string configFileName = "Godot.Offline.Config";
+
             if (Utils.OS.IsWindows)
             {
                 // %APPDATA% for both
-                return new[] { Path.Combine(applicationData, "NuGet", "NuGet.Config") };
+                return new[] { Path.Combine(applicationData, "NuGet", "config", configFileName) };
             }
 
             var paths = new string[2];
@@ -111,20 +55,20 @@ namespace GodotTools.Build
             string dotnetCliHome = Environment.GetEnvironmentVariable("DOTNET_CLI_HOME");
             if (!string.IsNullOrEmpty(dotnetCliHome))
             {
-                paths[0] = Path.Combine(dotnetCliHome, ".nuget", "NuGet", "NuGet.Config");
+                paths[0] = Path.Combine(dotnetCliHome, ".nuget", "NuGet", "config", configFileName);
             }
             else
             {
                 string home = Environment.GetEnvironmentVariable("HOME");
                 if (string.IsNullOrEmpty(home))
                     throw new InvalidOperationException("Required environment variable 'HOME' is not set.");
-                paths[0] = Path.Combine(home, ".nuget", "NuGet", "NuGet.Config");
+                paths[0] = Path.Combine(home, ".nuget", "NuGet", "config", configFileName);
             }
 
             // Mono/.NETFramework (standalone NuGet)
 
             // ApplicationData is $HOME/.config on Linux/macOS
-            paths[1] = Path.Combine(applicationData, "NuGet", "NuGet.Config");
+            paths[1] = Path.Combine(applicationData, "NuGet", "config", configFileName);
 
             return paths;
         }
@@ -141,29 +85,27 @@ namespace GodotTools.Build
         // The nuspec is not lower case inside the nupkg but must be made lower case when extracted.
 
         /// <summary>
-        /// Adds the specified fallback folder to the user NuGet.Config files,
+        /// Adds the specified fallback folder to the Godot.Offline.Config files,
         /// for both standalone NuGet (Mono/.NETFramework) and dotnet CLI NuGet.
         /// </summary>
-        public static void AddFallbackFolderToUserNuGetConfigs(string name, string path)
+        public static void AddFallbackFolderToGodotNuGetConfigs(string name, string path)
         {
-            foreach (string nuGetConfigPath in GetAllUserNuGetConfigFilePaths())
+            // Make sure the fallback folder exists to avoid error:
+            // MSB4018: The "ResolvePackageAssets" task failed unexpectedly.
+            System.IO.Directory.CreateDirectory(path);
+
+            foreach (string nuGetConfigPath in GetAllGodotNuGetConfigFilePaths())
             {
-                if (!System.IO.File.Exists(nuGetConfigPath))
+                string defaultConfig = @$"<?xml version=""1.0"" encoding=""utf-8""?>
-                {
-                    // It doesn't exist, so we create a default one
-                    const string defaultConfig = @"<?xml version=""1.0"" encoding=""utf-8""?>
 <configuration>
-  <packageSources>
+  <fallbackPackageFolders>
-    <add key=""nuget.org"" value=""https://api.nuget.org/v3/index.json"" protocolVersion=""3"" />
+    <add key=""{name}"" value=""{path}"" />
-  </packageSources>
+  </fallbackPackageFolders>
 </configuration>
 ";
                 System.IO.Directory.CreateDirectory(Path.GetDirectoryName(nuGetConfigPath));
                 System.IO.File.WriteAllText(nuGetConfigPath, defaultConfig, Encoding.UTF8); // UTF-8 with BOM
             }
-
-                AddFallbackFolderToNuGetConfig(nuGetConfigPath, name, path);
-            }
         }
 
         private static void AddPackageToFallbackFolder(string fallbackFolder,
@@ -189,6 +131,7 @@ namespace GodotTools.Build
             string destDir = Path.Combine(fallbackFolder, packageIdLower, packageVersionLower);
             string nupkgDestPath = Path.Combine(destDir, $"{packageIdLower}.{packageVersionLower}.nupkg");
             string nupkgSha512DestPath = Path.Combine(destDir, $"{packageIdLower}.{packageVersionLower}.nupkg.sha512");
+            string nupkgMetadataDestPath = Path.Combine(destDir, ".nupkg.metadata");
 
             if (File.Exists(nupkgDestPath) && File.Exists(nupkgSha512DestPath))
                 return; // Already added (for speed we don't check if every file is properly extracted)
@@ -197,12 +140,18 @@ namespace GodotTools.Build
 
             // Generate .nupkg.sha512 file
 
-            using (var alg = SHA512.Create())
+            byte[] hash = SHA512.HashData(File.ReadAllBytes(nupkgPath));
-            {
+            string base64Hash = Convert.ToBase64String(hash);
-                alg.ComputeHash(File.ReadAllBytes(nupkgPath));
-                string base64Hash = Convert.ToBase64String(alg.Hash);
             File.WriteAllText(nupkgSha512DestPath, base64Hash);
-            }
+
+            // Generate .nupkg.metadata file
+            // Spec: https://github.com/NuGet/Home/wiki/Nupkg-Metadata-File
+
+            File.WriteAllText(nupkgMetadataDestPath, @$"{{
+    ""version"": 2,
+    ""contentHash"": ""{base64Hash}"",
+    ""source"": null
+}}");
 
             // Extract nupkg
             ExtractNupkg(destDir, nupkgPath, packageId, packageVersion);
@@ -251,7 +200,7 @@ namespace GodotTools.Build
                         entryFullName.EndsWith(".nupkg.sha512", StringComparison.OrdinalIgnoreCase) ||
                         entryFullName.EndsWith(".nupkg.metadata", StringComparison.OrdinalIgnoreCase) ||
                         // Nuspec at root level. We already extracted it previously but in lower case.
-                        entryFullName.IndexOf('/') == -1 && entryFullName.EndsWith(".nuspec"))
+                        !entryFullName.Contains('/') && entryFullName.EndsWith(".nuspec"))
                     {
                         continue;
                     }
@@ -297,6 +246,8 @@ namespace GodotTools.Build
         {
             ("Godot.NET.Sdk", GeneratedGodotNupkgsVersions.GodotNETSdk),
             ("Godot.SourceGenerators", GeneratedGodotNupkgsVersions.GodotSourceGenerators),
+            ("GodotSharp", GeneratedGodotNupkgsVersions.GodotSharp),
+            ("GodotSharpEditor", GeneratedGodotNupkgsVersions.GodotSharp),
         };
     }
 }

modules/mono/editor/GodotTools/GodotTools/GodotSharpEditor.cs

@@ -123,7 +123,7 @@ namespace GodotTools
                     try
                     {
                         string fallbackFolder = NuGetUtils.GodotFallbackFolderPath;
-                        NuGetUtils.AddFallbackFolderToUserNuGetConfigs(NuGetUtils.GodotFallbackFolderName,
+                        NuGetUtils.AddFallbackFolderToGodotNuGetConfigs(NuGetUtils.GodotFallbackFolderName,
                             fallbackFolder);
                         NuGetUtils.AddBundledPackagesToFallbackFolder(fallbackFolder);
                     }
@@ -497,7 +497,7 @@ namespace GodotTools
             try
             {
                 // At startup we make sure NuGet.Config files have our Godot NuGet fallback folder included
-                NuGetUtils.AddFallbackFolderToUserNuGetConfigs(NuGetUtils.GodotFallbackFolderName,
+                NuGetUtils.AddFallbackFolderToGodotNuGetConfigs(NuGetUtils.GodotFallbackFolderName,
                     NuGetUtils.GodotFallbackFolderPath);
             }
             catch (Exception e)