在Windows上使ASP.NET Core服务器（Kestrel）区分大小写

Question

在Linux容器中运行的ASP.NET核心应用程序使用区分大小写的文件系统，这意味着CSS和JS文件引用必须是大小写正确的。

但是，Windows文件系统不区分大小写。因此，在开发过程中，您可以使用错误的大小写引用CSS和JS文件，但它们可以正常工作。所以在Windows开发过程中你不会知道你的应用程序在Linux服务器上运行时会破坏。

反正有没有让Windows上的Kestrel区分大小写，以便我们可以在上线之前获得一致的行为并找到参考错误？

Answer 1

我修复了使用ASP.NET Core中的中间件。而不是我使用的标准app.UseStaticFiles()：

 if (env.IsDevelopment()) app.UseStaticFilesCaseSensitive();
 else app.UseStaticFiles();

并将该方法定义为：

/// <summary>
/// Enforces case-correct requests on Windows to make it compatible with Linux.
/// </summary>
public static IApplicationBuilder UseStaticFilesCaseSensitive(this IApplicationBuilder app)
{
    var fileOptions = new StaticFileOptions
    {
        OnPrepareResponse = x =>
        {
            if (!x.File.PhysicalPath.AsFile().Exists()) return;
            var requested = x.Context.Request.Path.Value;
            if (requested.IsEmpty()) return;

            var onDisk = x.File.PhysicalPath.AsFile().GetExactFullName().Replace("\\", "/");
            if (!onDisk.EndsWith(requested))
            {
                throw new Exception("The requested file has incorrect casing and will fail on Linux servers." +
                    Environment.NewLine + "Requested:" + requested + Environment.NewLine +
                    "On disk: " + onDisk.Right(requested.Length));
            }
        }
    };

    return app.UseStaticFiles(fileOptions);
}

其中还使用：

public static string GetExactFullName(this FileSystemInfo @this)
{
    var path = @this.FullName;
    if (!File.Exists(path) && !Directory.Exists(path)) return path;

    var asDirectory = new DirectoryInfo(path);
    var parent = asDirectory.Parent;

    if (parent == null) // Drive:
        return asDirectory.Name.ToUpper();

    return Path.Combine(parent.GetExactFullName(), parent.GetFileSystemInfos(asDirectory.Name)[0].Name);
}

Answer 2

它可能在Windows 7而不是windows 10，据我所知，它在Windows Server上根本不可能。

我只能谈论操作系统，因为Kestrel文档说：

使用UseDirectoryBrowser和UseStaticFiles公开的内容的URL受基础文件系统的区分大小写和字符限制的约束。例如，Windows不区分大小写 - macOS而Linux则不区分大小写。

我建议所有文件名的约定（“全小写”通常效果最好）。要检查是否存在不一致，可以运行一个简单的PowerShell脚本，该脚本使用正则表达式来检查错误的外壳。为方便起见，该脚本可以按计划进行。

Answer 3

根据@Tratcher提案和this博客文章，这里有一个案例感知物理文件提供程序的解决方案，您可以选择强制区分大小写或允许任何外壳，无论操作系统如何。

public class CaseAwarePhysicalFileProvider : IFileProvider
{
    private readonly PhysicalFileProvider _provider;
    //holds all of the actual paths to the required files
    private static Dictionary<string, string> _paths;

    public bool CaseSensitive { get; set; } = false;

    public CaseAwarePhysicalFileProvider(string root)
    {
        _provider = new PhysicalFileProvider(root);
        _paths = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
    }

    public CaseAwarePhysicalFileProvider(string root, ExclusionFilters filters)
    {
        _provider = new PhysicalFileProvider(root, filters);
        _paths = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
    }

    public IFileInfo GetFileInfo(string subpath)
    {
        var actualPath = GetActualFilePath(subpath);
        if(CaseSensitive && actualPath != subpath) return new NotFoundFileInfo(subpath);
        return _provider.GetFileInfo(actualPath);
    }

    public IDirectoryContents GetDirectoryContents(string subpath)
    {
        var actualPath = GetActualFilePath(subpath);
        if(CaseSensitive && actualPath != subpath) return NotFoundDirectoryContents.Singleton;
        return _provider.GetDirectoryContents(actualPath);
    }

    public IChangeToken Watch(string filter) => _provider.Watch(filter);

    // Determines (and caches) the actual path for a file
    private string GetActualFilePath(string path)
    {
        // Check if this has already been matched before
        if (_paths.ContainsKey(path)) return _paths[path];

        // Break apart the path and get the root folder to work from
        var currPath = _provider.Root;
        var segments = path.Split(new [] { '/' }, StringSplitOptions.RemoveEmptyEntries);

        // Start stepping up the folders to replace with the correct cased folder name
        for (var i = 0; i < segments.Length; i++)
        {
            var part = segments[i];
            var last = i == segments.Length - 1;

            // Ignore the root
            if (part.Equals("~")) continue;

            // Process the file name if this is the last segment
            part = last ? GetFileName(part, currPath) : GetDirectoryName(part, currPath);

            // If no matches were found, just return the original string
            if (part == null) return path;

            // Update the actualPath with the correct name casing
            currPath = Path.Combine(currPath, part);
            segments[i] = part;
        }

        // Save this path for later use
        var actualPath = string.Join(Path.DirectorySeparatorChar, segments);
        _paths.Add(path, actualPath);
        return actualPath;
    }

    // Searches for a matching file name in the current directory regardless of case
    private static string GetFileName(string part, string folder) =>
        new DirectoryInfo(folder).GetFiles().FirstOrDefault(file => file.Name.Equals(part, StringComparison.OrdinalIgnoreCase))?.Name;

    // Searches for a matching folder in the current directory regardless of case
    private static string GetDirectoryName(string part, string folder) =>
        new DirectoryInfo(folder).GetDirectories().FirstOrDefault(dir => dir.Name.Equals(part, StringComparison.OrdinalIgnoreCase))?.Name;
}

然后在Startup类中，确保为内容和Web root注册提供程序，如下所示：

        _environment.ContentRootFileProvider = new CaseAwarePhysicalFileProvider(_environment.ContentRootPath);
        _environment.WebRootFileProvider = new CaseAwarePhysicalFileProvider(_environment.WebRootPath);