jellyfin/Jellyfin.Server/Middleware/BaseUrlRedirectionMiddleware.cs

using System;
using System.Threading.Tasks;
using MediaBrowser.Controller.Configuration;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;
using ConfigurationExtensions = MediaBrowser.Controller.Extensions.ConfigurationExtensions;

namespace Jellyfin.Server.Middleware
{
    /// <summary>
    /// Redirect requests without baseurl prefix to the baseurl prefixed URL.
    /// </summary>
    public class BaseUrlRedirectionMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly ILogger<BaseUrlRedirectionMiddleware> _logger;
        private readonly IConfiguration _configuration;

        /// <summary>
        /// Initializes a new instance of the <see cref="BaseUrlRedirectionMiddleware"/> class.
        /// </summary>
        /// <param name="next">The next delegate in the pipeline.</param>
        /// <param name="logger">The logger.</param>
        /// <param name="configuration">The application configuration.</param>
        public BaseUrlRedirectionMiddleware(
            RequestDelegate next,
            ILogger<BaseUrlRedirectionMiddleware> logger,
            IConfiguration configuration)
        {
            _next = next;
            _logger = logger;
            _configuration = configuration;
        }

        /// <summary>
        /// Executes the middleware action.
        /// </summary>
        /// <param name="httpContext">The current HTTP context.</param>
        /// <param name="serverConfigurationManager">The server configuration manager.</param>
        /// <returns>The async task.</returns>
        public async Task Invoke(HttpContext httpContext, IServerConfigurationManager serverConfigurationManager)
        {
            var localPath = httpContext.Request.Path.ToString();
            var baseUrlPrefix = serverConfigurationManager.Configuration.BaseUrl;

            if (string.Equals(localPath, baseUrlPrefix + "/", StringComparison.OrdinalIgnoreCase)
                || string.Equals(localPath, baseUrlPrefix, StringComparison.OrdinalIgnoreCase)
                || string.Equals(localPath, "/", StringComparison.OrdinalIgnoreCase)
                || string.IsNullOrEmpty(localPath)
                || !localPath.StartsWith(baseUrlPrefix, StringComparison.OrdinalIgnoreCase))
            {
                // Always redirect back to the default path if the base prefix is invalid or missing
                _logger.LogDebug("Normalizing an URL at {LocalPath}", localPath);
                httpContext.Response.Redirect(baseUrlPrefix + "/" + _configuration[ConfigurationExtensions.DefaultRedirectKey]);
                return;
            }

            await _next(httpContext).ConfigureAwait(false);
        }
    }
}