jellyfin/Jellyfin.Api/Middleware/BaseUrlRedirectionMiddleware.cs

using System;
using System.Threading.Tasks;
using Jellyfin.Networking.Configuration;
using MediaBrowser.Controller.Configuration;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;
using static MediaBrowser.Controller.Extensions.ConfigurationExtensions;

namespace Jellyfin.Api.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.GetNetworkConfiguration().BaseUrl;

            if (string.IsNullOrEmpty(localPath)
                || string.Equals(localPath, baseUrlPrefix, StringComparison.OrdinalIgnoreCase)
                || string.Equals(localPath, baseUrlPrefix + "/", StringComparison.OrdinalIgnoreCase)
                || string.Equals(localPath, baseUrlPrefix + "/web", StringComparison.OrdinalIgnoreCase)
                || string.Equals(localPath, baseUrlPrefix + "/web/", StringComparison.OrdinalIgnoreCase)
                || !localPath.StartsWith(baseUrlPrefix, StringComparison.OrdinalIgnoreCase)
               )
            {
                // Redirect health endpoint
                if (string.Equals(localPath, "/health", StringComparison.OrdinalIgnoreCase)
                    || string.Equals(localPath, "/health/", StringComparison.OrdinalIgnoreCase))
                {
                    _logger.LogDebug("Redirecting /health check");
                    httpContext.Response.Redirect(baseUrlPrefix + "/health");
                    return;
                }

                // Always redirect back to the default path if the base prefix is invalid or missing
                _logger.LogDebug("Normalizing an URL at {LocalPath}", localPath);

                var port = httpContext.Request.Host.Port ?? -1;
                var uri = new UriBuilder(httpContext.Request.Scheme, httpContext.Request.Host.Host, port, localPath).Uri;
                var redirectUri = new UriBuilder(httpContext.Request.Scheme, httpContext.Request.Host.Host, port, baseUrlPrefix + "/" + _configuration[DefaultRedirectKey]).Uri;
                var target = uri.MakeRelativeUri(redirectUri).ToString();
                _logger.LogDebug("Redirecting to {Target}", target);

                httpContext.Response.Redirect(target);
                return;
            }

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