More robust redirect detection and routing

Cellivar · Mar 14, 2021 · 01b1405 · 01b1405
1 parent e6ff9fd
commit 01b1405
Show file tree

Hide file tree

Showing 2 changed files with 32 additions and 6 deletions.
diff --git a/NetGoLynx/Redirects/RedirectWebUIRule.cs b/NetGoLynx/Redirects/RedirectWebUIRule.cs
@@ -3,6 +3,7 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.AspNetCore.Rewrite;
+using Microsoft.Extensions.Logging;
 using Microsoft.Net.Http.Headers;
 
 namespace NetGoLynx.Redirects
@@ -13,8 +14,10 @@ namespace NetGoLynx.Redirects
     public class RedirectWebUIRule : IRule
     {
         private readonly Uri _hostToRedirectTo;
+        private readonly ILogger _logger;
         private readonly string _redirectScheme;
         private readonly string _redirectHost;
+        private readonly bool _skipPortCheck;
 
         private readonly PathString _apiPrefix = new PathString("/_");
         private readonly PathString _healthcheckPrefix = new PathString("/_/health");
@@ -23,11 +26,19 @@ public class RedirectWebUIRule : IRule
         /// Instantiates a new instance of the <see cref="RedirectWebUIRule"/> class.
         /// </summary>
         /// <param name="hostToRedirectTo">The URI to redirect to if not already on that host.</param>
-        public RedirectWebUIRule(Uri hostToRedirectTo)
+        /// <param name="logger">The logger to use for logging</param>
+        public RedirectWebUIRule(Uri hostToRedirectTo, ILogger logger)
         {
             _hostToRedirectTo = hostToRedirectTo;
+            _logger = logger;
+
+            // Precalculate some details to save time on actual redirect analysis.
             _redirectScheme = _hostToRedirectTo.Scheme.ToLowerInvariant();
             _redirectHost = _hostToRedirectTo.Host.ToLowerInvariant();
+
+            // The port on the request will be omitted if it matches the scheme's default port.
+            _skipPortCheck = (_redirectScheme == "http" && _hostToRedirectTo.Port == 80)
+                || (_redirectScheme == "https" && _hostToRedirectTo.Port == 443);
         }
 
         /// <inheritdoc/>
@@ -42,15 +53,14 @@ public void ApplyRule(RewriteContext context)
                 return;
             }
 
-            // If the request matches the expected host it shouldn't be redirected.
-            if ((request.Host.Host.ToLowerInvariant() == _redirectHost)
-                && request.Host.Port == _hostToRedirectTo.Port
-                && (request.Scheme == _redirectScheme))
+            if (RequestMatchesExpectedHost(request))
             {
                 context.Result = RuleResult.ContinueRules;
                 return;
             }
 
+            _logger.LogDebug($"{nameof(RedirectWebUIRule)}: Redirect from {request.Scheme}://{request.Host.Host}:{request.Host.Port} to {_redirectScheme}://{_redirectHost}:{_hostToRedirectTo.Port}");
+
             var destination = new UriBuilder(request.GetDisplayUrl())
             {
                 Host = _hostToRedirectTo.Host,
@@ -63,5 +73,12 @@ public void ApplyRule(RewriteContext context)
             response.Headers[HeaderNames.Location] = destination.ToString();
             context.Result = RuleResult.EndResponse;
         }
+
+        private bool RequestMatchesExpectedHost(HttpRequest request)
+        {
+            return (request.Host.Host.ToLowerInvariant() == _redirectHost)
+                && (request.Scheme.ToLowerInvariant() == _redirectScheme)
+                && (_skipPortCheck || (request.Host.Port == _hostToRedirectTo.Port));
+        }
     }
 }
diff --git a/NetGoLynx/Startup.cs b/NetGoLynx/Startup.cs
@@ -21,6 +21,7 @@
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Diagnostics.HealthChecks;
 using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
 using NetGoLynx.Data;
 using NetGoLynx.Models.Configuration;
 using NetGoLynx.Models.Configuration.Authentication;
@@ -164,12 +165,20 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
             app.UseAuthentication();
             app.UseAuthorization();
 
+            // Create a simple logger for debugging purposes.
+            var loggerFactory = LoggerFactory.Create(builder =>
+            {
+                builder.AddConfiguration(Configuration);
+                builder.AddConsole();
+            });
+            var logger = loggerFactory.CreateLogger<Startup>();
+
             // If there are proxy settings there should probably be a host to redirect the web UI to.
             var proxySettings = Configuration.GetSection("ProxyNetworks").Get<ProxyNetworks>();
             if (proxySettings != null && proxySettings.WebInterfaceHost != null)
             {
                 app.UseRewriter(new RewriteOptions()
-                    .Add(new RedirectWebUIRule(proxySettings.WebInterfaceHost)));
+                    .Add(new RedirectWebUIRule(proxySettings.WebInterfaceHost, logger)));
             }
 
             app.UseEndpoints(endpoints =>