Provide a way to redirect URLs when the original resource is no longer available.
- if a URL matches an Umbraco page, it's not redirected
- if a URL matches an
*.aspxfile on disk, it's not redirected - if a URL is too long for
HostingEnvironment.MapPathto handle, it's not redirected - if a page is missing but a matching redirect is found, the redirect is executed
- querystrings on URLs are preserved when redirecting, unless the new URL already has a querystring
- if a page is missing and no matching redirect is found, it falls through to standard IIS/ASP.NET behaviour for 404 responses
Errors are reported to Exceptionless.
To implement redirects using this project add code to a custom error page for 404 responses to check for redirects before returning a 404 response. See the documentation for Escc.EastSussexGovUK for an example of how to configure a 404 page that checks for redirects.
You will need to inject and use a redirect matcher and redirect handlers before updating the response headers. This requires the Microsoft.AspNetCore.Diagnostics package to be installed.
Startup:
public void ConfigureServices(IServiceCollection services)
{
...
services.Configure<RedirectSettings>(options => configuration.GetSection("Escc.Redirects").Bind(options));
services.TryAddSingleton<INotFoundRequestPathResolver, NotFoundRequestPathResolver>();
services.TryAddSingleton<IRedirectMatcher, SqlServerRedirectMatcher>();
services.TryAddSingleton<IConvertToAbsoluteUrlHandler, ConvertToAbsoluteUrlHandler>();
services.TryAddSingleton<IPreserveQueryStringHandler, PreserveQueryStringHandler>();
...
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
...
app.UseStatusCodePagesWithReExecute("/HttpStatus/Status{0}");
...
}
Controller:
[AllowAnonymous]
public class HttpStatusController : Controller
{
private readonly INotFoundRequestPathResolver _notFoundRequestPathResolver;
private readonly IRedirectMatcher _redirectMatcher;
private readonly IConvertToAbsoluteUrlHandler _convertToAbsoluteUrlHandler;
private readonly IPreserveQueryStringHandler _preserveQueryStringHandler;
public HttpStatusController(INotFoundRequestPathResolver notFoundRequestPathResolver, IRedirectMatcher redirectMatcher, IConvertToAbsoluteUrlHandler convertToAbsoluteUrlHandler, IPreserveQueryStringHandler preserveQueryStringHandler)
{
_notFoundRequestPathResolver = notFoundRequestPathResolver;
_redirectMatcher = redirectMatcher;
_convertToAbsoluteUrlHandler = convertToAbsoluteUrlHandler;
_preserveQueryStringHandler = preserveQueryStringHandler;
}
[ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
public async Task<IActionResult> Status404()
{
var requestFeature = HttpContext.Features.Get<IHttpRequestFeature>();
var absoluteRequestedUrl = new Uri(new Uri(Request.GetDisplayUrl()), new Uri(requestFeature.RawTarget, UriKind.Relative));
absoluteRequestedUrl = _notFoundRequestPathResolver?.NormaliseRequestedPath(absoluteRequestedUrl);
var redirect = _redirectMatcher?.MatchRedirect(absoluteRequestedUrl);
if (redirect != null)
{
redirect = _convertToAbsoluteUrlHandler?.HandleRedirect(redirect);
redirect = _preserveQueryStringHandler?.HandleRedirect(redirect);
Response.Headers.Add("Location", redirect.DestinationUrl.ToString());
return new StatusCodeResult(redirect.StatusCode);
}
// No redirect matched - return a 404 view here
return View();
}
}
You will need to use handlers that update the HTTP response when a redirect is matched. For projects targeting .NET Framework, these are provided in the Escc.Redirects.Handlers project.
Controller:
using Escc.Redirects;
using Escc.Redirects.Handlers;
...
public async Task<ActionResult> NotFound()
{
var requestedPath = new NotFoundRequestPathResolver().NormaliseRequestedPath(Request.Url);
var matchers = new IRedirectMatcher[] { new SqlServerRedirectMatcher(ConfigurationManager.ConnectionStrings["RedirectsReader"].ConnectionString) };
var handlers = new IRedirectHandler[] { new ConvertToAbsoluteUrlHandler(), new PreserveQueryStringHandler(), new DebugInfoHandler(), new GoToUrlHandler() };
foreach (var matcher in matchers)
{
var redirect = matcher.MatchRedirect(requestedUrl);
if (redirect != null)
{
foreach (var handler in handlers)
{
redirect = handler.HandleRedirect(redirect);
}
return null;
}
}
return View();
}
To use the default SqlServerRedirectMatcher you need to create a database using the script in SqlServer.sql and configure the connection string.
For .NET Core in (for development) secrets.json:
{
"Escc.Redirects": {
"ConnectionString": "xxx"
}
}
For .NET Framework in web.config:
<configuration>
<connectionStrings>
<add name="RedirectsReader" connectionString="xxx" />
</connectionStrings>
</configuration>
An example 301 redirect in SQL Server from /page1.aspx to /page2.aspx:
INSERT INTO Redirect (Pattern, Destination, Type, Comment) VALUES ('page1.aspx', '/page2.aspx', 2, 'Example')
To redirect requests for a file extension which is not ordinarily processed by ASP.NET you need to add a handler in web.config. For IIS6 or IIS7+ in Classic mode:
<configuration>
<system.web>
<httpHandlers>
<add path="*.htm" verb="*" type="System.Web.UI.PageHandlerFactory" validate="true" />
</httpHandlers>
</system.web>
</configuration>
For IIS7+ in Integrated mode:
<configuration>
<system.web>
<compilation targetFramework="4.0">
<buildProviders>
<add extension=".htm" type="System.Web.Compilation.PageBuildProvider" />
</buildProviders>
</compilation>
</system.web>
<system.webServer>
<handlers>
<add name="PageHandlerFactory-Integrated-htm" path="*.htm" verb="GET,HEAD,POST,DEBUG" type="System.Web.UI.PageHandlerFactory" resourceType="Unspecified" requireAccess="Script" preCondition="integratedMode" />
</handlers>
</system.webServer>
</configuration>