Hey, I created a HttpHandler for downloading files from the server. It seems it is not handling anything...I put a breakpoint in the ProcessRequest, it never goes there.
public class DownloadHandler : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
//download stuff and break point
}
}
It never stops there, as mentioned. I also registered it in the web.config.
<add verb="*" path="????" type="DownloadHandler" />
I am not sure about the path part of that entry. What do I have to enter there? I am downloading txt files, but the URL does not contain the filename, I somehow have to pass it to the handler. How would I do this? Session maybe?
Thanks
Have you read How to register Http Handlers? Are you using IIS 6 or 7?
The path part should contain a (partial) url, so if in your case you are using a static url without the filenames, you should put that there. You can end the url in the name of a non-existent resource and map that to path
e.g. the url is http://myserver.com/pages/downloadfiles
and the path="downloadfiles"
If you do POST, you can put the filename in a hidden field, and extract it in the handler. If you're using GET, I'm not sure, either cross-post the viewstate or put the filename in the session like you said.
Any reason why you can't put the filename in the url?
The path for a handler needs to be the path you are trying to handle - bit of a tautology I know but it's as simple as that. Whatever path on your site (real or much more likely virtual) you want to be handled by this handler.
Now unless the kind of file at the end of that path is normally handled by ASP.NET (e.g. .aspx, .asmx but not a .txt) ASP will never see the request in order for it to go through it's pipeline and end up at your handler. In that case you have to bind the extension type in IIS to ASP.NET.
As far as identifying what file the handler is supposed to respond with you could achieve this any number of ways - I would strongly recommend avoiding session or cookies or anything temporal and implicit. I would instead suggest using the querystring or form values, basically anything which will show up as a request header.
Fianlly, I have to ask why you're using a handler for this at all - .txt will serve just fine normally so what additional feature are you trying to implement here? There might well be a better way.
Related
I have a Global.asx file that needs to do custom authentication, auditing and profiling stuff. This is needed because it supports a SAML based SSO system and needs to override the normal .Net authentication (which doesn't support either SAML or mixed authentication)
I don't want to fire it for static files, such as .js, .css, .png, etc
In Cassini/WebDev and IIS7 it does.
What I want to have is some simple check, like a this.Request.IsStaticFile (which doesn't exist, unfortunately) to identify the static files.
I realise that this would be fairly simple to write, but it feels like something that must already exist - IIS has already applied caching policy stuff for the static files and so on.
I need a code solution, rather than an IIS config change one.
Update
This is my current workaround:
/// <summary>Hold all the extensions we treat as static</summary>
static HashSet<string> allowedExtensions = new HashSet<string>(StringComparer.OrdinalIgnoreCase)
{
".js", ".css", ".png", ...
};
/// <summary>Is this a request for a static file?</summary>
/// <param name="request">The HTTP request instance to extend.</param>
/// <returns>True if the request is for a static file on disk, false otherwise.</returns>
public static bool IsStaticFile(this HttpRequest request)
{
string fileOnDisk = request.PhysicalPath;
if (string.IsNullOrEmpty(fileOnDisk))
{
return false;
}
string extension = Path.GetExtension(fileOnDisk);
return allowedExtensions.Contains(extension);
}
This works and is quick enough, but feels horribly clunky. In particular relying on extensions is going to be error prone if we add new static files not thought of.
Is there a better way without changing the IIS config?
You might be able to check which handler is dealing with the request.
In IIS6 only .net files, eg aspx are mapped to a handler that does stuff.
In IIS7 with the integrated pipeline, everything routes through .net, which is normally a good thing. Different handlers still deal with different file types though. In particular I believe the staticfilehandler is the one you need to check for. The httpcontext.handler property should allow you to figure it out.
You could create an extension method to add that IsStatic method...
Simon
There are a few options:
Adding authorization element and deny none for those paths that you do not need any authentication and contains your static files
You are using integrated pipeline. Turn it off on your IIS 7.
There is no doubt that you need to create a custom extension method because ASP.NET routing engine uses this code to decide whether a file exist,
if (!this.RouteExistingFiles)
{
string appRelativeCurrentExecutionFilePath = httpContext.Request.AppRelativeCurrentExecutionFilePath;
if (((appRelativeCurrentExecutionFilePath != "~/") && (this._vpp != null)) && (this._vpp.FileExists(appRelativeCurrentExecutionFilePath) || this._vpp.DirectoryExists(appRelativeCurrentExecutionFilePath)))
{
return null;
}
}
You will not able to decide whether the request is static in Application_BeginRequest using context.handler because Routing Module may change the handler and this module always execute after Application_BeginRequest. My suggestion is to use the similar code which ASP.NEt routing engine uses.
I have a HttpModule which intercepts all requests and loads data from the database based on routing rules. However, I run into one problem all the time; GetRouteData only works if the path does not exist:
var routeData = RouteTable.Routes.GetRouteData(new HttpContextWrapper(HttpContext.Current));
Assuming a request comes in for the url http://localhost/contact, I get the correct routing data relating to that url if that path does not exist in the file system. The problem appears when I want to customize the page at that url which I do by creating an aspx page in the path ~/contact/default.aspx. Once I do that, GetRouteData return null.
I have even tried creating a new HttpContext object, but I still can not retrieve route data if the page exists.
Has anyone ever run into this problem? Is there a solution/workaround?
All help will be greatly appreciated.
Set RouteCollection.RouteExistingFiles to true.
public static void RegisterRoutes(RouteCollection routes)
{
// Cause paths to be routed even if they exists physically
routes.RouteExistingFiles = true;
// Map routes
routes.MapPageRoute("...", "...", "...");
}
Beware though. IIS7 behaves a little differently than the server used when debugging within Visual Studio. I got bit by this when I deployed my application to the web. Check out this feedback I submitted to Microsoft Connection.
In ASP.NET I'd like to create a link which points to a specific Uri and send this link in an email to a user, for instance something like http://www.BlaBla.com/CustomerPortal/Order/9876. I can create the second part of the Uri /CustomerPortal/Order/9876 dynamically in code-behind. My question is: How can I create the base Uri http://www.BlaBla.com without hardcoding it in my application? Basically I want to have something like:
http://localhost:1234/CustomerPortal/Order/9876 (on my development machine)
http://testserver/CustomerPortal/Order/9876 (on an internal test server)
http://www.BlaBla.com/CustomerPortal/Order/9876 (on the production server)
So is there a way to ask the server where the application is running: "Please tell me the base Uri of the application" ? Or any other way?
Thank you in advance!
Something like this:
HttpContext.Current.Request.Url.GetLeftPart(UriPartial.Authority) + HttpContext.Current.Request.ApplicationPath.TrimEnd('/')
You have to put a key in config, something somewhere, because when you think about your web application, it's not really tied to a URL. For example:
http://localhost:1234/
http://yourMachineName:1234/
http://yourMachineName.domain.com:1234/
http://127.0.0.1:1234/
These are just a few ways to get to the same site on localhost....which is it? The same problem exists in production, dozens of domains or IPs may point to the same web application, and it uses host headers or maybe nothing to distinguish it. The point is, when outside the context of a request, the site doesn't really know what URL it goes with, could be anything, there's just not a 1:1 relation there.
If you are in the context of a request when sending an email, then take a look at HttpRequest.Url, this is a Uri type, and you can see the available properties here.
You can do something like this:
var host = HttpContext.Current.Url.Host;
//generate your link using the host
What about to place it into the web.config
<configuration>
<appSettings>
<add key="SendingUrlBase" value="http://www.BlaBla.com"/>
In my asp.net mvc 2 app, I'm wondering about the best way to implement this:
For every incoming request I need to perform custom authorization before allowing the file to be served. (This is based on headers and contents of the querystring. If you're familiar with how Amazon S3 does rest authentication - exactly that).
I'd like to do this in the most perfomant way possible, which probably means as light a touch as possible, with IIS doing as much of the actual work as possible.
The service will need to handle GET requests, as well as writing new files coming in via POST/PUT requests.
The requests are for an abitrary file, so it could be:
GET http://storage.foo.com/bla/egg/foo18/something.bin
POST http://storage.foo.com/else.txt
Right now I've half implemented it using an IHttpHandler which handles all routes (with routes.RouteExistingFiles = true), but not sure if that's the best, or if I should be hooking into the lifecycle somewhere else?
I'm also interested in supporting partial downloads with the Range header. Using
response.TransmitFile(finalPath);
as I am now means I'll have to do that manually, which seems a bit lowlevel?
Many thanks for any pointers.
(IIS7)
I think having a custom handler in the middle that takes care of this is exactly how you should be doing it.
TransmitFile is the lightest-weight programmatic way to serve a file that I am aware of.
However, you might not need to write your own HttpHandler. You can use the MVC handler and just dedicate a controller action to the job. Something like:
http://storage.foo.com/Files/Download/SomeFileIdentifier
...routing to...
public FilesController
{
public ActionResult Download(string id)
{
//...some logic to authenticate and to get the local file path
return File(theLocalFilePath, mimeType);
}
}
The File() method of controller uses TransmitFile in the background, I believe.
(PS, If you want shorter URLs, do it via custom routes in global.asax.)
How would I generate a proper URL for an MVC application to be included in an e-mail?
This is for my registration system which is separate from my controller/action. Basically, I want to send an email verification to fire an Action on a Controller. I don't want to hardcode the URL in, I would want something like the Url property on the Views.
In your Controller, the UrlHelper is just called "Url" - so:
void Index() {
string s = this.Url.Action("Index", "Controller");
}
The "this" is unnecessary, but it tells you where this Url variable comes from
I used:
Html.BuildUrlFromExpression<AccountController>(c=>c.Confirm(Model.confirmedGUID.Value))
It is part of the HTMLHelper (I think in the MVC Futures) so you may have to pass an instance of the HTMLHelper to your service layer, not sure. I use this directly in my view which renders to an email. That gives you the absolute URL and then I store the domain (http://www.mysite.com) in the config file and append it before the URL.
You should probably make the URL part of the configuration of your application.
I know you can do stuff with e.g. the Server property on your web application, but the application will never know if its IP or domain name is reachable from the outside as it might be hidden behind a proxy or a load balancer.
If I'm reading the question correctly, you need to controller/action outside the MVC code. If so, you will need to simply configure the URL in Application Configuration or some such place, unless you have access to the controller classes and use reflection to get the names.