HttpListenerRequest.Url Property

Gets the Uri object requested by the client.

Namespace:  System.Net
Assembly:  System (in System.dll)

public Uri Url { get; }

Property Value

Type: System.Uri
A Uri object that identifies the resource requested by the client.

The Url property allows you to obtain all the information available from a Uri object. If you need to know only the raw text of the URI request, consider using the RawUrl property instead.

The Url property is null if the Uri from the client could not be parsed.

The UnescapeRequestUrl property indicates if HttpListener uses the raw unescaped URI instead of the converted URI where any percent-encoded values are converted and other normalization steps are taken.

When a HttpListener instance receives a request through the http.sys service, it creates an instance of the URI string provided by http.sys, and exposes it as the HttpListenerRequest.Url property.

The http.sys service exposes two request URI strings:

  • Raw URI

  • Converted URI

The raw URI is the System.Uri provided in the request line of a HTTP request:

GET /path/

Host: www.contoso.com

The raw URI provided by http.sys for the request mentioned above, is "/path/". This represents the string following the HTTP verb as it was sent over the network.

The http.sys service creates a converted URI from the information provided in the request using the URI provided in the HTTP request line and the Host header to determine the origin server the request should be forwarded to. This is done by comparing the information from the request with a set of registered URI prefixes. In order to be able to compare those values, some normalization to the request needs to be done. For the sample above the converted URI would be as follows:

http://www.contoso.com/path/

The http.sys service combines the Uri.Host property value and the string in the request line to create a converted URI. In addition, http.sys and the System.Uri class also do the following:

  • Un-escapes all percent encoded values.

  • Converts percent-encoded non-ASCII characters into a UTF-16 character representation. Note that UTF-8 and ANSI/DBCS characters are supported as well as Unicode characters (Unicode encoding using the %uXXXX format).

  • Executes other normalization steps, like path compression.

Since the request doesn't contain any information about the encoding used for percent-encoded values, it may not be possible to determine the correct encoding just by parsing the percent-encoded values.

Therefore http.sys provides two registry keys for modifying the process:

Registry Key

Default Value

Description

EnableNonUTF8

1

If zero, http.sys accepts only UTF-8-encoded URLs.

If non-zero, http.sys also accepts ANSI-encoded or DBCS-encoded URLs in requests.

FavorUTF8

1

If non-zero, http.sys always tries to decode a URL as UTF-8 first; if that conversion fails and EnableNonUTF8 is non-zero, Http.sys then tries to decode it as ANSI or DBCS.

If zero (and EnableNonUTF8 is non-zero), http.sys tries to decode it as ANSI or DBCS; if that is not successful, it tries a UTF-8 conversion.

When HttpListener receives a request, it uses the converted URI from http.sys as input to the Url property.

There is a need for supporting characters besides characters and numbers in URIs. An example is the following URI, which is used to retrieve customer information for customer number "1/3812":

http://www.contoso.com/Customer('1%2F3812')/

Note the percent-encoded slash in the Uri (%2F). This is necessary, since in this case the slash character represents data and not a path delimiter.

Passing the string to Uri constructor will lead to the following URI:

http://www.contoso.com/Customer('1/3812')/

Splitting the path into its segments would result in the following elements:

Customer('1

3812')

This is not the intent of the sender of the request.

If the UnescapeRequestUrl property is set to false, then when the HttpListener receives a request, it uses the raw URI instead of the converted URI from http.sys as input to the Url property.

The following code example demonstrates using the Url property.


public static void ShowRequestProperties1 (HttpListenerRequest request)
{
    // Display the MIME types that can be used in the response.
    string[] types = request.AcceptTypes;
    if (types != null)
    {
        Console.WriteLine("Acceptable MIME types:");
        foreach (string s in types)
        {
            Console.WriteLine(s);
        }
    }
    // Display the language preferences for the response.
    types = request.UserLanguages;
    if (types != null)
    {
        Console.WriteLine("Acceptable natural languages:");
        foreach (string l in types)
        {
            Console.WriteLine(l);
        }
    }

    // Display the URL used by the client.
    Console.WriteLine("URL: {0}", request.Url.OriginalString);
    Console.WriteLine("Raw URL: {0}", request.RawUrl);
    Console.WriteLine("Query: {0}", request.QueryString);

    // Display the referring URI.
    Console.WriteLine("Referred by: {0}", request.UrlReferrer);

    //Display the HTTP method.
    Console.WriteLine("HTTP Method: {0}", request.HttpMethod);
    //Display the host information specified by the client;
    Console.WriteLine("Host name: {0}", request.UserHostName);
    Console.WriteLine("Host address: {0}", request.UserHostAddress);
    Console.WriteLine("User agent: {0}", request.UserAgent);
}


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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