WebHeaderCollection.IsRestricted Method (String)

Tests whether the specified HTTP header can be set for the request.

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

public static bool IsRestricted(
	string headerName
)

Parameters

headerName
Type: System.String

The header to test.

Return Value

Type: System.Boolean
true if the header is restricted; otherwise false.

ExceptionCondition
ArgumentNullException

headerName is null or Empty.

ArgumentException

headerName contains invalid characters.

The IsRestricted method returns true to indicate that a header is restricted and must be set using properties instead of directly or is set by the system. The restricted headers are:

  • Accept

  • Connection

  • Content-Length

  • Content-Type

  • Date

  • Expect

  • Host

  • If-Modified-Since

  • Range

  • Referer

  • Transfer-Encoding

  • User-Agent

  • Proxy-Connection

The following example checks the IsRestricted property to see if any headers are prohibited from being set.

		try {
			// Create a web request for "www.msn.com".
		 	HttpWebRequest myHttpWebRequest = (HttpWebRequest) WebRequest.Create("http://www.msn.com");

			// Get the associated response for the above request.
		 	HttpWebResponse myHttpWebResponse = (HttpWebResponse) myHttpWebRequest.GetResponse();

			// Get the headers associated with the response.
			WebHeaderCollection myWebHeaderCollection = myHttpWebResponse.Headers;
			
			for (int i = 0; i < myWebHeaderCollection.Count;i++)	
			{
  			// Check if the first response header is restricted. 
			if(WebHeaderCollection.IsRestricted(myWebHeaderCollection.AllKeys[i]))
				Console.WriteLine("'{0}' is a restricted header", myWebHeaderCollection.AllKeys[i]);
			else
				Console.WriteLine("'{0}' is not a restricted header", myWebHeaderCollection.AllKeys[i]);
			}
			myHttpWebResponse.Close();
		}
		catch(WebException e) {
			Console.WriteLine("\nWebException is thrown.\nMessage is:" + e.Message);
			if(e.Status == WebExceptionStatus.ProtocolError) {
				Console.WriteLine("Status Code : {0}", ((HttpWebResponse)e.Response).StatusCode);
				Console.WriteLine("Status Description : {0}", ((HttpWebResponse)e.Response).StatusDescription);
				Console.WriteLine("Server : {0}", ((HttpWebResponse)e.Response).Server);
			}
		}
		catch(Exception e) {
			Console.WriteLine("Exception is thrown. Message is :" + e.Message);
		}

	}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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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