I'm looking for a quick, easy and reliable way of getting the browser's HTTP Referrer in ASP.Net (C#). I know the HTTP Referrer itself is unreliable, but I do wa开发者_运维知识库nt a reliable way of getting the referrer if it is present.

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You could use the UrlReferrer property of the current request:

Request.UrlReferrer

This will read the Referer HTTP header from the request which may or may not be supplied by the client (user agent).

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Request.Headers["Referer"]

Explanation

The Request.UrlReferrer property will throw a System.UriFormatException if the referer HTTP header is malformed (which can happen since it is not usually under your control).

Therefore, the Request.UrlReferrer property is not 100% reliable - it may contain data that cannot be parsed into a Uri class. To ensure the value is always readable, use Request.Headers["Referer"] instead.

As for using Request.ServerVariables as others here have suggested, per MSDN:

Request.ServerVariables Collection

The ServerVariables collection retrieves the values of predetermined environment variables and request header information.

Request.Headers Property

Gets a collection of HTTP headers.

Request.Headers is a better choice than Request.ServerVariables, since Request.ServerVariables contains all of the environment variables as well as the headers, where Request.Headers is a much shorter list that only contains the headers.

So the most reliable solution is to use the Request.Headers collection to read the value directly. Do heed Microsoft's warnings about HTML encoding the value if you are going to display it on a form, though.

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Use the Request.UrlReferrer property.

Underneath the scenes it is just checking the ServerVariables("HTTP_REFERER") property.

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Like this: HttpRequest.UrlReferrer Property

Uri myReferrer = Request.UrlReferrer;
string actual = myReferrer.ToString();

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I'm using .Net Core 2 mvc, this one work for me ( to get the previews page) :

HttpContext.Request.Headers["Referer"];

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Since Google takes you to this post when searching for C# Web API Referrer here's the deal: Web API uses a different type of Request from normal MVC Request called HttpRequestMessage which does not include UrlReferrer. Since a normal Web API request does not include this information, if you really need it, you must have your clients go out of their way to include it. Although you could make this be part of your API Object, a better way is to use Headers.

First, you can extend HttpRequestMessage to provide a UrlReferrer() method:

public static string UrlReferrer(this HttpRequestMessage request)
{
    return request.Headers.Referrer == null ? "unknown" : request.Headers.Referrer.AbsoluteUri;
}

Then your clients need to set the Referrer Header to their API Request:

// Microsoft.AspNet.WebApi.Client
client.DefaultRequestHeaders.Referrer = new Uri(url);

And now the Web API Request includes the referrer data which you can access like this from your Web API:

Request.UrlReferrer();

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string referrer = HttpContext.Current.Request.UrlReferrer.ToString();

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Sometime you must to give all the link like this

System.Web.HttpContext.Current.Request.UrlReferrer.ToString();

(in option when "Current" not founded)

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Using .NET Core or .NET 5 I would recommend this:

httpContext.Request.Headers.TryGetValue("Referer", out var refererHeader)

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Belonging to other reply, I have added condition clause for getting null.

string ComingUrl = "";
if (Request.UrlReferrer != null)
{
    ComingUrl = System.Web.HttpContext.Current.Request.UrlReferrer.ToString();
}
else
{
    ComingUrl = "Direct"; // Your code
}