This function will return the final destination of a link — even if there are multiple redirects. It doesn’t account for JavaScript-based redirects or META redirects. Notice that the previous solution didn’t deal with Absolute & Relative URLs, since the LOCATION header could return something like “/newhome” you need to combine with the URL that served that response to identify the full URL destination.
public static string GetFinalRedirect(string url)
{
if(string.IsNullOrWhiteSpace(url))
return url;
int maxRedirCount = 8; // prevent infinite loops
string newUrl = url;
do
{
HttpWebRequest req = null;
HttpWebResponse resp = null;
try
{
req = (HttpWebRequest) HttpWebRequest.Create(url);
req.Method = "HEAD";
req.AllowAutoRedirect = false;
resp = (HttpWebResponse)req.GetResponse();
switch (resp.StatusCode)
{
case HttpStatusCode.OK:
return newUrl;
case HttpStatusCode.Redirect:
case HttpStatusCode.MovedPermanently:
case HttpStatusCode.RedirectKeepVerb:
case HttpStatusCode.RedirectMethod:
newUrl = resp.Headers["Location"];
if (newUrl == null)
return url;
if (newUrl.IndexOf("://", System.StringComparison.Ordinal) == -1)
{
// Doesn't have a URL Schema, meaning it's a relative or absolute URL
Uri u = new Uri(new Uri(url), newUrl);
newUrl = u.ToString();
}
break;
default:
return newUrl;
}
url = newUrl;
}
catch (WebException)
{
// Return the last known good URL
return newUrl;
}
catch (Exception ex)
{
return null;
}
finally
{
if (resp != null)
resp.Close();
}
} while (maxRedirCount-- > 0);
return newUrl;
}