One approach to this problem is to do the following steps:
- Determine if the URL is a loop-back. If so, proceed. One way to do this is using
Uri.IsLoopback.
- Determine the current computer's DNS host name. This can be done using the static
Dns class.
- Replace the host name portion of the URL with the current computer's one. This can be done using
UriBuilder.
Given this method signature:
Uri MakeExternallyUsable(Uri uri)
Here are two implementations to achieve the desired result:
General Solution
Dns.GetHostName can be used to get the possibly fully-qualified host name. However, I think it would be more robust to use the fully-qualified host name. A mechanism to do this is suggested in this answer.
If you use this approach, make sure to consider the permissions required and the possible exceptions.
if (uri.IsLoopback)
{
var builder = new UriBuilder(uri)
{
Host = Dns.GetHostEntry("LocalHost").HostName
};
return builder.Uri;
}
else
return uri;
ASP.NET
In the context of an ASP.NET response, I think the current computer's host name may not necessarily be the same as the one used by the requester. Also, the computer may have multiple different associated host names. Because of these, getting the host name from the HTTP request's URL seemed suitable to me. Modify the above implementation to use this host name:
/*Get HTTP request*/.Url.Host
