如何区分DirectoryEntry无效路径或无法连接到.NET中的LDAP？

Question

Let's say I have this LDAP path and I want to search for an object in AD using System.DirectoryServices.DirectoryEntry:

 var path = "LDAP://test.com/CN=bob,OU=Users,DC=test,DC=com"

This path was retrieved from AD 1 minute ago. What if the object was deleted that second or the connection to Active Directory dropped. In my application, i stored this path, and I want to change one of the attributes of that object. So, I retrieve the path and do whatever I want. In both cases, deleted object or no connection, I get the same Exception

"System.Runtime.InteropServices.COMException"

I want to throw an exception stating the problem, how do I distinguish between both cases? I want to do this because, in case it was a connection problem, i want to try again after a specific amount of time. However if the object is deleted, I want my Application user to know this.

DirectoryEntry Constructor does not do any kind of validation. In Addition, DirectoryEntry.Exsist(path) returns false, but does not give additional information. Any Suggestions?

Answer 1

There's nothing wrong with catching another exception, then throwing another:

try {
   my_dangerous_call();
} catch(COMException e) {
   throw new MyCustomException();
}