URL trailing period is swallowed by HttpListener

Question

I have created an System.Net.HttpListener-based WebDav server to provide access to a(n existing) document library stored in a database through a virtual file system. The purpose of this component is to provide a file-level access to the stored documents which can be attached as a network drive under Windows, so using a different client is out of the question.

The database stores the documents in a file system-like hierarchy, so I mapped the containers as WebDav collections (which in clients show up as folders), and everything seemed nice until I found out my users use collections which has trailing periods in their names. Please note, that this is a product which is in production for more than a decade, so introducing new naming conventions is out of the question. Since HttpListener uses the standard C# System.Uri class to provide the request URL, and that class swallows trailing periods of URLs.

https://www.something.com/xyz.

for example becomes

https://www.something.com/xyz

It would be bad enough in itself, but it could be solved by also checking for the period-extended folder name. But the problem is a lot worse than that, because the System.Uri class does not only mutilates the last segment of the path, but all of them, so

https://www.something.com/xyz./knm/xxx.doc

becomes

https://www.something.com/xyz/knm/xxx.doc

and

https://www.something.com/xyz./knm/./qwe./xyz.doc

becomes

https://www.something.com/xyz/knm/qwe/xyz.doc

which I have no way to handle.

what I have tried so far...

Escaping the period by replacing it with "%2E" doe not work, because it doesn't get unescaped in clients like Windows Explorer and Total Commander.
Returning an escaped version in the PROPFIND href node and a literal version in the dislpayname node does not work, because "displayname" is ignored by most clients.
The workaround described in this answer doesn't seem to work. (It doesn't do anything. Another answer in the same thread provides a way to hack a certain instance of the System.Uri class, but since the instance is created by the HttpListener - or one of its underlying mechanisms - that really does no help for me.)

In a thread from like 2008 I have found the following quote

This is a known bug. This was actually discussed on these forums not too long ago. An MSFT employee acknowledged the problem and stated that it will be considered for a future release.

Can anybody provide a workaround or actual solution to this problem?

score 2 · Accepted Answer · answered Feb 27 '18 at 14:02

2

Which version of .NET Framework are you using? I created a sample app and initialized a System.URI with string containing dots. .NET 4.0 removed the dots, but anything newer left them in.

Can you use a newer version of .NET?

class Program
{
    static void Main(string[] args)
    {
        var uri = new Uri("http://localhost:8080/one./two./three./my.doc");

        Console.WriteLine(uri.ToString());
    }
}

answered Feb 27 '18 at 14:02

Simply Ged

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Yes, my target framework was .NET 4.0. Sadly I can't use a newer one yet, but we plan to move further in the near future. – mg30rg Feb 27 '18 at 14:17

URL trailing period is swallowed by HttpListener

1 Answers1