[cups-devel] IPP backend not supporting multiple Authentication header fields?

[Michael Sweet]

Joschi,

We should be picking the first value we support and not just blindly using the last one.  Moreover, we don't support NTLM so it isn't even a suitable choice...

Please file a bug so we can track a fix:

    https://www.cups.org/str.php


On Oct 14, 2014, at 11:40 AM, Joschi Brauchle <joschi.brauchle at tum.de> wrote:

> Dear all,
> 
> I am trying to print via IPP to a kerberized windows print server, but the IPP backend always requests a username and password, instead of using Negotiate authentication.
> 
> 
> The problem seems to be that the windows print server returns the following header:
> ----------------------
> HTTP/1.1 401 Unauthorized
> Content-Type	text/html
> Server	Microsoft-IIS/8.5
> WWW-Authenticate	Negotiate
> WWW-Authenticate	NTLM
> Date	Tue, 14 Oct 2014 15:26:11 GMT
> Content-Length	1344
> ----------------------
> 
> I modified the ipp.c backend source code to debug print the authentication header field contents, which show "NTLM" only.
> Hence, the following ipp.c code lines
> ----------------------
>        if (!strncmp(www_auth, "Negotiate", 9))
>          auth_info_required = "negotiate";
>        else if (www_auth[0])
>          auth_info_required = "username,password";
> ----------------------
> fail to use negotiate auth and always go for username+password!
> 
> Is this observation correct that multiple authentication header fields are ignored except the last one?
> 
> Best regards,
> Joschi Brauchle
> -- 
> Dipl.-Ing. Joschi Brauchle, M.S.
> 
> Institute for Communications Engineering (LNT)
> Technische Universitaet Muenchen (TUM)
> 80290 Munich, Germany
> 
> Tel (work): +49 89 289-23474
> Fax (work): +49 89 289-23490
> E-mail: joschi.brauchle at tum.de
> Web: http://www.lnt.ei.tum.de/
> 
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_________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair