Re: [TLS] RFC-4366-bis and the unrecognized_name(112) alert

"Joseph Salowey (jsalowey)" <jsalowey@cisco.com> Wed, 09 June 2010 15:12 UTC

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Date: Wed, 09 Jun 2010 08:12:47 -0700
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Thread-Topic: [TLS] RFC-4366-bis and the unrecognized_name(112) alert
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References: <4C0FA538.7050309@pobox.com> from "Michael D'Errico" at Jun 9, 10 07:29:12 am <201006091456.o59EukJ3015376@fs4113.wdf.sap.corp>
From: "Joseph Salowey (jsalowey)" <jsalowey@cisco.com>
To: mrex@sap.com, Michael D'Errico <mike-list@pobox.com>
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Subject: Re: [TLS] RFC-4366-bis and the unrecognized_name(112) alert
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Thanks,  

The text below looks much better looks much better. Let's go with that. 

Joe
> -----Original Message-----
> From: Martin Rex [mailto:mrex@sap.com]
> Sent: Wednesday, June 09, 2010 7:57 AM
> To: Michael D'Errico
> Cc: Joseph Salowey (jsalowey); tls@ietf.org
> Subject: Re: [TLS] RFC-4366-bis and the unrecognized_name(112) alert
> 
> Michael D'Errico wrote:
> >
> > After reading this again, I think it's missing something.
> 
> I felt the same.
> 
> Another possible approach would be to slightly rearrange that part.
> 
>  "The ServerNameList MUST NOT contain more than one name of the same
>   name_type.  If the server understood the client hello extension,
> 
>   but does not recognize the server name, the server has two options.
>   Either abort the handshake sending a fatal unrecognized_name(112)
>   alert or continue the handshake using a default credential.
>   Sending a warning-level unrecognized_name(112) alert in the latter
>   case is NOT RECOMMENDED, since existing client behaviour is
>   unpredictable.
> 
> 
> > > A TLS client implementation that receives a
> > > warning-level unrecognized_name(112) alert SHOULD ignore this
alert
> and
> > > continue the TLS handshake.  If there is a mismatch between the
server
> > > name used by the client application and the server name of the
default
> > > credential chosen by the server, this mismatch will become
apparent
> when
> > > the client application performs the server endpoint
identification, at
> > > which point the client application will have to decide whether to
> > > proceed with the communication.  TLS implementations are
encouraged to
> > > make information available to application callers about
warning-level
> > > alerts that were received or sent during a TLS handshake.  Such
> > > information can be useful for diagnostic purposes."
> 
> -Martin