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

Peter Saint-Andre <stpeter@stpeter.im> Wed, 09 June 2010 17:28 UTC

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Date: Wed, 09 Jun 2010 11:28:47 -0600
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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> <AC1CFD94F59A264488DC2BEC3E890DE50AA7E552@xmb-sjc-225.amer.cisco.com> <p0624083bc83572582a36@[10.20.30.158]> <4C0FCC79.9010204@pobox.com>
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Subject: Re: [TLS] RFC-4366-bis and the unrecognized_name(112) alert
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On 6/9/10 11:16 AM, Michael D'Errico wrote:
> Paul Hoffman wrote:
>>
>> ... there is still not enough definitive wording. I propose:
>>
>> The ServerNameList MUST NOT contain more than one name of the same
>> name_type.  If the server understood the ClientHello extension but
>> does not recognize the server name, the server SHOULD take one of two
>> actions: abort the handshake by sending a fatal
>> unrecognized_name(112) alert, or continue the handshake using a
>> default credential. Sending a warning-level alert such as
>> unrecognized_name(112), but continuing the handshake, is NOT
>> RECOMMENDED because the client's expected behavior in response to
>> this is unpredictable.
> 
> The last sentence makes it unclear whether sending the alert is not
> recommended or if continuing the handshake is not recommended.

Perhaps this is better:

   It is NOT RECOMMENDED to send a warning-level alert such as
   unrecognized_name(112) but continue the handshake, because
   the client's expected behavior in this case is unpredictable.

/psa