Re: Fwd: New Version Notification for draft-wouters-edns-tcp-chain-query-00.txt

On 2013-09-10, at 23:44, Evan Hunt <[email protected]> wrote:

> On Tue, Sep 10, 2013 at 09:15:46PM -0400, Paul Wouters wrote:
>> Let's make DNSSEC on mobile phones possible without hacking dnssec into
>> X.509 blobs (or JSON or XML)
>> 
>> Abstract:
>>   This document defines an EDNS0 extension that can be used by a DNSSEC
>>   enabled Recursive Nameserver configured as a forwarder to send a
>>   single query over TCP requesting to receive a complete validation
>>   path along with the regular query answer.  Additionally, use of this
>>   option is considered a request to keep the TCP connection open to
>>   serve additional DNS requests.  Use of this option significantly
>>   reduces DNS latency for hosts deploying DNSSEC.
> 
> I'm not certain "request DNSSEC chain" and "keep the TCP connection open"
> should be combined in a single option, but I support both.

Isn't "keep the TCP connection open" superfluous, since in DNS the responsibility for closing the socket lies with the client, not the server?

A client expecting to receive a multi-message reply will presumably know to keep the socket open. A server capable of sending a multi-message reply would also know.

RFC 1035:

4.2.2. TCP usage

Messages sent over TCP connections use server port 53 (decimal).  The
message is prefixed with a two byte length field which gives the message
length, excluding the two byte length field.  This length field allows
the low-level processing to assemble a complete message before beginning
to parse it.

Several connection management policies are recommended:

   - The server should not block other activities waiting for TCP
     data.

   - The server should support multiple connections.

   - The server should assume that the client will initiate
     connection closing, and should delay closing its end of the
     connection until all outstanding client requests have been
     satisfied.

   - If the server needs to close a dormant connection to reclaim
     resources, it should wait until the connection has been idle
     for a period on the order of two minutes.  In particular, the
     server should allow the SOA and AXFR request sequence (which
     begins a refresh operation) to be made on a single connection.
     Since the server would be unable to answer queries anyway, a
     unilateral close or reset may be used instead of a graceful
     close.


Joe
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