Subject: Re: [PATCH net-next-2.6 v4 4/5] sctp: Add ASCONF operation on the single-homed host

From: Wei Yongjun <[email-masked]>
Date: Mon, 25 Apr 2011 08:57:31 +0800

> On Apr 22, 2011, at 13:10 , Wei Yongjun wrote:
>
>>> Since the sender MUST NOT use the  new IP address as a source for ANY SCTP
>>> packet except on  carrying an ASCONF Chunk. And ASCONF chunk can be bundled.
>>> How about this change. If so, you do not need change to sctp_outq_tail();
>>>
>>> diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
>>> index 1c88c89..bd6cc9c 100644
>>> --- a/net/sctp/outqueue.c
>>> +++ b/net/sctp/outqueue.c
>>> @@ -754,6 +754,13 @@ static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
>>> 	 */
>>>
>>> 	list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
>>> +		/* RFC 5061, 5.3
>>> +		 * F1) This ...
>>> +		 */
>>> +		if (q->asoc->src_out_of_asoc_ok &&
>>> +		    chunk->chunk_hdr->type != SCTP_CID_ASCONF)
>> SCTP_CID_ASCONF_ACK should be also allowed, the peer may
>> send ASCONF to do the same thing at the same time.
> Sorry for my bad understanding, 
> Do you mean the situation: "the peer (ASCONF receiver) may send ASCONF-ACK to the unconfirmed destination"?
> Or do you mean following situation?
> 1. the pear sends ADD/DEL ASCONF to me, 
> 2. I receive it, 
> 3. I migrate to the other network and get new address, 
> 4. I send ASCONF-ACK to the peer from the new address

Yes, If both side send ADD/DEL ASCONF to del the last one
address at the same time like this:

ASCONF  -----    ------ASCONF
(ADD/DEL)    \  /     (ADD/DEL)
              \/        
              /\
        <----/  \----->
ASCONF-ACK---\  /------ASCONF-ACK
              \/
              /\
        <----/  \----->

But I do not test for it. Not sure we need to do this, can you
check this before commit your new patchset?

>>> +			continue;
>>> +
>>> 		list_del_init(&chunk->list);
>>>
>>> 		/* Pick the right transport to use. */
>>> @@ -881,6 +888,9 @@ static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
>>> 		}
>>> 	}
>>>
>>> +	if (q->asoc->src_out_of_asoc_ok)
>>> +		goto sctp_flush_out;
>>> +
>>> 	/* Is it OK to send data chunks?  */
>>> 	switch (asoc->state) {
>>> 	case SCTP_STATE_COOKIE_ECHOED:
>>>
>>>
>>>
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