From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gui Jianfeng Subject: Re: [PATCH] SCTP: enable cookie-echo retransmission transport switch Date: Fri, 13 Jun 2008 08:47:41 +0800 Message-ID: <4851C3AD.9030600@cn.fujitsu.com> References: <4850A7F2.6090906@cn.fujitsu.com> <48513BA4.9030403@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: David Miller , linux-sctp@vger.kernel.org, netdev To: Vlad Yasevich Return-path: Received: from cn.fujitsu.com ([222.73.24.84]:59486 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752305AbYFMAuO (ORCPT ); Thu, 12 Jun 2008 20:50:14 -0400 In-Reply-To: <48513BA4.9030403@hp.com> Sender: netdev-owner@vger.kernel.org List-ID: Vlad, Thanks for your comments. Vlad Yasevich wrote: > Gui Jianfeng wrote: >> Vlad, >> This patch enables cookie-echo retransmission transport switch >> feature. If COOKIE-ECHO retransmission happens, it will be sent to the >> address other than the one last sent to. >> > > NAK. > > You can't blindly choose a different transport since they could > be unconfirmed and can't really be used until we confirm them > with HBs. So, you can only do this when the user issued an > sctp_connectx() and we have multiple confirmed transports. > > In this case only confirmed transports are allowed, otherwise > there is a possibility of hijacking associations. > Choosing a transport here just gives a suggestion for sctp_outq_flush(), sctp_outq_flush() will judge again. If the selected transport is in INACTIVE or UNCONFIRMED, active_path will be used. So COOKIE-ECHO won't be sent to a unconfirmed address. > > Also, looking at this, the same problem exists in current > code for selection INIT transports. > > We don't correctly treat peers passed to connectx() as confirmed > and don't select the correct transport. > > Once you fix that above, you can just re-use the function and > re-use init_last_sent_to. Will do. > > -vlad > > > -- Regards Gui Jianfeng