On 01/23/2013 08:46 AM, Neil Horman wrote:
On Wed, Jan 23, 2013 at 03:38:40PM +0800, xufengzhang.main@xxxxxxxxx wrote:From: Xufeng Zhang <xufeng.zhang@xxxxxxxxxxxxx> While sctp handling a duplicate COOKIE-ECHO and the action is 'Association restart', sctp_sf_do_dupcook_a() will processing the unexpected COOKIE-ECHO for peer restart, but it does not set the association state to SCTP_STATE_ESTABLISHED, so the association could stuck in SCTP_STATE_SHUTDOWN_PENDING state forever. This violates the sctp specification: RFC 4960 5.2.4. Handle a COOKIE ECHO when a TCB Exists Action A) In this case, the peer may have restarted. ..... After this, the endpoint shall enter the ESTABLISHED state. Fix this problem by adding a SCTP_CMD_NEW_STATE cmd to the command list so as to set the restart association to SCTP_STATE_ESTABLISHED state properly. Signed-off-by: Xufeng Zhang <xufeng.zhang@xxxxxxxxxxxxx> --- net/sctp/sm_statefuns.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index 618ec7e..528f1c8 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -1779,6 +1779,8 @@ static sctp_disposition_t sctp_sf_do_dupcook_a(struct net *net, /* Update the content of current association. */ sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC, SCTP_ASOC(new_asoc)); + sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, + SCTP_STATE(SCTP_STATE_ESTABLISHED)); sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl)); sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev)); return SCTP_DISPOSITION_CONSUME; -- 1.7.0.2Looks reasonable to me, thanks nit: The RFC indicate the association should enter the ESTABLISHED state after preforming all other actions, so it seems that the state change should occur after the ULP event is sent
I have a slight concern here that if we change state last, then any data that may have been bundled with COOKIE-ACK as part of CMD_REPLY will get the SACK_IMMEDIATE flag set since we are still in the SHUTDOWN_PENDING state.
I would be more correct (and would match sctp_sf_do_5_1D_ce) to do it in this order: UPDATE_ASSOC - resets all the congestion/association variables EVENT_UP - send RESTART to USER NEW_STATE - set ESTABLISHED state (as per spec) REPLY - Send cookie-ack along with any pending data. -vlad
Neil
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