Messages in this thread | | | Date | Wed, 23 Jan 2013 09:22:16 -0500 | From | Vlad Yasevich <> | Subject | Re: [PATCH] sctp: set association state to established in dupcook_a handler |
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On 01/23/2013 08:46 AM, Neil Horman wrote: > On Wed, Jan 23, 2013 at 03:38:40PM +0800, xufengzhang.main@gmail.com wrote: >> From: Xufeng Zhang <xufeng.zhang@windriver.com> >> >> 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@windriver.com> >> --- >> 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; >> -- >> 1.7.0.2 >> >> > > Looks 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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