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    SubjectRe: [PATCH] sctp: set association state to established in dupcook_a handler
    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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