Re: [PATCHv2 net-next 2/7] sctp: implement receiver-side procedures for the SSN/TSN Reset Request Parameter

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On Tue, Mar 21, 2017 at 2:04 AM, Marcelo Ricardo Leitner
<marcelo.leitner@xxxxxxxxx> wrote:
> On Fri, Mar 10, 2017 at 12:11:07PM +0800, Xin Long wrote:
>> This patch is to implement Receiver-Side Procedures for the SSN/TSN
>> Reset Request Parameter described in rfc6525 section 6.2.4.
>>
>> The process is kind of complicate, it's wonth having some comments
>> from section 6.2.4 in the codes.
>>
>> Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
>> ---
>>  include/net/sctp/sm.h   |  4 +++
>>  net/sctp/sm_statefuns.c |  3 ++
>>  net/sctp/stream.c       | 79 +++++++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 86 insertions(+)
>>
>> diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
>> index b6f682e..2629d66 100644
>> --- a/include/net/sctp/sm.h
>> +++ b/include/net/sctp/sm.h
>> @@ -293,6 +293,10 @@ struct sctp_chunk *sctp_process_strreset_inreq(
>>                               struct sctp_association *asoc,
>>                               union sctp_params param,
>>                               struct sctp_ulpevent **evp);
>> +struct sctp_chunk *sctp_process_strreset_tsnreq(
>> +                             struct sctp_association *asoc,
>> +                             union sctp_params param,
>> +                             struct sctp_ulpevent **evp);
>>
>>  /* Prototypes for statetable processing. */
>>
>> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
>> index e03bb1a..6982064 100644
>> --- a/net/sctp/sm_statefuns.c
>> +++ b/net/sctp/sm_statefuns.c
>> @@ -3872,6 +3872,9 @@ sctp_disposition_t sctp_sf_do_reconf(struct net *net,
>>               else if (param.p->type == SCTP_PARAM_RESET_IN_REQUEST)
>>                       reply = sctp_process_strreset_inreq(
>>                               (struct sctp_association *)asoc, param, &ev);
>> +             else if (param.p->type == SCTP_PARAM_RESET_TSN_REQUEST)
>> +                     reply = sctp_process_strreset_tsnreq(
>> +                             (struct sctp_association *)asoc, param, &ev);
>>               /* More handles for other types will be added here, by now it
>>                * just ignores other types.
>>                */
>> diff --git a/net/sctp/stream.c b/net/sctp/stream.c
>> index 1c6cc04..7e993b0 100644
>> --- a/net/sctp/stream.c
>> +++ b/net/sctp/stream.c
>> @@ -477,3 +477,82 @@ struct sctp_chunk *sctp_process_strreset_inreq(
>>
>>       return chunk;
>>  }
>> +
>> +struct sctp_chunk *sctp_process_strreset_tsnreq(
>> +                             struct sctp_association *asoc,
>> +                             union sctp_params param,
>> +                             struct sctp_ulpevent **evp)
>> +{
>> +     __u32 init_tsn = 0, next_tsn = 0, max_tsn_seen;
>> +     struct sctp_strreset_tsnreq *tsnreq = param.v;
>> +     struct sctp_stream *stream = asoc->stream;
>> +     __u32 result = SCTP_STRRESET_DENIED;
>> +     __u32 request_seq;
>> +     __u16 i;
>> +
>> +     request_seq = ntohl(tsnreq->request_seq);
>> +     if (request_seq > asoc->strreset_inseq) {
>> +             result = SCTP_STRRESET_ERR_BAD_SEQNO;
>> +             goto out;
>> +     } else if (request_seq == asoc->strreset_inseq) {
>> +             asoc->strreset_inseq++;
>> +     }
>
> I guess I already asked this, but.. why request_seq <
> asoc->strreset_inseq is allowed?
we can not just ignore or response with ERR.
rfc6525#section-5.2.1:

   ... If the received RE-CONFIG chunk contains at least
   one request and based on the analysis of the Re-configuration Request
   Sequence Numbers this is the last received RE-CONFIG chunk (i.e., a
   retransmission), the same RE-CONFIG chunk MUST to be sent back in
   response, as it was earlier.


>
>> +
>> +     if (!(asoc->strreset_enable & SCTP_ENABLE_RESET_ASSOC_REQ))
>> +             goto out;
>> +
>> +     if (asoc->strreset_outstanding) {
>> +             result = SCTP_STRRESET_ERR_IN_PROGRESS;
>> +             goto out;
>> +     }
>> +
>> +     /* G3: The same processing as though a SACK chunk with no gap report
>> +      *     and a cumulative TSN ACK of the Sender's Next TSN minus 1 were
>> +      *     received MUST be performed.
>> +      */
>> +     max_tsn_seen = sctp_tsnmap_get_max_tsn_seen(&asoc->peer.tsn_map);
>> +     sctp_ulpq_reasm_flushtsn(&asoc->ulpq, max_tsn_seen);
>> +     sctp_ulpq_abort_pd(&asoc->ulpq, GFP_ATOMIC);
>> +
>> +     /* G1: Compute an appropriate value for the Receiver's Next TSN -- the
>> +      *     TSN that the peer should use to send the next DATA chunk.  The
>> +      *     value SHOULD be the smallest TSN not acknowledged by the
>> +      *     receiver of the request plus 2^31.
>> +      */
>> +     init_tsn = sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map) + (1 << 31);
>> +     sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
>> +                      init_tsn, GFP_ATOMIC);
>> +
>> +     /* G4: The same processing as though a FWD-TSN chunk (as defined in
>> +      *     [RFC3758]) with all streams affected and a new cumulative TSN
>> +      *     ACK of the Receiver's Next TSN minus 1 were received MUST be
>> +      *     performed.
>> +      */
>> +     sctp_outq_free(&asoc->outqueue);
>> +
>> +     /* G2: Compute an appropriate value for the local endpoint's next TSN,
>> +      *     i.e., the next TSN assigned by the receiver of the SSN/TSN reset
>> +      *     chunk.  The value SHOULD be the highest TSN sent by the receiver
>> +      *     of the request plus 1.
>> +      */
>> +     next_tsn = asoc->next_tsn;
>> +     asoc->ctsn_ack_point = next_tsn - 1;
>> +     asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
>> +
>> +     /* G5:  The next expected and outgoing SSNs MUST be reset to 0 for all
>> +      *      incoming and outgoing streams.
>> +      */
>> +     for (i = 0; i < stream->outcnt; i++)
>> +             stream->out[i].ssn = 0;
>> +     for (i = 0; i < stream->incnt; i++)
>> +             stream->in[i].ssn = 0;
>> +
>> +     result = SCTP_STRRESET_PERFORMED;
>> +
>> +     *evp = sctp_ulpevent_make_assoc_reset_event(asoc, 0, init_tsn,
>> +                                                 next_tsn, GFP_ATOMIC);
>> +
>> +out:
>> +     return sctp_make_strreset_tsnresp(asoc, result, request_seq,
>> +                                       next_tsn, init_tsn);
>> +}
>> --
>> 2.1.0
>>
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