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SubjectRe: [PATCH] sctp: Make "Invalid Stream Identifier" ERROR follows SACK when bundling
On 07/19/2012 01:57 PM, xufengzhang.main@gmail.com wrote:
> When "Invalid Stream Identifier" ERROR happens after process the
> received DATA chunks, this ERROR chunk is enqueued into outqueue
> before SACK chunk, so when bundling ERROR chunk with SACK chunk,
> the ERROR chunk is always placed first in the packet because of
> the chunk's position in the outqueue.
> This violates sctp specification:
> RFC 4960 6.5. Stream Identifier and Stream Sequence Number
> ...The endpoint may bundle the ERROR chunk in the same
> packet as the SACK as long as the ERROR follows the SACK.
> So we must place SACK first when bundling "Invalid Stream Identifier"
> ERROR and SACK in one packet.
> Although we can do that by enqueue SACK chunk into outqueue before
> ERROR chunk, it will violate the side-effect interpreter processing.
> It's easy to do this job when dequeue chunks from the outqueue,
> by this way, we introduce a flag 'has_isi_err' which indicate
> whether or not the "Invalid Stream Identifier" ERROR happens.
>
> Signed-off-by: Xufeng Zhang<xufeng.zhang@windriver.com>
> ---
> include/net/sctp/structs.h | 2 ++
> net/sctp/output.c | 26 ++++++++++++++++++++++++++
> 2 files changed, 28 insertions(+), 0 deletions(-)
>
> diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
> index 88949a9..5adf4de 100644
> --- a/include/net/sctp/structs.h
> +++ b/include/net/sctp/structs.h
> @@ -842,6 +842,8 @@ struct sctp_packet {
> has_sack:1, /* This packet contains a SACK chunk. */
> has_auth:1, /* This packet contains an AUTH chunk */
> has_data:1, /* This packet contains at least 1 DATA chunk */
> + has_isi_err:1, /* This packet contains a "Invalid Stream
> + * Identifier" ERROR chunk */
> ipfragok:1, /* So let ip fragment this packet */
> malloced:1; /* Is it malloced? */
> };
> diff --git a/net/sctp/output.c b/net/sctp/output.c
> index 817174e..77fb1ae 100644
> --- a/net/sctp/output.c
> +++ b/net/sctp/output.c
> @@ -79,6 +79,7 @@ static void sctp_packet_reset(struct sctp_packet *packet)
> packet->has_sack = 0;
> packet->has_data = 0;
> packet->has_auth = 0;
> + packet->has_isi_err = 0;
> packet->ipfragok = 0;
> packet->auth = NULL;
> }
> @@ -267,6 +268,7 @@ static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt,
> sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet,
> struct sctp_chunk *chunk)
> {
> + struct sctp_chunk *lchunk;
> sctp_xmit_t retval = SCTP_XMIT_OK;
> __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length));
>
> @@ -316,7 +318,31 @@ sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet,
> packet->has_cookie_echo = 1;
> break;
>
> + case SCTP_CID_ERROR:
> + if (chunk->subh.err_hdr->cause& SCTP_ERROR_INV_STRM)
> + packet->has_isi_err = 1;
> + break;
> +
> case SCTP_CID_SACK:
> + /* RFC 4960
> + * 6.5 Stream Identifier and Stream Sequence Number
> + * The endpoint may bundle the ERROR chunk in the same
> + * packet as the SACK as long as the ERROR follows the SACK.
> + */
> + if (packet->has_isi_err) {
> + if (list_is_singular(&packet->chunk_list))
> + list_add(&chunk->list,&packet->chunk_list);
> + else {
> + lchunk = list_first_entry(&packet->chunk_list,
> + struct sctp_chunk, list);
> + list_add(&chunk->list,&lchunk->list);
> + }
>
And I should clarify the above judgment code.
AFAIK, there should be two cases for the bundling when invalid stream
identifier error happens:
1). COOKIE_ACK ERROR SACK
2). ERROR SACK
So I need to deal with the two cases differently.


Thanks,
Xufeng Zhang
> + packet->size += chunk_len;
> + chunk->transport = packet->transport;
> + packet->has_sack = 1;
> + goto finish;
> + }
> +
> packet->has_sack = 1;
> break;
>
>



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