sctp: implement assign_number for sctp_stream_interleave

assign_number is added as a member of sctp_stream_interleave, used
to assign ssn for data or mid (message id) for idata, called in
sctp_packet_append_data. sctp_chunk_assign_ssn is left as it is,
and sctp_chunk_assign_mid is added for sctp_stream_interleave_1.

This procedure is described in section 2.2.2 of RFC8260.

All sizeof(struct sctp_data_chunk) in tx path is replaced with
sctp_datachk_len, to make it right for idata as well. And also
adjust sctp_chunk_is_data for SCTP_CID_I_DATA.

After this patch, idata can be built and sent in tx path.

Note that if sp strm_interleave is set, it has to wait_connect in
sctp_sendmsg, as asoc intl_enable need to be known after 4 shake-
hands, to decide if it should use data or idata later. data and
idata can't be mixed to send in one asoc.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index 6f79415f6634..20c0c1be2ca7 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -444,13 +444,13 @@ static inline int sctp_frag_point(const struct sctp_association *asoc, int pmtu)
 	int frag = pmtu;
 
 	frag -= sp->pf->af->net_header_len;
-	frag -= sizeof(struct sctphdr) + sizeof(struct sctp_data_chunk);
+	frag -= sizeof(struct sctphdr) + sctp_datachk_len(&asoc->stream);
 
 	if (asoc->user_frag)
 		frag = min_t(int, frag, asoc->user_frag);
 
 	frag = SCTP_TRUNC4(min_t(int, frag, SCTP_MAX_CHUNK_LEN -
-					    sizeof(struct sctp_data_chunk)));
+					    sctp_datachk_len(&asoc->stream)));
 
 	return frag;
 }