[PATCHv4 net-next 4/5] sctp: add support for generating stream reconf add incoming/outgoing streams request chunk

[Xin Long]

This patch is to define Add Incoming/Outgoing Streams Request
Parameter described in rfc6525 section 4.5 and 4.6. They can
be in one same chunk trunk as rfc6525 section 3.1-7 describes,
so make them in one function.

Signed-off-by: Xin Long <lucien....@gmail.com>
---
 include/linux/sctp.h     |  7 +++++++
 include/net/sctp/sm.h    |  3 +++
 net/sctp/sm_make_chunk.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+)

diff --git a/include/linux/sctp.h b/include/linux/sctp.h
index 95b8ed3..f1f494f 100644
--- a/include/linux/sctp.h
+++ b/include/linux/sctp.h
@@ -742,4 +742,11 @@ struct sctp_strreset_tsnreq {
        __u32 request_seq;
 } __packed;
 
+struct sctp_strreset_addstrm {
+       sctp_paramhdr_t param_hdr;
+       __u32 request_seq;
+       __u16 number_of_streams;
+       __u16 reserved;
+} __packed;
+
 #endif /* __LINUX_SCTP_H__ */
diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
index ac37c17..3675fde 100644
--- a/include/net/sctp/sm.h
+++ b/include/net/sctp/sm.h
@@ -267,6 +267,9 @@ struct sctp_chunk *sctp_make_strreset_req(
                                bool out, bool in);
 struct sctp_chunk *sctp_make_strreset_tsnreq(
                                const struct sctp_association *asoc);
+struct sctp_chunk *sctp_make_strreset_addstrm(
+                               const struct sctp_association *asoc,
+                               __u16 out, __u16 in);
 void sctp_chunk_assign_tsn(struct sctp_chunk *);
 void sctp_chunk_assign_ssn(struct sctp_chunk *);
 
diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index 801450c..a44546d 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -3689,3 +3689,49 @@ struct sctp_chunk *sctp_make_strreset_tsnreq(
 
        return retval;
 }
+
+/* RE-CONFIG 4.5/4.6 (ADD STREAM)
+ *   0                   1                   2                   3
+ *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |     Parameter Type = 17       |      Parameter Length = 12    |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |          Re-configuration Request Sequence Number             |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *  |      Number of new streams    |         Reserved              |
+ *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ */
+struct sctp_chunk *sctp_make_strreset_addstrm(
+                               const struct sctp_association *asoc,
+                               __u16 out, __u16 in)
+{
+       struct sctp_strreset_addstrm addstrm;
+       __u16 size = sizeof(addstrm);
+       struct sctp_chunk *retval;
+
+       retval = sctp_make_reconf(asoc, (!!out + !!in) * size);
+       if (!retval)
+               return NULL;
+
+       if (out) {
+               addstrm.param_hdr.type = SCTP_PARAM_RESET_ADD_OUT_STREAMS;
+               addstrm.param_hdr.length = htons(size);
+               addstrm.number_of_streams = htons(out);
+               addstrm.request_seq = htonl(asoc->strreset_outseq);
+               addstrm.reserved = 0;
+
+               sctp_addto_chunk(retval, size, &addstrm);
+       }
+
+       if (in) {
+               addstrm.param_hdr.type = SCTP_PARAM_RESET_ADD_IN_STREAMS;
+               addstrm.param_hdr.length = htons(size);
+               addstrm.number_of_streams = htons(in);
+               addstrm.request_seq = htonl(asoc->strreset_outseq + !!out);
+               addstrm.reserved = 0;
+
+               sctp_addto_chunk(retval, size, &addstrm);
+       }
+
+       return retval;
+}
-- 
2.1.0