sctp: add basic structures and make chunk function for idata

sctp_idatahdr and sctp_idata_chunk are used to define and parse
I-DATA chunk format, and sctp_make_idata is a function to build
the chunk.

The I-DATA Chunk Format is defined in section 2.1 of RFC8260.

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>

4 files changed, 26 insertions, 0 deletions

diff --git a/include/linux/sctp.h b/include/linux/sctp.h
index 6d2bd64b6ffe..38e2cf66195f 100644
--- a/include/linux/sctp.h
+++ b/include/linux/sctp.h
@@ -243,6 +243,23 @@ struct sctp_data_chunk {
         struct sctp_datahdr data_hdr;
 };
 
+struct sctp_idatahdr {
+        __be32 tsn;
+        __be16 stream;
+        __be16 reserved;
+        __be32 mid;
+        union {
+                __u32 ppid;
+                __be32 fsn;
+        };
+        __u8 payload[0];
+};
+
+struct sctp_idata_chunk {
+        struct sctp_chunkhdr chunk_hdr;
+        struct sctp_idatahdr data_hdr;
+};
+
 /* DATA Chuck Specific Flags */
 enum {
         SCTP_DATA_MIDDLE_FRAG   = 0x00,
diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
index 70fb397f65b0..5389ae034cfa 100644
--- a/include/net/sctp/sm.h
+++ b/include/net/sctp/sm.h
@@ -197,6 +197,8 @@ struct sctp_chunk *sctp_make_cookie_ack(const struct sctp_association *asoc,
 struct sctp_chunk *sctp_make_cwr(const struct sctp_association *asoc,
                                  const __u32 lowest_tsn,
                                  const struct sctp_chunk *chunk);
+struct sctp_chunk *sctp_make_idata(const struct sctp_association *asoc,
+                                   __u8 flags, int paylen, gfp_t gfp);
 struct sctp_chunk *sctp_make_datafrag_empty(struct sctp_association *asoc,
                                             const struct sctp_sndrcvinfo *sinfo,
                                             int len, const __u8 flags,
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 7030cbe11f45..7026a8039367 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -575,6 +575,7 @@ struct sctp_chunk {
                 struct sctp_addiphdr *addip_hdr;
                 struct sctp_fwdtsn_hdr *fwdtsn_hdr;
                 struct sctp_authhdr *auth_hdr;
+                struct sctp_idatahdr *idata_hdr;
         } subh;
 
         __u8 *chunk_end;
diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index da33c8550170..b969397fb773 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -1425,6 +1425,12 @@ static struct sctp_chunk *sctp_make_data(const struct sctp_association *asoc,
         return _sctp_make_chunk(asoc, SCTP_CID_DATA, flags, paylen, gfp);
 }
 
+struct sctp_chunk *sctp_make_idata(const struct sctp_association *asoc,
+                                   __u8 flags, int paylen, gfp_t gfp)
+{
+        return _sctp_make_chunk(asoc, SCTP_CID_I_DATA, flags, paylen, gfp);
+}
+
 static struct sctp_chunk *sctp_make_control(const struct sctp_association *asoc,
                                             __u8 type, __u8 flags, int paylen,
                                             gfp_t gfp)