sctp: add pad chunk and its make function and event table

This chunk is defined in rfc4820#section-3, and used to pad an
SCTP packet. The receiver must discard this chunk and continue
processing the rest of the chunks in the packet.

Add it now, as it will be bundled with a heartbeat chunk to probe
pmtu in the following patches.

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

diff --git a/include/linux/sctp.h b/include/linux/sctp.h
index bb192658969310f3c0e31484f57cad8b49b4ef80..a86e852507b32a02e5fff5e189f95950f693e159 100644 (file)
--- a/include/linux/sctp.h
+++ b/include/linux/sctp.h
@@ -98,6 +98,7 @@ enum sctp_cid {
        SCTP_CID_I_FWD_TSN              = 0xC2,
        SCTP_CID_ASCONF_ACK             = 0x80,
        SCTP_CID_RECONF                 = 0x82,
+       SCTP_CID_PAD                    = 0x84,
 }; /* enum */
 
 
@@ -410,6 +411,12 @@ struct sctp_heartbeat_chunk {
 };
 
 
+/* PAD chunk could be bundled with heartbeat chunk to probe pmtu */
+struct sctp_pad_chunk {
+       struct sctp_chunkhdr uh;
+};
+
+
 /* For the abort and shutdown ACK we must carry the init tag in the
  * common header. Just the common header is all that is needed with a
  * chunk descriptor.

diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
index fd223c94589a67f0437caca260463ceedb7d9e1f..09c59154634defd0f2118e913cc18fc44261a47b 100644 (file)
--- a/include/net/sctp/sm.h
+++ b/include/net/sctp/sm.h
@@ -230,6 +230,7 @@ struct sctp_chunk *sctp_make_heartbeat_ack(const struct sctp_association *asoc,
                                           const struct sctp_chunk *chunk,
                                           const void *payload,
                                           const size_t paylen);
+struct sctp_chunk *sctp_make_pad(const struct sctp_association *asoc, int len);
 struct sctp_chunk *sctp_make_op_error(const struct sctp_association *asoc,
                                      const struct sctp_chunk *chunk,
                                      __be16 cause_code, const void *payload,

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index 5b44d228b6cacc720300d9f5951115a95a828163..e5d470cd7c40c76cdbd510b498ac16aee8a0ff8c 100644 (file)
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -1218,6 +1218,32 @@ nodata:
        return retval;
 }
 
+/* RFC4820 3. Padding Chunk (PAD)
+ *  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
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | Type = 0x84   |   Flags=0     |             Length            |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |                                                               |
+ * \                         Padding Data                          /
+ * /                                                               \
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ */
+struct sctp_chunk *sctp_make_pad(const struct sctp_association *asoc, int len)
+{
+       struct sctp_chunk *retval;
+
+       retval = sctp_make_control(asoc, SCTP_CID_PAD, 0, len, GFP_ATOMIC);
+       if (!retval)
+               return NULL;
+
+       skb_put_zero(retval->skb, len);
+       retval->chunk_hdr->length = htons(ntohs(retval->chunk_hdr->length) + len);
+       retval->chunk_end = skb_tail_pointer(retval->skb);
+
+       return retval;
+}
+
 /* Create an Operation Error chunk with the specified space reserved.
  * This routine can be used for containing multiple causes in the chunk.
  */

diff --git a/net/sctp/sm_statetable.c b/net/sctp/sm_statetable.c
index 88ea87f4f0e790dfb14cbb8261696655fa34fba8..c82c4233ec6bd173994a9a24f1e54c3a620746ed 100644 (file)
--- a/net/sctp/sm_statetable.c
+++ b/net/sctp/sm_statetable.c
@@ -526,6 +526,26 @@ auth_chunk_event_table[SCTP_NUM_AUTH_CHUNK_TYPES][SCTP_STATE_NUM_STATES] = {
        TYPE_SCTP_AUTH,
 }; /*state_fn_t auth_chunk_event_table[][] */
 
+static const struct sctp_sm_table_entry
+pad_chunk_event_table[SCTP_STATE_NUM_STATES] = {
+       /* SCTP_STATE_CLOSED */
+       TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
+       /* SCTP_STATE_COOKIE_WAIT */
+       TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
+       /* SCTP_STATE_COOKIE_ECHOED */
+       TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
+       /* SCTP_STATE_ESTABLISHED */
+       TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
+       /* SCTP_STATE_SHUTDOWN_PENDING */
+       TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
+       /* SCTP_STATE_SHUTDOWN_SENT */
+       TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
+       /* SCTP_STATE_SHUTDOWN_RECEIVED */
+       TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
+       /* SCTP_STATE_SHUTDOWN_ACK_SENT */
+       TYPE_SCTP_FUNC(sctp_sf_discard_chunk),
+};     /* chunk pad */
+
 static const struct sctp_sm_table_entry
 chunk_event_table_unknown[SCTP_STATE_NUM_STATES] = {
        /* SCTP_STATE_CLOSED */
@@ -992,6 +1012,9 @@ static const struct sctp_sm_table_entry *sctp_chunk_event_lookup(
 
        case SCTP_CID_AUTH:
                return &auth_chunk_event_table[0][state];
+
+       case SCTP_CID_PAD:
+               return &pad_chunk_event_table[state];
        }
 
        return &chunk_event_table_unknown[state];