[SCTP]: Implement the Supported Extensions Parameter

SCTP Supported Extenions parameter is specified in Section 4.2.7
of the ADD-IP draft (soon to be RFC).  The parameter is
encoded as:

      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 = 0x8008   |      Parameter Length         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | CHUNK TYPE 1  |  CHUNK TYPE 2 |  CHUNK TYPE 3 |  CHUNK TYPE 4 |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                             ....                              |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     | CHUNK TYPE N  |      PAD      |      PAD      |      PAD      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

It contains a list of chunks that a particular SCTP extension
uses.  Current extensions supported are Partial Reliability
(FWD-TSN) and ADD-IP (ASCONF and ASCONF-ACK).

When implementing new extensions (AUTH, PKT-DROP, etc..), new
chunks need to be added to this parameter.  Parameter processing
would be modified to negotiate support for these new features.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 10 insertions, 0 deletions

diff --git a/include/linux/sctp.h b/include/linux/sctp.h
index d70df61a029f..f4d717b72ddd 100644
--- a/include/linux/sctp.h
+++ b/include/linux/sctp.h
@@ -180,6 +180,9 @@ typedef enum {
         SCTP_PARAM_SUPPORTED_ADDRESS_TYPES      = __constant_htons(12),
         SCTP_PARAM_ECN_CAPABLE                  = __constant_htons(0x8000),
 
+        /* Add-IP: Supported Extensions, Section 4.2 */
+        SCTP_PARAM_SUPPORTED_EXT        = __constant_htons(0x8008),
+
         /* PR-SCTP Sec 3.1 */
         SCTP_PARAM_FWD_TSN_SUPPORT      = __constant_htons(0xc000),
 
@@ -296,6 +299,12 @@ typedef struct sctp_adaptation_ind_param {
         __be32 adaptation_ind;
 } __attribute__((packed)) sctp_adaptation_ind_param_t;
 
+/* ADDIP Section 4.2.7 Supported Extensions Parameter */
+typedef struct sctp_supported_ext_param {
+        struct sctp_paramhdr param_hdr;
+        __u8 chunks[0];
+} __attribute__((packed)) sctp_supported_ext_param_t;
+
 /* RFC 2960.  Section 3.3.3 Initiation Acknowledgement (INIT ACK) (2):
  *   The INIT ACK chunk is used to acknowledge the initiation of an SCTP
  *   association.
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 67c91d01b635..b4812a2d3bb0 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -440,6 +440,7 @@ union sctp_params {
         struct sctp_ipv6addr_param *v6;
         union sctp_addr_param *addr;
         struct sctp_adaptation_ind_param *aind;
+        struct sctp_supported_ext_param *ext;
 };
 
 /* RFC 2960.  Section 3.3.5 Heartbeat.