sctp: Add support to per-association statistics via a new SCTP_GET_ASSOC_STATS call

The current SCTP stack is lacking a mechanism to have per association
statistics. This is an implementation modeled after OpenSolaris'
SCTP_GET_ASSOC_STATS.

Userspace part will follow on lksctp if/when there is a general ACK on
this.
V4:
- Move ipackets++ before q->immediate.func() for consistency reasons
- Move sctp_max_rto() at the end of sctp_transport_update_rto() to avoid
  returning bogus RTO values
- return asoc->rto_min when max_obs_rto value has not changed

V3:
- Increase ictrlchunks in sctp_assoc_bh_rcv() as well
- Move ipackets++ to sctp_inq_push()
- return 0 when no rto updates took place since the last call

V2:
- Implement partial retrieval of stat struct to cope for future expansion
- Kill the rtxpackets counter as it cannot be precise anyway
- Rename outseqtsns to outofseqtsns to make it clearer that these are out
  of sequence unexpected TSNs
- Move asoc->ipackets++ under a lock to avoid potential miscounts
- Fold asoc->opackets++ into the already existing asoc check
- Kill unneeded (q->asoc) test when increasing rtxchunks
- Do not count octrlchunks if sending failed (SCTP_XMIT_OK != 0)
- Don't count SHUTDOWNs as SACKs
- Move SCTP_GET_ASSOC_STATS to the private space API
- Adjust the len check in sctp_getsockopt_assoc_stats() to allow for
  future struct growth
- Move association statistics in their own struct
- Update idupchunks when we send a SACK with dup TSNs
- return min_rto in max_rto when RTO has not changed. Also return the
  transport when max_rto last changed.

Signed-off: Michele Baldessari <michele@acksyn.org>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 75 insertions, 0 deletions

diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index 9c6414f..7fdf298 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -272,6 +272,18 @@ struct sctp_mib {
         unsigned long   mibs[SCTP_MIB_MAX];
 };
 
+/* helper function to track stats about max rto and related transport */
+static inline void sctp_max_rto(struct sctp_association *asoc,
+				struct sctp_transport *trans)
+{
+	if (asoc->stats.max_obs_rto < (__u64)trans->rto) {
+		asoc->stats.max_obs_rto = trans->rto;
+		memset(&asoc->stats.obs_rto_ipaddr, 0,
+			sizeof(struct sockaddr_storage));
+		memcpy(&asoc->stats.obs_rto_ipaddr, &trans->ipaddr,
+			trans->af_specific->sockaddr_len);
+	}
+}
 
 /* Print debugging messages.  */
 #if SCTP_DEBUG
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 2b2f61d..c252101 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -1312,6 +1312,40 @@ struct sctp_inithdr_host {
 	__u32 initial_tsn;
 };
 
+/* SCTP_GET_ASSOC_STATS counters */
+struct sctp_priv_assoc_stats {
+	/* Maximum observed rto in the association during subsequent
+	 * observations. Value is set to 0 if no RTO measurement took place
+	 * The transport where the max_rto was observed is returned in
+	 * obs_rto_ipaddr
+	 */
+	struct sockaddr_storage obs_rto_ipaddr;
+	__u64 max_obs_rto;
+	/* Total In and Out SACKs received and sent */
+	__u64 isacks;
+	__u64 osacks;
+	/* Total In and Out packets received and sent */
+	__u64 opackets;
+	__u64 ipackets;
+	/* Total retransmitted chunks */
+	__u64 rtxchunks;
+	/* TSN received > next expected */
+	__u64 outofseqtsns;
+	/* Duplicate Chunks received */
+	__u64 idupchunks;
+	/* Gap Ack Blocks received */
+	__u64 gapcnt;
+	/* Unordered data chunks sent and received */
+	__u64 ouodchunks;
+	__u64 iuodchunks;
+	/* Ordered data chunks sent and received */
+	__u64 oodchunks;
+	__u64 iodchunks;
+	/* Control chunks sent and received */
+	__u64 octrlchunks;
+	__u64 ictrlchunks;
+};
+
 /* RFC2960
  *
  * 12. Recommended Transmission Control Block (TCB) Parameters
@@ -1830,6 +1864,8 @@ struct sctp_association {
 
 	__u8 need_ecne:1,	/* Need to send an ECNE Chunk? */
 	     temp:1;		/* Is it a temporary association? */
+
+	struct sctp_priv_assoc_stats stats;
 };
 
 
diff --git a/include/net/sctp/user.h b/include/net/sctp/user.h
index 1b02d7a..9a0ae09 100644
--- a/include/net/sctp/user.h
+++ b/include/net/sctp/user.h
@@ -107,6 +107,7 @@ typedef __s32 sctp_assoc_t;
 #define SCTP_GET_LOCAL_ADDRS	109		/* Get all local address. */
 #define SCTP_SOCKOPT_CONNECTX	110		/* CONNECTX requests. */
 #define SCTP_SOCKOPT_CONNECTX3	111	/* CONNECTX requests (updated) */
+#define SCTP_GET_ASSOC_STATS	112	/* Read only */
 
 /*
  * 5.2.1 SCTP Initiation Structure (SCTP_INIT)
@@ -719,6 +720,32 @@ struct sctp_getaddrs {
 	__u8			addrs[0]; /*output, variable size*/
 };
 
+/* A socket user request obtained via SCTP_GET_ASSOC_STATS that retrieves
+ * association stats. All stats are counts except sas_maxrto and
+ * sas_obs_rto_ipaddr. maxrto is the max observed rto + transport since
+ * the last call. Will return 0 when RTO was not update since last call
+ */
+struct sctp_assoc_stats {
+	sctp_assoc_t	sas_assoc_id;    /* Input */
+					 /* Transport of observed max RTO */
+	struct sockaddr_storage sas_obs_rto_ipaddr;
+	__u64		sas_maxrto;      /* Maximum Observed RTO for period */
+	__u64		sas_isacks;	 /* SACKs received */
+	__u64		sas_osacks;	 /* SACKs sent */
+	__u64		sas_opackets;	 /* Packets sent */
+	__u64		sas_ipackets;	 /* Packets received */
+	__u64		sas_rtxchunks;   /* Retransmitted Chunks */
+	__u64		sas_outofseqtsns;/* TSN received > next expected */
+	__u64		sas_idupchunks;  /* Dups received (ordered+unordered) */
+	__u64		sas_gapcnt;      /* Gap Acknowledgements Received */
+	__u64		sas_ouodchunks;  /* Unordered data chunks sent */
+	__u64		sas_iuodchunks;  /* Unordered data chunks received */
+	__u64		sas_oodchunks;	 /* Ordered data chunks sent */
+	__u64		sas_iodchunks;	 /* Ordered data chunks received */
+	__u64		sas_octrlchunks; /* Control chunks sent */
+	__u64		sas_ictrlchunks; /* Control chunks received */
+};
+
 /* These are bit fields for msghdr->msg_flags.  See section 5.1.  */
 /* On user space Linux, these live in <bits/socket.h> as an enum.  */
 enum sctp_msg_flags {