[newlib 13/65] Make use of the stats(3) framework in the TCP stack.

[Sebastian Huber]

From: Edward Tomasz Napierala <trasz at FreeBSD.org>

This makes it possible to retrieve per-connection statistical
information such as the receive window size, RTT, or goodput,
using a newly added TCP_STATS getsockopt(3) option, and extract
them using the stats_voistat_fetch(3) API.

See the net/tcprtt port for an example consumer of this API.

Compared to the existing TCP_INFO system, the main differences
are that this mechanism is easy to extend without breaking ABI,
and provides statistical information instead of raw "snapshots"
of values at a given point in time.  stats(3) is more generic
and can be used in both userland and the kernel.

Reviewed by:	thj
Tested by:	thj
Obtained from:	Netflix
Relnotes:	yes
Sponsored by:	Klara Inc, Netflix
Differential Revision:	https://reviews.freebsd.org/D20655
---
 newlib/libc/sys/rtems/include/netinet/tcp.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/newlib/libc/sys/rtems/include/netinet/tcp.h b/newlib/libc/sys/rtems/include/netinet/tcp.h
index 125cacb28..4e06c9792 100644
--- a/newlib/libc/sys/rtems/include/netinet/tcp.h
+++ b/newlib/libc/sys/rtems/include/netinet/tcp.h
@@ -168,6 +168,7 @@ struct tcphdr {
 #define TCP_NOOPT	8	/* don't use TCP options */
 #define TCP_MD5SIG	16	/* use MD5 digests (RFC2385) */
 #define	TCP_INFO	32	/* retrieve tcp_info structure */
+#define	TCP_STATS	33	/* retrieve stats blob structure */
 #define	TCP_LOG		34	/* configure event logging for connection */
 #define	TCP_LOGBUF	35	/* retrieve event log for connection */
 #define	TCP_LOGID	36	/* configure log ID to correlate connections */
@@ -364,4 +365,18 @@ struct tcp_function_set {
  */
 #define	TLS_SET_RECORD_TYPE	1
 
+/*
+ * TCP specific variables of interest for tp->t_stats stats(9) accounting.
+ */
+#define	VOI_TCP_TXPB		0 /* Transmit payload bytes */
+#define	VOI_TCP_RETXPB		1 /* Retransmit payload bytes */
+#define	VOI_TCP_FRWIN		2 /* Foreign receive window */
+#define	VOI_TCP_LCWIN		3 /* Local congesiton window */
+#define	VOI_TCP_RTT		4 /* Round trip time */
+#define	VOI_TCP_CSIG		5 /* Congestion signal */
+#define	VOI_TCP_GPUT		6 /* Goodput */
+#define	VOI_TCP_CALCFRWINDIFF	7 /* Congestion avoidance LCWIN - FRWIN */
+#define	VOI_TCP_GPUT_ND		8 /* Goodput normalised delta */
+#define	VOI_TCP_ACKLEN		9 /* Average ACKed bytes per ACK */
+
 #endif /* !_NETINET_TCP_H_ */
-- 
2.35.3