Extend netstat to display TCP stack and detailed congestion state

Adding the "-c" option used to show detailed per-connection
congestion control state for TCP sessions.

This is one summary patch, which adds the relevant variables into
xtcpcb. As previous "spare" space is used, these changes are ABI
compatible.

Reviewed by:	tuexen
MFC after:	2 weeks
Sponsored by:	NetApp, Inc.
Differential Revision:	https://reviews.freebsd.org/D26518

usr.bin/netstat/inet.c

@@ -85,6 +85,8 @@ __FBSDID("$FreeBSD$");
 #include "netstat.h"
 #include "nl_defs.h"
 
+#define max(a, b) (((a) > (b)) ? (a) : (b))
+
 #ifdef INET
 static void inetprint(const char *, struct in_addr *, int, const char *, int,
     const int);
@@ -204,6 +206,7 @@ protopr(u_long off, const char *name, int af1, int proto)
 	struct xinpcb *inp;
 	struct xinpgen *xig, *oxig;
 	struct xsocket *so;
+	int fnamelen, cnamelen;
 
 	istcp = 0;
 	switch (proto) {
@@ -236,6 +239,28 @@ protopr(u_long off, const char *name, int af1, int proto)
 	if (!pcblist_sysctl(proto, name, &buf))
 		return;
 
+	if (cflag || Cflag) {
+		fnamelen = strlen("Stack");
+		cnamelen = strlen("CC");
+		oxig = xig = (struct xinpgen *)buf;
+		for (xig = (struct xinpgen*)((char *)xig + xig->xig_len);
+		    xig->xig_len > sizeof(struct xinpgen);
+		    xig = (struct xinpgen *)((char *)xig + xig->xig_len)) {
+			if (istcp) {
+				tp = (struct xtcpcb *)xig;
+				inp = &tp->xt_inp;
+			} else {
+				continue;
+			}
+			if (so->xso_protocol != proto)
+				continue;
+			if (inp->inp_gencnt > oxig->xig_gen)
+				continue;
+			fnamelen = max(fnamelen, (int)strlen(tp->xt_stack));
+			cnamelen = max(cnamelen, (int)strlen(tp->xt_cc));
+		}
+	}
+
 	oxig = xig = (struct xinpgen *)buf;
 	for (xig = (struct xinpgen *)((char *)xig + xig->xig_len);
 	    xig->xig_len > sizeof(struct xinpgen);
@@ -341,9 +366,19 @@ protopr(u_long off, const char *name, int af1, int proto)
 				xo_emit("  {T:/%8.8s} {T:/%5.5s}",
 				    "flowid", "ftype");
 			}
+			if (cflag) {
+				xo_emit(" {T:/%-*.*s}",
+					fnamelen, fnamelen, "Stack");
+			}
 			if (Cflag)
-				xo_emit(" {T:/%-*.*s}", TCP_CA_NAME_MAX,
-				    TCP_CA_NAME_MAX, "CC");
+				xo_emit(" {T:/%-*.*s} {T:/%10.10s}"
+					" {T:/%10.10s} {T:/%5.5s}"
+					" {T:/%3.3s}", cnamelen,
+					cnamelen, "CC",
+					"cwin",
+					"ssthresh",
+					"MSS",
+					"ECN");
 			if (Pflag)
 				xo_emit(" {T:/%s}", "Log ID");
 			xo_emit("\n");
@@ -518,9 +553,24 @@ protopr(u_long off, const char *name, int af1, int proto)
 			    inp->inp_flowtype);
 		}
 		if (istcp) {
+			if (cflag)
+				xo_emit(" {:stack/%-*.*s}",
+					
+					fnamelen, fnamelen, tp->xt_stack);
 			if (Cflag)
-				xo_emit(" {:cc/%-*.*s}", TCP_CA_NAME_MAX,
-				    TCP_CA_NAME_MAX, tp->xt_cc);
+				xo_emit(" {:cc/%-*.*s}"
+					" {:snd-cwnd/%10lu}"
+					" {:snd-ssthresh/%10lu}"
+					" {:t-maxseg/%5u} {:ecn/%3s}",
+					cnamelen, cnamelen, tp->xt_cc,
+					tp->t_snd_cwnd, tp->t_snd_ssthresh,
+					tp->t_maxseg,
+					(tp->t_state >= TCPS_ESTABLISHED ?
+					    (tp->xt_ecn > 0 ?
+						(tp->xt_ecn == 1 ?
+						    "ecn" : "ace")
+						: "off")
+					    : "n/a"));
 			if (Pflag)
 				xo_emit(" {:log-id/%s}",
 				    tp->xt_logid[0] == '\0' ?

usr.bin/netstat/main.c

@@ -205,7 +205,8 @@ int	Aflag;		/* show addresses of protocol control block */
 int	aflag;		/* show all sockets (including servers) */
 static int	Bflag;		/* show information about bpf consumers */
 int	bflag;		/* show i/f total bytes in/out */
-int	Cflag;		/* show congestion control */
+int	cflag;		/* show TCP congestion control stack */
+int	Cflag;		/* show congestion control algo and vars */
 int	dflag;		/* show i/f dropped packets */
 int	gflag;		/* show group (multicast) routing or stats */
 int	hflag;		/* show counters in human readable format */
@@ -251,7 +252,7 @@ main(int argc, char *argv[])
 	if (argc < 0)
 		exit(EXIT_FAILURE);
 
-	while ((ch = getopt(argc, argv, "46AaBbCdF:f:ghI:iLlM:mN:nOoPp:Qq:RrSTsuWw:xz"))
+	while ((ch = getopt(argc, argv, "46AaBbCcdF:f:ghI:iLlM:mN:nOoPp:Qq:RrSTsuWw:xz"))
 	    != -1)
 		switch(ch) {
 		case '4':
@@ -280,6 +281,9 @@ main(int argc, char *argv[])
 		case 'b':
 			bflag = 1;
 			break;
+		case 'c':
+			cflag = 1;
+			break;
 		case 'C':
 			Cflag = 1;
 			break;
@@ -886,7 +890,7 @@ static void
 usage(void)
 {
 	(void)xo_error("%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
-"usage: netstat [-46AaLnRSTWx] [-f protocol_family | -p protocol]\n"
+"usage: netstat [-46AaCcLnRSTWx] [-f protocol_family | -p protocol]\n"
 "               [-M core] [-N system]",
 "       netstat -i | -I interface [-46abdhnW] [-f address_family]\n"
 "               [-M core] [-N system]",

usr.bin/netstat/netstat.1

@@ -28,7 +28,7 @@
 .\"	@(#)netstat.1	8.8 (Berkeley) 4/18/94
 .\" $FreeBSD$
 .\"
-.Dd September 13, 2020
+.Dd September 25, 2020
 .Dt NETSTAT 1
 .Os
 .Sh NAME
@@ -172,8 +172,10 @@ associated with a socket; used for debugging.
 .It Fl a
 Show the state of all sockets;
 normally sockets used by server processes are not shown.
+.It Fl c
+Show the used TCP stack for each session.
 .It Fl C
-Show the congestion control of TCP sockets.
+Show the congestion control algorithm and diagnostic information of TCP sockets.
 .It Fl L
 Show the size of the various listen queues.
 The first count shows the number of unaccepted connections,

usr.bin/netstat/netstat.h

@@ -41,7 +41,8 @@
 extern int	Aflag;	/* show addresses of protocol control block */
 extern int	aflag;	/* show all sockets (including servers) */
 extern int	bflag;	/* show i/f total bytes in/out */
-extern int	Cflag;	/* show congestion control */
+extern int	cflag;	/* show congestion control stats */
+extern int	Cflag;	/* show congestion control algo and stack */
 extern int	dflag;	/* show i/f dropped packets */
 extern int	gflag;	/* show group (multicast) routing or stats */
 extern int	hflag;	/* show counters in human readable format */