[src/trunk]: src/sys/netinet Remove TCP_COMPAT_42. This feature is a workarou...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/ccaba13a3c86
branches:  trunk
changeset: 825721:ccaba13a3c86
user:      maxv <maxv%NetBSD.org@localhost>
date:      Fri Jul 28 19:16:41 2017 +0000

description:
Remove TCP_COMPAT_42. This feature is a workaround for a bug in the TCP
stack of BSD4.2. Having such features just does not make any sense, and
looking at the code, I'm not sure it actually works.

diffstat:

 sys/netinet/tcp_timer.c  |  22 +++++++---------------
 sys/netinet/tcp_usrreq.c |  10 ++--------
 sys/netinet/tcp_var.h    |   4 +---
 3 files changed, 10 insertions(+), 26 deletions(-)

diffs (99 lines):

diff -r 5f1dc574a3a3 -r ccaba13a3c86 sys/netinet/tcp_timer.c
--- a/sys/netinet/tcp_timer.c   Fri Jul 28 17:57:48 2017 +0000
+++ b/sys/netinet/tcp_timer.c   Fri Jul 28 19:16:41 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tcp_timer.c,v 1.91 2016/07/25 00:10:38 knakahara Exp $ */
+/*     $NetBSD: tcp_timer.c,v 1.92 2017/07/28 19:16:41 maxv Exp $      */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -93,7 +93,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tcp_timer.c,v 1.91 2016/07/25 00:10:38 knakahara Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tcp_timer.c,v 1.92 2017/07/28 19:16:41 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -564,19 +564,11 @@
                 * correspondent TCP to respond.
                 */
                TCP_STATINC(TCP_STAT_KEEPPROBE);
-               if (tcp_compat_42) {
-                       /*
-                        * The keepalive packet must have nonzero
-                        * length to get a 4.2 host to respond.
-                        */
-                       (void)tcp_respond(tp, tp->t_template,
-                           NULL, NULL, tp->rcv_nxt - 1,
-                           tp->snd_una - 1, 0);
-               } else {
-                       (void)tcp_respond(tp, tp->t_template,
-                           NULL, NULL, tp->rcv_nxt,
-                           tp->snd_una - 1, 0);
-               }
+
+               (void)tcp_respond(tp, tp->t_template,
+                   NULL, NULL, tp->rcv_nxt,
+                   tp->snd_una - 1, 0);
+
                TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepintvl);
        } else
                TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle);
diff -r 5f1dc574a3a3 -r ccaba13a3c86 sys/netinet/tcp_usrreq.c
--- a/sys/netinet/tcp_usrreq.c  Fri Jul 28 17:57:48 2017 +0000
+++ b/sys/netinet/tcp_usrreq.c  Fri Jul 28 19:16:41 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tcp_usrreq.c,v 1.214 2017/01/24 07:09:24 ozaki-r Exp $ */
+/*     $NetBSD: tcp_usrreq.c,v 1.215 2017/07/28 19:16:41 maxv Exp $    */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -99,7 +99,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tcp_usrreq.c,v 1.214 2017/01/24 07:09:24 ozaki-r Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tcp_usrreq.c,v 1.215 2017/07/28 19:16:41 maxv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -2152,12 +2152,6 @@
                       CTL_NET, pf, IPPROTO_TCP, TCPCTL_TSTAMP, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
-                      CTLTYPE_INT, "compat_42",
-                      SYSCTL_DESCR("Enable workarounds for 4.2BSD TCP bugs"),
-                      NULL, 0, &tcp_compat_42, 0,
-                      CTL_NET, pf, IPPROTO_TCP, TCPCTL_COMPAT_42, CTL_EOL);
-       sysctl_createv(clog, 0, NULL, NULL,
-                      CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "cwm",
                       SYSCTL_DESCR("Hughes/Touch/Heidemann Congestion Window "
                                    "Monitoring"),
diff -r 5f1dc574a3a3 -r ccaba13a3c86 sys/netinet/tcp_var.h
--- a/sys/netinet/tcp_var.h     Fri Jul 28 17:57:48 2017 +0000
+++ b/sys/netinet/tcp_var.h     Fri Jul 28 19:16:41 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tcp_var.h,v 1.178 2017/07/07 01:37:34 ozaki-r Exp $    */
+/*     $NetBSD: tcp_var.h,v 1.179 2017/07/28 19:16:41 maxv Exp $       */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -811,7 +811,6 @@
 extern int tcp_init_win_local; /* initial window for local nets */
 extern int tcp_init_win_max[11];/* max sizes for values of tcp_init_win_* */
 extern int tcp_mss_ifmtu;      /* take MSS from interface, not in_maxmtu */
-extern int tcp_compat_42;      /* work around ancient broken TCP peers */
 extern int tcp_cwm;            /* enable Congestion Window Monitoring */
 extern int tcp_cwm_burstsize;  /* burst size allowed by CWM */
 extern int tcp_ack_on_push;    /* ACK immediately on PUSH */
@@ -877,7 +876,6 @@
        { 1, 0, &tcp_do_sack },                 \
        { 1, 0, &tcp_do_win_scale },            \
        { 1, 0, &tcp_do_timestamps },           \
-       { 1, 0, &tcp_compat_42 },               \
        { 1, 0, &tcp_cwm },                     \
        { 1, 0, &tcp_cwm_burstsize },           \
        { 1, 0, &tcp_ack_on_push },             \