svn commit: r300240 - head/sys/netinet

[Don Lewis]

Author: truckman
Date: Thu May 19 22:20:35 2016
New Revision: 300240
URL: https://svnweb.freebsd.org/changeset/base/300240

Log:
  Change net.inet.tcp.ecn.enable sysctl mib from a binary off/on
  control to a three way setting.
    0 - Totally disable ECN. (no change)
    1 - Enable ECN if incoming connections request it.  Outgoing
        connections will request ECN.  (no change from present != 0 setting)
    2 - Enable ECN if incoming connections request it.  Outgoing
        conections will not request ECN.
  
  Change the default value of net.inet.tcp.ecn.enable from 0 to 2.
  
  Linux version 2.4.20 and newer, Solaris, and Mac OS X 10.5 and newer have
  similar capabilities.  The actual values above match Linux, and the default
  matches the current Linux default.
  
  Reviewed by:	eadler
  MFC after:	1 month
  MFH:		yes
  Sponsored by:	https://reviews.freebsd.org/D6386

Modified:
  head/sys/netinet/tcp_input.c
  head/sys/netinet/tcp_output.c

Modified: head/sys/netinet/tcp_input.c
==============================================================================
--- head/sys/netinet/tcp_input.c	Thu May 19 22:19:35 2016	(r300239)
+++ head/sys/netinet/tcp_input.c	Thu May 19 22:20:35 2016	(r300240)
@@ -185,7 +185,7 @@ SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_
 
 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, ecn, CTLFLAG_RW, 0, "TCP ECN");
 
-VNET_DEFINE(int, tcp_do_ecn) = 0;
+VNET_DEFINE(int, tcp_do_ecn) = 2;
 SYSCTL_INT(_net_inet_tcp_ecn, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW,
     &VNET_NAME(tcp_do_ecn), 0,
     "TCP ECN support");

Modified: head/sys/netinet/tcp_output.c
==============================================================================
--- head/sys/netinet/tcp_output.c	Thu May 19 22:19:35 2016	(r300239)
+++ head/sys/netinet/tcp_output.c	Thu May 19 22:20:35 2016	(r300240)
@@ -1117,7 +1117,7 @@ send:
 	 * resend those bits a number of times as per
 	 * RFC 3168.
 	 */
-	if (tp->t_state == TCPS_SYN_SENT && V_tcp_do_ecn) {
+	if (tp->t_state == TCPS_SYN_SENT && V_tcp_do_ecn == 1) {
 		if (tp->t_rxtshift >= 1) {
 			if (tp->t_rxtshift <= V_tcp_ecn_maxretries)
 				flags |= TH_ECE|TH_CWR;