From 2f0581b84d1b86815ee58d1bd8d1754db09bfa6c Mon Sep 17 00:00:00 2001
From: florian <florian@openbsd.org>
Date: Sun, 25 Oct 2015 12:47:26 +0000
Subject: [PATCH] Implement ping(8)'s -L option in ping6: Disable the loopback,
 so the transmitting host doesn't see the ICMP requests. For multicast pings.
 OK benno@

---
 sbin/ping6/ping6.8 | 10 +++++++---
 sbin/ping6/ping6.c | 21 +++++++++++++++++----
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/sbin/ping6/ping6.8 b/sbin/ping6/ping6.8
index b597b934602..cbfa002cf54 100644
--- a/sbin/ping6/ping6.8
+++ b/sbin/ping6/ping6.8
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: ping6.8,v 1.57 2015/10/17 13:08:14 florian Exp $
+.\"	$OpenBSD: ping6.8,v 1.58 2015/10/25 12:47:26 florian Exp $
 .\"	$KAME: ping6.8,v 1.57 2002/05/26 13:18:25 itojun Exp $
 .\"
 .\" Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -28,7 +28,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: October 17 2015 $
+.Dd $Mdocdate: October 25 2015 $
 .Dt PING6 8
 .Os
 .Sh NAME
@@ -36,7 +36,7 @@
 .Nd send ICMPv6 ECHO_REQUEST packets to network hosts
 .Sh SYNOPSIS
 .Nm ping6
-.Op Fl dEefHmnqv
+.Op Fl dEefHLmnqv
 .Op Fl c Ar count
 .Op Fl g Ar gateway
 .Op Fl h Ar hoplimit
@@ -132,6 +132,10 @@ The default is to wait for one second between each packet.
 This option is incompatible with the
 .Fl f
 option.
+.It Fl L
+Disable the loopback, so the transmitting host doesn't see the ICMP
+requests.
+For multicast pings.
 .It Fl l Ar preload
 If
 .Ar preload
diff --git a/sbin/ping6/ping6.c b/sbin/ping6/ping6.c
index 47ab09dbace..02d0dc6f948 100644
--- a/sbin/ping6/ping6.c
+++ b/sbin/ping6/ping6.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ping6.c,v 1.131 2015/10/24 16:59:15 florian Exp $	*/
+/*	$OpenBSD: ping6.c,v 1.132 2015/10/25 12:47:26 florian Exp $	*/
 /*	$KAME: ping6.c,v 1.163 2002/10/25 02:19:06 itojun Exp $	*/
 
 /*
@@ -148,6 +148,10 @@ struct payload {
 #define F_AUD_MISS	0x400000
 u_int options;
 
+/* multicast options */
+int moptions;
+#define	MULTICAST_NOLOOP	0x001
+
 #define DUMMY_PORT	10101
 
 /*
@@ -235,7 +239,7 @@ main(int argc, char *argv[])
 	struct cmsghdr *scmsgp = NULL;
 	struct in6_pktinfo *pktinfo = NULL;
 	double intval;
-	int mflag = 0;
+	int mflag = 0, loop = 1;
 	uid_t uid;
 	u_int rtableid = 0;
 
@@ -250,7 +254,7 @@ main(int argc, char *argv[])
 	preload = 0;
 	datap = &outpack[ICMP6ECHOLEN + ICMP6ECHOTMLEN];
 	while ((ch = getopt(argc, argv,
-	    "c:dEefg:Hh:I:i:l:mNnp:qS:s:V:vw:")) != -1) {
+	    "c:dEefg:Hh:I:i:Ll:mNnp:qS:s:V:vw:")) != -1) {
 		switch (ch) {
 		case 'c':
 			npackets = strtonum(optarg, 0, INT_MAX, &errstr);
@@ -326,6 +330,10 @@ main(int argc, char *argv[])
 			}
 			options |= F_INTERVAL;
 			break;
+		case 'L':
+			moptions |= MULTICAST_NOLOOP;
+			loop = 0;
+			break;
 		case 'l':
 			if (getuid()) {
 				errno = EPERM;
@@ -463,6 +471,11 @@ main(int argc, char *argv[])
 	if ((options & F_FLOOD) && (options & (F_AUD_RECV | F_AUD_MISS)))
 		warnx("No audible output for flood pings");
 
+	if ((moptions & MULTICAST_NOLOOP) &&
+	    setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &loop,
+	    sizeof(loop)) < 0)
+		err(1, "setsockopt IP6_MULTICAST_LOOP");
+
 	if (datalen >= sizeof(struct payload)) {
 		/* we can time transfer */
 		timing = 1;
@@ -1645,7 +1658,7 @@ void
 usage(void)
 {
 	(void)fprintf(stderr,
-	    "usage: ping6 [-dEefHmnqv] [-c count] [-g gateway] [-h hoplimit] "
+	    "usage: ping6 [-dEefHLmnqv] [-c count] [-g gateway] [-h hoplimit] "
 	    "[-I sourceaddr]\n\t[-i wait] [-l preload] [-p pattern] "
 	    "[-s packetsize] [-V rtable]\n\t[-w maxwait] host\n");
 	exit(1);
-- 
2.20.1