Use FF02:0:0:0:0:2:FF00::/104 prefix for IPv6 Node Information Group

Address.  Although KAME implementation used FF02:0:0:0:0:2::/96 based on
older versions of draft-ietf-ipngwg-icmp-name-lookup, it has been changed
in RFC 4620.

The kernel always joins the /104-prefixed address, and additionally does
/96-prefixed one only when net.inet6.icmp6.nodeinfo_oldmcprefix=1.
The default value of the sysctl is 1.

ping6(8) -N flag now uses /104-prefixed one.  When this flag is specified
twice, it uses /96-prefixed one instead.

Reviewed by:		ume
Based on work by:	Thomas Scheffler
PR:			conf/174957
MFC after:		2 weeks

2 files changed, 35 insertions, 9 deletions

diff --git a/sbin/ping6/ping6.8 b/sbin/ping6/ping6.8
index b720aef..0d1e5f0 100644
--- a/sbin/ping6/ping6.8
+++ b/sbin/ping6/ping6.8
@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 20, 2010
+.Dd May 5, 2013
 .Dt PING6 8
 .Os
 .Sh NAME
@@ -215,8 +215,8 @@ unicast and multicast packets.
 Numeric output only.
 No attempt will be made to lookup symbolic names from addresses in the reply.
 .It Fl N
-Probe node information multicast group
-.Pq Li ff02::2:xxxx:xxxx .
+Probe node information multicast group address
+.Pq Li ff02::2:ffxx:xxxx .
 .Ar host
 must be string hostname of the target
 (must not be a numeric IPv6 address).
@@ -227,6 +227,15 @@ Since node information multicast group is a link-local multicast group,
 outgoing interface needs to be specified by
 .Fl I
 option.
+.Pp
+When specified twice, the address
+.Pq Li ff02::2:xxxx:xxxx
+is used instead.
+The former is in RFC 4620, the latter is in an old Internet Draft
+draft-ietf-ipngwg-icmp-name-lookup.
+Note that KAME-derived implementations including
+.Fx 
+use the latter.
 .It Fl o
 Exit successfully after receiving one reply packet.
 .It Fl p Ar pattern
diff --git a/sbin/ping6/ping6.c b/sbin/ping6/ping6.c
index 8c3e16b..01e29a1 100644
--- a/sbin/ping6/ping6.c
+++ b/sbin/ping6/ping6.c
@@ -287,7 +287,7 @@ void	 pr_retip(struct ip6_hdr *, u_char *);
 void	 summary(void);
 void	 tvsub(struct timeval *, struct timeval *);
 int	 setpolicy(int, char *);
-char	*nigroup(char *);
+char	*nigroup(char *, int);
 void	 usage(void);
 
 int
@@ -306,6 +306,7 @@ main(int argc, char *argv[])
 	struct addrinfo hints;
 	int cc, i;
 	int ch, hold, packlen, preload, optval, ret_ga;
+	int nig_oldmcprefix = -1;
 	u_char *datap;
 	char *e, *target, *ifname = NULL, *gateway = NULL;
 	int ip6optlen = 0;
@@ -490,6 +491,7 @@ main(int argc, char *argv[])
 			break;
 		case 'N':
 			options |= F_NIGROUP;
+			nig_oldmcprefix++;
 			break;
 		case 'o':
 			options |= F_ONCE;
@@ -605,7 +607,7 @@ main(int argc, char *argv[])
 	}
 
 	if (options & F_NIGROUP) {
-		target = nigroup(argv[argc - 1]);
+		target = nigroup(argv[argc - 1], nig_oldmcprefix);
 		if (target == NULL) {
 			usage();
 			/*NOTREACHED*/
@@ -2723,7 +2725,7 @@ setpolicy(int so __unused, char *policy)
 #endif
 
 char *
-nigroup(char *name)
+nigroup(char *name, int nig_oldmcprefix)
 {
 	char *p;
 	char *q;
@@ -2733,6 +2735,7 @@ nigroup(char *name)
 	size_t l;
 	char hbuf[NI_MAXHOST];
 	struct in6_addr in6;
+	int valid;
 
 	p = strchr(name, '.');
 	if (!p)
@@ -2748,7 +2751,7 @@ nigroup(char *name)
 			*q = tolower(*(unsigned char *)q);
 	}
 
-	/* generate 8 bytes of pseudo-random value. */
+	/* generate 16 bytes of pseudo-random value. */
 	memset(&ctxt, 0, sizeof(ctxt));
 	MD5Init(&ctxt);
 	c = l & 0xff;
@@ -2756,9 +2759,23 @@ nigroup(char *name)
 	MD5Update(&ctxt, (unsigned char *)name, l);
 	MD5Final(digest, &ctxt);
 
-	if (inet_pton(AF_INET6, "ff02::2:0000:0000", &in6) != 1)
+	if (nig_oldmcprefix) {
+		/* draft-ietf-ipngwg-icmp-name-lookup */
+		valid = inet_pton(AF_INET6, "ff02::2:0000:0000", &in6);
+	} else {
+		/* RFC 4620 */
+		valid = inet_pton(AF_INET6, "ff02::2:ff00:0000", &in6);
+	}
+	if (valid != 1)
 		return NULL;	/*XXX*/
-	bcopy(digest, &in6.s6_addr[12], 4);
+	
+	if (nig_oldmcprefix) {
+		/* draft-ietf-ipngwg-icmp-name-lookup */
+		bcopy(digest, &in6.s6_addr[12], 4);
+	} else {
+		/* RFC 4620 */
+		bcopy(digest, &in6.s6_addr[13], 3);
+	}
 
 	if (inet_ntop(AF_INET6, &in6, hbuf, sizeof(hbuf)) == NULL)
 		return NULL;