Add mount options 'noinet4' and 'noinet6' which prevent using those

address families.

This is useful for preventing NFS mounts from using IPv6 on hosts
that have both A and AAAA records for the same name.

2 files changed, 20 insertions, 0 deletions

diff --git a/sbin/mount_nfs/mount_nfs.8 b/sbin/mount_nfs/mount_nfs.8
index 56a2ba6..3fe82e5 100644
--- a/sbin/mount_nfs/mount_nfs.8
+++ b/sbin/mount_nfs/mount_nfs.8
@@ -227,6 +227,10 @@ upper and lower bounds of the timeouts for ``directory'' attributes and
 for regular files, and 30 -> 60 seconds for directories.  The algorithm to
 calculate the timeout is based on the age of the file.  The older the file,
 the longer the cache is considered valid, subject to the limits above.
+.It noinet4
+.It noinet6
+Disables AF_INET or AF_INET6 connections.  Useful for hosts that have
+both an A record and an AAAA record for the same name.
 .El
 .Pp
 .Bl -tag -width "dumbtimerXX"
diff --git a/sbin/mount_nfs/mount_nfs.c b/sbin/mount_nfs/mount_nfs.c
index 7bbfa7e..fd2e5f9 100644
--- a/sbin/mount_nfs/mount_nfs.c
+++ b/sbin/mount_nfs/mount_nfs.c
@@ -98,6 +98,8 @@ static const char rcsid[] =
 #define ALTF_ACDIRMIN	0x20000
 #define ALTF_ACDIRMAX	0x40000
 #define ALTF_NOLOCKD	0x80000
+#define ALTF_NOINET4	0x100000
+#define ALTF_NOINET6	0x200000
 
 struct mntopt mopts[] = {
 	MOPT_STDOPTS,
@@ -121,6 +123,8 @@ struct mntopt mopts[] = {
 	{ "acdirmin=", 0, ALTF_ACDIRMIN, 1 },
 	{ "acdirmax=", 0, ALTF_ACDIRMAX, 1 },
 	{ "lockd", 1, ALTF_NOLOCKD, 1 },
+	{ "inet4", 1, ALTF_NOINET4, 1 },
+	{ "inet6", 1, ALTF_NOINET6, 1 },
 	{ NULL }
 };
 
@@ -172,6 +176,8 @@ struct nfhret {
 };
 #define	BGRND	1
 #define	ISBGRND	2
+#define	OF_NOINET4	4
+#define	OF_NOINET6	8
 int retrycnt = -1;
 int opflags = 0;
 int nfsproto = IPPROTO_UDP;
@@ -333,6 +339,10 @@ main(argc, argv)
 			 */
 			if (altflags & ALTF_BG)
 				opflags |= BGRND;
+			if (altflags & ALTF_NOINET4)
+				opflags |= OF_NOINET4;
+			if (altflags & ALTF_NOINET6)
+				opflags |= OF_NOINET6;
 			if (altflags & ALTF_MNTUDP)
 				mnttcp_ok = 0;
 			if (altflags & ALTF_TCP) {
@@ -529,6 +539,12 @@ getnfsargs(spec, nfsargsp)
 		 */
 		remoteerr = 0;
 		for (ai = ai_nfs; ai != NULL; ai = ai->ai_next) {
+			if ((ai->ai_family == AF_INET6) &&
+			    (opflags & OF_NOINET6))
+				continue;
+			if ((ai->ai_family == AF_INET) && 
+			    (opflags & OF_NOINET4))
+				continue;
 			ret = nfs_tryproto(nfsargsp, ai, hostp, spec, &errstr);
 			if (ret == TRYRET_SUCCESS)
 				break;