ip address: do not set nodad option for IPv4 addresses

Duplicate Address Detection (RFC 4862) is available only for IPv6
addresses. As a consequence, 'nodad' option, turning it off, should
be available only for IPv6, and is defined like that in the man page.

However it is possible to set nodad on IPv4 addresses, too:

$ ip link add dummy0 type dummy
$ ip -4 addr add 192.168.1.1 dev dummy0 nodad
$ ip a
1: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN group default qlen 1000
   link/ether 1a:6d:c6:96:ca:f8 brd ff:ff:ff:ff:ff:ff
   inet 192.168.1.1/32 scope global nodad dummy0
      valid_lft forever preferred_lft forever

Fix this adding a check on the protocol family before setting
IFA_F_NODAD flag.

Fixes: bac735c53a36d ("enabled to manipulate the flags of IFA_F_HOMEADDRESS or IFA_F_NODAD from ip.")
Signed-off-by: Andrea Claudi <aclaudi@redhat.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index fd79f978435dacf37e7fa000298010815c436acc..1b8ab783074ab5c8368292f2dffb2db39f509332 100644 (file)
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -2249,7 +2249,10 @@ static int ipaddr_modify(int cmd, int flags, int argc, char **argv)
                } else if (strcmp(*argv, "home") == 0) {
                        ifa_flags |= IFA_F_HOMEADDRESS;
                } else if (strcmp(*argv, "nodad") == 0) {
-                       ifa_flags |= IFA_F_NODAD;
+                       if (req.ifa.ifa_family == AF_INET6)
+                               ifa_flags |= IFA_F_NODAD;
+                       else
+                               fprintf(stderr, "Warning: nodad option can be set only for IPv6 addresses\n");
                } else if (strcmp(*argv, "mngtmpaddr") == 0) {
                        ifa_flags |= IFA_F_MANAGETEMPADDR;
                } else if (strcmp(*argv, "noprefixroute") == 0) {