ip: allow ip address show to list addresses with certain flags not being set

Sometimes it's needed to have "ip address show" list only addresses
with certain flags not being set, e.g. in network scripts.
As an example one might want to exclude addresses in "tentative"
or "deprecated" state.

Support listing addresses with flags tentative, deprecated, dadfailed
not being set by prefixing the respective flag with a minus.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>

ip/ipaddress.c

@@ -80,7 +80,7 @@ static void usage(void)
 	fprintf(stderr, "SCOPE-ID := [ host | link | global | NUMBER ]\n");
 	fprintf(stderr, "FLAG-LIST := [ FLAG-LIST ] FLAG\n");
 	fprintf(stderr, "FLAG  := [ permanent | dynamic | secondary | primary |\n");
-	fprintf(stderr, "           tentative | deprecated | dadfailed | temporary |\n");
+	fprintf(stderr, "           [-]tentative | [-]deprecated | [-]dadfailed | temporary |\n");
 	fprintf(stderr, "           CONFFLAG-LIST ]\n");
 	fprintf(stderr, "CONFFLAG-LIST := [ CONFFLAG-LIST ] CONFFLAG\n");
 	fprintf(stderr, "CONFFLAG  := [ home | nodad | mngtmpaddr | noprefixroute ]\n");
@@ -1261,9 +1261,15 @@ static int ipaddr_list_flush_or_save(int argc, char **argv, int action)
 		} else if (strcmp(*argv, "tentative") == 0) {
 			filter.flags |= IFA_F_TENTATIVE;
 			filter.flagmask |= IFA_F_TENTATIVE;
+		} else if (strcmp(*argv, "-tentative") == 0) {
+			filter.flags &= ~IFA_F_TENTATIVE;
+			filter.flagmask |= IFA_F_TENTATIVE;
 		} else if (strcmp(*argv, "deprecated") == 0) {
 			filter.flags |= IFA_F_DEPRECATED;
 			filter.flagmask |= IFA_F_DEPRECATED;
+		} else if (strcmp(*argv, "-deprecated") == 0) {
+			filter.flags &= ~IFA_F_DEPRECATED;
+			filter.flagmask |= IFA_F_DEPRECATED;
 		} else if (strcmp(*argv, "home") == 0) {
 			filter.flags |= IFA_F_HOMEADDRESS;
 			filter.flagmask |= IFA_F_HOMEADDRESS;
@@ -1279,6 +1285,9 @@ static int ipaddr_list_flush_or_save(int argc, char **argv, int action)
 		} else if (strcmp(*argv, "dadfailed") == 0) {
 			filter.flags |= IFA_F_DADFAILED;
 			filter.flagmask |= IFA_F_DADFAILED;
+		} else if (strcmp(*argv, "-dadfailed") == 0) {
+			filter.flags &= ~IFA_F_DADFAILED;
+			filter.flagmask |= IFA_F_DADFAILED;
 		} else if (strcmp(*argv, "label") == 0) {
 			NEXT_ARG();
 			filter.label = *argv;