ip/ipconfig: use defaults for loopback

- do not write /net/ndb for loopback medium unless -p is specified
- use defmask() instead of hardcoded /64 for v6 to get correct /128 mask for ::1
- only do duplicate address detection on ethernet

sys/src/cmd/ip/ipconfig/dhcp.c

@@ -264,7 +264,6 @@ dhcpwatch(int needconfig)
 			 * leave everything we've learned somewhere that
 			 * other procs can find it.
 			 */
-			if(beprimary)
 			putndb();
 			refresh();
 		}

sys/src/cmd/ip/ipconfig/ipconfig.h

@@ -98,7 +98,6 @@ struct Ctl
 
 extern Conf	conf;
 extern int	myifc;
-extern int	beprimary;
 extern int	noconfig;
 
 extern int	debug;
@@ -120,6 +119,7 @@ void	ipunconfig(void);
 void	adddefroute(uchar*, uchar*, uchar*, uchar*);
 void	removedefroute(uchar*, uchar*, uchar*, uchar*);
 
+int	isether(void);
 long	jitter(void);
 void	catch(void*, char*);
 int	countaddrs(uchar *a, int len);

sys/src/cmd/ip/ipconfig/ipv6.c

@@ -151,12 +151,6 @@ uchar v6solpfx[IPaddrlen] = {
 	0xff, 0, 0, 0,
 };
 
-uchar v6defmask[IPaddrlen] = {
-	0xff, 0xff, 0xff, 0xff,
-	0xff, 0xff, 0xff, 0xff,
-	0, 0, 0, 0,
-	0, 0, 0, 0
-};
 
 void
 v6paraminit(Conf *cf)
@@ -366,7 +360,7 @@ ip6cfg(void)
 	if(!validip(conf.laddr) || isv4(conf.laddr))
 		return -1;
 
-	tentative = dupl_disc;
+	tentative = dupl_disc && isether();
 
 Again:
 	if(tentative)
@@ -376,7 +370,7 @@ Again:
 
 	n += snprint(buf+n, sizeof buf-n, " %I", conf.laddr);
 	if(!validip(conf.mask))
-		ipmove(conf.mask, v6defmask);
+		ipmove(conf.mask, defmask(conf.laddr));
 	n += snprint(buf+n, sizeof buf-n, " %M", conf.mask);
 	if(validip(conf.raddr)){
 		n += snprint(buf+n, sizeof buf-n, " %I", conf.raddr);
@@ -770,7 +764,6 @@ recvrahost(uchar buf[], int pktlen)
 		if(noconfig)
 			continue;
 
-		if(beprimary)
 		putndb();
 		refresh();
 	}

sys/src/cmd/ip/ipconfig/main.c

@@ -211,11 +211,11 @@ parseargs(int argc, char **argv)
 		switch(verb){
 		case Vether:
 		case Vgbe:
-		case Vppp:
 		case Vloopback:
+		case Vpkt:
+		case Vppp:
 		case Vtorus:
 		case Vtree:
-		case Vpkt:
 			conf.type = *argv++;
 			argc--;
 			if(argc > 0){
@@ -283,10 +283,15 @@ findifc(char *net, char *dev)
 	return -1;
 }
 
-static int
+int
 isether(void)
 {
-	return strcmp(conf.type, "ether") == 0 || strcmp(conf.type, "gbe") == 0;
+	switch(parseverb(conf.type)){
+	case Vether:
+	case Vgbe:
+		return 1;
+	}
+	return 0;
 }
 
 /* create a client id */
@@ -394,6 +399,9 @@ main(int argc, char **argv)
 
 	action = parseargs(argc, argv);
 
+	if(beprimary == -1 && (ipv6auto || parseverb(conf.type) == Vloopback))
+		beprimary = 0;
+
 	myifc = findifc(conf.mpoint, conf.dev);
 	if(myifc < 0) {
 		switch(action){
@@ -420,6 +428,7 @@ main(int argc, char **argv)
 		mkclientid();
 		if(dondbconfig){
 			dodhcp = 0;
+			beprimary = 0;
 			ndbconfig();
 			break;
 		}
@@ -457,14 +466,14 @@ doadd(void)
 		dhcpquery(!noconfig, Sselecting);
 	}
 
-	if(!validip(conf.laddr))
+	if(!validip(conf.laddr)){
 		if(rflag && dodhcp && !noconfig){
 			warning("couldn't determine ip address, retrying");
 			dhcpwatch(1);
 			return;
 		} else
 			sysfatal("no success with DHCP");
-
+	}
 	DEBUG("adding address %I %M on %s", conf.laddr, conf.mask, conf.dev);
 	if(noconfig)
 		return;
@@ -480,7 +489,6 @@ doadd(void)
 	}
 
 	/* leave everything we've learned somewhere other procs can find it */
-	if(beprimary && !dondbconfig && !ipv6auto)
 	putndb();
 	refresh();
 }
@@ -661,6 +669,9 @@ putndb(void)
 	Ndb *db;
 	int fd;
 
+	if(beprimary == 0)
+		return;
+
 	p = buf;
 	e = buf + sizeof buf;
 	p = seprint(p, e, "ip=%I ipmask=%M ipgw=%I\n",