avoid broadcast addr

add.go

@@ -7,7 +7,9 @@ func Add(hostname string, owner string, description string) {//, publicKey strin
 	presharedKey := GenerateJSONKey()
 	publicKey := privateKey.PublicKey()
 
-	conf.ChooseIP()
+	IP, err := conf.ChooseIP()
+
+	check(err)
 
 	peer := PeerConfig{
 		Owner: owner,

types.go

@@ -100,8 +100,8 @@ func (conf DsnetConfig) ChooseIP() (net.IP, error) {
 	network := conf.Network.IPNet
 	ones, bits := network.Mask.Size()
 	zeros := bits - ones
-	min := 1
-	max := (1 << zeros) -1
+	min := 1  // avoids network addr
+	max := (1 << zeros) -2  // avoids broadcast addr + overflow
 
 	for i := min; i <= max; i++ {
 		IP := make(net.IP, len(network.IP))