Validate Zone IPv6 DNS

Prevent deploying IPv6 network if zone has no IPv6 DNS configured.

Author: GabrielBrascher

server/src/main/java/com/cloud/network/NetworkServiceImpl.java

@@ -726,10 +726,10 @@ public NicSecondaryIp allocateSecondaryGuestIP(final long nicId, IpAddresses req
         String ip6addr = null;
         //Isolated network can exist in Basic zone only, so no need to verify the zone type
         if (network.getGuestType() == Network.GuestType.Isolated) {
-            if ((ipv4Address != null || NetUtils.isIpv4(network.getGateway()) && org.apache.commons.lang3.StringUtils.isBlank(ipv6Address))) {
+            if ((ipv4Address != null || NetUtils.isIpv4(network.getGateway()) && isBlank(ipv6Address))) {
                 ipaddr = _ipAddrMgr.allocateGuestIP(network, ipv4Address);
             }
-            if (ipv6Address != null) {
+            if (isNotBlank(ipv6Address)) {
                 ip6addr = ipv6AddrMgr.allocateGuestIpv6(network, ipv6Address);
             }
         } else if (network.getGuestType() == Network.GuestType.Shared) {
@@ -763,7 +763,7 @@ public NicSecondaryIp allocateSecondaryGuestIP(final long nicId, IpAddresses req
             return null;
         }
 
-        if (ipaddr != null || ip6addr != null) {
+        if (isNotBlank(ipaddr) || isNotBlank(ip6addr)) {
             // we got the ip addr so up the nics table and secodary ip
             final String ip4AddrFinal = ipaddr;
             final String ip6AddrFinal = ip6addr;
@@ -1270,6 +1270,10 @@ public Network createGuestNetwork(CreateNetworkCmd cmd) throws InsufficientCapac
             }
             _networkModel.checkIp6Parameters(startIPv6, endIPv6, ip6Gateway, ip6Cidr);
 
+            if(isBlank(zone.getIp6Dns1()) && isBlank(zone.getIp6Dns2())) {
+                throw new InvalidParameterValueException("Can only create IPv6 network if the zone has IPv6 DNS! Please configure the zone IPv6 DNS1 and/or IPv6 DNS2.");
+            }
+
             if (zone.getNetworkType() != NetworkType.Advanced || ntwkOff.getGuestType() != Network.GuestType.Shared) {
                 throw new InvalidParameterValueException("Can only support create IPv6 network with advance shared network!");
             }
@@ -2749,7 +2753,7 @@ private void verifyAlreadyMigratedTiers(long migratedVpcId, long vpcOfferingId,
         for (Network tier : migratedTiers) {
             String tierNetworkOfferingUuid = networkToOffering.get(tier.getUuid());
 
-            if (!StringUtils.isNotBlank(tierNetworkOfferingUuid)) {
+            if (!isNotBlank(tierNetworkOfferingUuid)) {
                 throwInvalidIdException("Failed to resume migrating VPC as the specified tierNetworkOfferings is not complete", String.valueOf(tier.getUuid()), "networkUuid");
             }