WLAN configuration (static address): reject IPv6 addresses.

Without this, entering an IPv6 address as the interface address (or possibly
also others, such as gateway address) will, on connection to that WLAN,
trigger an uncaught exception:

*** FATAL EXCEPTION IN SYSTEM PROCESS: WifiStateMachine
java.lang.IllegalArgumentException: command '59 interface setcfg wlan0 2001:db8::ffff 24 up' failed with '501 59 Flag unsupported'
	at com.android.server.NetworkManagementService.setInterfaceConfig(NetworkManagementService.java:546)
	at android.net.wifi.WifiStateMachine$ObtainingIpState.enter(WifiStateMachine.java:3449)
	at com.android.internal.util.StateMachine$SmHandler.invokeEnterMethods(StateMachine.java:958)
[etc.]

followed by a restart of the UI then another connection attempt. So long as
the misconfigured-for AP is present (and preferred?), this will continue to
happen.

Change-Id: I524480339c37ad079fd21d90a6b1fc5864089cb5

Conflicts:

	src/com/android/settings/wifi/WifiConfigController.java

src/com/android/settings/wifi/WifiConfigController.java

@@ -55,6 +55,7 @@
 import com.android.settings.R;
 
 import java.net.InetAddress;
+import java.net.Inet6Address;
 import java.util.Iterator;
 
 /**
@@ -456,6 +457,16 @@ private boolean ipAndProxyFieldsAreValid() {
         return true;
     }
 
+    private InetAddress numericToInet4Address(String addrString)
+            throws IllegalArgumentException {
+        // We need IPv4 for 'legacy' wireless networking static address assignments
+        InetAddress inetAddr = NetworkUtils.numericToInetAddress(addrString);
+        if (inetAddr instanceof Inet6Address) {
+            throw new IllegalArgumentException("Sorry, IPv4 only");
+        }
+        return inetAddr;
+    }
+
     private int validateIpConfigFields(LinkProperties linkProperties) {
         if (mIpAddressView == null) return 0;
 
@@ -464,7 +475,7 @@ private int validateIpConfigFields(LinkProperties linkProperties) {
 
         InetAddress inetAddr = null;
         try {
-            inetAddr = NetworkUtils.numericToInetAddress(ipAddr);
+            inetAddr = numericToInet4Address(ipAddr);
         } catch (IllegalArgumentException e) {
             return R.string.wifi_ip_settings_invalid_ip_address;
         }
@@ -496,7 +507,7 @@ private int validateIpConfigFields(LinkProperties linkProperties) {
         } else {
             InetAddress gatewayAddr = null;
             try {
-                gatewayAddr = NetworkUtils.numericToInetAddress(gateway);
+                gatewayAddr = numericToInet4Address(gateway);
             } catch (IllegalArgumentException e) {
                 return R.string.wifi_ip_settings_invalid_gateway;
             }
@@ -511,7 +522,7 @@ private int validateIpConfigFields(LinkProperties linkProperties) {
             mDns1View.setText(mConfigUi.getContext().getString(R.string.wifi_dns1_hint));
         } else {
             try {
-                dnsAddr = NetworkUtils.numericToInetAddress(dns);
+                dnsAddr = numericToInet4Address(dns);
             } catch (IllegalArgumentException e) {
                 return R.string.wifi_ip_settings_invalid_dns;
             }
@@ -521,7 +532,7 @@ private int validateIpConfigFields(LinkProperties linkProperties) {
         if (mDns2View.length() > 0) {
             dns = mDns2View.getText().toString();
             try {
-                dnsAddr = NetworkUtils.numericToInetAddress(dns);
+                dnsAddr = numericToInet4Address(dns);
             } catch (IllegalArgumentException e) {
                 return R.string.wifi_ip_settings_invalid_dns;
             }