Support static address configuration

Application can specify static ipv4 server and client address to setup
tethering and this is one shot configuration. Tethering service would
not save the configuration and the configuration would be reset when
tethering stop or start failure.

When startTethering callback fired, it just mean tethering is requested
successful. Therefore, callers may call startTethering again if
startTethering successful but do not receive following tethering active
notification for a while. Tethering service never actually does anything
synchronously when startTethering is called:
  -startProvisioningIfNeeded just posts a message to the handler thread.
  -enableTetheringInternal doesn't do anything synchronously, it just
  asks the downstreams to get their interfaces ready and waits for
  callbacks.
If tethering is already enabled with a different request,
tethering would be disabled and re-enabled.

Bug: 141256482
Test: -build, flash, boot
      -atest TetheringTests
      -atest CtsTetheringTest

Change-Id: I0399917e7cefa1547d617e688225544c4fc1a231

Tethering/src/android/net/ip/IpServer.java

@@ -34,6 +34,7 @@ import android.net.MacAddress;
 import android.net.RouteInfo;
 import android.net.TetheredClient;
 import android.net.TetheringManager;
+import android.net.TetheringRequestParcel;
 import android.net.dhcp.DhcpLeaseParcelable;
 import android.net.dhcp.DhcpServerCallbacks;
 import android.net.dhcp.DhcpServingParamsParcel;
@@ -242,6 +243,10 @@ public class IpServer extends StateMachine {
     private IDhcpServer mDhcpServer;
     private RaParams mLastRaParams;
     private LinkAddress mIpv4Address;
+
+    private LinkAddress mStaticIpv4ServerAddr;
+    private LinkAddress mStaticIpv4ClientAddr;
+
     @NonNull
     private List<TetheredClient> mDhcpLeases = Collections.emptyList();
 
@@ -544,6 +549,8 @@ public class IpServer extends StateMachine {
         // into calls to InterfaceController, shared with startIPv4().
         mInterfaceCtrl.clearIPv4Address();
         mIpv4Address = null;
+        mStaticIpv4ServerAddr = null;
+        mStaticIpv4ClientAddr = null;
     }
 
     private boolean configureIPv4(boolean enabled) {
@@ -554,7 +561,10 @@ public class IpServer extends StateMachine {
         final Inet4Address srvAddr;
         int prefixLen = 0;
         try {
-            if (mInterfaceType == TetheringManager.TETHERING_USB
+            if (mStaticIpv4ServerAddr != null) {
+                srvAddr = (Inet4Address) mStaticIpv4ServerAddr.getAddress();
+                prefixLen = mStaticIpv4ServerAddr.getPrefixLength();
+            } else if (mInterfaceType == TetheringManager.TETHERING_USB
                     || mInterfaceType == TetheringManager.TETHERING_NCM) {
                 srvAddr = (Inet4Address) parseNumericAddress(USB_NEAR_IFACE_ADDR);
                 prefixLen = USB_PREFIX_LENGTH;
@@ -599,10 +609,6 @@ public class IpServer extends StateMachine {
             return false;
         }
 
-        if (!configureDhcp(enabled, srvAddr, prefixLen)) {
-            return false;
-        }
-
         // Directly-connected route.
         final IpPrefix ipv4Prefix = new IpPrefix(mIpv4Address.getAddress(),
                 mIpv4Address.getPrefixLength());
@@ -614,7 +620,8 @@ public class IpServer extends StateMachine {
             mLinkProperties.removeLinkAddress(mIpv4Address);
             mLinkProperties.removeRoute(route);
         }
-        return true;
+
+        return configureDhcp(enabled, srvAddr, prefixLen);
     }
 
     private String getRandomWifiIPv4Address() {
@@ -934,6 +941,13 @@ public class IpServer extends StateMachine {
         mLinkProperties.setInterfaceName(mIfaceName);
     }
 
+    private void maybeConfigureStaticIp(final TetheringRequestParcel request) {
+        if (request == null) return;
+
+        mStaticIpv4ServerAddr = request.localIPv4Address;
+        mStaticIpv4ClientAddr = request.staticClientAddress;
+    }
+
     class InitialState extends State {
         @Override
         public void enter() {
@@ -948,9 +962,11 @@ public class IpServer extends StateMachine {
                     mLastError = TetheringManager.TETHER_ERROR_NO_ERROR;
                     switch (message.arg1) {
                         case STATE_LOCAL_ONLY:
+                            maybeConfigureStaticIp((TetheringRequestParcel) message.obj);
                             transitionTo(mLocalHotspotState);
                             break;
                         case STATE_TETHERED:
+                            maybeConfigureStaticIp((TetheringRequestParcel) message.obj);
                             transitionTo(mTetheredState);
                             break;
                         default: