Ignore errors when untethering

Sometimes the interface is removed before we can untether leading to
errors when cleanup up various rules (iptables).  Do as much as we can
and then let a re-tether result in error if needed.

bug:5536516
Change-Id: Ib1d064ecc8e9022566f9b0e4678b33144906971c

1 files changed, 27 insertions, 52 deletions

diff --git a/services/java/com/android/server/connectivity/Tethering.java b/services/java/com/android/server/connectivity/Tethering.java
index 1107fe9af4f7..7bd29d90cca0 100644
--- a/services/java/com/android/server/connectivity/Tethering.java
+++ b/services/java/com/android/server/connectivity/Tethering.java
@@ -73,7 +73,7 @@ public class Tethering extends INetworkManagementEventObserver.Stub {
     private Context mContext;
     private final static String TAG = "Tethering";
     private final static boolean DBG = true;
-    private final static boolean VDBG = false;
+    private final static boolean VDBG = true;
 
     // TODO - remove both of these - should be part of interface inspection/selection stuff
     private String[] mTetherableUsbRegexs;
@@ -920,6 +920,29 @@ public class Tethering extends INetworkManagementEventObserver.Stub {
                 setTethered(true);
                 sendTetherStateChangedBroadcast();
             }
+
+            void cleanupUpstream() {
+                if (mMyUpstreamIfaceName != null) {
+                    // note that we don't care about errors here.
+                    // sometimes interfaces are gone before we get
+                    // to remove their rules, which generates errors.
+                    // just do the best we can.
+                    try {
+                        // about to tear down NAT; gather remaining statistics
+                        mStatsService.forceUpdate();
+                    } catch (Exception e) {
+                        if (VDBG) Log.e(TAG, "Exception in forceUpdate: " + e.toString());
+                    }
+                    try {
+                        mNMService.disableNat(mIfaceName, mMyUpstreamIfaceName);
+                    } catch (Exception e) {
+                        if (VDBG) Log.e(TAG, "Exception in disableNat: " + e.toString());
+                    }
+                    mMyUpstreamIfaceName = null;
+                }
+                return;
+            }
+
             @Override
             public boolean processMessage(Message message) {
                 if (VDBG) Log.d(TAG, "TetheredState.processMessage what=" + message.what);
@@ -928,23 +951,7 @@ public class Tethering extends INetworkManagementEventObserver.Stub {
                 switch (message.what) {
                     case CMD_TETHER_UNREQUESTED:
                     case CMD_INTERFACE_DOWN:
-                        if (mMyUpstreamIfaceName != null) {
-                            try {
-                                // about to tear down NAT; gather remaining statistics
-                                mStatsService.forceUpdate();
-
-                                mNMService.disableNat(mIfaceName, mMyUpstreamIfaceName);
-                                mMyUpstreamIfaceName = null;
-                            } catch (Exception e) {
-                                try {
-                                    mNMService.untetherInterface(mIfaceName);
-                                } catch (Exception ee) {}
-
-                                setLastErrorAndTransitionToInitialState(
-                                        ConnectivityManager.TETHER_ERROR_DISABLE_NAT_ERROR);
-                                break;
-                            }
-                        }
+                        cleanupUpstream();
                         try {
                             mNMService.untetherInterface(mIfaceName);
                         } catch (Exception e) {
@@ -975,23 +982,7 @@ public class Tethering extends INetworkManagementEventObserver.Stub {
                             if (VDBG) Log.d(TAG, "Connection changed noop - dropping");
                             break;
                         }
-                        if (mMyUpstreamIfaceName != null) {
-                            try {
-                                // about to tear down NAT; gather remaining statistics
-                                mStatsService.forceUpdate();
-
-                                mNMService.disableNat(mIfaceName, mMyUpstreamIfaceName);
-                                mMyUpstreamIfaceName = null;
-                            } catch (Exception e) {
-                                try {
-                                    mNMService.untetherInterface(mIfaceName);
-                                } catch (Exception ee) {}
-
-                                setLastErrorAndTransitionToInitialState(
-                                        ConnectivityManager.TETHER_ERROR_DISABLE_NAT_ERROR);
-                                break;
-                            }
-                        }
+                        cleanupUpstream();
                         if (newUpstreamIfaceName != null) {
                             try {
                                 mNMService.enableNat(mIfaceName, newUpstreamIfaceName);
@@ -1016,23 +1007,7 @@ public class Tethering extends INetworkManagementEventObserver.Stub {
                         error = true;
                         // fall through
                     case CMD_TETHER_MODE_DEAD:
-                        if (mMyUpstreamIfaceName != null) {
-                            try {
-                                // about to tear down NAT; gather remaining statistics
-                                mStatsService.forceUpdate();
-
-                                mNMService.disableNat(mIfaceName, mMyUpstreamIfaceName);
-                                mMyUpstreamIfaceName = null;
-                            } catch (Exception e) {
-                                try {
-                                    mNMService.untetherInterface(mIfaceName);
-                                } catch (Exception ee) {}
-
-                                setLastErrorAndTransitionToInitialState(
-                                        ConnectivityManager.TETHER_ERROR_DISABLE_NAT_ERROR);
-                                break;
-                            }
-                        }
+                        cleanupUpstream();
                         try {
                             mNMService.untetherInterface(mIfaceName);
                         } catch (Exception e) {