diff --git a/core/java/android/net/ConnectivityManager.java b/core/java/android/net/ConnectivityManager.java
index 5fd7d15..b7ba970 100644
--- a/core/java/android/net/ConnectivityManager.java
+++ b/core/java/android/net/ConnectivityManager.java
@@ -427,6 +427,16 @@
             "android.net.conn.PROMPT_LOST_VALIDATION";
 
     /**
+     * Action used to display a dialog that asks the user whether to stay connected to a network
+     * that has not validated. This intent is used to start the dialog in settings via
+     * startActivity.
+     *
+     * @hide
+     */
+    public static final String ACTION_PROMPT_PARTIAL_CONNECTIVITY =
+            "android.net.conn.PROMPT_PARTIAL_CONNECTIVITY";
+
+    /**
      * Invalid tethering type.
      * @see #startTethering(int, boolean, OnStartTetheringCallback)
      * @hide
@@ -4018,7 +4028,7 @@
      *
      * @hide
      */
-    @RequiresPermission(android.Manifest.permission.CONNECTIVITY_INTERNAL)
+    @RequiresPermission(android.Manifest.permission.NETWORK_SETTINGS)
     public void setAcceptUnvalidated(Network network, boolean accept, boolean always) {
         try {
             mService.setAcceptUnvalidated(network, accept, always);
@@ -4028,6 +4038,29 @@
     }
 
     /**
+     * Informs the system whether it should consider the network as validated even if it only has
+     * partial connectivity. If {@code accept} is true, then the network will be considered as
+     * validated even if connectivity is only partial. If {@code always} is true, then the choice
+     * is remembered, so that the next time the user connects to this network, the system will
+     * switch to it.
+     *
+     * @param network The network to accept.
+     * @param accept Whether to consider the network as validated even if it has partial
+     *               connectivity.
+     * @param always Whether to remember this choice in the future.
+     *
+     * @hide
+     */
+    @RequiresPermission(android.Manifest.permission.NETWORK_STACK)
+    public void setAcceptPartialConnectivity(Network network, boolean accept, boolean always) {
+        try {
+            mService.setAcceptPartialConnectivity(network, accept, always);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
      * Informs the system to penalize {@code network}'s score when it becomes unvalidated. This is
      * only meaningful if the system is configured not to penalize such networks, e.g., if the
      * {@code config_networkAvoidBadWifi} configuration variable is set to 0 and the {@code
@@ -4037,7 +4070,7 @@
      *
      * @hide
      */
-    @RequiresPermission(android.Manifest.permission.CONNECTIVITY_INTERNAL)
+    @RequiresPermission(android.Manifest.permission.NETWORK_SETTINGS)
     public void setAvoidUnvalidated(Network network) {
         try {
             mService.setAvoidUnvalidated(network);
diff --git a/core/java/android/net/IConnectivityManager.aidl b/core/java/android/net/IConnectivityManager.aidl
index 9fc56b4..2df4e75 100644
--- a/core/java/android/net/IConnectivityManager.aidl
+++ b/core/java/android/net/IConnectivityManager.aidl
@@ -176,6 +176,7 @@
     void releaseNetworkRequest(in NetworkRequest networkRequest);
 
     void setAcceptUnvalidated(in Network network, boolean accept, boolean always);
+    void setAcceptPartialConnectivity(in Network network, boolean accept, boolean always);
     void setAvoidUnvalidated(in Network network);
     void startCaptivePortalApp(in Network network);
     void startCaptivePortalAppInternal(in Network network, in Bundle appExtras);
diff --git a/core/java/android/net/NetworkCapabilities.java b/core/java/android/net/NetworkCapabilities.java
index 0a63e75..e1cfe99 100644
--- a/core/java/android/net/NetworkCapabilities.java
+++ b/core/java/android/net/NetworkCapabilities.java
@@ -143,7 +143,8 @@
             NET_CAPABILITY_NOT_CONGESTED,
             NET_CAPABILITY_NOT_SUSPENDED,
             NET_CAPABILITY_OEM_PAID,
-            NET_CAPABILITY_MCX
+            NET_CAPABILITY_MCX,
+            NET_CAPABILITY_PARTIAL_CONNECTIVITY,
     })
     public @interface NetCapability { }
 
@@ -304,8 +305,15 @@
      */
     public static final int NET_CAPABILITY_MCX = 23;
 
+    /**
+     * Indicates that this network was tested to only provide partial connectivity.
+     * @hide
+     */
+    @SystemApi
+    public static final int NET_CAPABILITY_PARTIAL_CONNECTIVITY = 24;
+
     private static final int MIN_NET_CAPABILITY = NET_CAPABILITY_MMS;
-    private static final int MAX_NET_CAPABILITY = NET_CAPABILITY_MCX;
+    private static final int MAX_NET_CAPABILITY = NET_CAPABILITY_PARTIAL_CONNECTIVITY;
 
     /**
      * Network capabilities that are expected to be mutable, i.e., can change while a particular
@@ -320,7 +328,8 @@
             | (1 << NET_CAPABILITY_NOT_ROAMING)
             | (1 << NET_CAPABILITY_FOREGROUND)
             | (1 << NET_CAPABILITY_NOT_CONGESTED)
-            | (1 << NET_CAPABILITY_NOT_SUSPENDED);
+            | (1 << NET_CAPABILITY_NOT_SUSPENDED)
+            | (1 << NET_CAPABILITY_PARTIAL_CONNECTIVITY);
 
     /**
      * Network capabilities that are not allowed in NetworkRequests. This exists because the
@@ -375,6 +384,15 @@
             (1 << NET_CAPABILITY_WIFI_P2P);
 
     /**
+     * Capabilities that are managed by ConnectivityService.
+     */
+    private static final long CONNECTIVITY_MANAGED_CAPABILITIES =
+            (1 << NET_CAPABILITY_VALIDATED)
+            | (1 << NET_CAPABILITY_CAPTIVE_PORTAL)
+            | (1 << NET_CAPABILITY_FOREGROUND)
+            | (1 << NET_CAPABILITY_PARTIAL_CONNECTIVITY);
+
+    /**
      * Adds the given capability to this {@code NetworkCapability} instance.
      * Multiple capabilities may be applied sequentially.  Note that when searching
      * for a network to satisfy a request, all capabilities requested must be satisfied.
@@ -507,6 +525,14 @@
                 && ((mUnwantedNetworkCapabilities & (1 << capability)) != 0);
     }
 
+    /**
+     * Check if this NetworkCapabilities has system managed capabilities or not.
+     * @hide
+     */
+    public boolean hasConnectivityManagedCapability() {
+        return ((mNetworkCapabilities & CONNECTIVITY_MANAGED_CAPABILITIES) != 0);
+    }
+
     /** Note this method may result in having the same capability in wanted and unwanted lists. */
     private void combineNetCapabilities(NetworkCapabilities nc) {
         this.mNetworkCapabilities |= nc.mNetworkCapabilities;
@@ -1599,31 +1625,32 @@
      */
     public static String capabilityNameOf(@NetCapability int capability) {
         switch (capability) {
-            case NET_CAPABILITY_MMS:            return "MMS";
-            case NET_CAPABILITY_SUPL:           return "SUPL";
-            case NET_CAPABILITY_DUN:            return "DUN";
-            case NET_CAPABILITY_FOTA:           return "FOTA";
-            case NET_CAPABILITY_IMS:            return "IMS";
-            case NET_CAPABILITY_CBS:            return "CBS";
-            case NET_CAPABILITY_WIFI_P2P:       return "WIFI_P2P";
-            case NET_CAPABILITY_IA:             return "IA";
-            case NET_CAPABILITY_RCS:            return "RCS";
-            case NET_CAPABILITY_XCAP:           return "XCAP";
-            case NET_CAPABILITY_EIMS:           return "EIMS";
-            case NET_CAPABILITY_NOT_METERED:    return "NOT_METERED";
-            case NET_CAPABILITY_INTERNET:       return "INTERNET";
-            case NET_CAPABILITY_NOT_RESTRICTED: return "NOT_RESTRICTED";
-            case NET_CAPABILITY_TRUSTED:        return "TRUSTED";
-            case NET_CAPABILITY_NOT_VPN:        return "NOT_VPN";
-            case NET_CAPABILITY_VALIDATED:      return "VALIDATED";
-            case NET_CAPABILITY_CAPTIVE_PORTAL: return "CAPTIVE_PORTAL";
-            case NET_CAPABILITY_NOT_ROAMING:    return "NOT_ROAMING";
-            case NET_CAPABILITY_FOREGROUND:     return "FOREGROUND";
-            case NET_CAPABILITY_NOT_CONGESTED:  return "NOT_CONGESTED";
-            case NET_CAPABILITY_NOT_SUSPENDED:  return "NOT_SUSPENDED";
-            case NET_CAPABILITY_OEM_PAID:       return "OEM_PAID";
-            case NET_CAPABILITY_MCX:            return "MCX";
-            default:                            return Integer.toString(capability);
+            case NET_CAPABILITY_MMS:                  return "MMS";
+            case NET_CAPABILITY_SUPL:                 return "SUPL";
+            case NET_CAPABILITY_DUN:                  return "DUN";
+            case NET_CAPABILITY_FOTA:                 return "FOTA";
+            case NET_CAPABILITY_IMS:                  return "IMS";
+            case NET_CAPABILITY_CBS:                  return "CBS";
+            case NET_CAPABILITY_WIFI_P2P:             return "WIFI_P2P";
+            case NET_CAPABILITY_IA:                   return "IA";
+            case NET_CAPABILITY_RCS:                  return "RCS";
+            case NET_CAPABILITY_XCAP:                 return "XCAP";
+            case NET_CAPABILITY_EIMS:                 return "EIMS";
+            case NET_CAPABILITY_NOT_METERED:          return "NOT_METERED";
+            case NET_CAPABILITY_INTERNET:             return "INTERNET";
+            case NET_CAPABILITY_NOT_RESTRICTED:       return "NOT_RESTRICTED";
+            case NET_CAPABILITY_TRUSTED:              return "TRUSTED";
+            case NET_CAPABILITY_NOT_VPN:              return "NOT_VPN";
+            case NET_CAPABILITY_VALIDATED:            return "VALIDATED";
+            case NET_CAPABILITY_CAPTIVE_PORTAL:       return "CAPTIVE_PORTAL";
+            case NET_CAPABILITY_NOT_ROAMING:          return "NOT_ROAMING";
+            case NET_CAPABILITY_FOREGROUND:           return "FOREGROUND";
+            case NET_CAPABILITY_NOT_CONGESTED:        return "NOT_CONGESTED";
+            case NET_CAPABILITY_NOT_SUSPENDED:        return "NOT_SUSPENDED";
+            case NET_CAPABILITY_OEM_PAID:             return "OEM_PAID";
+            case NET_CAPABILITY_MCX:                  return "MCX";
+            case NET_CAPABILITY_PARTIAL_CONNECTIVITY: return "PARTIAL_CONNECTIVITY";
+            default:                                  return Integer.toString(capability);
         }
     }
 
diff --git a/core/java/android/net/NetworkMisc.java b/core/java/android/net/NetworkMisc.java
index c0487b5..6fb2390 100644
--- a/core/java/android/net/NetworkMisc.java
+++ b/core/java/android/net/NetworkMisc.java
@@ -52,6 +52,12 @@
     public boolean acceptUnvalidated;
 
     /**
+     * Whether the user explicitly set that this network should be validated even if presence of
+     * only partial internet connectivity.
+     */
+    public boolean acceptPartialConnectivity;
+
+    /**
      * Set to avoid surfacing the "Sign in to network" notification.
      * if carrier receivers/apps are registered to handle the carrier-specific provisioning
      * procedure, a carrier specific provisioning notification will be placed.
diff --git a/core/java/android/net/TcpSocketKeepalive.java b/core/java/android/net/TcpSocketKeepalive.java
index 8f6ee7b..f691a0d 100644
--- a/core/java/android/net/TcpSocketKeepalive.java
+++ b/core/java/android/net/TcpSocketKeepalive.java
@@ -45,13 +45,14 @@
      * - The application must not write to or read from the socket after calling this method, until
      *   onDataReceived, onStopped, or onError are called. If it does, the keepalive will fail
      *   with {@link #ERROR_SOCKET_NOT_IDLE}, or {@code #ERROR_INVALID_SOCKET} if the socket
-     *   experienced an error (as in poll(2) returned POLLERR); if this happens, the data received
-     *   from the socket may be invalid, and the socket can't be recovered.
+     *   experienced an error (as in poll(2) returned POLLERR or POLLHUP); if this happens, the data
+     *   received from the socket may be invalid, and the socket can't be recovered.
      * - If the socket has data in the send or receive buffer, then this call will fail with
      *   {@link #ERROR_SOCKET_NOT_IDLE} and can be retried after the data has been processed.
-     *   An app could ensure this by using an application-layer protocol where it can receive
-     *   acknowledgement that it will go into keepalive mode. It could then go into keepalive
-     *   mode after having read the acknowledgement, draining the socket.
+     *   An app could ensure this by using an application-layer protocol to receive acknowledgement
+     *   that indicates all data has been delivered to server, e.g. HTTP 200 OK.
+     *   Then the app could go into keepalive mode after reading all remaining data within the
+     *   acknowledgement.
      */
     @Override
     void startImpl(int intervalSec) {
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index 38a2771..dbfc327 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -25,6 +25,7 @@
 import static android.net.ConnectivityManager.TYPE_VPN;
 import static android.net.ConnectivityManager.getNetworkTypeName;
 import static android.net.ConnectivityManager.isNetworkTypeValid;
+import static android.net.INetworkMonitor.NETWORK_TEST_RESULT_PARTIAL_CONNECTIVITY;
 import static android.net.INetworkMonitor.NETWORK_TEST_RESULT_VALID;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_CAPTIVE_PORTAL;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_FOREGROUND;
@@ -34,6 +35,7 @@
 import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_ROAMING;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_SUSPENDED;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_VPN;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_PARTIAL_CONNECTIVITY;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_VALIDATED;
 import static android.net.NetworkCapabilities.TRANSPORT_VPN;
 import static android.net.NetworkPolicyManager.RULE_NONE;
@@ -489,6 +491,15 @@
     public static final int EVENT_TIMEOUT_NOTIFICATION = 44;
 
     /**
+     * Used to specify whether a network should be used even if connectivity is partial.
+     * arg1 = whether to accept the network if its connectivity is partial (1 for true or 0 for
+     * false)
+     * arg2 = whether to remember this choice in the future (1 for true or 0 for false)
+     * obj  = network
+     */
+    private static final int EVENT_SET_ACCEPT_PARTIAL_CONNECTIVITY = 45;
+
+    /**
      * Argument for {@link #EVENT_PROVISIONING_NOTIFICATION} to indicate that the notification
      * should be shown.
      */
@@ -2488,9 +2499,7 @@
             switch (msg.what) {
                 case NetworkAgent.EVENT_NETWORK_CAPABILITIES_CHANGED: {
                     final NetworkCapabilities networkCapabilities = (NetworkCapabilities) msg.obj;
-                    if (networkCapabilities.hasCapability(NET_CAPABILITY_CAPTIVE_PORTAL) ||
-                            networkCapabilities.hasCapability(NET_CAPABILITY_VALIDATED) ||
-                            networkCapabilities.hasCapability(NET_CAPABILITY_FOREGROUND)) {
+                    if (networkCapabilities.hasConnectivityManagedCapability()) {
                         Slog.wtf(TAG, "BUG: " + nai + " has CS-managed capability.");
                     }
                     updateCapabilities(nai.getCurrentScore(), nai, networkCapabilities);
@@ -2515,6 +2524,14 @@
                     }
                     nai.networkMisc.explicitlySelected = true;
                     nai.networkMisc.acceptUnvalidated = msg.arg1 == 1;
+                    // Mark the network as temporarily accepting partial connectivity so that it
+                    // will be validated (and possibly become default) even if it only provides
+                    // partial internet access. Note that if user connects to partial connectivity
+                    // and choose "don't ask again", then wifi disconnected by some reasons(maybe
+                    // out of wifi coverage) and if the same wifi is available again, the device
+                    // will auto connect to this wifi even though the wifi has "no internet".
+                    // TODO: Evaluate using a separate setting in IpMemoryStore.
+                    nai.networkMisc.acceptPartialConnectivity = msg.arg1 == 1;
                     break;
                 }
                 case NetworkAgent.EVENT_SOCKET_KEEPALIVE: {
@@ -2532,6 +2549,23 @@
                     final NetworkAgentInfo nai = getNetworkAgentInfoForNetId(msg.arg2);
                     if (nai == null) break;
 
+                    final boolean partialConnectivity =
+                            (msg.arg1 == NETWORK_TEST_RESULT_PARTIAL_CONNECTIVITY)
+                                    // If user accepts partial connectivity network, NetworkMonitor
+                                    // will skip https probing. It will make partial connectivity
+                                    // network becomes valid. But user still need to know this
+                                    // network is limited. So, it's needed to refer to
+                                    // acceptPartialConnectivity to add
+                                    // NET_CAPABILITY_PARTIAL_CONNECTIVITY into NetworkCapabilities
+                                    // of this network. So that user can see "Limited connection"
+                                    // in the settings.
+                                    || (nai.networkMisc.acceptPartialConnectivity
+                                            && nai.partialConnectivity);
+                    // Once a network is determined to have partial connectivity, it cannot
+                    // go back to full connectivity without a disconnect.
+                    final boolean partialConnectivityChange =
+                            (partialConnectivity && !nai.partialConnectivity);
+
                     final boolean valid = (msg.arg1 == NETWORK_TEST_RESULT_VALID);
                     final boolean wasValidated = nai.lastValidated;
                     final boolean wasDefault = isDefaultNetwork(nai);
@@ -2540,6 +2574,17 @@
                         nai.captivePortalLoginNotified = true;
                         showNetworkNotification(nai, NotificationType.LOGGED_IN);
                     }
+                    // If this network has just connected and partial connectivity has just been
+                    // detected, tell NetworkMonitor if the user accepted partial connectivity on a
+                    // previous connect.
+                    if ((msg.arg1 == NETWORK_TEST_RESULT_PARTIAL_CONNECTIVITY)
+                            && nai.networkMisc.acceptPartialConnectivity) {
+                        try {
+                            nai.networkMonitor().notifyAcceptPartialConnectivity();
+                        } catch (RemoteException e) {
+                            e.rethrowFromSystemServer();
+                        }
+                    }
 
                     final String redirectUrl = (msg.obj instanceof String) ? (String) msg.obj : "";
 
@@ -2569,6 +2614,9 @@
                             mNotifier.clearNotification(nai.network.netId,
                                     NotificationType.LOST_INTERNET);
                         }
+                    } else if (partialConnectivityChange) {
+                        nai.partialConnectivity = partialConnectivity;
+                        updateCapabilities(nai.getCurrentScore(), nai, nai.networkCapabilities);
                     }
                     updateInetCondition(nai);
                     // Let the NetworkAgent know the state of its network
@@ -2607,7 +2655,7 @@
                     }
                     if (!visible) {
                         // Only clear SIGN_IN and NETWORK_SWITCH notifications here, or else other
-                        // notifications belong to the same network may be cleared unexpected.
+                        // notifications belong to the same network may be cleared unexpectedly.
                         mNotifier.clearNotification(netId, NotificationType.SIGN_IN);
                         mNotifier.clearNotification(netId, NotificationType.NETWORK_SWITCH);
                     } else {
@@ -3215,14 +3263,21 @@
 
     @Override
     public void setAcceptUnvalidated(Network network, boolean accept, boolean always) {
-        enforceConnectivityInternalPermission();
+        enforceNetworkStackSettingsOrSetup();
         mHandler.sendMessage(mHandler.obtainMessage(EVENT_SET_ACCEPT_UNVALIDATED,
                 encodeBool(accept), encodeBool(always), network));
     }
 
     @Override
+    public void setAcceptPartialConnectivity(Network network, boolean accept, boolean always) {
+        enforceNetworkStackSettingsOrSetup();
+        mHandler.sendMessage(mHandler.obtainMessage(EVENT_SET_ACCEPT_PARTIAL_CONNECTIVITY,
+                encodeBool(accept), encodeBool(always), network));
+    }
+
+    @Override
     public void setAvoidUnvalidated(Network network) {
-        enforceConnectivityInternalPermission();
+        enforceNetworkStackSettingsOrSetup();
         mHandler.sendMessage(mHandler.obtainMessage(EVENT_SET_AVOID_UNVALIDATED, network));
     }
 
@@ -3248,6 +3303,10 @@
         if (accept != nai.networkMisc.acceptUnvalidated) {
             int oldScore = nai.getCurrentScore();
             nai.networkMisc.acceptUnvalidated = accept;
+            // If network becomes partial connectivity and user already accepted to use this
+            // network, we should respect the user's option and don't need to popup the
+            // PARTIAL_CONNECTIVITY notification to user again.
+            nai.networkMisc.acceptPartialConnectivity = accept;
             rematchAllNetworksAndRequests(nai, oldScore);
             sendUpdatedScoreToFactories(nai);
         }
@@ -3266,6 +3325,48 @@
 
     }
 
+    private void handleSetAcceptPartialConnectivity(Network network, boolean accept,
+            boolean always) {
+        if (DBG) {
+            log("handleSetAcceptPartialConnectivity network=" + network + " accept=" + accept
+                    + " always=" + always);
+        }
+
+        final NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
+        if (nai == null) {
+            // Nothing to do.
+            return;
+        }
+
+        if (nai.lastValidated) {
+            // The network validated while the dialog box was up. Take no action.
+            return;
+        }
+
+        if (accept != nai.networkMisc.acceptPartialConnectivity) {
+            nai.networkMisc.acceptPartialConnectivity = accept;
+        }
+
+        // TODO: Use the current design or save the user choice into IpMemoryStore.
+        if (always) {
+            nai.asyncChannel.sendMessage(
+                    NetworkAgent.CMD_SAVE_ACCEPT_UNVALIDATED, encodeBool(accept));
+        }
+
+        if (!accept) {
+            // Tell the NetworkAgent to not automatically reconnect to the network.
+            nai.asyncChannel.sendMessage(NetworkAgent.CMD_PREVENT_AUTOMATIC_RECONNECT);
+            // Tear down the network.
+            teardownUnneededNetwork(nai);
+        } else {
+            try {
+                nai.networkMonitor().notifyAcceptPartialConnectivity();
+            } catch (RemoteException e) {
+                e.rethrowFromSystemServer();
+            }
+        }
+    }
+
     private void handleSetAvoidUnvalidated(Network network) {
         NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
         if (nai == null || nai.lastValidated) {
@@ -3436,6 +3537,9 @@
             case LOST_INTERNET:
                 action = ConnectivityManager.ACTION_PROMPT_LOST_VALIDATION;
                 break;
+            case PARTIAL_CONNECTIVITY:
+                action = ConnectivityManager.ACTION_PROMPT_PARTIAL_CONNECTIVITY;
+                break;
             default:
                 Slog.wtf(TAG, "Unknown notification type " + type);
                 return;
@@ -3458,22 +3562,36 @@
         if (VDBG || DDBG) log("handlePromptUnvalidated " + network);
         NetworkAgentInfo nai = getNetworkAgentInfoForNetwork(network);
 
-        // Only prompt if the network is unvalidated and was explicitly selected by the user, and if
-        // we haven't already been told to switch to it regardless of whether it validated or not.
-        // Also don't prompt on captive portals because we're already prompting the user to sign in.
-        if (nai == null || nai.everValidated || nai.everCaptivePortalDetected ||
-                !nai.networkMisc.explicitlySelected || nai.networkMisc.acceptUnvalidated) {
+        // Only prompt if the network is unvalidated or network has partial internet connectivity
+        // and was explicitly selected by the user, and if we haven't already been told to switch
+        // to it regardless of whether it validated or not. Also don't prompt on captive portals
+        // because we're already prompting the user to sign in.
+        if (nai == null || nai.everValidated || nai.everCaptivePortalDetected
+                || !nai.networkMisc.explicitlySelected || nai.networkMisc.acceptUnvalidated
+                || nai.networkMisc.acceptPartialConnectivity) {
             return;
         }
-        showNetworkNotification(nai, NotificationType.NO_INTERNET);
+        // TODO: Evaluate if it's needed to wait 8 seconds for triggering notification when
+        // NetworkMonitor detects the network is partial connectivity. Need to change the design to
+        // popup the notification immediately when the network is partial connectivity.
+        if (nai.partialConnectivity) {
+            // Treat PARTIAL_CONNECTIVITY as NO_INTERNET temporary until Settings has been updated.
+            // TODO: Need to change back to PARTIAL_CONNECTIVITY when Settings part is merged.
+            showNetworkNotification(nai, NotificationType.NO_INTERNET);
+        } else {
+            showNetworkNotification(nai, NotificationType.NO_INTERNET);
+        }
     }
 
     private void handleNetworkUnvalidated(NetworkAgentInfo nai) {
         NetworkCapabilities nc = nai.networkCapabilities;
         if (DBG) log("handleNetworkUnvalidated " + nai.name() + " cap=" + nc);
 
-        if (nc.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) &&
-            mMultinetworkPolicyTracker.shouldNotifyWifiUnvalidated()) {
+        if (!nc.hasTransport(NetworkCapabilities.TRANSPORT_WIFI)) {
+            return;
+        }
+
+        if (mMultinetworkPolicyTracker.shouldNotifyWifiUnvalidated()) {
             showNetworkNotification(nai, NotificationType.LOST_INTERNET);
         }
     }
@@ -3565,6 +3683,12 @@
                     handleSetAcceptUnvalidated(network, toBool(msg.arg1), toBool(msg.arg2));
                     break;
                 }
+                case EVENT_SET_ACCEPT_PARTIAL_CONNECTIVITY: {
+                    Network network = (Network) msg.obj;
+                    handleSetAcceptPartialConnectivity(network, toBool(msg.arg1),
+                            toBool(msg.arg2));
+                    break;
+                }
                 case EVENT_SET_AVOID_UNVALIDATED: {
                     handleSetAvoidUnvalidated((Network) msg.obj);
                     break;
@@ -5489,6 +5613,11 @@
         } else {
             newNc.addCapability(NET_CAPABILITY_NOT_SUSPENDED);
         }
+        if (nai.partialConnectivity) {
+            newNc.addCapability(NET_CAPABILITY_PARTIAL_CONNECTIVITY);
+        } else {
+            newNc.removeCapability(NET_CAPABILITY_PARTIAL_CONNECTIVITY);
+        }
 
         return newNc;
     }
diff --git a/services/core/java/com/android/server/connectivity/KeepaliveTracker.java b/services/core/java/com/android/server/connectivity/KeepaliveTracker.java
index 6cff57d..cc4c173 100644
--- a/services/core/java/com/android/server/connectivity/KeepaliveTracker.java
+++ b/services/core/java/com/android/server/connectivity/KeepaliveTracker.java
@@ -239,7 +239,12 @@
                                 .sendMessage(CMD_START_SOCKET_KEEPALIVE, slot, mInterval, mPacket);
                         break;
                     case TYPE_TCP:
-                        mTcpController.startSocketMonitor(mFd, this, mSlot);
+                        try {
+                            mTcpController.startSocketMonitor(mFd, this, mSlot);
+                        } catch (InvalidSocketException e) {
+                            handleStopKeepalive(mNai, mSlot, ERROR_INVALID_SOCKET);
+                            return;
+                        }
                         mNai.asyncChannel
                                 .sendMessage(CMD_ADD_KEEPALIVE_PACKET_FILTER, slot, 0 /* Unused */,
                                         mPacket);
diff --git a/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java b/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
index f11a0de..65eb158 100644
--- a/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
+++ b/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
@@ -156,6 +156,9 @@
     // last detected.
     public boolean captivePortalLoginNotified;
 
+    // Set to true when partial connectivity was detected.
+    public boolean partialConnectivity;
+
     // Networks are lingered when they become unneeded as a result of their NetworkRequests being
     // satisfied by a higher-scoring network. so as to allow communication to wrap up before the
     // network is taken down.  This usually only happens to the default network. Lingering ends with
@@ -592,6 +595,8 @@
         for (LingerTimer timer : mLingerTimers) { pw.println(timer); }
     }
 
+    // TODO: Print shorter members first and only print the boolean variable which value is true
+    // to improve readability.
     public String toString() {
         return "NetworkAgentInfo{ ni{" + networkInfo + "}  "
                 + "network{" + network + "}  nethandle{" + network.getNetworkHandle() + "}  "
@@ -604,6 +609,8 @@
                 + "everCaptivePortalDetected{" + everCaptivePortalDetected + "} "
                 + "lastCaptivePortalDetected{" + lastCaptivePortalDetected + "} "
                 + "captivePortalLoginNotified{" + captivePortalLoginNotified + "} "
+                + "partialConnectivity{" + partialConnectivity + "} "
+                + "acceptPartialConnectivity{" + networkMisc.acceptPartialConnectivity + "} "
                 + "clat{" + clatd + "} "
                 + "}";
     }
diff --git a/services/core/java/com/android/server/connectivity/NetworkNotificationManager.java b/services/core/java/com/android/server/connectivity/NetworkNotificationManager.java
index b50477b..053da0d 100644
--- a/services/core/java/com/android/server/connectivity/NetworkNotificationManager.java
+++ b/services/core/java/com/android/server/connectivity/NetworkNotificationManager.java
@@ -47,8 +47,9 @@
         LOST_INTERNET(SystemMessage.NOTE_NETWORK_LOST_INTERNET),
         NETWORK_SWITCH(SystemMessage.NOTE_NETWORK_SWITCH),
         NO_INTERNET(SystemMessage.NOTE_NETWORK_NO_INTERNET),
-        SIGN_IN(SystemMessage.NOTE_NETWORK_SIGN_IN),
-        LOGGED_IN(SystemMessage.NOTE_NETWORK_LOGGED_IN);
+        LOGGED_IN(SystemMessage.NOTE_NETWORK_LOGGED_IN),
+        PARTIAL_CONNECTIVITY(SystemMessage.NOTE_NETWORK_PARTIAL_CONNECTIVITY),
+        SIGN_IN(SystemMessage.NOTE_NETWORK_SIGN_IN);
 
         public final int eventId;
 
@@ -169,11 +170,18 @@
         CharSequence details;
         int icon = getIcon(transportType);
         if (notifyType == NotificationType.NO_INTERNET && transportType == TRANSPORT_WIFI) {
-            title = r.getString(R.string.wifi_no_internet, 0);
+            title = r.getString(R.string.wifi_no_internet,
+                    WifiInfo.removeDoubleQuotes(nai.networkCapabilities.getSSID()));
             details = r.getString(R.string.wifi_no_internet_detailed);
+        } else if (notifyType == NotificationType.PARTIAL_CONNECTIVITY
+                && transportType == TRANSPORT_WIFI) {
+            title = r.getString(R.string.network_partial_connectivity,
+                    WifiInfo.removeDoubleQuotes(nai.networkCapabilities.getSSID()));
+            details = r.getString(R.string.network_partial_connectivity_detailed);
         } else if (notifyType == NotificationType.LOST_INTERNET &&
                 transportType == TRANSPORT_WIFI) {
-            title = r.getString(R.string.wifi_no_internet, 0);
+            title = r.getString(R.string.wifi_no_internet,
+                    WifiInfo.removeDoubleQuotes(nai.networkCapabilities.getSSID()));
             details = r.getString(R.string.wifi_no_internet_detailed);
         } else if (notifyType == NotificationType.SIGN_IN) {
             switch (transportType) {
@@ -316,6 +324,8 @@
         }
         switch (t) {
             case SIGN_IN:
+                return 5;
+            case PARTIAL_CONNECTIVITY:
                 return 4;
             case NO_INTERNET:
                 return 3;
diff --git a/services/core/java/com/android/server/connectivity/TcpKeepaliveController.java b/services/core/java/com/android/server/connectivity/TcpKeepaliveController.java
index 65de83b..3e21b5b 100644
--- a/services/core/java/com/android/server/connectivity/TcpKeepaliveController.java
+++ b/services/core/java/com/android/server/connectivity/TcpKeepaliveController.java
@@ -215,18 +215,20 @@
      * Start monitoring incoming packets.
      *
      * @param fd socket fd to monitor.
-     * @param messenger a callback to notify socket status.
+     * @param ki a {@link KeepaliveInfo} that tracks information about a socket keepalive.
      * @param slot keepalive slot.
      */
     public void startSocketMonitor(@NonNull final FileDescriptor fd,
-            @NonNull final KeepaliveInfo ki, final int slot) {
+            @NonNull final KeepaliveInfo ki, final int slot)
+            throws IllegalArgumentException, InvalidSocketException {
         synchronized (mListeners) {
             if (null != mListeners.get(slot)) {
                 throw new IllegalArgumentException("This slot is already taken");
             }
             for (int i = 0; i < mListeners.size(); ++i) {
                 if (fd.equals(mListeners.valueAt(i))) {
-                    throw new IllegalArgumentException("This fd is already registered");
+                    Log.e(TAG, "This fd is already registered.");
+                    throw new InvalidSocketException(ERROR_INVALID_SOCKET);
                 }
             }
             mFdHandlerQueue.addOnFileDescriptorEventListener(fd, FD_EVENTS, (readyFd, events) -> {
diff --git a/tests/net/java/android/net/NetworkCapabilitiesTest.java b/tests/net/java/android/net/NetworkCapabilitiesTest.java
index 4d4915b..ad76388 100644
--- a/tests/net/java/android/net/NetworkCapabilitiesTest.java
+++ b/tests/net/java/android/net/NetworkCapabilitiesTest.java
@@ -20,6 +20,7 @@
 import static android.net.NetworkCapabilities.NET_CAPABILITY_CAPTIVE_PORTAL;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_CBS;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_EIMS;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_FOREGROUND;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_MMS;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_METERED;
@@ -27,6 +28,7 @@
 import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_ROAMING;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_VPN;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_OEM_PAID;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_PARTIAL_CONNECTIVITY;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_VALIDATED;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_WIFI_P2P;
 import static android.net.NetworkCapabilities.RESTRICTED_CAPABILITIES;
@@ -335,6 +337,24 @@
     }
 
     @Test
+    public void testConnectivityManagedCapabilities() {
+        NetworkCapabilities nc = new NetworkCapabilities();
+        assertFalse(nc.hasConnectivityManagedCapability());
+        // Check every single system managed capability.
+        nc.addCapability(NET_CAPABILITY_CAPTIVE_PORTAL);
+        assertTrue(nc.hasConnectivityManagedCapability());
+        nc.removeCapability(NET_CAPABILITY_CAPTIVE_PORTAL);
+        nc.addCapability(NET_CAPABILITY_FOREGROUND);
+        assertTrue(nc.hasConnectivityManagedCapability());
+        nc.removeCapability(NET_CAPABILITY_FOREGROUND);
+        nc.addCapability(NET_CAPABILITY_PARTIAL_CONNECTIVITY);
+        assertTrue(nc.hasConnectivityManagedCapability());
+        nc.removeCapability(NET_CAPABILITY_PARTIAL_CONNECTIVITY);
+        nc.addCapability(NET_CAPABILITY_VALIDATED);
+        assertTrue(nc.hasConnectivityManagedCapability());
+    }
+
+    @Test
     public void testEqualsNetCapabilities() {
         NetworkCapabilities nc1 = new NetworkCapabilities();
         NetworkCapabilities nc2 = new NetworkCapabilities();
diff --git a/tests/net/java/com/android/server/ConnectivityServiceTest.java b/tests/net/java/com/android/server/ConnectivityServiceTest.java
index 982f13b..83ef62e 100644
--- a/tests/net/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/net/java/com/android/server/ConnectivityServiceTest.java
@@ -28,6 +28,7 @@
 import static android.net.ConnectivityManager.TYPE_NONE;
 import static android.net.ConnectivityManager.TYPE_WIFI;
 import static android.net.INetworkMonitor.NETWORK_TEST_RESULT_INVALID;
+import static android.net.INetworkMonitor.NETWORK_TEST_RESULT_PARTIAL_CONNECTIVITY;
 import static android.net.INetworkMonitor.NETWORK_TEST_RESULT_VALID;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_CAPTIVE_PORTAL;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_CBS;
@@ -43,6 +44,7 @@
 import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_SUSPENDED;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_VPN;
+import static android.net.NetworkCapabilities.NET_CAPABILITY_PARTIAL_CONNECTIVITY;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_RCS;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_SUPL;
 import static android.net.NetworkCapabilities.NET_CAPABILITY_TRUSTED;
@@ -443,6 +445,11 @@
             mNmValidationRedirectUrl = redirectUrl;
         }
 
+        void setNetworkPartial() {
+            mNmValidationResult = NETWORK_TEST_RESULT_PARTIAL_CONNECTIVITY;
+            mNmValidationRedirectUrl = null;
+        }
+
         MockNetworkAgent(int transport) {
             this(transport, new LinkProperties());
         }
@@ -485,6 +492,7 @@
             try {
                 doAnswer(validateAnswer).when(mNetworkMonitor).notifyNetworkConnected();
                 doAnswer(validateAnswer).when(mNetworkMonitor).forceReevaluation(anyInt());
+                doAnswer(validateAnswer).when(mNetworkMonitor).notifyAcceptPartialConnectivity();
             } catch (RemoteException e) {
                 fail(e.getMessage());
             }
@@ -670,6 +678,11 @@
             connect(false);
         }
 
+        public void connectWithPartialConnectivity() {
+            setNetworkPartial();
+            connect(false);
+        }
+
         public void suspend() {
             mNetworkInfo.setDetailedState(DetailedState.SUSPENDED, null, null);
             mNetworkAgent.sendNetworkInfo(mNetworkInfo);
@@ -2512,6 +2525,106 @@
     }
 
     @Test
+    public void testPartialConnectivity() {
+        // Register network callback.
+        NetworkRequest request = new NetworkRequest.Builder()
+                .clearCapabilities().addCapability(NET_CAPABILITY_INTERNET)
+                .build();
+        TestNetworkCallback callback = new TestNetworkCallback();
+        mCm.registerNetworkCallback(request, callback);
+
+        // Bring up validated mobile data.
+        mCellNetworkAgent = new MockNetworkAgent(TRANSPORT_CELLULAR);
+        mCellNetworkAgent.connect(true);
+        callback.expectAvailableThenValidatedCallbacks(mCellNetworkAgent);
+
+        // Bring up wifi with partial connectivity.
+        mWiFiNetworkAgent = new MockNetworkAgent(TRANSPORT_WIFI);
+        mWiFiNetworkAgent.connectWithPartialConnectivity();
+        callback.expectAvailableCallbacksUnvalidated(mWiFiNetworkAgent);
+        callback.expectCapabilitiesWith(NET_CAPABILITY_PARTIAL_CONNECTIVITY, mWiFiNetworkAgent);
+
+        // Mobile data should be the default network.
+        assertEquals(mCellNetworkAgent.getNetwork(), mCm.getActiveNetwork());
+        callback.assertNoCallback();
+
+        // If the user chooses yes to use this partial connectivity wifi, switch the default
+        // network to wifi and check if wifi becomes valid or not.
+        mCm.setAcceptPartialConnectivity(mWiFiNetworkAgent.getNetwork(), true /* accept */,
+                false /* always */);
+        // With https probe disabled, NetworkMonitor should pass the network validation with http
+        // probe.
+        mWiFiNetworkAgent.setNetworkValid();
+        waitForIdle();
+        try {
+            verify(mWiFiNetworkAgent.mNetworkMonitor,
+                    timeout(TIMEOUT_MS).times(1)).notifyAcceptPartialConnectivity();
+        } catch (RemoteException e) {
+            fail(e.getMessage());
+        }
+        callback.expectCallback(CallbackState.LOSING, mCellNetworkAgent);
+        NetworkCapabilities nc = callback.expectCapabilitiesWith(NET_CAPABILITY_VALIDATED,
+                mWiFiNetworkAgent);
+        assertTrue(nc.hasCapability(NET_CAPABILITY_PARTIAL_CONNECTIVITY));
+        assertEquals(mWiFiNetworkAgent.getNetwork(), mCm.getActiveNetwork());
+
+        // Disconnect and reconnect wifi with partial connectivity again.
+        mWiFiNetworkAgent.disconnect();
+        callback.expectCallback(CallbackState.LOST, mWiFiNetworkAgent);
+        mWiFiNetworkAgent = new MockNetworkAgent(TRANSPORT_WIFI);
+        mWiFiNetworkAgent.connectWithPartialConnectivity();
+        callback.expectAvailableCallbacksUnvalidated(mWiFiNetworkAgent);
+        callback.expectCapabilitiesWith(NET_CAPABILITY_PARTIAL_CONNECTIVITY, mWiFiNetworkAgent);
+
+        // Mobile data should be the default network.
+        assertEquals(mCellNetworkAgent.getNetwork(), mCm.getActiveNetwork());
+
+        // If the user chooses no, disconnect wifi immediately.
+        mCm.setAcceptPartialConnectivity(mWiFiNetworkAgent.getNetwork(), false/* accept */,
+                false /* always */);
+        callback.expectCallback(CallbackState.LOST, mWiFiNetworkAgent);
+
+        // If user accepted partial connectivity before, and device reconnects to that network
+        // again, but now the network has full connectivity. The network shouldn't contain
+        // NET_CAPABILITY_PARTIAL_CONNECTIVITY.
+        mWiFiNetworkAgent = new MockNetworkAgent(TRANSPORT_WIFI);
+        // acceptUnvalidated is also used as setting for accepting partial networks.
+        mWiFiNetworkAgent.explicitlySelected(true /* acceptUnvalidated */);
+        mWiFiNetworkAgent.connect(true);
+        callback.expectAvailableCallbacksUnvalidated(mWiFiNetworkAgent);
+        callback.expectCallback(CallbackState.LOSING, mCellNetworkAgent);
+        nc = callback.expectCapabilitiesWith(NET_CAPABILITY_VALIDATED, mWiFiNetworkAgent);
+        assertFalse(nc.hasCapability(NET_CAPABILITY_PARTIAL_CONNECTIVITY));
+        // Wifi should be the default network.
+        assertEquals(mWiFiNetworkAgent.getNetwork(), mCm.getActiveNetwork());
+        mWiFiNetworkAgent.disconnect();
+        callback.expectCallback(CallbackState.LOST, mWiFiNetworkAgent);
+
+        // If user accepted partial connectivity before, and now the device reconnects to the
+        // partial connectivity network. The network should be valid and contain
+        // NET_CAPABILITY_PARTIAL_CONNECTIVITY.
+        mWiFiNetworkAgent = new MockNetworkAgent(TRANSPORT_WIFI);
+        mWiFiNetworkAgent.explicitlySelected(true /* acceptUnvalidated */);
+        mWiFiNetworkAgent.connectWithPartialConnectivity();
+        callback.expectAvailableCallbacksUnvalidated(mWiFiNetworkAgent);
+        // TODO: If the user accepted partial connectivity, we shouldn't switch to wifi until
+        // NetworkMonitor detects partial connectivity
+        assertEquals(mWiFiNetworkAgent.getNetwork(), mCm.getActiveNetwork());
+        mWiFiNetworkAgent.setNetworkValid();
+        waitForIdle();
+        try {
+            verify(mWiFiNetworkAgent.mNetworkMonitor,
+                    timeout(TIMEOUT_MS).times(1)).notifyAcceptPartialConnectivity();
+        } catch (RemoteException e) {
+            fail(e.getMessage());
+        }
+        callback.expectCallback(CallbackState.LOSING, mCellNetworkAgent);
+        callback.expectCapabilitiesWith(NET_CAPABILITY_PARTIAL_CONNECTIVITY, mWiFiNetworkAgent);
+        // Wifi should be the default network.
+        assertEquals(mWiFiNetworkAgent.getNetwork(), mCm.getActiveNetwork());
+    }
+
+    @Test
     public void testCaptivePortal() {
         final TestNetworkCallback captivePortalCallback = new TestNetworkCallback();
         final NetworkRequest captivePortalRequest = new NetworkRequest.Builder()