Add setting that controls network rate limit

The INGRESS_RATE_LIMIT_BYTES_PER_SECOND setting controls the rate limit
for internet networks. If set to -1, no rate limit applies.  There is
one global rate limit that will be applied to all networks with
NET_CAPABILITY_INTERNET.

Test: atest ConnectivitySettingsManagerTest
Bug: 157552970
Change-Id: Ia82aa867686d484ce46734f76d4a48bf864eff84

framework/src/android/net/ConnectivitySettingsManager.java

@@ -383,6 +383,14 @@ public class ConnectivitySettingsManager {
     public static final String UIDS_ALLOWED_ON_RESTRICTED_NETWORKS =
             "uids_allowed_on_restricted_networks";
 
+    /**
+     * A global rate limit that applies to all networks with NET_CAPABILITY_INTERNET when enabled.
+     *
+     * @hide
+     */
+    public static final String INGRESS_RATE_LIMIT_BYTES_PER_SECOND =
+            "ingress_rate_limit_bytes_per_second";
+
     /**
      * Get mobile data activity timeout from {@link Settings}.
      *
@@ -1071,4 +1079,37 @@ public class ConnectivitySettingsManager {
         Settings.Global.putString(context.getContentResolver(), UIDS_ALLOWED_ON_RESTRICTED_NETWORKS,
                 uids);
     }
+
+    /**
+     * Get the global network bandwidth rate limit.
+     *
+     * The limit is only applicable to networks that provide internet connectivity. If the setting
+     * is unset, it defaults to -1.
+     *
+     * @param context The {@link Context} to query the setting.
+     * @return The rate limit in number of bytes per second or -1 if disabled.
+     */
+    public static long getIngressRateLimitInBytesPerSecond(@NonNull Context context) {
+        return Settings.Global.getLong(context.getContentResolver(),
+                INGRESS_RATE_LIMIT_BYTES_PER_SECOND, -1);
+    }
+
+    /**
+     * Set the global network bandwidth rate limit.
+     *
+     * The limit is only applicable to networks that provide internet connectivity.
+     *
+     * @param context The {@link Context} to set the setting.
+     * @param rateLimitInBytesPerSec The rate limit in number of bytes per second or -1 to disable.
+     */
+    public static void setIngressRateLimitInBytesPerSecond(@NonNull Context context,
+            @IntRange(from = -1, to = Integer.MAX_VALUE) long rateLimitInBytesPerSec) {
+        if (rateLimitInBytesPerSec < -1) {
+            throw new IllegalArgumentException(
+                    "Rate limit must be within the range [-1, Integer.MAX_VALUE]");
+        }
+        Settings.Global.putLong(context.getContentResolver(),
+                INGRESS_RATE_LIMIT_BYTES_PER_SECOND,
+                rateLimitInBytesPerSec);
+    }
 }