android: add experimental option to force all connections to use IPv6

library/common/config/config.cc

@@ -78,6 +78,7 @@ const char* brotli_config_insert = R"(
 // clang-format off
 const std::string config_header = R"(
 !ignore default_defs:
+- &android_force_ipv6 false
 - &connect_timeout 30s
 - &dns_fail_base_interval 2s
 - &dns_fail_max_interval 10s
@@ -513,6 +514,7 @@ stats_sinks: *stats_sinks
           disallow_global_stats: true
           reloadable_features:
             allow_multiple_dns_addresses: *dns_multiple_addresses
+            android_always_use_v6: *android_force_ipv6
             http2_delay_keepalive_timeout: *h2_delay_keepalive_timeout
 )"
 // Needed due to warning in

library/java/io/envoyproxy/envoymobile/engine/EnvoyConfiguration.java

@@ -42,6 +42,7 @@ public enum TrustChainVerification {
   public final Boolean enableBrotli;
   public final Boolean enableHappyEyeballs;
   public final Boolean enableInterfaceBinding;
+  public final Boolean forceIPv6;
   public final Integer h2ConnectionKeepaliveIdleIntervalMilliseconds;
   public final Integer h2ConnectionKeepaliveTimeoutSeconds;
   public final Boolean h2ExtendKeepaliveTimeout;
@@ -82,6 +83,7 @@ public enum TrustChainVerification {
    * @param enableBrotli                 whether to enable response brotli decompression.
    * @param enableHappyEyeballs          whether to enable RFC 6555 handling for IPv4/IPv6.
    * @param enableInterfaceBinding       whether to allow interface binding.
+   * @param forceIPv6                    whether to force connections to use IPv6.
    * @param h2ConnectionKeepaliveIdleIntervalMilliseconds rate in milliseconds seconds to send h2
    *     pings on stream creation.
    * @param h2ConnectionKeepaliveTimeoutSeconds rate in seconds to timeout h2 pings.
@@ -108,12 +110,12 @@ public EnvoyConfiguration(
       String dnsPreresolveHostnames, List<String> dnsFallbackNameservers,
       Boolean dnsFilterUnroutableFamilies, boolean enableDrainPostDnsRefresh, boolean enableHttp3,
       boolean enableGzip, boolean enableBrotli, boolean enableHappyEyeballs,
-      boolean enableInterfaceBinding, int h2ConnectionKeepaliveIdleIntervalMilliseconds,
-      int h2ConnectionKeepaliveTimeoutSeconds, boolean h2ExtendKeepaliveTimeout,
-      List<String> h2RawDomains, int maxConnectionsPerHost, int statsFlushSeconds,
-      int streamIdleTimeoutSeconds, int perTryIdleTimeoutSeconds, String appVersion, String appId,
-      TrustChainVerification trustChainVerification, String virtualClusters,
-      List<EnvoyNativeFilterConfig> nativeFilterChain,
+      boolean enableInterfaceBinding, boolean forceIPv6,
+      int h2ConnectionKeepaliveIdleIntervalMilliseconds, int h2ConnectionKeepaliveTimeoutSeconds,
+      boolean h2ExtendKeepaliveTimeout, List<String> h2RawDomains, int maxConnectionsPerHost,
+      int statsFlushSeconds, int streamIdleTimeoutSeconds, int perTryIdleTimeoutSeconds,
+      String appVersion, String appId, TrustChainVerification trustChainVerification,
+      String virtualClusters, List<EnvoyNativeFilterConfig> nativeFilterChain,
       List<EnvoyHTTPFilterFactory> httpPlatformFilterFactories,
       Map<String, EnvoyStringAccessor> stringAccessors,
       Map<String, EnvoyKeyValueStore> keyValueStores) {
@@ -135,6 +137,7 @@ public EnvoyConfiguration(
     this.enableBrotli = enableBrotli;
     this.enableHappyEyeballs = enableHappyEyeballs;
     this.enableInterfaceBinding = enableInterfaceBinding;
+    this.forceIPv6 = forceIPv6;
     this.h2ConnectionKeepaliveIdleIntervalMilliseconds =
         h2ConnectionKeepaliveIdleIntervalMilliseconds;
     this.h2ConnectionKeepaliveTimeoutSeconds = h2ConnectionKeepaliveTimeoutSeconds;
@@ -250,6 +253,7 @@ String resolveTemplate(final String configTemplate, final String platformFilterT
                               enableDrainPostDnsRefresh ? "true" : "false"))
         .append(String.format("- &enable_interface_binding %s\n",
                               enableInterfaceBinding ? "true" : "false"))
+        .append(String.format("- &android_force_ipv6 %s\n", forceIPv6 ? "true" : "false"))
         .append(String.format("- &h2_connection_keepalive_idle_interval %ss\n",
                               h2ConnectionKeepaliveIdleIntervalMilliseconds / 1000.0))
         .append(String.format("- &h2_connection_keepalive_timeout %ss\n",

library/java/org/chromium/net/impl/NativeCronetEngineBuilderImpl.java

@@ -48,6 +48,7 @@ public class NativeCronetEngineBuilderImpl extends CronetEngineBuilderImpl {
   private boolean mEnableGzip = true;
   private boolean mEnableHappyEyeballs = false;
   private boolean mEnableInterfaceBinding = false;
+  private boolean mForceIPv6 = false;
   private int mH2ConnectionKeepaliveIdleIntervalMilliseconds = 100000000;
   private int mH2ConnectionKeepaliveTimeoutSeconds = 10;
   private boolean mH2ExtendKeepaliveTimeout = false;
@@ -108,10 +109,10 @@ private EnvoyConfiguration createEnvoyConfiguration() {
         mDnsQueryTimeoutSeconds, mDnsMinRefreshSeconds, mDnsPreresolveHostnames,
         mDnsFallbackNameservers, mEnableDnsFilterUnroutableFamilies, mEnableDrainPostDnsRefresh,
         mEnableHttp3, mEnableGzip, brotliEnabled(), mEnableHappyEyeballs, mEnableInterfaceBinding,
-        mH2ConnectionKeepaliveIdleIntervalMilliseconds, mH2ConnectionKeepaliveTimeoutSeconds,
-        mH2ExtendKeepaliveTimeout, mH2RawDomains, mMaxConnectionsPerHost, mStatsFlushSeconds,
-        mStreamIdleTimeoutSeconds, mPerTryIdleTimeoutSeconds, mAppVersion, mAppId,
-        mTrustChainVerification, mVirtualClusters, nativeFilterChain, platformFilterChain,
-        stringAccessors, keyValueStores);
+        mForceIPv6, mH2ConnectionKeepaliveIdleIntervalMilliseconds,
+        mH2ConnectionKeepaliveTimeoutSeconds, mH2ExtendKeepaliveTimeout, mH2RawDomains,
+        mMaxConnectionsPerHost, mStatsFlushSeconds, mStreamIdleTimeoutSeconds,
+        mPerTryIdleTimeoutSeconds, mAppVersion, mAppId, mTrustChainVerification, mVirtualClusters,
+        nativeFilterChain, platformFilterChain, stringAccessors, keyValueStores);
   }
 }

library/kotlin/io/envoyproxy/envoymobile/EngineBuilder.kt

@@ -46,6 +46,7 @@ open class EngineBuilder(
   private var enableGzip = true
   private var enableBrotli = false
   private var enableInterfaceBinding = false
+  private var forceIPv6 = false
   private var h2ConnectionKeepaliveIdleIntervalMilliseconds = 1
   private var h2ConnectionKeepaliveTimeoutSeconds = 10
   private var h2ExtendKeepaliveTimeout = false
@@ -284,6 +285,19 @@ open class EngineBuilder(
     return this
   }
 
+  /**
+   * Specify whether to remap IPv4 addresses to the IPv6 space and always force connections
+   * to use IPv6. Note this is an experimental option and should be enabled with caution.
+   *
+   * @param forceIPv6 whether to force connections to use IPv6.
+   *
+   * @return This builder.
+   */
+  fun forceIPv6(forceIPv6: Boolean): EngineBuilder {
+    this.forceIPv6 = forceIPv6
+    return this
+  }
+
   /**
    * Add a rate at which to ping h2 connections on new stream creation if the connection has
    * sat idle. Defaults to 1 millisecond which effectively enables h2 ping functionality
@@ -571,6 +585,7 @@ open class EngineBuilder(
       enableBrotli,
       enableHappyEyeballs,
       enableInterfaceBinding,
+      forceIPv6,
       h2ConnectionKeepaliveIdleIntervalMilliseconds,
       h2ConnectionKeepaliveTimeoutSeconds,
       h2ExtendKeepaliveTimeout,