[Android] Added Happy Eyeballs for address selection

ReactAndroid/src/main/java/com/facebook/react/modules/network/HappyEyeballs.java

@@ -0,0 +1,219 @@
+package com.facebook.react.modules.network;
+
+import android.os.Handler;
+
+import androidx.annotation.NonNull;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.io.IOException;
+import java.net.Inet4Address;
+import java.net.Inet6Address;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.Proxy;
+import java.net.UnknownHostException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReferenceArray;
+
+import okhttp3.Call;
+import okhttp3.Callback;
+import okhttp3.Connection;
+import okhttp3.Dns;
+import okhttp3.EventListener;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+
+/**
+ * Simplistic HappyEyeballs implementation for OkHttp3. It currently is lacking preferential address
+ * selection based on previous requests in the same network.
+ * */
+
+public class HappyEyeballs {
+  private final OkHttpClient.Builder mClientBuilder;
+  private final Request.Builder mRequestBuilder;
+  private final Callback mCallback;
+
+  private List<InetAddress> mOrderedAddresses;
+  private final AtomicInteger mSelectedConnectionIndex;
+  private final AtomicReferenceArray<Call> mCalls;
+  private final AtomicInteger mFailedCallsCount;
+
+  private final Handler mHandler;
+  private Runnable mNextRequest;
+
+  private static final int INITIAL_SELECTED_CONNECTION_INDEX = -1;
+  private static final int MAX_ADDRESSES = 8;
+
+  HappyEyeballs(OkHttpClient.Builder clientBuilder, Request.Builder requestBuilder, Callback callback) {
+    mClientBuilder = clientBuilder;
+    mRequestBuilder = requestBuilder;
+    mCallback = callback;
+
+    mSelectedConnectionIndex = new AtomicInteger(INITIAL_SELECTED_CONNECTION_INDEX);
+    mCalls = new AtomicReferenceArray<>(MAX_ADDRESSES);
+    mFailedCallsCount = new AtomicInteger(0);
+
+    mHandler = new Handler();
+
+    // the runnable ensures thread safety of mOrderedAddresses
+    request(0, () -> queueNextRequest(1, 400));
+  }
+
+  private void request(int index, Runnable onResolveAddresses) {
+    OkHttpClient client = mClientBuilder
+      .dns(new NthAddress(index, onResolveAddresses))
+      .eventListener(new SelectConnectionOnAcquire(index))
+      .build();
+
+    Call call = client
+      .newCall(mRequestBuilder.build());
+
+    mCalls.set(index, call);
+
+    // one of the previous connections resolved -> no need to enqueue this one
+    if (mSelectedConnectionIndex.get() != INITIAL_SELECTED_CONNECTION_INDEX) {
+      return;
+    }
+
+    call.enqueue(new Callback() {
+      @Override
+      public void onFailure(@NonNull Call call, @NonNull IOException e) {
+        // check if DNS resolution or a step before failed
+        if (mOrderedAddresses == null) {
+          mCallback.onFailure(call, e);
+          return;
+        }
+
+        int failedCallsCount = mFailedCallsCount.incrementAndGet();
+        boolean isLastCall = failedCallsCount == mOrderedAddresses.size();
+
+        if (isLastCall || mSelectedConnectionIndex.get() == index) {
+          mCallback.onFailure(call, e);
+        }
+      }
+
+      @Override
+      public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
+        if (mSelectedConnectionIndex.get() != index) {
+          return;
+        }
+
+        mCallback.onResponse(call, response);
+      }
+    });
+  }
+
+  private void queueNextRequest(int index, int delayMillis) {
+    if (
+      mOrderedAddresses == null // DNS resolution or a step before failed
+      || mOrderedAddresses.size() <= index
+    ) {
+      return;
+    }
+
+    Runnable nextRequest = () -> {
+      request(index, null);
+      queueNextRequest(index + 1, Math.min(
+        Math.round(1.5f * delayMillis),
+        2000 // see https://datatracker.ietf.org/doc/html/rfc8305#section-5
+      ));
+    };
+
+    mHandler.postDelayed(nextRequest, delayMillis);
+    mNextRequest = nextRequest;
+  }
+
+  private final class NthAddress implements Dns {
+    private final int mAddressIndex;
+    private final Runnable mOnResolveDNS;
+
+    NthAddress(int addressIndex, Runnable onResolveDNS) {
+      mAddressIndex = addressIndex;
+      mOnResolveDNS = onResolveDNS;
+    }
+
+    public List<InetAddress> lookup(@NotNull String hostname) throws UnknownHostException {
+      if (mOrderedAddresses == null) {
+        try {
+          mOrderedAddresses = getOrderedAddresses(hostname);
+        } finally {
+          if (mOnResolveDNS != null) {
+            mOnResolveDNS.run();
+          }
+        }
+      }
+
+      if (mOrderedAddresses.size() <= mAddressIndex) {
+        throw new UnknownHostException();
+      }
+
+      return mOrderedAddresses.subList(mAddressIndex, mAddressIndex + 1);
+    }
+
+    private List<InetAddress> getOrderedAddresses(@NotNull String hostname) throws UnknownHostException {
+      List<InetAddress> addresses = Dns.SYSTEM.lookup(hostname);
+
+      List<Inet4Address> inet4Addresses = new ArrayList<>();
+      List<Inet6Address> inet6Addresses = new ArrayList<>();
+      for (InetAddress address : addresses) {
+        if (address instanceof Inet4Address) {
+          inet4Addresses.add((Inet4Address) address);
+        } else {
+          inet6Addresses.add((Inet6Address) address);
+        }
+      }
+
+      List<InetAddress> zippedAddresses = new ArrayList<>();
+      for (int i = 0; i < Math.min(
+        Math.max(inet4Addresses.size(), inet6Addresses.size()),
+        MAX_ADDRESSES / 2
+      ); i++) {
+        if (inet6Addresses.size() > i) zippedAddresses.add(inet6Addresses.get(i));
+        if (inet4Addresses.size() > i) zippedAddresses.add(inet4Addresses.get(i));
+      }
+
+      return zippedAddresses;
+    }
+  }
+
+  private final class SelectConnectionOnAcquire extends EventListener {
+    private final int mConnectionIndex;
+
+    SelectConnectionOnAcquire(int connectionIndex) {
+      mConnectionIndex = connectionIndex;
+    }
+
+    @Override
+    public void connectStart(@NonNull Call call, @NonNull InetSocketAddress inetSocketAddress, @NonNull Proxy proxy) {
+      // combat runnable race conditions
+      if (mSelectedConnectionIndex.get() != INITIAL_SELECTED_CONNECTION_INDEX) {
+        call.cancel();
+      }
+    }
+
+    @Override
+    public void connectionAcquired(@NonNull Call call, @NonNull Connection connection) {
+      boolean isSelectedConnection =
+        mSelectedConnectionIndex.compareAndSet(INITIAL_SELECTED_CONNECTION_INDEX, mConnectionIndex);
+
+      if (isSelectedConnection) {
+        mHandler.removeCallbacks(mNextRequest);
+
+        for (int i = 0; i < MAX_ADDRESSES; i++) {
+          if (i == mConnectionIndex) {
+            continue;
+          }
+
+          Call other = mCalls.get(i);
+          if (other != null) {
+            other.cancel();
+          }
+        }
+      }
+    }
+  }
+}