Move IpClient to NetworkStack

Test: atest FrameworksNetTests NetworkStackTests
Bug: b/112869080
Change-Id: I7d00848c052382cd1b6ce458868bed6a1e9e8ec5

1 files changed, 254 insertions, 0 deletions

diff --git a/src/android/net/util/FdEventsReader.java b/src/android/net/util/FdEventsReader.java
new file mode 100644
index 0000000..8bbf449
--- /dev/null
+++ b/src/android/net/util/FdEventsReader.java
@@ -0,0 +1,254 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.net.util;
+
+import static android.os.MessageQueue.OnFileDescriptorEventListener.EVENT_INPUT;
+import static android.os.MessageQueue.OnFileDescriptorEventListener.EVENT_ERROR;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.os.Handler;
+import android.os.Looper;
+import android.os.MessageQueue;
+import android.system.ErrnoException;
+import android.system.OsConstants;
+
+import libcore.io.IoUtils;
+
+import java.io.FileDescriptor;
+
+
+/**
+ * This class encapsulates the mechanics of registering a file descriptor
+ * with a thread's Looper and handling read events (and errors).
+ *
+ * Subclasses MUST implement createFd() and SHOULD override handlePacket(). They MAY override
+ * onStop() and onStart().
+ *
+ * Subclasses can expect a call life-cycle like the following:
+ *
+ *     [1] when a client calls start(), createFd() is called, followed by the onStart() hook if all
+ *         goes well. Implementations may override onStart() for additional initialization.
+ *
+ *     [2] yield, waiting for read event or error notification:
+ *
+ *             [a] readPacket() && handlePacket()
+ *
+ *             [b] if (no error):
+ *                     goto 2
+ *                 else:
+ *                     goto 3
+ *
+ *     [3] when a client calls stop(), the onStop() hook is called (unless already stopped or never
+ *         started). Implementations may override onStop() for additional cleanup.
+ *
+ * The packet receive buffer is recycled on every read call, so subclasses
+ * should make any copies they would like inside their handlePacket()
+ * implementation.
+ *
+ * All public methods MUST only be called from the same thread with which
+ * the Handler constructor argument is associated.
+ *
+ * @hide
+ */
+public abstract class FdEventsReader<BufferType> {
+    private static final int FD_EVENTS = EVENT_INPUT | EVENT_ERROR;
+    private static final int UNREGISTER_THIS_FD = 0;
+
+    @NonNull
+    private final Handler mHandler;
+    @NonNull
+    private final MessageQueue mQueue;
+    @NonNull
+    private final BufferType mBuffer;
+    @Nullable
+    private FileDescriptor mFd;
+    private long mPacketsReceived;
+
+    protected static void closeFd(FileDescriptor fd) {
+        IoUtils.closeQuietly(fd);
+    }
+
+    protected FdEventsReader(@NonNull Handler h, @NonNull BufferType buffer) {
+        mHandler = h;
+        mQueue = mHandler.getLooper().getQueue();
+        mBuffer = buffer;
+    }
+
+    public void start() {
+        if (onCorrectThread()) {
+            createAndRegisterFd();
+        } else {
+            mHandler.post(() -> {
+                logError("start() called from off-thread", null);
+                createAndRegisterFd();
+            });
+        }
+    }
+
+    public void stop() {
+        if (onCorrectThread()) {
+            unregisterAndDestroyFd();
+        } else {
+            mHandler.post(() -> {
+                logError("stop() called from off-thread", null);
+                unregisterAndDestroyFd();
+            });
+        }
+    }
+
+    @NonNull
+    public Handler getHandler() { return mHandler; }
+
+    protected abstract int recvBufSize(@NonNull BufferType buffer);
+
+    public int recvBufSize() { return recvBufSize(mBuffer); }
+
+    /**
+     * Get the number of successful calls to {@link #readPacket(FileDescriptor, Object)}.
+     *
+     * <p>A call was successful if {@link #readPacket(FileDescriptor, Object)} returned a value > 0.
+     */
+    public final long numPacketsReceived() { return mPacketsReceived; }
+
+    /**
+     * Subclasses MUST create the listening socket here, including setting
+     * all desired socket options, interface or address/port binding, etc.
+     */
+    @Nullable
+    protected abstract FileDescriptor createFd();
+
+    /**
+     * Implementations MUST return the bytes read or throw an Exception.
+     *
+     * <p>The caller may throw a {@link ErrnoException} with {@link OsConstants#EAGAIN} or
+     * {@link OsConstants#EINTR}, in which case {@link FdEventsReader} will ignore the buffer
+     * contents and respectively wait for further input or retry the read immediately. For all other
+     * exceptions, the {@link FdEventsReader} will be stopped with no more interactions with this
+     * method.
+     */
+    protected abstract int readPacket(@NonNull FileDescriptor fd, @NonNull BufferType buffer)
+            throws Exception;
+
+    /**
+     * Called by the main loop for every packet.  Any desired copies of
+     * |recvbuf| should be made in here, as the underlying byte array is
+     * reused across all reads.
+     */
+    protected void handlePacket(@NonNull BufferType recvbuf, int length) {}
+
+    /**
+     * Called by the main loop to log errors.  In some cases |e| may be null.
+     */
+    protected void logError(@NonNull String msg, @Nullable Exception e) {}
+
+    /**
+     * Called by start(), if successful, just prior to returning.
+     */
+    protected void onStart() {}
+
+    /**
+     * Called by stop() just prior to returning.
+     */
+    protected void onStop() {}
+
+    private void createAndRegisterFd() {
+        if (mFd != null) return;
+
+        try {
+            mFd = createFd();
+            if (mFd != null) {
+                // Force the socket to be non-blocking.
+                IoUtils.setBlocking(mFd, false);
+            }
+        } catch (Exception e) {
+            logError("Failed to create socket: ", e);
+            closeFd(mFd);
+            mFd = null;
+        }
+
+        if (mFd == null) return;
+
+        mQueue.addOnFileDescriptorEventListener(
+                mFd,
+                FD_EVENTS,
+                (fd, events) -> {
+                    // Always call handleInput() so read/recvfrom are given
+                    // a proper chance to encounter a meaningful errno and
+                    // perhaps log a useful error message.
+                    if (!isRunning() || !handleInput()) {
+                        unregisterAndDestroyFd();
+                        return UNREGISTER_THIS_FD;
+                    }
+                    return FD_EVENTS;
+                });
+        onStart();
+    }
+
+    private boolean isRunning() { return (mFd != null) && mFd.valid(); }
+
+    // Keep trying to read until we get EAGAIN/EWOULDBLOCK or some fatal error.
+    private boolean handleInput() {
+        while (isRunning()) {
+            final int bytesRead;
+
+            try {
+                bytesRead = readPacket(mFd, mBuffer);
+                if (bytesRead < 1) {
+                    if (isRunning()) logError("Socket closed, exiting", null);
+                    break;
+                }
+                mPacketsReceived++;
+            } catch (ErrnoException e) {
+                if (e.errno == OsConstants.EAGAIN) {
+                    // We've read everything there is to read this time around.
+                    return true;
+                } else if (e.errno == OsConstants.EINTR) {
+                    continue;
+                } else {
+                    if (isRunning()) logError("readPacket error: ", e);
+                    break;
+                }
+            } catch (Exception e) {
+                if (isRunning()) logError("readPacket error: ", e);
+                break;
+            }
+
+            try {
+                handlePacket(mBuffer, bytesRead);
+            } catch (Exception e) {
+                logError("handlePacket error: ", e);
+                break;
+            }
+        }
+
+        return false;
+    }
+
+    private void unregisterAndDestroyFd() {
+        if (mFd == null) return;
+
+        mQueue.removeOnFileDescriptorEventListener(mFd);
+        closeFd(mFd);
+        mFd = null;
+        onStop();
+    }
+
+    private boolean onCorrectThread() {
+        return (mHandler.getLooper() == Looper.myLooper());
+    }
+}