1 /*
2 * Copyright 2019 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * https://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package io.netty.handler.address;
17
18 import io.netty.channel.ChannelFuture;
19 import io.netty.channel.ChannelFutureListener;
20 import io.netty.channel.ChannelHandlerContext;
21 import io.netty.channel.ChannelOutboundHandler;
22 import io.netty.channel.ChannelOutboundHandlerAdapter;
23 import io.netty.channel.ChannelPromise;
24
25 import java.net.NetworkInterface;
26 import java.net.SocketAddress;
27
28 /**
29 * {@link ChannelOutboundHandler} implementation which allows to dynamically replace the used
30 * {@code remoteAddress} and / or {@code localAddress} when making a connection attempt.
31 * <p>
32 * This can be useful to for example bind to a specific {@link NetworkInterface} based on
33 * the {@code remoteAddress}.
34 */
35 public abstract class DynamicAddressConnectHandler extends ChannelOutboundHandlerAdapter {
36
37 @Override
38 public final void connect(ChannelHandlerContext ctx, SocketAddress remoteAddress,
39 SocketAddress localAddress, ChannelPromise promise) {
40 final SocketAddress remote;
41 final SocketAddress local;
42 try {
43 remote = remoteAddress(remoteAddress, localAddress);
44 local = localAddress(remoteAddress, localAddress);
45 } catch (Exception e) {
46 promise.setFailure(e);
47 return;
48 }
49 ctx.connect(remote, local, promise).addListener(new ChannelFutureListener() {
50 @Override
51 public void operationComplete(ChannelFuture future) {
52 if (future.isSuccess()) {
53 // We only remove this handler from the pipeline once the connect was successful as otherwise
54 // the user may try to connect again.
55 future.channel().pipeline().remove(DynamicAddressConnectHandler.this);
56 }
57 }
58 });
59 }
60
61 /**
62 * Returns the local {@link SocketAddress} to use for
63 * {@link ChannelHandlerContext#connect(SocketAddress, SocketAddress)} based on the original {@code remoteAddress}
64 * and {@code localAddress}.
65 * By default, this method returns the given {@code localAddress}.
66 */
67 protected SocketAddress localAddress(
68 @SuppressWarnings("unused") SocketAddress remoteAddress, SocketAddress localAddress) throws Exception {
69 return localAddress;
70 }
71
72 /**
73 * Returns the remote {@link SocketAddress} to use for
74 * {@link ChannelHandlerContext#connect(SocketAddress, SocketAddress)} based on the original {@code remoteAddress}
75 * and {@code localAddress}.
76 * By default, this method returns the given {@code remoteAddress}.
77 */
78 protected SocketAddress remoteAddress(
79 SocketAddress remoteAddress, @SuppressWarnings("unused") SocketAddress localAddress) throws Exception {
80 return remoteAddress;
81 }
82 }