/*
    * Copyright 2024 The Netty Project
    *
    * The Netty Project licenses this file to you 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:
    *
    *   https://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 io.netty.example.ipfilter;
  
  import io.netty.bootstrap.ServerBootstrap;
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.ChannelFuture;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelInitializer;
  import io.netty.channel.ChannelPipeline;
  import io.netty.channel.EventLoopGroup;
  import io.netty.channel.SimpleChannelInboundHandler;
  import io.netty.channel.nio.NioEventLoopGroup;
  import io.netty.channel.socket.SocketChannel;
  import io.netty.channel.socket.nio.NioServerSocketChannel;
  import io.netty.handler.ipfilter.IpFilterRuleType;
  import io.netty.handler.ipfilter.IpSubnetFilter;
  import io.netty.handler.ipfilter.IpSubnetFilterRule;
  import io.netty.handler.logging.LogLevel;
  import io.netty.handler.logging.LoggingHandler;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Discards any incoming data from a blacklisteded IP address subnet and accepts the rest.
   */
  public final class IpSubnetFilterExample {
  
      static final int PORT = Integer.parseInt(System.getProperty("port", "8009"));
  
      public static void main(String[] args) throws Exception {
          EventLoopGroup bossGroup = new NioEventLoopGroup(1);
          EventLoopGroup workerGroup = new NioEventLoopGroup(1);
  
          try {
              List<IpSubnetFilterRule> rules = new ArrayList<IpSubnetFilterRule>();
  
              // Reject 10.10.10.0/24 and 192.168.0.0/16 ranges but accept the rest
              rules.add(new IpSubnetFilterRule("10.10.10.0", 24, IpFilterRuleType.REJECT));
              rules.add(new IpSubnetFilterRule("192.168.0.0", 16, IpFilterRuleType.REJECT));
  
              // Share this same Handler instance with multiple ChannelPipeline(s).
              final IpSubnetFilter ipFilter = new IpSubnetFilter(rules);
  
              ServerBootstrap b = new ServerBootstrap();
              b.group(bossGroup, workerGroup)
                      .channel(NioServerSocketChannel.class)
                      .handler(new LoggingHandler(LogLevel.INFO))
                      .childHandler(new ChannelInitializer<SocketChannel>() {
                          @Override
                          public void initChannel(SocketChannel ch) {
                              ChannelPipeline p = ch.pipeline();
                              p.addFirst(ipFilter);
  
                              p.addLast(new SimpleChannelInboundHandler<ByteBuf>() {
                                  @Override
                                  protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
                                      System.out.println("Received data from: " + ctx.channel().remoteAddress());
                                  }
                              });
                          }
                      });
  
              // Bind and start to accept incoming connections.
              ChannelFuture f = b.bind(PORT).sync();
  
              // Wait until the server socket is closed.
              // In this example, this does not happen, but you can do that to gracefully
              // shut down your server.
              f.channel().closeFuture().sync();
          } finally {
              workerGroup.shutdownGracefully();
              bossGroup.shutdownGracefully();
          }
      }
  }