content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF 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
   *
   *      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 org.apache.camel.component.syslog.netty;
  
  import java.util.List;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.Unpooled;
  import io.netty.channel.ChannelHandler;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.handler.codec.ByteToMessageDecoder;
  import org.apache.camel.component.netty.ChannelHandlerFactory;
  
  public class Rfc5425FrameDecoder extends ByteToMessageDecoder implements ChannelHandlerFactory {
  
      private Integer currentFramelength;
  
      @Override
      protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
          if (currentFramelength == null) {
              // find index of the first space, it should be after the length field
              int index = indexOf(in, Unpooled.wrappedBuffer(new byte[] { ' ' }));
  
              // Read part until the first space, if we have found one
              StringBuilder lengthbuffer = new StringBuilder();
              if (index > -1) {
                  ByteBuf byteBuf = in.readBytes(index);
                  byte[] dest = new byte[byteBuf.readableBytes()];
                  byteBuf.readBytes(dest);
                  lengthbuffer.append(new String(dest));
              }
  
              int length;
              try {
                  // add one because we have to take in account the space after
                  // the length field
                  length = Integer.parseInt(lengthbuffer.toString()) + 1;
              } catch (NumberFormatException e) {
                  length = -1;
              }
  
              // We have not found the length field, reset the buffer so we can
              // retry next time
              if (length < 0) {
                  in.resetReaderIndex();
                  return;
              }
              currentFramelength = length;
          }
  
          // Buffer does not contain enough data yet, wait until it does
          if (in.readableBytes() < currentFramelength) {
              return;
          }
  
          // read the message
          int lengthToRead = currentFramelength;
          currentFramelength = null;
          out.add(in.readBytes(lengthToRead));
      }
  
      /**
       * Borrowed from the DelimiterBasedFrameDecoder Returns the number of bytes between the readerIndex of the haystack
       * and the first needle found in the haystack. -1 is returned if no needle is found in the haystack.
       */
      private static int indexOf(ByteBuf haystack, ByteBuf needle) {
          for (int i = haystack.readerIndex(); i < haystack.writerIndex(); i++) {
              int haystackIndex = i;
              int needleIndex;
              for (needleIndex = 0; needleIndex < needle.capacity(); needleIndex++) {
                  if (haystack.getByte(haystackIndex) != needle.getByte(needleIndex)) {
                      break;
                  } else {
                      haystackIndex++;
                      if (haystackIndex == haystack.writerIndex() && needleIndex != needle.capacity() - 1) {
                          return -1;
                      }
                  }
              }
  
              if (needleIndex == needle.capacity()) {
                  // Found the needle from the haystack!
                  return i - haystack.readerIndex();
              }
          }
          return -1;
      }
  
      @Override
      public ChannelHandler newChannelHandler() {
          return new Rfc5425FrameDecoder();
      }
  }
  