content: /*
   * Copyright The OpenTelemetry Authors
   * SPDX-License-Identifier: Apache-2.0
   */
  
  package io.opentelemetry.javaagent.instrumentation.netty.v4_0;
  
  import static io.opentelemetry.javaagent.instrumentation.netty.v4_0.client.NettyClientSingletons.sslInstrumenter;
  import static net.bytebuddy.matcher.ElementMatchers.isMethod;
  import static net.bytebuddy.matcher.ElementMatchers.nameStartsWith;
  import static net.bytebuddy.matcher.ElementMatchers.named;
  import static net.bytebuddy.matcher.ElementMatchers.takesArgument;
  
  import io.netty.channel.ChannelHandler;
  import io.netty.channel.ChannelPipeline;
  import io.netty.handler.codec.http.HttpClientCodec;
  import io.netty.handler.codec.http.HttpRequestDecoder;
  import io.netty.handler.codec.http.HttpRequestEncoder;
  import io.netty.handler.codec.http.HttpResponseDecoder;
  import io.netty.handler.codec.http.HttpResponseEncoder;
  import io.netty.handler.codec.http.HttpServerCodec;
  import io.opentelemetry.instrumentation.api.util.VirtualField;
  import io.opentelemetry.instrumentation.netty.common.v4_0.internal.client.NettySslInstrumentationHandler;
  import io.opentelemetry.javaagent.bootstrap.CallDepth;
  import io.opentelemetry.javaagent.extension.instrumentation.TypeTransformer;
  import io.opentelemetry.javaagent.instrumentation.netty.v4.common.AbstractNettyChannelPipelineInstrumentation;
  import io.opentelemetry.javaagent.instrumentation.netty.v4_0.client.HttpClientRequestTracingHandler;
  import io.opentelemetry.javaagent.instrumentation.netty.v4_0.client.HttpClientResponseTracingHandler;
  import io.opentelemetry.javaagent.instrumentation.netty.v4_0.client.HttpClientTracingHandler;
  import io.opentelemetry.javaagent.instrumentation.netty.v4_0.server.HttpServerRequestTracingHandler;
  import io.opentelemetry.javaagent.instrumentation.netty.v4_0.server.HttpServerResponseTracingHandler;
  import io.opentelemetry.javaagent.instrumentation.netty.v4_0.server.HttpServerTracingHandler;
  import net.bytebuddy.asm.Advice;
  
  public class NettyChannelPipelineInstrumentation
      extends AbstractNettyChannelPipelineInstrumentation {
  
    @Override
    public void transform(TypeTransformer transformer) {
      super.transform(transformer);
  
      transformer.applyAdviceToMethod(
          isMethod()
              .and(nameStartsWith("add").or(named("replace")))
              .and(takesArgument(2, named("io.netty.channel.ChannelHandler"))),
          NettyChannelPipelineInstrumentation.class.getName() + "$ChannelPipelineAddAdvice");
    }
  
    /**
     * When certain handlers are added to the pipeline, we want to add our corresponding tracing
     * handlers. If those handlers are later removed, we may want to remove our handlers.
     */
    @SuppressWarnings("unused")
    public static class ChannelPipelineAddAdvice {
  
      @Advice.OnMethodEnter
      public static CallDepth trackCallDepth() {
        CallDepth callDepth = CallDepth.forClass(ChannelPipeline.class);
        callDepth.getAndIncrement();
        return callDepth;
      }
  
      @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)
      public static void addHandler(
          @Advice.This ChannelPipeline pipeline,
          @Advice.Argument(2) ChannelHandler handler,
          @Advice.Enter CallDepth callDepth) {
  
        if (callDepth.decrementAndGet() > 0) {
          return;
        }
  
        VirtualField<ChannelHandler, ChannelHandler> instrumentationHandlerField =
            VirtualField.find(ChannelHandler.class, ChannelHandler.class);
  
        // don't add another instrumentation handler if there already is one attached
        if (instrumentationHandlerField.get(handler) != null) {
          return;
        }
  
        ChannelHandler ourHandler = null;
        // Server pipeline handlers
        if (handler instanceof HttpServerCodec) {
          ourHandler = new HttpServerTracingHandler();
        } else if (handler instanceof HttpRequestDecoder) {
          ourHandler = new HttpServerRequestTracingHandler();
        } else if (handler instanceof HttpResponseEncoder) {
          ourHandler = new HttpServerResponseTracingHandler();
          // Client pipeline handlers
        } else if (handler instanceof HttpClientCodec) {
          ourHandler = new HttpClientTracingHandler();
        } else if (handler instanceof HttpRequestEncoder) {
          ourHandler = new HttpClientRequestTracingHandler();
        } else if (handler instanceof HttpResponseDecoder) {
          ourHandler = new HttpClientResponseTracingHandler();
          // the SslHandler lives in the netty-handler module, using class name comparison to avoid
          // adding a dependency
        } else if (handler.getClass().getName().equals("io.netty.handler.ssl.SslHandler")) {
          ourHandler = new NettySslInstrumentationHandler(sslInstrumenter(), handler);
        }
  
        if (ourHandler != null) {
          try {
            pipeline.addLast(ourHandler.getClass().getName(), ourHandler);
            // associate our handle with original handler so they could be removed together
            instrumentationHandlerField.set(handler, ourHandler);
          } catch (IllegalArgumentException e) {
            // Prevented adding duplicate handlers.
          }
        }
      }
    }
  }
  