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 com.alibaba.metrics.nginx;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.OutputStream;
  import java.net.InetSocketAddress;
  import java.net.Socket;
  
  public class NetUtils {
  
      /**
       * Implementation Notes:
       *   sun.net.www.protocol.http.HttpURLConnection does not allow overriding the `Host` header,
       *   although we -Dsun.net.http.allowRestrictedHeaders=true to work around this issue,
       *   it is a global configuration and may raise potential security concerns for other components.
       *   Therefore we use the plain socket to get the http response, which is equivalent to:
       *   curl -v http://127.0.0.1:80/nginx_status -H "Host: 127.0.0.1"
       * @param nginxHost the nginx host, normally will be localhost
       * @param port the nginx status port, normally will be 80
       * @param statusPath the nginx status path
       * @param statusHost the nginx status host
       * @return the nginx stats, for example:
       *          Active connections: 1
                  server accepts handled requests request_time
                   23 23 23 9818
                  Reading: 0 Writing: 1 Waiting: 0
       */
      public static Response request(String nginxHost, int port, String statusPath, String statusHost) {
          BufferedReader br = null;
          Socket s = new Socket();
          try {
              s.connect(new InetSocketAddress(nginxHost, port), 100);
              OutputStream outputStream = s.getOutputStream();
              StringBuilder requestPayload = new StringBuilder();
              requestPayload.append("GET ").append(statusPath).append(" HTTP/1.1\r\n")
                      .append("Host: ").append(statusHost).append("\r\n")
                      .append("User-Agent: Ali-metrics Java Client\r\n")
                      .append("Connection: close\r\n")
                      .append("\r\n");
              outputStream.write(requestPayload.toString().getBytes());
              outputStream.flush();
              br = new BufferedReader(new InputStreamReader(s.getInputStream()));
              StringBuilder sb = new StringBuilder();
              String line = null;
              boolean start = false;
              boolean success = false;
              while ((line = br.readLine()) != null) {
                  if (start) {
                      sb.append(line).append("\n");
                  }
                  if ("".equals(line)) {
                      start = true;
                  }
                  if ("HTTP/1.1 200 OK".equals(line)) {
                      success = true;
                  }
              }
              String result = sb.toString().trim();
              return new Response(result, success);
          } catch (Exception e) {
              return new Response(e.getMessage(), false);
          } finally {
              if (br != null) {
                  try {
                      br.close();
                  } catch (IOException e) {
                      // ignore
                  }
              }
              try {
                  s.close();
              } catch (IOException e) {
                  // ignore
              }
          }
      }
  
      public static class Response {
  
          private boolean success;
          private String content;
  
          public Response(String content, boolean success) {
              this.success = success;
              this.content = content;
          }
  
          public Response(String content) {
              this.content = content;
              this.success = true;
          }
  
          public boolean isSuccess() {
              return success;
          }
  
          public String getContent() {
              return content;
          }
      }
  }
  