text: //
  // sync_client.cpp
  // ~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
  //
  // Distributed under the Boost Software License, Version 1.0. (See accompanying
  // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  //
  
  #include <iostream>
  #include <istream>
  #include <ostream>
  #include <string>
  #include <boost/asio.hpp>
  
  using boost::asio::ip::tcp;
  
  int main(int argc, char* argv[])
  {
    try
    {
      if (argc != 3)
      {
        std::cout << "Usage: sync_client <server> <path>\n";
        std::cout << "Example:\n";
        std::cout << "  sync_client www.boost.org /LICENSE_1_0.txt\n";
        return 1;
      }
  
      boost::asio::io_context io_context;
  
      // Get a list of endpoints corresponding to the server name.
      tcp::resolver resolver(io_context);
      tcp::resolver::results_type endpoints = resolver.resolve(argv[1], "http");
  
      // Try each endpoint until we successfully establish a connection.
      tcp::socket socket(io_context);
      boost::asio::connect(socket, endpoints);
  
      // Form the request. We specify the "Connection: close" header so that the
      // server will close the socket after transmitting the response. This will
      // allow us to treat all data up until the EOF as the content.
      boost::asio::streambuf request;
      std::ostream request_stream(&request);
      request_stream << "GET " << argv[2] << " HTTP/1.0\r\n";
      request_stream << "Host: " << argv[1] << "\r\n";
      request_stream << "Accept: */*\r\n";
      request_stream << "Connection: close\r\n\r\n";
  
      // Send the request.
      boost::asio::write(socket, request);
  
      // Read the response status line. The response streambuf will automatically
      // grow to accommodate the entire line. The growth may be limited by passing
      // a maximum size to the streambuf constructor.
      boost::asio::streambuf response;
      boost::asio::read_until(socket, response, "\r\n");
  
      // Check that response is OK.
      std::istream response_stream(&response);
      std::string http_version;
      response_stream >> http_version;
      unsigned int status_code;
      response_stream >> status_code;
      std::string status_message;
      std::getline(response_stream, status_message);
      if (!response_stream || http_version.substr(0, 5) != "HTTP/")
      {
        std::cout << "Invalid response\n";
        return 1;
      }
      if (status_code != 200)
      {
        std::cout << "Response returned with status code " << status_code << "\n";
        return 1;
      }
  
      // Read the response headers, which are terminated by a blank line.
      boost::asio::read_until(socket, response, "\r\n\r\n");
  
      // Process the response headers.
      std::string header;
      while (std::getline(response_stream, header) && header != "\r")
        std::cout << header << "\n";
      std::cout << "\n";
  
      // Write whatever content we already have to output.
      if (response.size() > 0)
        std::cout << &response;
  
      // Read until EOF, writing data to output as we go.
      boost::system::error_code error;
      while (boost::asio::read(socket, response,
            boost::asio::transfer_at_least(1), error))
        std::cout << &response;
      if (error != boost::asio::error::eof)
        throw boost::system::system_error(error);
    }
    catch (std::exception& e)
    {
      std::cout << "Exception: " << e.what() << "\n";
    }
  
    return 0;
  }
  