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# http/client/sync_client.cpp

    #include <iostream>
    #include <istream>
    #include <ostream>
    #include <string>
    #include <boost/asio.hpp>
    #include <boost/regex.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_service io_service;

        // Get a list of endpoints corresponding to the server name.
        tcp::resolver resolver(io_service);
        tcp::resolver::query query(argv[1], "http");
        tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
        tcp::resolver::iterator end;

        // Try each endpoint until we successfully establish a connection.
        tcp::socket socket(io_service);
        boost::asio::error error = boost::asio::error::host_not_found;
        while (error && endpoint_iterator != end)
        {
          socket.close();
          socket.connect(*endpoint_iterator++, boost::asio::assign_error(error));
        }
        if (error)
          throw error;

        // 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.
        boost::asio::streambuf response;
        boost::asio::read_until(socket, response, boost::regex("\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, boost::regex("\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.
        while (boost::asio::read(socket, response,
              boost::asio::transfer_at_least(1),
              boost::asio::assign_error(error)))
          std::cout << &response;
        if (error != boost::asio::error::eof)
          throw error;
      }
      catch (std::exception& e)
      {
        std::cout << "Exception: " << e.what() << "\n";
      }

      return 0;
    }

| Copyright © 2003 - 2006 Christopher M. Kohlhoff