使用boost.asio實現網絡通訊

#include <boost/asio.hpp>

#define USING_SSL   //是否加密

#ifdef USING_SSL
#include <boost/asio/ssl.hpp>  
#endif

using boost::asio::ip::tcp;
using std::string;

int post(const string& host, const string& port, const string& page, const string& data, string& reponse_data)
{
  try
  {
    boost::asio::io_service io_service;
    //如果io_service存在復用的情況
   // if(io_service.stopped())
   //   io_service.reset();

    // 從dns取得域名下的所有ip
    tcp::resolver resolver(io_service);
    tcp::resolver::query query(host, port);
    tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
 
	// 嘗試連接到其中的某個ip直到成功 
#ifdef USING_SSL
	boost::asio::ssl::context context(boost::asio::ssl::context::sslv23); 
	context.set_default_verify_paths(); 
	boost::asio::ssl::stream<boost::asio::ip::tcp::socket> socket(io_service, context); 
	socket.set_verify_mode(boost::asio::ssl::context::verify_none);
	boost::asio::connect(socket.lowest_layer(), endpoint_iterator);
	socket.handshake(boost::asio::ssl::stream_base::client);
#else
	tcp::socket socket(io_service);
	boost::asio::connect(socket, endpoint_iterator);
#endif

    // 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 << "POST " << page << " HTTP/1.1\r\n";
    request_stream << "Host: " << host << "\r\n";
    request_stream << "Content-Length: " << data.length() << "\r\n";
    // Content-Type: 視實際情況修改，or“application/octet-stream”
    request_stream << "Content-Type: application/json; charset=UTF-8\r\n";
	request_stream << "Accept: */*\r\n";
    request_stream << "Connection: close\r\n\r\n";
    request_stream << data;

    // 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/")
    {
      reponse_data = "Invalid response";
      return -2;
    }
    // 如果服務器返回非200都認為有錯,不支持301/302等跳轉
    if (status_code != 200)
    {
		std::stringstream oss;
		oss << "Response returned with status code" << " : " << status_code;
		reponse_data = oss.str();
        return -3;
    }

    // 傳說中的包頭可以讀下來了
    std::string header;
    std::vector<string> headers;        
//		string content_length_header("Content-Length: ");
//		size_t content_length = 0;
    while (std::getline(response_stream, header) && header != "\r")
	{
		/*	if(string::npos != header.find(content_length_header))
			{
				string tmp(header.substr(content_length_header.size()));
				stringstream ss;
				ss << tmp;
				ss >> content_length;
			}*/
      headers.push_back(header);
	  //std::cout << header << std::endl;
	}

    // 讀取所有剩下的數據作為包體
    boost::system::error_code error;
    while (boost::asio::read(socket, response,
        boost::asio::transfer_at_least(1), error))
    {           
    }

	// 返回值為eof,認為是正確的
	if (error != boost::asio::error::eof && error.value() != 0x140000db)
	{
		std::stringstream oss;
		oss << error.value() << " : " <<  error.message();
		reponse_data = oss.str();
		return -4;
	}

    //響應有數據
    if (response.size())
    {
      std::istream response_stream(&response);
      std::istreambuf_iterator<char> eos;
      reponse_data = string(std::istreambuf_iterator<char>(response_stream), eos);                        
    }
  }
  catch(std::exception& e)
  {
    reponse_data = e.what();
      return -1;  
  }
  return 0;
}

　

參考資料：

跨平台c++/boost/asio 簡單的HTTP POST請求 客戶端模型
http://www.cnblogs.com/linbc/p/5034286.html

C++ Post/Get請求（Boost.Asio庫）
https://blog.csdn.net/csnd_ayo/article/details/64437935

 boost::asio ssl

https://blog.csdn.net/aalbertini/article/details/38300757

 基於boost asio實現的支持ssl的通用socket框架

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