跨平台c++/boost/asio 简单的HTTP POST请求 客户端模型

 作为一个呼应,写一个c++版本的同步http post客户端功能,如果你需要纯C版本,移步这里

linux下纯C简单的HTTP POST请求 客户端模型

讲解一下基本的的http post协议

通过\r\n,实现tcp的消息边界
每个请求的第一段 POST /a.b HTTP/1.1
POST http的方法,还有最常用的GET,当然还有其他的几种,略过
/a.b 请求的网页路径,比如如果是首页,最经常的就是/
HTTP/1.1 http协议的版本号,传说中已经出了2了,还有神奇的谷歌出的用来替代http协议的SPDY
通过这条信息表明这是一个表单
Content-Type: application/x-www-form-urlencoded
通过这条信息来表示这次httppost 的包体长度,非必需项
Content-Length:12
然后就是一个空行,代表接下来都是包体
刚才是请求,谈一下响应就更简单了

响应内容 HTTP/1.1 200 OK
200就是传送中的状态,404没找喔等等
HTTP/1.1 表示http的版本号
当然,如果包头也是可以存在,此处不介绍
然后就是一个空行,分割是包体
好了,直接上代码吧

复制代码
#include <iostream>
#include <istream>
#include <ostream>
#include <string>
#include <boost/asio.hpp>

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存在复用的情况
if(io_service.stopped())
io_service.reset();

// 从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);

// 尝试连接到其中的某个ip直到成功
tcp::socket socket(io_service);
boost::asio::connect(socket, endpoint_iterator);

// 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/1.0\r\n";
request_stream << "Host: " << host << ":" << port << "\r\n";
request_stream << "Accept: */*\r\n";
request_stream << "Content-Length: " << data.length() << "\r\n";
request_stream << "Content-Type: application/x-www-form-urlencoded\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;
}
// 如果服务器返回非200都认为有错,不支持301/302等跳转
if (status_code != 200)
{
reponse_data = "Response returned with status code != 200 " ;
return status_code;
}

// 传说中的包头可以读下来了
std::string header;
std::vector<string> headers;
while (std::getline(response_stream, header) && header != "\r")
headers.push_back(header);

// 读取所有剩下的数据作为包体
boost::system::error_code error;
while (boost::asio::read(socket, response,
boost::asio::transfer_at_least(1), error))
{
}

//响应有数据
if (response.size())
{
std::istream response_stream(&response);
std::istreambuf_iterator<char> eos;
reponse_data = string(std::istreambuf_iterator<char>(response_stream), eos);
}

if (error != boost::asio::error::eof)
{
reponse_data = error.message();
return -3;
}
}
catch(std::exception& e)
{
reponse_data = e.what();
return -4;
}
return 0;
}

int main(int argc, char* argv[])
{
string host = "127.0.0.1";
string port = "80";
string page = "/auth/login";
string data = "user_name=linbc&password=a";
string reponse_data;

int ret = post(host, port, page, data, reponse_data);
if (ret != 0)
std::cout << "error_code:" << ret << std::endl;

std::cout << reponse_data << std::endl;

return 0;
}
复制代码
编译一下吧。。

g++ post.cc -std=c++11 -pthread -lboost_system

发表评论

您的电子邮箱地址不会被公开。