HTTP POST 请求不允许我定义上下文类型

Question

我正在使用Ubuntu18.04和boost.asio向其余API发送POST请求。当服务器接收到请求时，它会捕获它，但我似乎无法定义它的内容类型。我有一个函数collectRequestData，它应该解析请求的主体并返回，然后将其保存到MySQL数据库中。当我打印函数返回的内容时，它会打印null，而它应该是发送的JSON文本。当我在调用函数之前打印"Content-Type"时，当我认为它应该是"application/json"时，它会打印未定义的。我在这里的最终目标是，当我通过./file.o localhost 8080 /licence '{JSON formatted text}'运行客户端代码时，它会连接到localhost端口8080路径/许可证(这是正确的(，然后将JSON文本保存到MySQL数据库。它做得不正确，我很确定原因是"Content-Type"。我是服务器和JavaScript的新手，所以如果有人看到我做错了什么，请指出。此外，如果你能提供额外的细节来帮助我理解一个建议，我将不胜感激。

---

下面是我发送POST请求的客户端代码

#include <iostream>
#include <istream>
#include <ostream>
#include <string>
#include <boost/asio.hpp>
using boost::asio::ip::tcp;
using namespace std;
int main(int argc, char* argv[])
{
cout << "main -start" << endl;
try
{
boost::asio::io_service io_service;
string ipAddress = argv[1]; //"localhost" for loop back or ip address otherwise, i.e.- www.boost.org;       
string portNum = argv[2]; //"8000" for instance;
string hostAddress;
if (portNum.compare("80") != 0) // add the ":" only if the port number is not 80 (proprietary port number).
{
hostAddress = ipAddress + ":" + portNum;
}
else 
{ 
hostAddress = ipAddress;
}
string wordToQuery = "";//this will be used for entry indexing
string queryStr = argv[3]; //"/api/v1/similar?word=" + wordToQuery;
string json = argv[4];
// Get a list of endpoints corresponding to the server name.
tcp::resolver resolver(io_service);
tcp::resolver::query query(ipAddress, portNum);
tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
// Try each endpoint until we successfully establish a connection.
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.
string typeJSON = application/json;
boost::asio::streambuf request;
std::ostream request_stream(&request);
request_stream << "POST " << queryStr << " HTTP/1.1rn";  // note that you can change it if you wish to HTTP/1.0
request_stream << "Host: " << hostAddress << "rn";
request_stream << "User-Agent: C/1.0";
request_stream << "Content-Type: application/json; charset=utf-8rn";
request_stream << "Accept: */*rn";
request_stream << "Content-Length: " << json.length() << "rn"; 
request_stream << "Connection: closernrn";
request_stream << json;
// 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, "rn");
// 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 responsen";
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, "rnrn");
// 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;
}

---

下面是我的服务器处理POST请求的部分

app.post('/licence', function (req, res) {
collectRequestData(req, result => {
//console.log(request.headers['Content-Type']);
console.log(result);
sleep(5000);
connection.query('INSERT INTO licence SET ?', result, function (error, results) {
if (error) throw error;
res.end(JSON.stringify(results));
});
//res.end(`Parsed data belonging to ${result.fname}`);
});
});
function collectRequestData(request, callback) {
console.log(request.headers['Content-Type']);
const FORM_URLENCODED = 'application/json';
if(request.headers['Content-Type'] === FORM_URLENCODED) {
let body = '';
request.on('data', chunk => {
body += chunk.toString();
});
request.on('end', () => {
callback(JSON.parse(body));
});
}
else {
callback(null);
}
}

Answer 1

您缺少一个行尾

request_stream << "User-Agent: C/1.0";

应该是

request_stream << "User-Agent: C/1.0rn";

意味着你的内容类型标题永远不会被识别，因为它不在单独的行上

Answer 2

感觉是web服务器问题，您可能不符合http协议规范。尝试使用boost:：beast，可在boost1.66及以上版本中使用。它是对boost:：asio的包装，添加了高级web服务器和web套接字功能。您不需要为低级HTTP实现而烦恼。

样本代码

Answer 3

我假设您将nodeJS用于服务器

nodejs为您提供小写的请求标头

所以

function collectRequestData(request, callback) {
console.log(request.headers['content-type']);
const FORM_URLENCODED = 'application/json';
if(request.headers['content-type'] === FORM_URLENCODED) {
let body = '';

一旦你修复了@john发现的另一个问题，当然是

即

您缺少一个行尾

request_stream << "User-Agent: C/1.0";

应该是

request_stream << "User-Agent: C/1.0rn";

Answer 4

首先，我认为您应该仔细检查服务器是否正确。提供一种方法：

curl "http://localhost:8080/licence" --data "{json format text}" -v

如果此命令的响应结果与您的相同，则说明是服务器的问题。如果没有，请尝试在代码中组装与curl相同的请求包内容，特别是"\r\n"等。

Answer 5

正确的解决方案是@john和@Jaromanda X所说的内容的组合，我还必须将const FORM_URLENCODED = 'application/json';更改为const FORM_URLENCODED = 'application/json; charset=utf-8'