POST Request in WinHttp c++ - c++

Question

I'm trying to make a POST request in c++ with the WinHTTP api Click to the Microsoft Guide, the problem is that the example that is available in the microsoft webpage is a "GET" request so I came up with this code searching on the internet:
First we call the code:
HttpsWebRequestPost("example.com", "/api.php?action=UserLogin", "loginUsername=" + USERNAME + "&loginPassword=" + PASSWORD + "&url=/index.php?page=Portal");
Then:
#include <Windows.h>
#include <WinHttp.h>
#include <stdio.h>
#include <iostream> //getchar
#include <fstream>
#pragma comment(lib, "winhttp.lib")
using namespace std;
std::wstring get_utf16(const std::string &str, int codepage)
{
if (str.empty()) return std::wstring();
int sz = MultiByteToWideChar(codepage, 0, &str[0], (int)str.size(), 0, 0);
std::wstring res(sz, 0);
MultiByteToWideChar(codepage, 0, &str[0], (int)str.size(), &res[0], sz);
return res;
}
string HttpsWebRequestPost(string domain, string url, string dat)
{
//Extra
LPSTR data = const_cast<char *>(dat.c_str());;
DWORD data_len = strlen(data);
wstring sdomain = get_utf16(domain, CP_UTF8);
wstring surl = get_utf16(url, CP_UTF8);
string response;
DWORD dwSize = 0;
DWORD dwDownloaded = 0;
LPSTR pszOutBuffer;
BOOL bResults = FALSE;
HINTERNET hSession = NULL,
hConnect = NULL,
hRequest = NULL;
// Use WinHttpOpen to obtain a session handle.
hSession = WinHttpOpen(L"WinHTTP Example/1.0",
WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
WINHTTP_NO_PROXY_NAME,
WINHTTP_NO_PROXY_BYPASS, 0);
// Specify an HTTP server.
if (hSession)
hConnect = WinHttpConnect(hSession, sdomain.c_str(),
INTERNET_DEFAULT_HTTP_PORT, 0);
// Create an HTTP request handle.
if (hConnect)
hRequest = WinHttpOpenRequest(hConnect, L"POST", surl.c_str(),
NULL, WINHTTP_NO_REFERER,
WINHTTP_DEFAULT_ACCEPT_TYPES,
0);
// Send a request.
if (hRequest)
bResults = WinHttpSendRequest(hRequest,
WINHTTP_NO_ADDITIONAL_HEADERS, 0,
(LPVOID)data, data_len,
data_len, 0);
// End the request.
if (bResults)
bResults = WinHttpReceiveResponse(hRequest, NULL);
// Keep checking for data until there is nothing left.
if (bResults)
{
do
{
// Check for available data.
dwSize = 0;
if (!WinHttpQueryDataAvailable(hRequest, &dwSize))
printf("Error %u in WinHttpQueryDataAvailable.\n",
GetLastError());
// Allocate space for the buffer.
pszOutBuffer = new char[dwSize + 1];
if (!pszOutBuffer)
{
printf("Out of memory\n");
dwSize = 0;
}
else
{
// Read the data.
ZeroMemory(pszOutBuffer, dwSize + 1);
if (!WinHttpReadData(hRequest, (LPVOID)pszOutBuffer,
dwSize, &dwDownloaded))
printf("Error %u in WinHttpReadData.\n", GetLastError());
else
//printf("%s", pszOutBuffer);
response = response + string(pszOutBuffer);
// Free the memory allocated to the buffer.
delete[] pszOutBuffer;
}
} while (dwSize > 0);
}
// Report any errors.
if (!bResults)
printf("Error %d has occurred.\n", GetLastError());
// Close any open handles.
if (hRequest) WinHttpCloseHandle(hRequest);
if (hConnect) WinHttpCloseHandle(hConnect);
if (hSession) WinHttpCloseHandle(hSession);
return response;
}
But using WireShark I only get:
Hypertext Transfer Protocol
POST ***************** HTTP/1.1\r\n
Connection: Keep-Alive\r\n
User-Agent: WinHTTP Example/1.0\r\n
Content-Length: **\r\n
Host: ******\r\n
\r\n
Anyone can help meto fix this or know an easier method?
Thanks

Answer 1

In order for PHP (or any other post-processing language) to recognise POST data, add this:
LPCWSTR additionalHeaders = L"Content-Type: application/x-www-form-urlencoded\r\n";
DWORD headersLength = -1;
bResults = WinHttpSendRequest( hRequest,
additionalHeaders,
headersLength ,
(LPVOID)data,
data_len,
data_len,
0);
The rest of a code is functional, should work:

Answer 2

The following code works for me when I tried to post text in key(info) and value(this is some info) pair. The status code 200 returned at the end.
int main()
{
DWORD dwSize = 0;
LPVOID lpOutBuffer = NULL;
BOOL bResults = FALSE;
HINTERNET hSession = NULL,
hConnect = NULL,
hRequest = NULL;
// Use WinHttpOpen to obtain a session handle.
hSession = WinHttpOpen(L"A WinHTTP Example Program/1.0",
WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
WINHTTP_NO_PROXY_NAME,
WINHTTP_NO_PROXY_BYPASS, 0);
std::wstring url{ L"http://app.pomdit.com:3010/uploadfile" };
URL_COMPONENTS components{};
components.dwStructSize = sizeof(components);
components.dwHostNameLength = (DWORD)-1;
components.dwUrlPathLength = (DWORD)-1;
if (!WinHttpCrackUrl(url.c_str(), static_cast<DWORD>(url.length()), 0, &components)) {
wprintf((L"WinHttpCrackUrl(): " + ErrorMessage(GetLastError())).c_str());
}
std::wstring hostName(components.lpszHostName ? std::wstring{ components.lpszHostName, components.dwHostNameLength } : L"localhost");
// Specify an HTTP server.
if (hSession)
hConnect = WinHttpConnect(hSession, hostName.c_str(),
components.nPort, 0);
// Create an HTTP request handle.
if (hConnect)
hRequest = WinHttpOpenRequest(hConnect, L"POST", components.lpszUrlPath,
NULL, WINHTTP_NO_REFERER,
WINHTTP_DEFAULT_ACCEPT_TYPES,
0);
const WCHAR* ContentType =
L"Content-Type: multipart/form-data;boundary = 19024605111143684786787635207";
const char* MultipartRequestBody =
"--19024605111143684786787635207\r\n"
"Content-Disposition: form-data; name=\"info\"\r\n"
"\r\n"
"this is some info\r\n"
"--19024605111143684786787635207\r\n";
bResults = WinHttpSendRequest(hRequest, ContentType, wcslen(ContentType),
(LPVOID)MultipartRequestBody,
strlen(MultipartRequestBody),
strlen(MultipartRequestBody),
NULL);
// End the request.
if (bResults)
bResults = WinHttpReceiveResponse(hRequest, NULL);
// First, use WinHttpQueryHeaders to obtain the size of the buffer.
if (bResults)
{
DWORD status{}, len = sizeof(status);
bResults = WinHttpQueryHeaders(hRequest, WINHTTP_QUERY_STATUS_CODE | WINHTTP_QUERY_FLAG_NUMBER, NULL, &status, &len, NULL);
if (bResults)
{
printf("Status code = %d.\n", status);
}
}
else
{
wprintf(L"WinHttpReceiveResponse(): %s\n", ErrorMessage(GetLastError()).c_str());
}
// Close any open handles.
if (hRequest) WinHttpCloseHandle(hRequest);
if (hConnect) WinHttpCloseHandle(hConnect);
if (hSession) WinHttpCloseHandle(hSession);
}