WinInet(MFC)を使ったhttpとhttps(自己証明書) - Qiita

CInternetSession session; CHttpConnection *pConn = NULL; CString strServer, strObj, strHeader; INTERNET_PORT nPort; DWORD dwServiceType; CHttpFile *pFile = NULL; // ShiftJIS -> UTF-8 変換 CString cstrBody = "{}"; // Body部 CString cstrUtf8Body = SjistoUTF8(cstrBody); // URLを作成 CString cstrUrl = "http://localhost" // URL情報を解析 ::AfxParseURL(cstrUrl, dwServiceType, strServer, strObj, nPort); // ポート番号を設定