wininetを使用してPOST要求応答を取得できません

Question

XMLデータ（http://freecite.library.brown.edu/welcome/api_instructions）を取得するために、APIにPOSTリクエストを行う必要があります。これは正常に動作しますcurl：

curl -H "Accept: application/xml" --data "citation=Udvarhelyi, I.S., Gatsonis, C.A., Epstein, A.M., Pashos, C.L., Newhouse, J.P. and McNeil, B.J. Acute Myocardial Infarction in the Medicare population: process of care and clinical outcomes. Journal of the American Medical Association, 1992; 18:2530-2536. " http://freecite.library.brown.edu:80/citations/create 

私はWin32 SDKを使用して同様のことをしようとしています。これは私のコードです：

void LoadData() 
{ 
    wil::unique_hinternet hInternet(InternetOpen(L"Dummy", INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0)); 
    wil::unique_hinternet hConnect(InternetConnect(hInternet.get(), L"http://freecite.library.brown.edu", 80, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0)); 
    wil::unique_hinternet hRequest(HttpOpenRequest(hConnect.get(), L"POST", L"/citations/create", NULL, NULL, NULL, NULL, NULL)); 
    wstring data = L"citation=Udvarhelyi, I.S., Gatsonis, C.A., Epstein, A.M., Pashos, C.L., Newhouse, J.P. and McNeil, B.J. Acute Myocardial Infarction in the Medicare population: process of care and clinical outcomes. Journal of the American Medical Association, 1992; 18:2530-2536."; 
    PCWSTR szHeaders = L"Accept: application/xml"; 

    HttpSendRequest(hRequest.get(), szHeaders, 0, (LPVOID)data.c_str(), static_cast<int>(data.length())); 

    DWORD availableBytes = 0; 
    InternetQueryDataAvailable(hRequest.get(), &availableBytes, 0, 0); 
    PBYTE outputBuffer = (PBYTE)HeapAlloc(GetProcessHeap(), 0, availableBytes); 
    PBYTE nextBytes = outputBuffer; 
    DWORD bytesUsed = 0; // number of used bytes. 
    while (availableBytes) 
    { 
     DWORD downloadedBytes; 
     InternetReadFile(hRequest.get(), nextBytes, availableBytes, &downloadedBytes); 
     bytesUsed = bytesUsed + downloadedBytes; 

     InternetQueryDataAvailable(hRequest.get(), &availableBytes, 0, 0); 
     if (availableBytes > 0) 
     { 
      // lazy buffer growth here. Only alloc for what we need. could be optimized if we end up with huge payloads (>10MB). 
      // otherwise, this is good enough. 
      outputBuffer = (PBYTE)HeapReAlloc(GetProcessHeap(), 0, outputBuffer, bytesUsed + availableBytes); 
      nextBytes = outputBuffer + bytesUsed; // careful, pointer might have moved! Update cursor. 
     } 
    } 

    // Convert outputed XML to wide char 
    int size_needed = MultiByteToWideChar(CP_UTF8, 0, (PCCH)outputBuffer, bytesUsed, NULL, 0); 
    std::wstring wstrTo(size_needed, 0); 
    MultiByteToWideChar(CP_UTF8, 0, (PCCH)outputBuffer, bytesUsed, &wstrTo[0], size_needed); 

    wstring res = wstrTo; 
} 

問題は、さえInternetQueryDataAvailableを呼び出した後、forループに入る前に、あるavailableBytesは、結果として0に出てくる、私は最終的にレスポンスとして空の文字列を取得して終了します私はXMLレスポンスを期待していました。

私は間違って何をしているのか誰に教えてもらえますか？

Answer 1

InternetConnectは、サーバー名またはIPアドレスを想定しているため、アドレスに"http://"を含めないでください。変更：

InternetConnect(handle, L"freecite.library.brown.edu"...); 

dataにはUTF-8を使用してください。 WinAPI関数のその他のパラメータは、UTF-16を使用して正しく、必要な変換を自動的に行います。

変更ヘッダ：

std::wstring szHeaders = L"Content-Type: application/x-www-form-urlencoded\r\n"; 

acceptはHttpOpenRequest

const wchar_t *accept[] = { L"text/xml", NULL }; 
HINTERNET hrequest = HttpOpenRequest(hconnect, L"POST", L"/citations/create", 
    NULL, NULL, accept, 0, 0); 

注意、あなたが（その場所にNULLを使用）acceptを指定しない場合、結果はですることができ介して送信されるべきプレーンhtml。

次の例では、あなたはAPI呼び出しのいずれかに任意のエラー処理を行っていないXMLデータに

std::wstring get_utf16(const std::string &str); 
std::string get_utf8(const std::wstring &wstr); 

int main() 
{ 
    HINTERNET hsession = NULL; 
    HINTERNET hconnect = NULL; 
    HINTERNET hrequest = NULL; 
    std::wstring result; 
    std::wstring szHeaders = L"Content-Type: application/x-www-form-urlencoded\r\n"; 
    std::wstring data_w = L"citation=Udvarhelyi, I.S., Gatsonis, C.A., Epstein, A.M., Pashos, C.L., Newhouse, J.P. and McNeil, B.J. Acute Myocardial Infarction in the Medicare population: process of care and clinical outcomes. Journal of the American Medical Association, 1992; 18:2530-2536."; 
    std::string data = get_utf8(data_w); 

    hsession = InternetOpen(L"appname", INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0); 
    if(!hsession) 
     goto cleanup; 

    hconnect = InternetConnect(hsession, L"freecite.library.brown.edu", 
     INTERNET_DEFAULT_HTTP_PORT, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0); 
    if(!hconnect) 
     goto cleanup; 

    const wchar_t *accept[] = { L"text/xml", NULL }; 
    hrequest = HttpOpenRequest(hconnect, L"POST", L"/citations/create", 
     NULL, NULL, accept, 0, 0); 
    if(!hrequest) 
     goto cleanup; 
    BOOL sent = HttpSendRequest(hrequest, szHeaders.c_str(), szHeaders.size(), 
     &data[0], data.size()); 

    if(sent) 
    { 
     DWORD blocksize = 4096; 
     DWORD received = 0; 
     std::string temp; 
     std::string block(blocksize, 0); 
     while(InternetReadFile(hrequest, &block[0], blocksize, &received) && received) 
     { 
      block.resize(received); 
      temp += block; 
     } 
     result = get_utf16(temp); 
     std::wcout << result << std::endl; 
    } 

cleanup: 
    if(hrequest) InternetCloseHandle(hrequest); 
    if(hconnect) InternetCloseHandle(hconnect); 
    if(hsession) InternetCloseHandle(hsession); 
    return 0; 
} 

std::wstring get_utf16(const std::string &str) 
{ 
    if(str.empty()) return std::wstring(); 
    int sz = MultiByteToWideChar(CP_UTF8, 0, &str[0], -1, 0, 0); 
    std::wstring res(sz, 0); 
    MultiByteToWideChar(CP_UTF8, 0, &str[0], -1, &res[0], sz); 
    return res; 
} 

std::string get_utf8(const std::wstring &wstr) 
{ 
    int sz = WideCharToMultiByte(CP_UTF8, 0, &wstr[0], -1, 0, 0, 0, 0); 
    std::string res(sz, 0); 
    WideCharToMultiByte(CP_UTF8, 0, &wstr[0], -1, &res[0], sz, 0, 0); 
    return res; 
}