WinInet 上传文件

Question

我编写了一个 C++ 函数来使用 WinInet 库执行上传文件。代码编译执行不返回错误，但我无法在服务器端处理文件。 php 和 python 服务器都不能识别文件。 这是代码：

#define DEFAULT_USERAGENT "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.1" 
#define MY_HOST "192.168.1.101"
#define ALT_HTTP_PORT 8080
#define METHOD_POST "POST"
#define BUFSIZE 1024

void UploadFile()
{
    char szHeaders[] = "Content-Type: multipart/form-data; boundary=---------------------------974767299852498929531610575";
    char szContent[] = "---------------------------974767299852498929531610575\r\nContent-Disposition: form-data; name=\"file\"; filename=\"main.cpp\"\r\nContent-Type: application/octet-stream\r\n\r\n";
    char szEndData[] = "\r\n---------------------------974767299852498929531610575--\r\n";
    unsigned char c;
    char szBuffer[BUFSIZE];
    memset(szBuffer, 0, BUFSIZE);
    char* szData = NULL;
    DWORD dwBytes;
    HANDLE hIn = CreateFile("main.cpp", GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
    for(int i = 0; i < BUFSIZE - 1 ; i++){
        ReadFile(hIn, &c, 1, NULL, NULL);
        szBuffer[i] = c;
    }
    szBuffer[BUFSIZE - 1] = '\0';
    CloseHandle(hIn);
    size_t sDataSize = strlen(szBuffer) + strlen(szContent) + strlen(szEndData) + 1;
    szData = new char[sDataSize];
    SecureZeroMemory(szData, sizeof(szData));
    strcat(szData, szContent);
    strcat(szData, szBuffer);
    strcat(szData, szEndData);
    szData[sDataSize] = '\0';

    HINTERNET io = InternetOpen(DEFAULT_USERAGENT, INTERNET_OPEN_TYPE_DIRECT, NULL, NULL, 0);
    if(!io){
        std::cerr << "InternetOpen Error" << std::endl;
        return;
    }
    HINTERNET ic = InternetConnect(io, MY_HOST, ALT_HTTP_PORT, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0);
    if(!ic){
        std::cerr << "InternetConnect Error" << std::endl;
        return;
    }

    HINTERNET hreq = HttpOpenRequest(ic, METHOD_POST, "/upload", NULL,NULL, NULL, 0, 0);
    if(!hreq){
        std::cerr << "HttpOpenRequest Error" << std::endl;
        return;
    }
    HttpSendRequest(hreq, szHeaders, strlen(szHeaders), szData, strlen(szData));
    InternetCloseHandle(io);
    InternetCloseHandle(ic);
    InternetCloseHandle(hreq);
    delete[] szData;
}

Answer 1

szContent 和 szEndData 中的 MIME 边界线是错误的。阅读RFC 2046。内容数据中的边界线以两个 - 字符开头，然后是 Content-Type 标头的 boundary 参数中指定的文本（在结束边界线的情况下，然后是另外两个 @987654327 @ 字符）。

您在内容数据中使用的边界线缺少这两个前导 - 字符。 boundary 标头中有 27 个前导破折号，因此内容中需要 29 个前导破折号，而不是像您那样的 27 个。

另外，您假设输入文件的大小正好是 1023 字节。但是，更重要的是，您没有对 CreateFile() 调用进行任何错误处理以确保文件实际上是打开的，或者对 ReadFile() 调用进行任何错误处理以确保实际读取数据（提示：当第5个参数为NULL时，第4个参数不能为NULL）。

您正在尝试将整个文件（嗯，最多 1023 个字节）读入内存，然后发送。至少，您应该使用GetFileSize() 来获取实际的文件大小，然后相应地分配szData 并直接读取它。你根本不需要szBuffer。

您的代码中还有其他小错误。比如误用sizeof()，假设文件数据中不包含任何空字节，内存泄漏等。

试试类似的方法：

#define DEFAULT_USERAGENT "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.1" 
#define MY_HOST "192.168.1.101"
#define ALT_HTTP_PORT 8080
#define METHOD_POST "POST"

#include <vector>
#include <memory>

struct FileCloser
{
    typedef HANDLE pointer;

    void operator()(HANDLE h)
    {
        if (h != INVALID_HANDLE_VALUE)
            CloseHandle(h);
    }
};

struct InetCloser
{
    typedef HINTERNET pointer;

    void operator()(HINTERNET h)
    {
        if (h != NULL)
            InternetCloseHandle(h);
    }
}; 

void UploadFile()
{
    const char *szHeaders = "Content-Type: multipart/form-data; boundary=----974767299852498929531610575";
    const char *szContent = "------974767299852498929531610575\r\nContent-Disposition: form-data; name=\"file\"; filename=\"main.cpp\"\r\nContent-Type: application/octet-stream\r\n\r\n";
    const char *szEndData = "\r\n------974767299852498929531610575--\r\n";

    std::unique_ptr<HANDLE, FileCloser> hIn(CreateFile("main.cpp", GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL));
    if (hIn.get() == INVALID_HANDLE_VALUE)
    {
        std::cerr << "CreateFile Error" << std::endl;
        return;
    }

    DWORD dwFileSize = GetFileSize(hIn.get(), NULL);
    if (dwFileSize == INVALID_FILE_SIZE)
    {
        std::cerr << "GetFileSize Error" << std::endl;
        return;
    }

    size_t sContentSize = strlen(szContent);
    size_t sEndDataSize = strlen(szEndData);

    std::vector<char> vBuffer(sContentSize + dwFileSize + sEndDataSize);
    char *szData = &vBuffer[0];

    memcpy(szData, szContent, sContentSize);
    szData += sContentSize;

    DWORD dw = 0, dwBytes;
    while (dw < dwFileSize)
    {
        if (!ReadFile(hIn.get(), szData, dwFileSize-dw, &dwBytes, NULL))
        {
            std::cerr << "ReadFile Error" << std::endl;
            return;
        }
        szData += dwBytes;
        dw += dwBytes;
    }

    hIn.reset();

    memcpy(szData, szEndData, sEndDataSize);

    std::unique_ptr<HINTERNET, InetCloser> io(InternetOpen(DEFAULT_USERAGENT, INTERNET_OPEN_TYPE_DIRECT, NULL, NULL, 0));
    if (io.get() == NULL)
    {
        std::cerr << "InternetOpen Error" << std::endl;
        return;
    }

    std::unique_ptr<HINTERNET, InetCloser> ic(InternetConnect(io.get(), MY_HOST, ALT_HTTP_PORT, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0));
    if (ic.get() == NULL)
    {
        std::cerr << "InternetConnect Error" << std::endl;
        return;
    }

    std::unique_ptr<HINTERNET, InetCloser> hreq(HttpOpenRequest(ic.get(), METHOD_POST, "/upload", NULL, NULL, NULL, 0, 0));
    if (hreq.get() == NULL)
    {
        std::cerr << "HttpOpenRequest Error" << std::endl;
        return;
    }

    if (!HttpSendRequest(hreq.get(), szHeaders, -1, &vBuffer[0], vBuffer.size()))
        std::cerr << "HttpSendRequest Error" << std::endl;
}

另一种选择是改用HttpSendRequestEx()，这样您就可以在循环中使用InternetWriteFile()，在每次循环迭代时以块的形式读取+发送文件。这样，您不必在发送之前将整个文件读入内存：

#define DEFAULT_USERAGENT "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.1" 
#define MY_HOST "192.168.1.101"
#define ALT_HTTP_PORT 8080
#define METHOD_POST "POST"
#define BUFSIZE 1024
    
#include <memory>
#include <algorithm>

struct FileCloser
{
    typedef HANDLE pointer;

    void operator()(HANDLE h)
    {
        if (h != INVALID_HANDLE_VALUE)
            CloseHandle(h);
    }
};

struct InetCloser
{
    typedef HINTERNET pointer;

    void operator()(HINTERNET h)
    {
        if (h != NULL)
            InternetCloseHandle(h);
    }
}; 

bool WriteToInternet(HINTERNET hInet, const void *Data, DWORD DataSize)
{
    const BYTE *pData = (const BYTE *) Data;
    DWORD dwBytes;

   while (DataSize > 0)
   {
       if (!InternetWriteFile(hInet, pData, DataSize, &dwBytes))
           return false;
       pData += dwBytes;
       DataSize -= dwBytes;
   }

   return true;
}

void UploadFile()
{
    const char *szHeaders = "Content-Type: multipart/form-data; boundary=----974767299852498929531610575";
    const char *szContent = "------974767299852498929531610575\r\nContent-Disposition: form-data; name=\"file\"; filename=\"main.cpp\"\r\nContent-Type: application/octet-stream\r\n\r\n";
    const char *szEndData = "\r\n------974767299852498929531610575--\r\n";

    std::unique_ptr<HANDLE, FileCloser> hIn(CreateFile("main.cpp", GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL));
    if (hIn.get() == INVALID_HANDLE_VALUE)
    {
        std::cerr << "CreateFile Error" << std::endl;
        return;
    }

    DWORD dwFileSize = GetFileSize(hIn.get(), NULL);
    if (dwFileSize == INVALID_FILE_SIZE)
    {
        std::cerr << "GetFileSize Error" << std::endl;
        return;
    }

    std::unique_ptr<HINTERNET, InetCloser> io(InternetOpen(DEFAULT_USERAGENT, INTERNET_OPEN_TYPE_DIRECT, NULL, NULL, 0));
    if (io.get() == NULL)
    {
        std::cerr << "InternetOpen Error" << std::endl;
        return;
    }

    std::unique_ptr<HINTERNET, InetCloser> ic(InternetConnect(io.get(), MY_HOST, ALT_HTTP_PORT, NULL, NULL, INTERNET_SERVICE_HTTP, 0, 0));
    if (ic.get() == NULL)
    {
        std::cerr << "InternetConnect Error" << std::endl;
        return;
    }

    std::unique_ptr<HINTERNET, InetCloser> hreq(HttpOpenRequest(ic.get(), METHOD_POST, "/upload", NULL, NULL, NULL, 0, 0));
    if (hreq.get() == NULL)
    {
        std::cerr << "HttpOpenRequest Error" << std::endl;
        return;
    }

    if (!HttpAddRequestHeaders(hreq.get(), szHeaders, -1, HTTP_ADDREQ_FLAG_REPLACE | HTTP_ADDREQ_FLAG_ADD))
    {
        std::cerr << "HttpAddRequestHeaders Error" << std::endl;
        return;
    } 

    size_t sContentSize = strlen(szContent);
    size_t sEndDataSize = strlen(szEndData);

    INTERNET_BUFFERS bufferIn = {};
    bufferIn.dwStructSize  = sizeof(INTERNET_BUFFERS);
    bufferIn.dwBufferTotal = sContentSize + dwFileSize + sEndDataSize;

    if (!HttpSendRequestEx(hreq.get(), &bufferIn, NULL, HSR_INITIATE, 0))
    {
        std::cerr << "HttpSendRequestEx Error" << std::endl;
        return;
    }

    if (!WriteToInternet(hreq.get(), szContent, sContentSize)))
    {
        std::cerr << "InternetWriteFile Error" << std::endl;
        return;
    }

    char szData[BUFSIZE];
    DWORD dw = 0, dwBytes;

    while (dw < dwFileSize)
    {
        if (!ReadFile(hIn.get(), szData, std::min(dwFileSize-dw, sizeof(szData)), &dwBytes, NULL))
        {
            std::cerr << "ReadFile Error" << std::endl;
            return;
        }

        if (!WriteToInternet(hreq.get(), szData, dwBytes))
        {
            std::cerr << "InternetWriteFile Error" << std::endl;
            return;
        }

        dw += dwBytes;
    }

    if (!WriteToInternet(hreq.get(), szEndData, sEndDataSize))
    {
        std::cerr << "InternetWriteFile Error" << std::endl;
        return;
    }

    if (!HttpEndRequest(hreq.get(), NULL, HSR_INITIATE, 0))
        std::cerr << "HttpEndRequest Error" << std::endl;
}