VC++ FTP文件上传（断点续传）

#include <WinInet.h>
#pragma comment(lib, "WinInet.lib")

HINTERNET hInternet, hConnect = NULL;

// 建立会话
hInternet = InternetOpen(_T("WinInet Ftp"), INTERNET_OPEN_TYPE_PRECONFIG, NULL, NULL, 0/*INTERNET_FLAG_ASYNC*/);
if (hInternet == nullptr)
	return ;

// 建立连接
hConnect = InternetConnect(hInternet, "192.168.1.8", 21/*INTERNET_INVALID_PORT_NUMBER*/, "admin", "password",
	INTERNET_SERVICE_FTP, INTERNET_FLAG_EXISTING_CONNECT || INTERNET_FLAG_PASSIVE, 0);
if (hConnect == nullptr)
{
	InternetCloseHandle(hInternet);
	return ;
}

// 获取远程文件大小信息
LARGE_INTEGER liSize = { 0 };
WIN32_FIND_DATA fileData;
std::string sRemoteFilename = "/远程文件名.xxx";
HINTERNET hRemoteFile = FtpFindFirstFile(hConnect, sRemoteFilename.c_str(), &fileData, 0, 0);
if (hRemoteFile == nullptr)
{
	// 服务器不存在该文件
	if (FtpPutFile(hConnect, "本地文件名.xxx", sRemoteFilename.c_str(), FTP_TRANSFER_TYPE_BINARY, 0))
	{
		// 文件上传成功
	}
	else
	{
		// 文件上传失败
	}
}
else
{
	// 服务器存在该文件，启用断点续传
	liSize.HighPart = fileData.nFileSizeHigh;
	liSize.LowPart = fileData.nFileSizeLow;
	InternetCloseHandle(hRemoteFile);

	// 获取本地文件大小
	HANDLE hLocalFile = CreateFile("本地文件名.xxx", GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ |
		FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_ARCHIVE, NULL);
	if (INVALID_HANDLE_VALUE != hLocalFile)
	{
		// 获取文件大小
		DWORD dwSize = GetFileSize(hLocalFile, NULL);
		BOOL bUploadOk = FALSE;
		if (dwSize > liSize.QuadPart)
		{
			// 建立数据传输通道
			HINTERNET hRemoteFile = nullptr;
			std::string sCommand = format("REST %d", liSize.QuadPart);
			BOOL bRet = FtpCommand(hConnect, FALSE, FTP_TRANSFER_TYPE_BINARY, _T("REST 3\r\n"), 0, NULL);

			sCommand = format("APPE %s", sRemoteFilename.c_str());
			bRet = FtpCommand(hConnect, TRUE, FTP_TRANSFER_TYPE_BINARY, sCommand.c_str(), 0, &hRemoteFile);
			if (bRet && hRemoteFile != nullptr)
			{
				// 本地文件大小比远程大，则续传
				SetFilePointer(hLocalFile, liSize.QuadPart, NULL, FILE_BEGIN);
				while (TRUE)
				{
					char buffer[1024];
					DWORD dwRet = 0;
					if (ReadFile(hLocalFile, buffer, 1024, &dwRet, NULL))
					{
						if (dwRet == 0)
						{
							// 文件发送完毕
							break;
						}

						DWORD dwSize = 0;
						if (!InternetWriteFile(hRemoteFile, buffer, dwRet, &dwSize))
						{
							// 发送失败
							break;
						}
					}
					else
					{
						break;
					}
				}

				InternetCloseHandle(hRemoteFile);
			}
			else
			{
				// 远程文件访问失败
				DWORD dwError;
				TCHAR tpszBuff[2 * 1024];
				DWORD dwBuffLen = 2 * 1024;
				bRet = ::InternetGetLastResponseInfo(&dwError, tpszBuff, &dwBuffLen);				
			}
		}

		CloseHandle(hLocalFile);
	}
	else
	{
		// 本地文件打开失败
	}
}

InternetCloseHandle(hConnect);
InternetCloseHandle(hInternet);