Creating an MFC Extension DLL that Implements Some Handy FTP Features

Environment: Network

Introduction

Anyone who has used the WinInet FTP functions has probably noticed that many features are lacking. In particular, I wanted some code that:

• Supports wildcards
• Can recursively look into the sub directories for upload/download/delete
• Can upload/download multiple files with a single line of code
• Can delete multiple files/folders with a single line of code
• Can get the file listing with a single line of code
• Automatically shows a progress bar and lets the user cancel the transfer

Functions

The main class is the CFTPClient class:

class AFX_EXT_CLASS CFTPClient
{
protected:
    CInternetSession m_InternetSession;
    CFtpConnection *m_pFtpConnection;
    CString m_sFTPRootFolder;
    void SeperateFilename (const CString &sFullName,
                                 CString &sFolder,
                                 CString &sFilename,
                                 TCHAR cFolderSeperator);

public:
    CFTPClient ();
    ~CFTPClient ();

    bool IsInitialized  ();
    void Login  (const CString &sHost, const CString &sUsername,
        const CString &sPassword, BOOL bPASV = FALSE,
                                  int nPort = 21,
                                  int nRetries = 1,
                                  int nRetryDelay = 10);
    void Logoff ();

    void Download   (const CString &sRemoteFiles,
                     const CString &sLocalFolder,
                     bool *pbAbort, bool bRecursive = true,
                     DWORD dwTransferType =
                           FTP_TRANSFER_TYPE_BINARY);
    void Upload (const CString &sLocalFiles,
                 const CString &sRemoteFolder,
                 bool *pbAbort, bool bRecursive = true,
                 DWORD dwTransferType =
                       FTP_TRANSFER_TYPE_BINARY);

    void DeleteFiles    (const CString &sOrgRemoteFiles,
                         bool *pbAbort,
        bool bRecursive, bool bAbortIfFailsOnce);
    void DeleteFolders  (const CString &sRemoteFolder,
                         bool *pbAbort,
        bool bRecursive, bool bAbortIfFailsOnce);

    void CreateMultiFolder  (const CString &sRemoteFolder);

    void GetFileList    (const CString &sRemoteFolder,
                               bool bFullPathGiven,
                               CStringArray &sFileNameArray,
                               bool bRecursive,
                               bool bExcludeHidden = false);

private:
    void DeleteRemoteFiles  (bool bDeleteFirs,
                             const CString &sOrgRemote,
                             bool *pbAbort, bool bRecursive,
                             bool bAbortIfFailsOnce);

    friend class CFTPDownload;
    friend class CFTPUpload;
};

void Login (const CString &sHost,
            const CString &sUsername,
            const CString &sPassword,
            BOOL bPASV = FALSE,
            int nPort = 21,
            int nRetries = 1,
            int nRetryDelay = 10)

To connect using passive mode, set bPASV to TRUE. nRetires represents the number of retransmissions. nRetryDelay is the delay between each retry attempt.

void Logoff ()

Disconnects from the server.

void Download (const CString &sRemoteFiles,
               const CString &sLocalFolder,
               bool *pbAbort,
               bool bRecursive = true,
               DWORD dwTransferType = FTP_TRANSFER_TYPE_BINARY)

• sRemoteFiles are the files to be downloaded. Usage of wildcard characters is accepted.
• sLocalFolder is the destination folder.
• pbAbort is a pointer to a boolean. It is used to abort the transfers. If *pbAbort is set to true, the function aborts the current operation and returns.

If bRecursive is true, all the subfolders and their contents also will be downloaded.

void Upload (const CString &sLocalFiles,
             const CString &sRemoteFolder,
             bool *pbAbort,
             bool bRecursive = true,
             DWORD dwTransferType = FTP_TRANSFER_TYPE_BINARY)

• sLocalFiles are the files to be uploaded. Usage of wildcard characters is accepted.
• sRemoteFolder is the destination folder.
• pbAbort is a pointer to a boolean. It is used to abort the transfers. If *pbAbort is set to true, the functions aborts the current operation and returns.

If bRecursive is true, all the subfolders and their contents also will be uploaded.

void DeleteFiles (const CString &sOrgRemoteFiles,
                  bool *pbAbort,
                  bool bRecursive,
                  bool bAbortIfFailsOnce)

• sOrgRemoteFiles are the files to be deleted. Usage of wildcard characters is allowed.
• pbAbort is a pointer to a boolean. It is used to abort the transfers. If *pbAbort is set to true, the function aborts the current operation and returns.

If bRecursive is true, all the files in the subfolders also will be deleted. If bAbortIfFailsOnce is set to true, the function will abort on the first error. Otherwise, it will try to delete the other files and then return.

void DeleteFolders (const CString &sRemoteFolder,
                    bool *pbAbort,
                    bool bRecursive,
                    bool bAbortIfFailsOnce)

• sOrgRemoteFolders are the folders to be deleted. Usage of wildcard characters is allowed. Please note that the folder MUST be empty before the deletion. You can use the DeleteFiles function to delete the contents of the folders and then use DeleteFolders function to delete the empty folders.
• pbAbort is a pointer to a boolean. It is used to abort the transfers. If *pbAbort is set to true, the function aborts the current operation and returns.

If bRecursive is true, all the files in the subfolders also will be deleted. If bAbortIfFailsOnce is set to true, the function will abort on the first error. Otherwise, it will try to delete the other files and then return.

void CreateMultiFolder (const CString &sRemoteFolder)

sRemoteFolder is the folder to be created.

If, in order to create sRemoteFolder, multiple folders should be created, the function automatically creates the lower-level directories first. For example, suppose you want to create a folder /html/my_folder1/my_folder2/my_folder3. If my_folder1 does not exist, the function first creates my_folder1, and then my_folder2, and lastly my_folder3.

void GetFileList (const CString >sRemoteFolder,
                  bool bFullPathGiven,
                  CStringArray >sFileNameArray,
                  bool bRecursive,
                  bool bExcludeHidden = false)

Puts all the filenames into sFileNameArray. bFullPathGiven should be set to false.

Exception Handling

All of the functions above throw CFTPException. Here is the CFTPException class:

class AFX_EXT_CLASS CFTPException : public CException
{
public:
    enum FTPError
    {
        FTP_Unknown,
        FTP_LoginFailed,
        FTP_AlreadyConnected,
        FTP_NotConnected,
        FTP_Local_FileCreateFailed,
        FTP_Local_FileOpenFailed,
        FTP_Local_UnknownFileError,
        FTP_Remote_SetCurDirFailed,
        FTP_Remote_FileOpenFailed,
        FTP_Remote_FileWriteFailed,
        FTP_CreateFolderFailed,
        FTP_DeleteFilesFailed,
        FTP_DeleteFoldersFailed,
        FTP_DeleteRootFolderNotAllowed,
        FTP_InvalidLocalFileName,
        FTP_InvalidRemoteFileName,
        FTP_UserAborted
    };

    int m_nError;
    CString m_sDesc;

    CFTPException (FTPError nError,
        const CString &sDesc) : CException (TRUE)
    {
        m_nError = nError;
        m_sDesc = sDesc;
    }
};

• FTP_Unknown: An unknown error occurred. See sDesc for details.
• FTP_LoginFailed: Login to the server failed. See sDesc for details.
• FTP_AlreadyConnected: The object already has an active connection. First, call Logoff () to close the connection.
• FTP_NotConnected: The object has no active connection yet. Call Login function first.
• FTP_Local_FileCreateFailed: Cannot create the local file. See sDesc for details.
• FTP_Local_FileOpenFailed: Cannot open the specified local file. See sDesc for details.
• FTP_Local_UnknownFileError: An unknown file error occurred. See sDesc for details.
• FTP_Remote_SetCurDirFailed: Setting current FTP directory failed. The directory may not exist or you may not have permissions to access the directory. See sDesc for details.
• FTP_Remote_FileOpenFailed: Cannot read from the remote file. The file may not exist or you may not have the permissions to read that file. See sDesc for details.
• FTP_Remote_FileWriteFailed: Cannot write to the remote file. The filename given may be invalid, or you may not have the permissions to write to that file. See sDesc for details.
• FTP_CreateFolderFailed: Cannot create the folder. If it is on the remote machine, be sure that you have permissions to create a folder. Also, be sure that another file does not have the destination folder name. See sDesc for details.
• FTP_DeleteFilesFailed: Cannot delete files from the server. Be sure that you have the permissions to delete files. See sDesc for details.
• FTP_DeleteFoldersFailed: Cannot delete folders from the server. Be sure that the folders are empty and you have the permissions to delete folders. See sDesc for details.
• FTP_DeleteRootFolderNotAllowed: Deletion of root folder is not allowed!
• FTP_InvalidLocalFileName: The filename given is invalid. See sDesc for details.
• FTP_InvalidRemoteFileName: The filename given is invalid. See sDesc for details.
• FTP_UserAborted: User pressed the cancel button and thus the transfer is aborted.

Usage

In order to use these classes, you should:

• Include FTPClient.h.
• In StdAfx.h, include <afxinet.h> for MFC Internet support.
• Add WinInet.lib to the Object/Library Modules section in Linker options.
• Copy FTPClient.dll to your executable's folder.

Examples

Upload some files to the server

try
{
    bool bAbort = false;
    m_FTPClient.Upload ("c:\\my_web\\*", "public_html/",
                                         &bAbort, true);
}
catch (CFTPException *pEx)
{
    switch (pEx->m_nError)
    {
        // You can check for all exception types here!
    case FTP_NotConnected:
        break;
    }
    CString sDesc = pEx->m_sDesc;
    pEx->Delete ();
    AfxMessageBox (sDesc);
}

Download files from the server

try
{
    bool bAbort = false;
    m_FTPClient.Download ("public_html/*", "c:\\my_web\\",
                                            &bAbort, true);
}
catch (CFTPException *pEx)
{
    switch (pEx->m_nError)
    {
        // You can check for all exception types here!
    case FTP_NotConnected:
        break;
    }
    CString sDesc = pEx->m_sDesc;
    pEx->Delete ();
    AfxMessageBox (sDesc);
}

Delete all files and folders

try
{
    bool bAbort = false;
    // First, delete all the files
    m_FTPClient.DeleteFiles ("tmp/*", &bAbort, true, true);
    // Now, all the folders are empty. We can safely delete them.
    m_FTPClient.DeleteFolders ("tmp/*", &bAbort, true, true);
}
catch (CFTPException *pEx) 
{
    switch (pEx->m_nError)
    {
        // You can check for all exception types here!
    case FTP_NotConnected:
        break;
    }
    CString sDesc = pEx->m_sDesc;
    pEx->Delete ();
    AfxMessageBox (sDesc);
}

A Demo Program

The demo program uses FTPClient.dll and implements a very primitive FTP program.

Thanks

• To Pablo van der Meer for FTPWanderer.
• To Antonio Tejada Lacaci for the CFileInfoArray class.

Some Points that You Should Keep in Mind

• I have not tested these classes extensively yet. There may be some bugs in the code.
• If you have any comments, suggestions, or corrections, please mail me at admin@macroangel.com.

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