csharp: using wininet.dll

/// <summary>
/// Windows Embedded CE 6.0 R3  WinInet Functions
/// https://technet.microsoft.com/zh-cn/aa914184 /// Windows   WinINet Functions
/// https://technet.microsoft.com/zh-cn/windows/aa385473(v=vs.71) ///
/// </summary>
public class NetUtil
{
[DllImport("wininet.dll")]
private extern static bool InternetGetConnectedState(int Description, int ReservedValue);

/// <summary>
/// 用于检查网络是否可以连接互联网,true表示连接成功,false表示连接失败
/// </summary>
/// <returns></returns>
public static bool IsConnectInternet()
{
int Description = 0;
return InternetGetConnectedState(Description, 0);
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public class WIN32_FIND_DATA
{
public UInt32 dwFileAttributes = 0;
public FILETIME ftCreationTme;
public FILETIME ftLastAccessTime;
public FILETIME ftLastWriteTime;
public UInt32 nFileSizeHigh = 0;
public UInt32 nFileSizeLow = 0;
public UInt32 dwReserved0 = 0;
public UInt32 dwReserved1 = 0;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public string cFileName = null;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 14)]
public string cAlternateFileName = null;
};

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public class FILETIME
{
public int dwLowDateTime = 0;
public int dwHighDateTime = 0;
};

//以下是对WININET.DLL中的重要函数的托管转换
[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool InternetGetLastResponseInfo(ref uint ulError,
[MarshalAs(UnmanagedType.LPTStr)] string strBuffer, ref uint ulBufferLength);

[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern IntPtr InternetOpen(string strAppName, ulong
ulAccessType, string strProxy, string strProxyBypass, ulong ulFlags);

[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool InternetFindNextFile(IntPtr hFind, [In, Out] WIN32_FIND_DATA
dirData);

[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern IntPtr InternetConnect(IntPtr ulSession, string
strServer, uint ulPort, string strUser, string strPassword, uint ulService, uint ulFlags,
uint ulContext);

[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool InternetGetConnectedState(ref uint ulFlags, uint
ulReserved);

[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool FtpSetCurrentDirectory(IntPtr ulSession, string
strPath);

[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern IntPtr FtpFindFirstFile(IntPtr ulSession, string strPath
, [In, Out] WIN32_FIND_DATA dirData, ulong ulFlags, ulong ulContext);

[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool FtpGetFile(IntPtr ulSession, string strRemoteFile,
string strLocalFile, bool bolFailIfExist, ulong ulFlags, ulong ulInetFals, ulong
ulContext);

[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool FtpPutFile(IntPtr ulSession, string strLocalFile,
string strRemoteFile, ulong ulFlags, ulong ulContext);

[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool FtpDeleteFile(IntPtr ulSession, string strFileName);

[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool InternetCloseHandle(IntPtr ulSession);

/// <summary>
//STRUCTURE to hold the directory information - implemented as a class
/// <summary>
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public class FileData
{
public int fileAttributes = 0;
// creationTime was embedded FILETIME structure
public int creationTime_lowDateTime = 0;
public int creationTime_highDateTime = 0;
// lastAccessTime was embedded FILETIME structure
public int lastAccessTime_lowDateTime = 0;
public int lastAccessTime_highDateTime = 0;
// lastWriteTime was embedded FILETIME structure
public int lastWriteTime_lowDateTime = 0;
public int lastWriteTime_highDateTime = 0;
public int nFileSizeHigh = 0;
public int nFileSizeLow = 0;
public int dwReserved0 = 0;
public int dwReserved1 = 0;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public String fileName = null;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 14)]
public String alternateFileName = null;
} //end of class FileDate

/// <summary>
/// Class FtpDll implements the 'wininet.dll' api for FTP connection over firewalls!
/// </summary>
public class FtpDll
{
//DECLARATIONS
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
public static extern uint SetLastError(uint uiErrorCode);
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
public static extern uint GetLastError();
[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool InternetGetLastResponseInfo(ref uint ulError, [MarshalAs(UnmanagedType.LPTStr)] string strBuffer, ref uint ulBufferLength);
[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern IntPtr InternetOpen(string strAppName, ulong ulAccessType, string strProxy, string strProxyBypass, ulong ulFlags);
[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern IntPtr InternetConnect(IntPtr ulSession, string strServer, uint ulPort, string strUser, string strPassword, uint ulService, uint ulFlags, uint ulContext);
[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool InternetGetConnectedState(ref uint ulFlags, uint ulReserved);
//        [DllImport("wininet.dll", CharSet = CharSet.Auto)]
//        public static extern bool FtpGetCurrentDirectory(IntPtr ulSession, string strPath, ulong ulBuffLength);
[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool FtpSetCurrentDirectory(IntPtr ulSession, string strPath);
[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern IntPtr FtpFindFirstFile(IntPtr ulSession, string strPath, [In, Out] FileData dirData, ulong ulFlags, ulong ulContext); //returns handle for InternetFindNextFile
//        [DllImport("wininet.dll", CharSet = CharSet.Auto)]
//        public static extern bool InternetFindNextFile(ulong ulFindFirst, [In, Out] FileData dirData);
[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool FtpGetFile(IntPtr ulSession, string strRemoteFile, string strLocalFile, bool bolFailIfExist, ulong ulFlags, ulong ulInetFals, ulong ulContext);
[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool FtpPutFile(IntPtr ulSession, string strLocalFile, string strRemoteFile, ulong ulFlags, ulong ulContext);
//        [DllImport("wininet.dll", CharSet = CharSet.Auto)]
//        public static extern bool FtpRenameFile(IntPtr ulSession, string strExisting, string strNew);
[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool FtpDeleteFile(IntPtr ulSession, string strFileName);
[DllImport("wininet.dll", CharSet = CharSet.Auto)]
public static extern bool InternetCloseHandle(IntPtr ulSession);

//CONSTANTS - there are plenty more of these, only the important ones are here!
//InternetOpen:aul_AccessType flags
public const uint OPEN_TYPE_PRECONFIG = 0;
public const uint OPEN_TYPE_DIRECT = 1;
public const uint OPEN_TYPE_GATEWAY = 2;
public const uint OPEN_TYPE_PROXY = 3;
//Ports
public const uint INVALID_PORT_NUMBER = 0;
public const uint DEFAULT_FTP_PORT = 21;
public const uint DEFAULT_GOPHER_PORT = 70;
public const uint DEFAULT_HTTP_PORT = 80;
public const uint DEFAULT_HTTPS_PORT = 443;
public const uint DEFAULT_SOCKS_PORT = 1080;
//Service/Command types
public const uint SERVICE_FTP = 1;
public const uint SERVICE_GOPHER = 2;
public const uint SERVICE_HTTP = 3;
//Internet connection flags
public const uint CONNECTION_MODEM = 1;
public const uint CONNECTION_LAN = 2;
public const uint CONNECTION_PROXY = 4;
public const uint CONNECTION_MODEM_BUSY = 8;
//FTP transfer flags
public const uint FTP_TRANSFER_TYPE_ASCII = 1;
public const uint FTP_TRANSFER_TYPE_BINARY = 2;

//VARIABLES
IntPtr hInternetSession = new IntPtr(0); //handle to the Internet session
IntPtr hInternetConnection = new IntPtr(0); //handle to the Internet connection
uint intErrorValue = 0; //error value
string strErrorText = "";
FileData myFileData;
bool bolDebug = true;

public FtpDll()
{ //constructor
myFileData = new FileData(); //instance the FileData class to hold the dir info
}

public void funIOpen()
{
string strProxy = "";
string strProxyBypass = "";
try
{
funClearError(); //clear the 'last error' value
hInternetSession = FtpDll.InternetOpen("FTPTest", FtpDll.OPEN_TYPE_DIRECT, strProxy, strProxyBypass, 0);
if (funGetError())
{
if (intErrorValue != 127) //hum... seem to always get 127 back!?!
throw new Exception("funIOpen failed, error value: " + intErrorValue + " - " + strErrorText);
}
}
catch (Exception e)
{
if (bolDebug) Console.WriteLine(e.Message);
throw e; //pass this exception back to the caller
}
}

public bool funIConnected()
{ //check if we are connected
bool bolOnLine = false;
try
{
if (hInternetConnection != IntPtr.Zero)
{ //we have an internet connection handle
uint uintFlags = 0;
funClearError(); //clear the 'last error' value
FtpDll.InternetGetConnectedState(ref uintFlags, 0); //ask for the connection status
//if (uintFlags & FtpDll.CONNECTION_LAN > 0) //so long as we have a connection value...
if (uintFlags > 0) //so long as we have a connection value...
bolOnLine = true;
if (funGetError())
throw new Exception("funIConnected failed, error value: " + intErrorValue + " - " + strErrorText);
}
else
throw new Exception("funIConnected failed; need to establish an Internet session first!");
}
catch (Exception e)
{
if (bolDebug) Console.WriteLine(e.Message);
throw e; //pass this exception back to the caller
}
return bolOnLine;
}

public void funIConnect()
{ //connect using default values
try
{
string strHostURL = "ftp.microsoft.com";
string strUser = "anonymous";
string strPW = "fred@test.com";
funIConnect(strHostURL, strUser, strPW);
}
catch (Exception e)
{
if (bolDebug) Console.WriteLine(e.Message);
throw e; //pass this exception back to the caller
}
}

public void funIConnect(string strHostURL, string strUser, string strPW)
{
if (hInternetSession == IntPtr.Zero)
funIOpen(); //we always need a session first
try
{
funClearError(); //make sure we are clean before starting to connect
hInternetConnection = FtpDll.InternetConnect(hInternetSession, strHostURL, FtpDll.DEFAULT_FTP_PORT, strUser, strPW, FtpDll.SERVICE_FTP, 0, 0);
if (funGetError())
throw new Exception("funIConnect failed, error value: " + intErrorValue + " - " + strErrorText);
if (hInternetConnection == IntPtr.Zero) //if the handle is still zero....
throw new Exception("Failed to get a handle in funIConnect - no error code given!");
}
catch (Exception e)
{
if (bolDebug) Console.WriteLine(e.Message);
throw e; //pass this exception back to the caller
}
}

public void funFTPChangeDir(string strDir)
{
try
{
if (!funIConnected())
throw new Exception("Please connect to FTP host first!");
funClearError(); //clear the 'last error' value
FtpDll.FtpSetCurrentDirectory(hInternetConnection, strDir);
if (funGetError())
throw new Exception("funFTPChangeDir failed, error value: " + intErrorValue + " - " + strErrorText);
}
catch (Exception e)
{
if (bolDebug) Console.WriteLine(e.Message);
throw e; //pass this exception back to the caller
}
}

public string funFTPFirstFile(string strPath)
{
string strFileName = "";
try
{
if (!funIConnected())
throw new Exception("Please connect to FTP host first!");
funClearError(); //clear the 'last error' value
FtpDll.FtpFindFirstFile(hInternetConnection, strPath, myFileData, 0, 0);
if (funGetError())
throw new Exception("funFTPFirstFile failed, error value: " + intErrorValue + " - " + strErrorText);
strFileName = myFileData.fileName;
}
catch (Exception e)
{
if (bolDebug) Console.WriteLine(e.Message);
throw e; //pass this exception back to the caller
}
return strFileName;
}

public void funFTPGetFile(string strRemoteFile, string strLocalFile)
{
try
{
if (!funIConnected())
throw new Exception("Please connect to FTP host first!");
funClearError(); //clear the 'last error' value
FtpDll.FtpGetFile(hInternetConnection, strRemoteFile, strLocalFile, false, 0, 0, 0);
if (funGetError())
throw new Exception("funFTPGet failed, error value: " + intErrorValue + " - " + strErrorText);
}
catch (Exception e)
{
if (bolDebug) Console.WriteLine(e.Message);
throw e; //pass this exception back to the caller
}
}

public void funFTPPutFile(string strLocalFile, string strRemoteFile)
{
try
{
if (!funIConnected())
throw new Exception("Please connect to FTP host first!");
funClearError(); //clear the 'last error' value
FtpDll.FtpPutFile(hInternetConnection, strLocalFile, strRemoteFile, 0, 0);
if (funGetError())
throw new Exception("funFTPPut failed, error value: " + intErrorValue + " - " + strErrorText);
}
catch (Exception e)
{
if (bolDebug) Console.WriteLine(e.Message);
throw e; //pass this exception back to the caller
}
}

public void funFTPDeleteFile(string strFileName)
{
try
{
if (!funIConnected())
throw new Exception("Please connect to FTP host first!");
funClearError(); //clear the 'last error' value
FtpDll.FtpDeleteFile(hInternetConnection, strFileName);
if (funGetError())
{
if (intErrorValue == 2)
{ //special case? the function seems otherwise OK?!?!?!
if (bolDebug) Console.WriteLine("funFTPDeleteFile succeeded, but returned an error code 2 - ignored!");
}
else
throw new Exception("funFTPDeleteFile failed, error value: " + intErrorValue + " - " + strErrorText);
}
}
catch (Exception e)
{
if (bolDebug) Console.WriteLine(e.Message);
throw e; //pass this exception back to the caller
}
}

public void funFTPDisconnect()
{
if (hInternetSession != IntPtr.Zero)
{ //if and only if we have a session...
try
{
funClearError(); //clear the 'last error' value
FtpDll.InternetCloseHandle(hInternetSession);
if (funGetError())
throw new Exception("funFTPDisconnect failed, error value: " + intErrorValue + " - " + strErrorText);
}
catch (Exception e)
{
if (bolDebug) Console.WriteLine(e.Message);
throw e; //pass this exception back to the caller
}
}
hInternetSession = IntPtr.Zero; //reset this handle?
}

public void funClearError()
{ //clear the 'last error' value
FtpDll.SetLastError(0);
}

public bool funGetError()
{ //return true if an error found
intErrorValue = FtpDll.GetLastError();
switch (intErrorValue)
{
case 127: //ERROR_PROC_NOT_FOUND
strErrorText = "The specified procedure could not be found.";
break;
case 2: //ERROR_FILE_NOT_FOUND
strErrorText = "The system cannot find the file specified.";
break;
case 18: //ERROR_NO_MORE_FILES
strErrorText = "There are no more files.";
break;
case 123: //ERROR_INVALID_NAME
strErrorText = "The filename, directory name, or volume label syntax is incorrect.";
break;
case 12003: //ERROR_INTERNET_EXTENDED_ERROR
try
{
string strExtErrorText = "";//to hold the ExtErrorText
uint uiExtErrorTextLength = 0;//start as zero length
FtpDll.InternetGetLastResponseInfo(ref intErrorValue, strExtErrorText, ref uiExtErrorTextLength);
if (uiExtErrorTextLength > 0)
{//indicasting the length of the message to collect
strExtErrorText += new string(' ', (int)uiExtErrorTextLength);//beef up the string buffer
FtpDll.InternetGetLastResponseInfo(ref intErrorValue, strExtErrorText, ref uiExtErrorTextLength);
if (uiExtErrorTextLength > 0)
strErrorText = "The server has returned an extended error: " + strExtErrorText;
else
strErrorText = "The server has returned an extended error, but the text can not be recovered at all?!?.";
}
else
strErrorText = "The server has returned an extended error, but the text can not be recovered!?.";
}
catch (Exception e)
{
if (bolDebug) Console.WriteLine(e.Message);
}
break;
case 12111:    //ERROR_FTP_DROPPED
strErrorText = "The FTP operation was not completed because the session was aborted.";
break;
case 12110: //ERROR_FTP_TRANSFER_IN_PROGRESS
strErrorText = "The requested operation cannot be made on the FTP session handle because an operation is already in progress.";
break;
case 12137: //ERROR_GOPHER_ATTRIBUTE_NOT_FOUND
strErrorText = "The requested attribute could not be located.";
break;
case 12132: //ERROR_GOPHER_DATA_ERROR
strErrorText = "An error was detected while receiving data from the Gopher server.";
break;
case 12133: //ERROR_GOPHER_END_OF_DATA
strErrorText = "The end of the data has been reached.";
break;
case 12135: //ERROR_GOPHER_INCORRECT_LOCATOR_TYPE
strErrorText = "The type of the locator is not correct for this operation.";
break;
case 12134: //ERROR_GOPHER_INVALID_LOCATOR
strErrorText = "The supplied locator is not valid.";
break;
case 12131: //ERROR_GOPHER_NOT_FILE
strErrorText = "The request must be made for a file locator.";
break;
case 12136: //ERROR_GOPHER_NOT_GOPHER_PLUS
strErrorText = "The requested operation can only be made against a Gopher+ server, or with a locator that specifies a Gopher+ operation.";
break;
case 12130: //ERROR_GOPHER_PROTOCOL_ERROR
strErrorText = "An error was detected while parsing data returned from the Gopher server.";
break;
case 12138: //ERROR_GOPHER_UNKNOWN_LOCATOR
strErrorText = "The locator type is unknown.";
break;
case 12151: //ERROR_HTTP_DOWNLEVEL_SERVER
strErrorText = "The server did not return any headers.";
break;
case 12155: //ERROR_HTTP_HEADER_ALREADY_EXISTS
strErrorText = "The header could not be added because it already exists.";
break;
case 12150: //ERROR_HTTP_HEADER_NOT_FOUND
strErrorText = "The requested header could not be located.";
break;
case 12153: //ERROR_HTTP_INVALID_HEADER
strErrorText = "The supplied header is invalid.";
break;
case 12154: //ERROR_HTTP_INVALID_QUERY_REQUEST
strErrorText = "The request made to HttpQueryInfo is invalid.";
break;
case 12156: //ERROR_HTTP_REDIRECT_FAILED
strErrorText = "The redirection failed because either the scheme changed (HTTP to FTP) or all attempts made to redirect failed.";
break;
case 12168: //ERROR_HTTP_REDIRECT_NEEDS_CONFIRMATION
strErrorText = "The redirection requires user confirmation.";
break;
case 12152: //ERROR_HTTP_INVALID_SERVER_RESPONSE
strErrorText = "The server response could not be parsed.";
break;
case 12047: //ERROR_INTERNET_ASYNC_THREAD_FAILED
strErrorText = "The application could not start an asynchronous thread.";
break;
case 12010: //ERROR_INTERNET_BAD_OPTION_LENGTH
strErrorText = "The length of an option supplied to InternetQueryOption or InternetSetOption is incorrect for the type of option specified.";
break;
case 12166: //ERROR_INTERNET_BAD_AUTO_PROXY_SCRIPT
strErrorText = "There was an error in the automatic proxy configuration script.";
break;
case 12022: //ERROR_INTERNET_BAD_REGISTRY_PARAMETER
strErrorText = "A required registry value was located but is an incorrect type or has an invalid value.";
break;
case 12029: //ERROR_INTERNET_CANNOT_CONNECT
strErrorText = "The attempt to connect to the server failed.";
break;
case 12042: //ERROR_INTERNET_CHG_POST_IS_NON_SECURE
strErrorText = "The application is posting and attempting to change multiple lines of text on a server that is not secure.";
break;
case 12044: //ERROR_INTERNET_CLIENT_AUTH_CERT_NEEDED
strErrorText = "The server is requesting client authentication.";
break;
case 12046: //ERROR_INTERNET_CLIENT_AUTH_NOT_SETUP
strErrorText = "Client authorization is not set up on this computer.";
break;
case 12030: //ERROR_INTERNET_CONNECTION_ABORTED
strErrorText = "The connection with the server has been terminated.";
break;
case 12031: //ERROR_INTERNET_CONNECTION_RESET
strErrorText = "The connection with the server has been reset.";
break;
case 12049: //ERROR_INTERNET_DIALOG_PENDING
strErrorText = "Another thread has a password dialog in progress.";
break;
case 12163: //ERROR_INTERNET_DISCONNECTED
strErrorText = "The Internet connection has been lost.";
break;
case 12171: //ERROR_INTERNET_FAILED_DUETOSECURITYCHECK
strErrorText = "The function failed due to a security check.";
break;
case 12032: //ERROR_INTERNET_FORCE_RETRY
strErrorText = "The Win32 Internet function needs to redo the request.";
break;
case 12036: //ERROR_INTERNET_HANDLE_EXISTS
strErrorText = "The request failed because the handle already exists.";
break;
case 12039: //ERROR_INTERNET_HTTP_TO_HTTPS_ON_REDIR
strErrorText = "The application is moving from a non-SSL to an SSL connection because of a redirect.";
break;
case 12040: //ERROR_INTERNET_HTTPS_TO_HTTP_ON_REDIR
strErrorText = "The application is moving from an SSL to an non-SSL connection because of a redirect.";
break;
case 12027: //ERROR_INTERNET_INCORRECT_FORMAT
strErrorText = "The format of the request is invalid.";
break;
case 12019: //ERROR_INTERNET_INCORRECT_HANDLE_STATE
strErrorText = "The requested operation cannot be carried out because the handle supplied is not in the correct state.";
break;
case 12018: //ERROR_INTERNET_INCORRECT_HANDLE_TYPE
strErrorText = "The type of handle supplied is incorrect for this operation.";
break;
case 12014: //ERROR_INTERNET_INCORRECT_PASSWORD
strErrorText = "The request to connect and log on to an FTP server could not be completed because the supplied password is incorrect.";
break;
case 12013: //ERROR_INTERNET_INCORRECT_USER_NAME
strErrorText = "The request to connect and log on to an FTP server could not be completed because the supplied user name is incorrect.";
break;
case 12053: //ERROR_INTERNET_INSERT_CDROM
strErrorText = "The request requires a CD-ROM to be inserted in the CD-ROM drive to locate the resource requested.";
break;
case 12004: //ERROR_INTERNET_INTERNAL_ERROR
strErrorText = "An internal error has occurred.";
break;
case 12045: //ERROR_INTERNET_INVALID_CA
strErrorText = "The function is unfamiliar with the Certificate Authority that generated the server's certificate.";
break;
case 12016: //ERROR_INTERNET_INVALID_OPERATION
strErrorText = "The requested operation is invalid.";
break;
case 12009: //ERROR_INTERNET_INVALID_OPTION
strErrorText = "A request to InternetQueryOption or InternetSetOption specified an invalid option value.";
break;
case 12033: //ERROR_INTERNET_INVALID_PROXY_REQUEST
strErrorText = "The request to the proxy was invalid.";
break;
case 12005: //ERROR_INTERNET_INVALID_URL
strErrorText = "The URL is invalid.";
break;
case 12028: //ERROR_INTERNET_ITEM_NOT_FOUND
strErrorText = "The requested item could not be located.";
break;
case 12015: //ERROR_INTERNET_LOGIN_FAILURE
strErrorText = "The request to connect and log on to an FTP server failed.";
break;
case 12041: //ERROR_INTERNET_MIXED_SECURITY
strErrorText = "The content is not entirely secure. Some of the content being viewed may have come from unsecured servers.";
break;
case 12007: //ERROR_INTERNET_NAME_NOT_RESOLVED
strErrorText = "The server name could not be resolved.";
break;
case 12034: //ERROR_INTERNET_NEED_UI
strErrorText = "A user interface or other blocking operation has been requested.";
break;
case 12025: //ERROR_INTERNET_NO_CALLBACK
strErrorText = "An asynchronous request could not be made because a callback function has not been set.";
break;
case 12024: //ERROR_INTERNET_NO_CONTEXT
strErrorText = "An asynchronous request could not be made because a zero context value was supplied.";
break;
case 12023: //ERROR_INTERNET_NO_DIRECT_ACCESS
strErrorText = "Direct network access cannot be made at this time.";
break;
case 12020: //ERROR_INTERNET_NOT_PROXY_REQUEST
strErrorText = "The request cannot be made via a proxy.";
break;
case 12017: //ERROR_INTERNET_OPERATION_CANCELLED
strErrorText = "The operation was canceled, usually because the handle on which the request was operating was closed before the operation completed.";
break;
case 12011: //ERROR_INTERNET_OPTION_NOT_SETTABLE
strErrorText = "The requested option cannot be set, only queried.";
break;
case 12001: //ERROR_INTERNET_OUT_OF_HANDLES
strErrorText = "No more handles could be generated at this time.";
break;
case 12043: //ERROR_INTERNET_POST_IS_NON_SECURE
strErrorText = "The application is posting data to a sever that is not secure.";
break;
case 12008: //ERROR_INTERNET_PROTOCOL_NOT_FOUND
strErrorText = "The requested protocol could not be located.";
break;
case 12165: //ERROR_INTERNET_PROXY_SERVER_UNREACHABLE
strErrorText = "The designated proxy server cannot be reached.";
break;
case 12048: //ERROR_INTERNET_REDIRECT_SCHEME_CHANGE
strErrorText = "The function could not handle the redirection, because the scheme changed (HTTP to FTP).";
break;
case 12021: //ERROR_INTERNET_REGISTRY_VALUE_NOT_FOUND
strErrorText = "A required registry value could not be located.";
break;
case 12026: //ERROR_INTERNET_REQUEST_PENDING
strErrorText = "The required operation could not be completed because one or more requests are pending.";
break;
case 12038: //ERROR_INTERNET_SEC_CERT_CN_INVALID
strErrorText = "SSL certificate common name (host name field) is incorrect. eg if you entered www.server.com and the common name on the certificate says www.different.com.";
break;
case 12037: //ERROR_INTERNET_SEC_CERT_DATE_INVALID
strErrorText = "SSL certificate date that was received from the server is bad. The certificate is expired.";
break;
case 12170: //ERROR_INTERNET_SEC_CERT_REVOKED
strErrorText = "SSL certificate was revoked.";
break;
case 12169: //ERROR_INTERNET_SEC_INVALID_CERT
strErrorText = "SSL certificate is invalid.";
break;
case 12157: //ERROR_INTERNET_SECURITY_CHANNEL_ERROR
strErrorText = "The application experienced an internal error loading the SSL libraries.";
break;
case 12164: //ERROR_INTERNET_SERVER_UNREACHABLE
strErrorText = "The Web site or server indicated is unreachable.";
break;
case 12012: //ERROR_INTERNET_SHUTDOWN
strErrorText = "The Win32 Internet function support is being shut down or unloaded.";
break;
case 12159: //ERROR_INTERNET_TCPIP_NOT_INSTALLED
strErrorText = "The required protocol stack is not loaded and the application cannot start WinSock.";
break;
case 12002: //ERROR_INTERNET_TIMEOUT
strErrorText = "The request has timed out.";
break;
case 12158: //ERROR_INTERNET_UNABLE_TO_CACHE_FILE
strErrorText = "The function was unable to cache the file.";
break;
case 12167: //ERROR_INTERNET_UNABLE_TO_DOWNLOAD_SCRIPT
strErrorText = "The automatic proxy configuration script could not be downloaded. The INTERNET_FLAG_MUST_CACHE_REQUEST flag was set.";
break;
case 12006: //ERROR_INTERNET_UNRECOGNIZED_SCHEME
strErrorText = "The URL scheme could not be recognized, or is not supported.";
break;
default:
strErrorText = "Unknown error code: " + intErrorValue;
break;
}
return (intErrorValue != 0);
}
} //end of class FtpDll

/*

try {
TestFtpDll myTest = new TestFtpDll();
FtpDll myFtpDll = new FtpDll(); //instance the FtpDll class to access the FTP functions
myFtpDll.funIOpen();
Console.WriteLine("Connecting...");
myFtpDll.funIConnect(); //use default connection parameters
Console.WriteLine("Change dir to developr...");
myFtpDll.funFTPChangeDir("developr");
Console.WriteLine("Reading first file name in this dir...");
string strFileName = myFtpDll.funFTPFirstFile("*.txt");
Console.WriteLine(strFileName + " found, now uploading...");
myFtpDll.funFTPGetFile(strFileName, strFileName);
//                if (new System.IO.FileInfo(strFileName).Exists) {
//                    Console.WriteLine("Now deleting " + strFileName + " from dir outgoing...");
//                    myFtpDll.funFTPDeleteFile(strFileName);
//                }
//                else
//                    Console.WriteLine("Local copy of the file not found!");
Console.WriteLine("Disconnecting...");
myFtpDll.funFTPDisconnect();
Console.WriteLine("Press N-I key to continue...");
Console.ReadLine();

myFtpDll.funIOpen();
Console.WriteLine("Connecting...");
myFtpDll.funIConnect();
Console.WriteLine("Change dir to developr...");
myFtpDll.funFTPChangeDir("developr");
Console.WriteLine("Now sending test.txt to this dir...");
myFtpDll.funFTPPutFile("test.txt", "test.txt");
Console.WriteLine("Disconnecting...");
myFtpDll.funFTPDisconnect();
Console.WriteLine("Press N-I key to continue...");
Console.ReadLine();
}
catch (Exception e) {
Console.WriteLine("Failed..." + e.Message);
Console.WriteLine("Press N-I key to continue...");
Console.ReadLine();
}
*/
}