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[ASP.net教程]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();      }     */  }