TFTPClient Class

Properties   Methods   Events   Config Settings   Errors  

The TFTPClient class is used to exchange files with TFTP servers via the TFTP protocol defined in RFC 783.

Syntax

ipworks.TFTPClient

Remarks

To use the class, first specify the TFTPServer, then a LocalFile and a RemoteFile, and then call GetFile or PutFile. The Transfer event shows the progress of the transfer.

Potential transmission errors and packet loss are managed by the Timeout property, which controls the maximum time to wait for a response from the server, and the MaxRetransmits property, which specifies how many times to resend a failed packet before giving up.

Property List


The following is the full list of the properties of the class with short descriptions. Click on the links for further details.

IdleThis property specifies the current status of the class.
LocalFileThis property includes a file on the local host to transfer the data to or from.
LocalHostThis property includes the name of the local host or user-assigned IP interface through which connections are initiated or accepted.
MaxRetransmitsThis property specifies the number of times to retry sending a failed packet before disconnecting.
RemoteFileThis property includes the file on the remote host.
RetransmitTimeoutThis property includes the maximum time in seconds to wait for a reply packet from the server before retransmitting the last packet.
TFTPPortThis property specifies the User Datagram Protocol (UDP) port where the remote TFTP server is listening.
TFTPServerThis property includes the address of the TFTP server to exchange files with.
TimeoutThis property includes the timeout for the class.

Method List


The following is the full list of the methods of the class with short descriptions. Click on the links for further details.

ConfigSets or retrieves a configuration setting.
DoEventsThis method processes events from the internal message queue.
GetFileThis method downloads a RemoteFile from the TFTP server.
InterruptThis method interrupts the current method.
PutFileThis method uploads a file specified by LocalFile to the TFTP server.
ResetThis method resets the class.
SetDownloadStreamThis method sets the stream to which the downloaded data from the server will be written.
SetUploadStreamThis method sets the stream to be uploaded to the server.

Event List


The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.

EndTransferThis event is fired when a file finishes downloading or uploading.
ErrorFired when information is available about errors during data delivery.
StartTransferThis event fires when a file starts downloading or uploading.
TransferThis event is fired during the file download or upload.

Config Settings


The following is a list of config settings for the class with short descriptions. Click on the links for further details.

BlockSizeDetermines the block size that will be used when transferring a file.
CloseStreamAfterTransferIf true, the class will close the upload or download stream after the transfer.
TransferModeDetermines the transfer mode that will be used when transferring a file.
CaptureIPPacketInfoUsed to capture the packet information.
DelayHostResolutionWhether the hostname is resolved when RemoteHost is set.
DestinationAddressUsed to get the destination address from the packet information.
DontFragmentUsed to set the Don't Fragment flag of outgoing packets.
LocalHostThe name of the local host through which connections are initiated or accepted.
LocalPortThe port in the local host where the class binds.
MaxPacketSizeThe maximum length of the packets that can be received.
QOSDSCPValueUsed to specify an arbitrary QOS/DSCP setting (optional).
QOSTrafficTypeUsed to specify QOS/DSCP settings (optional).
ShareLocalPortIf set to True, allows more than one instance of the class to be active on the same local port.
UseConnectionDetermines whether to use a connected socket.
UseIPv6Whether or not to use IPv6.
AbsoluteTimeoutDetermines whether timeouts are inactivity timeouts or absolute timeouts.
FirewallDataUsed to send extra data to the firewall.
InBufferSizeThe size in bytes of the incoming queue of the socket.
OutBufferSizeThe size in bytes of the outgoing queue of the socket.
BuildInfoInformation about the product's build.
GUIAvailableWhether or not a message loop is available for processing events.
LicenseInfoInformation about the current license.
MaskSensitiveDataWhether sensitive data is masked in log messages.
UseDaemonThreadsWhether threads created by the class are daemon threads.
UseInternalSecurityAPIWhether or not to use the system security libraries or an internal implementation.

Idle Property (TFTPClient Class)

This property specifies the current status of the class.

Syntax


public boolean isIdle();


Default Value

True

Remarks

Idle will be False if the component is currently busy (communicating or waiting for an answer), and True at all other times.

This property is read-only.

LocalFile Property (TFTPClient Class)

This property includes a file on the local host to transfer the data to or from.

Syntax


public String getLocalFile();


public void setLocalFile(String localFile);

Default Value

""

Remarks

If GetFile is called, and LocalFile already exists, it is overwritten. If PutFile is called, LocalFile must point to a valid file or an error will be returned.

LocalHost Property (TFTPClient Class)

This property includes the name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax


public String getLocalHost();


public void setLocalHost(String localHost);

Default Value

""

Remarks

The LocalHost property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multihomed hosts (machines with more than one IP interface) setting LocalHost to the IP address of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface. It is recommended to provide an IP address rather than a hostname when setting this property to ensure the desired interface is used.

If the class is connected, the LocalHost property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multihomed hosts (machines with more than one IP interface).

Note: LocalHost is not persistent. You must always set it in code, and never in the property window.

MaxRetransmits Property (TFTPClient Class)

This property specifies the number of times to retry sending a failed packet before disconnecting.

Syntax


public int getMaxRetransmits();


public void setMaxRetransmits(int maxRetransmits);

Default Value

3

Remarks

This property allows you to specify the number of times that you would like to try resending the last data packet if the original packet fails.

The RetransmitTimeout determines the wait time (in seconds) between successive retransmissions.

The default value for the MaxRetransmits property is 3.

RemoteFile Property (TFTPClient Class)

This property includes the file on the remote host.

Syntax


public String getRemoteFile();


public void setRemoteFile(String remoteFile);

Default Value

""

Remarks

When the GetFile is called, this must be a valid file on the TFTPServer.

RetransmitTimeout Property (TFTPClient Class)

This property includes the maximum time in seconds to wait for a reply packet from the server before retransmitting the last packet.

Syntax


public int getRetransmitTimeout();


public void setRetransmitTimeout(int retransmitTimeout);

Default Value

5

Remarks

Please refer to the MaxRetransmits property for the number of retransmit efforts before an error is returned.

The default value for the RetransmitTimeout is 5 seconds.

TFTPPort Property (TFTPClient Class)

This property specifies the User Datagram Protocol (UDP) port where the remote TFTP server is listening.

Syntax


public int getTFTPPort();


public void setTFTPPort(int TFTPPort);

Default Value

69

Remarks

The TFTPPort is the UDP port on the TFTPServer to send TFTP requests to.

This property is not available at design time.

TFTPServer Property (TFTPClient Class)

This property includes the address of the TFTP server to exchange files with.

Syntax


public String getTFTPServer();


public void setTFTPServer(String TFTPServer);

Default Value

""

Remarks

To be able to transfer file via TFTP, the remote host must be running TFTP services on port TFTPPort (default 69).

Example. Get a File:

TFTPControl.TFTPServer = "MyServer" TFTPControl.LocalFile = "C:\filename.txt" TFTPControl.RemoteFile = "/remotefile.txt" TFTPControl.GetFile()

Timeout Property (TFTPClient Class)

This property includes the timeout for the class.

Syntax


public int getTimeout();


public void setTimeout(int timeout);

Default Value

60

Remarks

If the Timeout property is set to 0, all operations will run uninterrupted until successful completion or an error condition is encountered.

If Timeout is set to a positive value, the class will wait for the operation to complete before returning control.

The class will use DoEvents to enter an efficient wait loop during any potential waiting period, making sure that all system events are processed immediately as they arrive. This ensures that the host application does not freeze and remains responsive.

If Timeout expires, and the operation is not yet complete, the class throws an exception.

Note: By default, all timeouts are inactivity timeouts, that is, the timeout period is extended by Timeout seconds when any amount of data is successfully sent or received.

The default value for the Timeout property is 60 seconds.

Config Method (TFTPClient Class)

Sets or retrieves a configuration setting.

Syntax

public String config(String configurationString);

Remarks

Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

DoEvents Method (TFTPClient Class)

This method processes events from the internal message queue.

Syntax

public void doEvents();

Remarks

When DoEvents is called, the class processes any available events. If no events are available, it waits for a preset period of time, and then returns.

GetFile Method (TFTPClient Class)

This method downloads a RemoteFile from the TFTP server.

Syntax

public void getFile();

Remarks

The remote file specified by RemoteFile is downloaded to the local file specified by LocalFile, or it is retrieved through the Transfer event, if the LocalFile property is "" (empty string).

Example. Get a File:

TFTPControl.TFTPServer = "MyServer" TFTPControl.LocalFile = "C:\filename.txt" TFTPControl.RemoteFile = "/remotefile.txt" TFTPControl.GetFile()

Interrupt Method (TFTPClient Class)

This method interrupts the current method.

Syntax

public void interrupt();

Remarks

If there is no method in progress, Interrupt simply returns, doing nothing.

PutFile Method (TFTPClient Class)

This method uploads a file specified by LocalFile to the TFTP server.

Syntax

public void putFile();

Remarks

The local file specified by LocalFile is uploaded to the remote file specified by RemoteFile.

Example. Put a File:

TFTPControl.TFTPServer = "MyServer" TFTPControl.LocalFile = "C:\filename.txt" TFTPControl.RemoteFile = "/remotefile.txt" TFTPControl.PutFile()

Reset Method (TFTPClient Class)

This method resets the class.

Syntax

public void reset();

Remarks

This method will reset the class's properties to their default values.

SetDownloadStream Method (TFTPClient Class)

This method sets the stream to which the downloaded data from the server will be written.

Syntax

public void setDownloadStream(java.io.OutputStream downloadStream);

Remarks

If a download stream is set before the GetFile method is called, the downloaded data will be written to the stream. The stream should be open and normally set to position 0. The class will automatically close this stream if CloseStreamAfterTransfer is set to True (default). If the stream is closed, you will need to call SetDownloadStream again before calling GetFile again. The downloaded content will be written starting at the current position in the stream.

Note: SetDownloadStream and LocalFile will reset the other.

SetUploadStream Method (TFTPClient Class)

This method sets the stream to be uploaded to the server.

Syntax

public void setUploadStream(java.io.InputStream uploadStream);

Remarks

If an upload stream is set before the PutFile method is called, the content of the stream will be read by the class and uploaded to the server; The stream should be open and normally set to position 0. The class will automatically close this stream if CloseStreamAfterTransfer is set to True (default). If the stream is closed, you will need to call SetUploadStream again before calling PutFile again. The content of the stream will be read from the current position all the way to the end.

Note: SetUploadStream and LocalFile will reset the other.

EndTransfer Event (TFTPClient Class)

This event is fired when a file finishes downloading or uploading.

Syntax

public class DefaultTFTPClientEventListener implements TFTPClientEventListener {
  ...
  public void endTransfer(TFTPClientEndTransferEvent e) {}
  ...
}

public class TFTPClientEndTransferEvent {
  public int direction;
}

Remarks

The EndTransfer event fires when a Data Interface connection is closed. This occurs when the file finishes transferring or a directory listing is finished.

The Direction parameter shows whether the client (0) or the server (1) is sending the data.

Error Event (TFTPClient Class)

Fired when information is available about errors during data delivery.

Syntax

public class DefaultTFTPClientEventListener implements TFTPClientEventListener {
  ...
  public void error(TFTPClientErrorEvent e) {}
  ...
}

public class TFTPClientErrorEvent {
  public int errorCode;
  public String description;
}

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class throws an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

StartTransfer Event (TFTPClient Class)

This event fires when a file starts downloading or uploading.

Syntax

public class DefaultTFTPClientEventListener implements TFTPClientEventListener {
  ...
  public void startTransfer(TFTPClientStartTransferEvent e) {}
  ...
}

public class TFTPClientStartTransferEvent {
  public int direction;
}

Remarks

The StartTransfer event fires when a Data Interface connection is created. This is when the file starts transferring or a directory listing is started.

The Direction parameter shows whether the client (0) or the server (1) is sending the data.

Transfer Event (TFTPClient Class)

This event is fired during the file download or upload.

Syntax

public class DefaultTFTPClientEventListener implements TFTPClientEventListener {
  ...
  public void transfer(TFTPClientTransferEvent e) {}
  ...
}

public class TFTPClientTransferEvent {
  public int direction;
  public long bytesTransferred;
  public int percentDone;
  public byte[] text;
}

Remarks

One or more Transfer events are fired during file transfer. The BytesTransferred parameter shows the number of bytes transferred since the beginning of the transfer.

Text contains the portion of the file data being delivered.

The Direction parameter shows whether the client (0) or the server (1) is sending the data.

The PercentDone parameter shows the progress of the transfer in the corresponding direction. If PercentDone can not be calculated the value will be -1.

Note: Events are not re-entrant. Performing time-consuming operations within this event will prevent it from firing again in a timely manner and may affect overall performance.

Config Settings (TFTPClient Class)

The class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

TFTPClient Config Settings

BlockSize:   Determines the block size that will be used when transferring a file.

This should be set to the number of bytes the block should be. This configuration setting uses the blocksize option as defined in RFC 2348. The default is 512.

CloseStreamAfterTransfer:   If true, the component will close the upload or download stream after the transfer.

This configuration setting determines whether the input or output stream is closed after the transfer completes. When set to True (default), all streams will be closed after a transfer is completed. To keep streams open after the transfer of data, set this to False. The default value is True.

TransferMode:   Determines the transfer mode that will be used when transferring a file.

The available modes are as follows:

ValueDescription
0 (default) Binary (Octet)
1 Ascii (Netascii)

UDP Config Settings

CaptureIPPacketInfo:   Used to capture the packet information.

If this is set to True, the component will capture the IP packet information.

The default value for this setting is False.

Note: This configuration setting is available only in Windows.

DelayHostResolution:   Whether the hostname is resolved when RemoteHost is set.

This configuration setting specifies whether a hostname is resolved immediately when RemoteHost is set. If true the class will resolve the hostname and the IP address will be present in the RemoteHost property. If false, the hostname is not resolved until needed by the component when a method to connect or send data is called. If desired, ResolveRemoteHost may be called to manually resolve the value in RemoteHost at any time.

The default value is false.

DestinationAddress:   Used to get the destination address from the packet information.

If CaptureIPPacketInfo is set to True, then this will be populated with the packet's destination address when a packet is received. This information will be accessible in the DataIn event.

Note: This configuration setting is available only in Windows.

DontFragment:   Used to set the Don't Fragment flag of outgoing packets.

When set to True, packets sent by the class will have the Don't Fragment flag set. The default value is False.

LocalHost:   The name of the local host through which connections are initiated or accepted.

The LocalHost setting contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multihomed hosts (machines with more than one IP interface), setting LocalHost to the value of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface.

If the class is connected, the LocalHost setting shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multihomed hosts (machines with more than one IP interface).

LocalPort:   The port in the local host where the class binds.

This configuration setting must be set before a connection is attempted. It instructs the class to bind to a specific port (or communication endpoint) in the local machine.

Setting this to 0 (default) enables the system to choose a port at random. The chosen port will be shown by LocalPort after the connection is established.

LocalPort cannot be changed once a connection is made. Any attempt to set this when a connection is active will generate an error.

This configuration setting is useful when trying to connect to services that require a trusted port on the client side. An example is the remote shell (rsh) service in UNIX systems.

MaxPacketSize:   The maximum length of the packets that can be received.

This configuration setting specifies the maximum size of the datagrams that the class will accept without truncation.

QOSDSCPValue:   Used to specify an arbitrary QOS/DSCP setting (optional).

UseConnection must be True to use this configuration setting. This option allows you to specify an arbitrary DSCP value between 0 and 63. The default is 0. When set to the default value, the component will not set a DSCP value.

Note: This configuration setting uses the qWAVE API and is available only on Windows 7, Windows Server 2008 R2, and later.

QOSTrafficType:   Used to specify QOS/DSCP settings (optional).

UseConnection must be True to use this setting. You may specify either the text or integer values: BestEffort (0), Background (1), ExcellentEffort (2), AudioVideo (3), Voice (4), and Control (5).

Note: This configuration setting uses the qWAVE API and is available only on Windows Vista and Windows Server 2008 or above.

Note: QOSTrafficType must be set before setting Active to True.

ShareLocalPort:   If set to True, allows more than one instance of the class to be active on the same local port.

This option must be set before the class is activated through the Active property or it will have no effect.

The default value for this setting is False.

UseConnection:   Determines whether to use a connected socket.

UseConnection specifies whether or not the class should use a connected socket. The connection is defined as an association in between the local address/port and the remote address/port. As such, this is not a connection in the traditional Transmission Control Protocol (TCP) sense. It means only that the class will send and receive data to and from the specified destination.

The default value for this setting is False.

UseIPv6:   Whether or not to use IPv6.

By default, the component expects an IPv4 address for local and remote host properties, and it will create an IPv4 socket. To use IPv6 instead, set this to True.

Socket Config Settings

AbsoluteTimeout:   Determines whether timeouts are inactivity timeouts or absolute timeouts.

If AbsoluteTimeout is set to True, any method that does not complete within Timeout seconds will be aborted. By default, AbsoluteTimeout is False, and the timeout is an inactivity timeout.

Note: This option is not valid for User Datagram Protocol (UDP) ports.

FirewallData:   Used to send extra data to the firewall.

When the firewall is a tunneling proxy, use this property to send custom (additional) headers to the firewall (e.g., headers for custom authentication schemes).

InBufferSize:   The size in bytes of the incoming queue of the socket.

This is the size of an internal queue in the Transmission Control Protocol (TCP)/IP stack. You can increase or decrease its size depending on the amount of data that you will be receiving. In some cases, increasing the value of the InBufferSize setting can provide significant improvements in performance.

Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the class is activated the InBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.

OutBufferSize:   The size in bytes of the outgoing queue of the socket.

This is the size of an internal queue in the TCP/IP stack. You can increase or decrease its size depending on the amount of data that you will be sending. In some cases, increasing the value of the OutBufferSize setting can provide significant improvements in performance.

Some TCP/IP implementations do not support variable buffer sizes. If that is the case, when the class is activated the OutBufferSize reverts to its defined size. The same happens if you attempt to make it too large or too small.

Base Config Settings

BuildInfo:   Information about the product's build.

When queried, this setting will return a string containing information about the product's build.

GUIAvailable:   Whether or not a message loop is available for processing events.

In a GUI-based application, long-running blocking operations may cause the application to stop responding to input until the operation returns. The class will attempt to discover whether or not the application has a message loop and, if one is discovered, it will process events in that message loop during any such blocking operation.

In some non-GUI applications, an invalid message loop may be discovered that will result in errant behavior. In these cases, setting GUIAvailable to false will ensure that the class does not attempt to process external events.

LicenseInfo:   Information about the current license.

When queried, this setting will return a string containing information about the license this instance of a class is using. It will return the following information:

  • Product: The product the license is for.
  • Product Key: The key the license was generated from.
  • License Source: Where the license was found (e.g., RuntimeLicense, License File).
  • License Type: The type of license installed (e.g., Royalty Free, Single Server).
  • Last Valid Build: The last valid build number for which the license will work.
MaskSensitiveData:   Whether sensitive data is masked in log messages.

In certain circumstances it may be beneficial to mask sensitive data, like passwords, in log messages. Set this to true to mask sensitive data. The default is true.

This setting only works on these classes: AS3Receiver, AS3Sender, Atom, Client(3DS), FTP, FTPServer, IMAP, OFTPClient, SSHClient, SCP, Server(3DS), Sexec, SFTP, SFTPServer, SSHServer, TCPClient, TCPServer.

UseDaemonThreads:   Whether threads created by the class are daemon threads.

If set to True (default), when the class creates a thread, the thread's Daemon property will be explicitly set to True. When set to False, the class will not set the Daemon property on the created thread. The default value is True.

UseInternalSecurityAPI:   Whether or not to use the system security libraries or an internal implementation.

When set to false, the class will use the system security libraries by default to perform cryptographic functions where applicable.

Setting this configuration setting to true tells the class to use the internal implementation instead of using the system security libraries.

This setting is set to false by default on all platforms.

Trappable Errors (TFTPClient Class)

TFTPClient Errors

122   Packet too large.
123   Wrong response type from server.
124   Server error. Description contains detailed information.
125   Invalid server response.
126   A valid LocalFile must be provided for PUT operations.
127   Cannot open local file.
128   Cannot write to local file.
129   Cannot read local file.
130   Busy performing the current transfer.
301   Timeout while waiting for server.
305   Server error.
306   Wrong or invalid response type received from server.
307   Invalid response from server.

UDP Errors

104   UDP is already Active.
106   You cannot change the LocalPort while the class is Active.
107   You cannot change the LocalHost at this time. A connection is in progress.
109   The class must be Active for this operation.
112   You cannot change MaxPacketSize while the class is Active.
113   You cannot change ShareLocalPort option while the class is Active.
114   You cannot change RemoteHost when UseConnection is set and the class Active.
115   You cannot change RemotePort when UseConnection is set and the class is Active.
116   RemotePort cannot be zero when UseConnection is set. Please specify a valid service port number.
117   You cannot change UseConnection while the class is Active.
118   Message cannot be longer than MaxPacketSize.
119   Message too short.
434   Unable to convert string to selected CodePage.

SSL Errors

270   Cannot load specified security library.
271   Cannot open certificate store.
272   Cannot find specified certificate.
273   Cannot acquire security credentials.
274   Cannot find certificate chain.
275   Cannot verify certificate chain.
276   Error during handshake.
280   Error verifying certificate.
281   Could not find client certificate.
282   Could not find server certificate.
283   Error encrypting data.
284   Error decrypting data.

TCP/IP Errors

10004   [10004] Interrupted system call.
10009   [10009] Bad file number.
10013   [10013] Access denied.
10014   [10014] Bad address.
10022   [10022] Invalid argument.
10024   [10024] Too many open files.
10035   [10035] Operation would block.
10036   [10036] Operation now in progress.
10037   [10037] Operation already in progress.
10038   [10038] Socket operation on nonsocket.
10039   [10039] Destination address required.
10040   [10040] Message is too long.
10041   [10041] Protocol wrong type for socket.
10042   [10042] Bad protocol option.
10043   [10043] Protocol is not supported.
10044   [10044] Socket type is not supported.
10045   [10045] Operation is not supported on socket.
10046   [10046] Protocol family is not supported.
10047   [10047] Address family is not supported by protocol family.
10048   [10048] Address already in use.
10049   [10049] Cannot assign requested address.
10050   [10050] Network is down.
10051   [10051] Network is unreachable.
10052   [10052] Net dropped connection or reset.
10053   [10053] Software caused connection abort.
10054   [10054] Connection reset by peer.
10055   [10055] No buffer space available.
10056   [10056] Socket is already connected.
10057   [10057] Socket is not connected.
10058   [10058] Cannot send after socket shutdown.
10059   [10059] Too many references, cannot splice.
10060   [10060] Connection timed out.
10061   [10061] Connection refused.
10062   [10062] Too many levels of symbolic links.
10063   [10063] File name is too long.
10064   [10064] Host is down.
10065   [10065] No route to host.
10066   [10066] Directory is not empty
10067   [10067] Too many processes.
10068   [10068] Too many users.
10069   [10069] Disc Quota Exceeded.
10070   [10070] Stale NFS file handle.
10071   [10071] Too many levels of remote in path.
10091   [10091] Network subsystem is unavailable.
10092   [10092] WINSOCK DLL Version out of range.
10093   [10093] Winsock is not loaded yet.
11001   [11001] Host not found.
11002   [11002] Nonauthoritative 'Host not found' (try again or check DNS setup).
11003   [11003] Nonrecoverable errors: FORMERR, REFUSED, NOTIMP.
11004   [11004] Valid name, no data record (check DNS setup).