TFTPServer Component

Properties   Methods   Events   Config Settings   Errors  

The TFTPServer Component is used to create a TFTP Server.

Syntax

TipwTFTPServer

Remarks

The TFTPServer component provides a simple way to create a TFTP server. Any TFTP client will be able to connect and transfer files to and from the server.

Getting Started

By default, the server will listen on port 69. You can specify the listening port by setting the LocalPort property.

Optionally set the LocalDir property to a valid local path. If this property is set the component will serve files from this location. When clients connect, they can request files from this location. If this property is not set then the component will fire events allowing customized responses for each operation.

To start the server, call the StartListening method.

Handling Events

Event handlers are the primary method of customizing the component's functionality. When a client attempts to connect, open a file, etc, the corresponding TFTPServer event will fire to allow for custom handling of the client's request.

The following events are fired once the requested operation is executed:

• Error
• Log
• Connected
• ConnectionRequest
• Disconnected
• EndTransfer
• StartTransfer
• Transfer

Property List

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

Method List

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

Event List

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

Config Settings

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

Connections Property (TFTPServer Component)

This property is a collection of currently connected clients.

Syntax

property Connections: TipwTFTPConnectionList read get_Connections;

Remarks

This is a collection of TFTPConnection elements that contain information about each connected client.

This property is read-only and not available at design time.

Please refer to the TFTPConnection type for a complete list of fields.

Listening Property (TFTPServer Component)

If set to True, the component accepts incoming connections on LocalPort.

Syntax

property Listening: Boolean read get_Listening write set_Listening;

Default Value

false

Remarks

This property indicates whether the component is listening for connections on the port specified by the LocalPort property.

Note: Use the StartListening and StopListening methods to control whether the component is listening.

This property is not available at design time.

LocalDir Property (TFTPServer Component)

The local file directory for the server.

Syntax

property LocalDir: String read get_LocalDir write set_LocalDir;

Default Value

''

Remarks

This property defines the local file directory on the server. Files can be downloaded to or uploaded from this directory.

This property is not available at design time.

LocalHost Property (TFTPServer Component)

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

Syntax

property LocalHost: String read get_LocalHost write set_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 multi-homed hosts (machines with more than one IP interface) setting LocalHost to the value of an interface will make the component initiate connections (or accept in the case of server components) only through that interface.

If the component 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 multi-homed 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.

LocalPort Property (TFTPServer Component)

This is the port that the server will listen on.

Syntax

property LocalPort: Integer read get_LocalPort write set_LocalPort;

Default Value

69

Remarks

This property contains the port that the TFTP Server listens on. The default value is 69.

MaxRetransmits Property (TFTPServer Component)

The number of times to retry sending a failed packet before disconnecting.

Syntax

property MaxRetransmits: Integer read get_MaxRetransmits write set_MaxRetransmits;

Default Value

3

Remarks

This property allows you to specify the number of times that you would like to try re-sending 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.

RetransmitTimeout Property (TFTPServer Component)

Maximum time in seconds to wait for a reply packet from the server before retransmitting the last packet.

Syntax

property RetransmitTimeout: Integer read get_RetransmitTimeout write set_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.

Timeout Property (TFTPServer Component)

A timeout for the component.

Syntax

property Timeout: Integer read get_Timeout write set_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 component will wait for the operation to complete before returning control.

The component 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 component raises an exception.

Please note that by default, all timeouts are inactivity timeouts, i.e. 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 (TFTPServer Component)

Sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): String;

Remarks

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

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, 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 (TFTPServer Component)

Processes events from the internal message queue.

Syntax

procedure DoEvents();

Remarks

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

StartListening Method (TFTPServer Component)

This method starts listening for incoming connections.

Syntax

procedure StartListening();

Remarks

This method begins listening for incoming connections on the port specified by LocalPort. Once listening, events will fire as new clients connect and data are transferred.

To stop listening for new connections, call StopListening. To stop listening for new connections and to disconnect all existing clients, call Shutdown.

StopListening Method (TFTPServer Component)

This method stops listening for new connections.

Syntax

procedure StopListening();

Remarks

This method stops listening for new connections. After being called, any new connection attempts will be rejected. Calling this method does not disconnect existing connections.

To stop listening and to disconnect all existing clients, call Shutdown instead.

Connected Event (TFTPServer Component)

This event fires immediately after a connection completes (or fails).

Syntax

type TConnectedEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnConnected: TConnectedEvent read FOnConnected write FOnConnected;

Remarks

The ConnectionId is the Id of the connected client that caused the event to fire.

Upon a successful connection, the SatusCode is 0, and the Description is "OK." If the connection is not successful, the StatusCode will contain the error code. The Description will contain a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

ConnectionRequest Event (TFTPServer Component)

This event fires anytime a connected client attempts a connection to the server.

Syntax

type TConnectionRequestEvent = procedure (
  Sender: TObject;
  const RemoteHost: String;
  RemotePort: Integer;
  const Filename: String;
  const TransferMode: String;
  Operation: Integer;
  var Accept: Boolean
) of Object;

property OnConnectionRequest: TConnectionRequestEvent read FOnConnectionRequest write FOnConnectionRequest;

Remarks

The RemoteHost parameter specifies the IP address (IP number in dotted internet format) of the client attempting to connect.

The RemotePort is the port of the client attempting a connection.

The Filename parameter is the path of the file to upload or download.

The TransferMode parameter specifies which transfer mode to use.

The Operation indicates whether the requested operation is read or write.

The Accept parameter indicates whether to accept or deny the connection. All connections are accepted by default. If you want to refuse a connection, set the Accept parameter to false.

Disconnected Event (TFTPServer Component)

This event fires after a transfer is completed.

Syntax

type TDisconnectedEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  StatusCode: Integer;
  const Description: String
) of Object;

property OnDisconnected: TDisconnectedEvent read FOnDisconnected write FOnDisconnected;

Remarks

ConnectionID will be the ConnectionID of the client that has disconnected.

Upon successful transfer and disconnection, the StatusCode will be 0 and the Description will be "OK." If a transfer is unsuccessful or a client disconnects due to an error, the StatusCode will contain the error code. The Description will be a textual description of the error.

EndTransfer Event (TFTPServer Component)

This event fires once a transfer is completed.

Syntax

type TEndTransferEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  Direction: Integer
) of Object;

property OnEndTransfer: TEndTransferEvent read FOnEndTransfer write FOnEndTransfer;

Remarks

The ConnectionId will be the the ConnectionId of the connected client.

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

Error Event (TFTPServer Component)

Fired when information is available about errors during data delivery.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the component raises 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.

Log Event (TFTPServer Component)

This event fires once for each log message.

Syntax

type TLogEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  LogLevel: Integer;
  const Message: String;
  const LogType: String
) of Object;

property OnLog: TLogEvent read FOnLog write FOnLog;

Remarks

This event fires once for each log message generated by the component. The verbosity is controlled by the LogLevel setting.

LogLevel indicates the level of message. Possible values are as follows:

The value 1 (Info) logs basic information, including users logging in and out, files transferred, and directories listed.

The value 2 (Verbose) includes logs from the PITrail event as well as basic information about data transfer channels.

The value 3 (Debug) logs additional debug information, such as extended socket connection and data transfer information.

Message is the log entry.

LogType identifies the type of log entry. Possible values are as follows:

• "Info"
• "Error"
• "Verbose"
• "Debug"
• "PITrail"

StartTransfer Event (TFTPServer Component)

This event fires immediately after a client initiates a file transfer.

Syntax

type TStartTransferEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  Direction: Integer
) of Object;

property OnStartTransfer: TStartTransferEvent read FOnStartTransfer write FOnStartTransfer;

Remarks

ConnectionId is the ConnectionId of the connected client. Direction represents the direction in which the transfer is going.

Transfer Event (TFTPServer Component)

This event fires repeatedly while data is being transferred. A transfer is marked as complete once a packet that is less than 512 bytes is received.

Syntax

type TTransferEvent = procedure (
  Sender: TObject;
  ConnectionId: Integer;
  Direction: Integer;
  BytesTransferred: Int64;
  PercentDone: Integer;
  Text: String;
  TextB: TBytes
) of Object;

property OnTransfer: TTransferEvent read FOnTransfer write FOnTransfer;

Remarks

The ConnectionId parameter is the ConnectionId of the client who initiated the transfer.

BytesTransferred specifies the number of bytes transferred.

The Text parameter contains the data being transferred.

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.

TFTPConnection Type

This is a client currently connected to the server.

Remarks

This type represents a client connection to the server.

See the Connections property for more information.

Fields

Constructors

constructor Create();

Config Settings (TFTPServer Component)

The component 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 component, access to these internal properties is provided through the Config method.

TFTPServer Config Settings

UDP Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (TFTPServer Component)

TFTPServer 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   Can't open local file.
	128   Can't write to local file.
	129   Can't 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.

The component may also return one of the following error codes, which are inherited from other components.

UDP Errors

	104   UDP is already Active.
	106   You cannot change the LocalPort while the component is Active.
	107   You cannot change the LocalHost at this time. A connection is in progress.
	109   The component must be Active for this operation.
	112   Cannot change MaxPacketSize while the component is Active.
	113   Cannot change ShareLocalPort option while the component is Active.
	114   Cannot change RemoteHost when UseConnection is set and the component Active.
	115   Cannot change RemotePort when UseConnection is set and the component is Active.
	116   RemotePort can't be zero when UseConnection is set. Please specify a valid service port number.
	117   Cannot change UseConnection while the component is Active.
	118   Message can't 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 non-socket.
	10039   [10039] Destination address required.
	10040   [10040] Message too long.
	10041   [10041] Protocol wrong type for socket.
	10042   [10042] Bad protocol option.
	10043   [10043] Protocol not supported.
	10044   [10044] Socket type not supported.
	10045   [10045] Operation not supported on socket.
	10046   [10046] Protocol family not supported.
	10047   [10047] Address family not supported by protocol family.
	10048   [10048] Address already in use.
	10049   [10049] Can't 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] Can't send after socket shutdown.
	10059   [10059] Too many references, can't splice.
	10060   [10060] Connection timed out.
	10061   [10061] Connection refused.
	10062   [10062] Too many levels of symbolic links.
	10063   [10063] File name too long.
	10064   [10064] Host is down.
	10065   [10065] No route to host.
	10066   [10066] Directory 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 not loaded yet.
	11001   [11001] Host not found.
	11002   [11002] Non-authoritative 'Host not found' (try again or check DNS setup).
	11003   [11003] Non-recoverable errors: FORMERR, REFUSED, NOTIMP.
	11004   [11004] Valid name, no data record (check DNS setup).