SFTPServer Component

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The SFTPServer component provides server-side functionality for SFTP connections.

Syntax

TsbxSFTPServer

Remarks

SFTPServer is an implementation for SSH File Transfer Protocol server. It works over a secure SSH channel, and should not be confused with the FTP/FTPS protocol.

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.

Active Property (SFTPServer Component)

Specifies whether the SFTP server has started and ready to accept connections.

Syntax

property Active: Boolean read get_Active;

Default Value

false

Remarks

Check this property to find out whether the SFTP server is in active mode. Use Start and Stop methods to activate or deactivate the server.

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

AuthTypes Property (SFTPServer Component)

Defines allowed authentication types.

Syntax

property AuthTypes: Integer read get_AuthTypes write set_AuthTypes;

Default Value

30

Remarks

Use this property to define which authentication types are allowed on the server, set of

BaseDir Property (SFTPServer Component)

Specifies the server's base (root) directory.

Syntax

property BaseDir: String read get_BaseDir write set_BaseDir;

Default Value

''

Remarks

Use this property to set the base (root) directory on the server.

ClientFileEntry Property (SFTPServer Component)

A container for file entry details.

Syntax

property ClientFileEntry: TsbxSFTPListEntry read get_ClientFileEntry write set_ClientFileEntry;

Remarks

This property is a placeholder for file entry details. Use it communicate file details from your code to the server component and back. Pass the contents of ClientFileEntry to the server with SetClientFileEntry method, and retrieve them with GetClientFileEntry method.

This property may come handy when customizing file system operations, such as file listings or attribute requests.

This property is not available at design time.

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

CompressionLevel Property (SFTPServer Component)

Specifies the preferable compression level.

Syntax

property CompressionLevel: Integer read get_CompressionLevel write set_CompressionLevel;

Default Value

9

Remarks

Set this property before starting the server. Possible values range from 0 (lowest compression) to 9 (maximum compression). This property is ignored if compression wasn't accepted.

ExternalCrypto Property (SFTPServer Component)

Provides access to external signing and DC parameters.

Syntax

property ExternalCrypto: TsbxExternalCrypto read get_ExternalCrypto;

Remarks

Use this property to tune-up remote cryptography settings. SecureBlackbox supports two independent types of external cryptography: synchronous (based on the ExternalSign event) and asynchronous (based on the DC protocol and the DCAuth signing component).

This property is read-only.

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

FIPSMode Property (SFTPServer Component)

Reserved.

Syntax

property FIPSMode: Boolean read get_FIPSMode write set_FIPSMode;

Default Value

false

Remarks

This property is reserved for future use.

ForceCompression Property (SFTPServer Component)

This property specifies whether server explicitly requires data compression.

Syntax

property ForceCompression: Boolean read get_ForceCompression write set_ForceCompression;

Default Value

false

Remarks

Set this property before starting the server. If it is set to true, the component will explicitly request data compression. If it is set to False, the component will support compression, although compression will be used only if the remote party doesn't support algorithms without compression.

Host Property (SFTPServer Component)

Specifies server's host name.

Syntax

property Host: String read get_Host write set_Host;

Default Value

''

Remarks

Use this property to set the host name for this server.

Key Property (SFTPServer Component)

Contains client's public key.

Syntax

property Key: TsbxSSHKey read get_Key;

Remarks

This property returns the currently pinned client's public key. Call PinClient to propagate the key of a particular client prior to checking this property.

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

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

MaxSFTPVersion Property (SFTPServer Component)

Maximum SFTP version supported.

Syntax

property MaxSFTPVersion: Integer read get_MaxSFTPVersion write set_MaxSFTPVersion;

Default Value

6

Remarks

MaxSFTPVersion and MinSFTPVersion properties control the range of SFTP protocol versions supported by this server.

MinSFTPVersion Property (SFTPServer Component)

Minimum SFTP version supported.

Syntax

property MinSFTPVersion: Integer read get_MinSFTPVersion write set_MinSFTPVersion;

Default Value

0

Remarks

MaxSFTPVersion and MinSFTPVersion properties control the range of SFTP protocol versions supported by this server.

PinnedClient Property (SFTPServer Component)

Populates the pinned client details.

Syntax

property PinnedClient: TsbxSSHClientEntry read get_PinnedClient;

Remarks

Use this property to access the details of the client connection previously pinned with PinClient method.

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

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

Port Property (SFTPServer Component)

Specifies the listening port number.

Syntax

property Port: Integer read get_Port write set_Port;

Default Value

22

Remarks

Use this property to specify on which port the component will be listening to client connections.

ReadOnly Property (SFTPServer Component)

Specifies whether files on the server are read-only.

Syntax

property ReadOnly: Boolean read get_ReadOnly write set_ReadOnly;

Default Value

false

Remarks

Set this property to true to deny all client requests to change files on the server.

ServerKeys Property (SFTPServer Component)

The server's SSH keys.

Syntax

property ServerKeys: TsbxSSHKeyList read get_ServerKeys write set_ServerKeys;

Remarks

Use this property to provide a list of SSH private keys for the server endpoint.

An SSH endpoint needs a private key to be able to accept secure connections. Apart from being employed for the handshake, the key is also used as a unique server identifier.

The collection may include more than one endpoint key. A typical usage scenario is to include two or three keys (ECDSA, RSA, and DSS), to cater for clients with different algorithm preferences.

This property is not available at design time.

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

SocketSettings Property (SFTPServer Component)

Manages network connection settings.

Syntax

property SocketSettings: TsbxSocketSettings read get_SocketSettings;

Remarks

Use this property to tune up network connection parameters.

This property is read-only.

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

SSHSettings Property (SFTPServer Component)

The SSH connection settings.

Syntax

property SSHSettings: TsbxSSHSettings read get_SSHSettings;

Remarks

Use this property to access and tune-up the SSH layer settings.

This property is read-only.

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

Users Property (SFTPServer Component)

A collection of known users.

Syntax

property Users: TsbxUserAccountList read get_Users write set_Users;

Remarks

This property provides access to registered user database.

This property is not available at design time.

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

UseUTF8 Property (SFTPServer Component)

Specifies whether UTF8 conversion is to be used when parsing file names.

Syntax

property UseUTF8: Boolean read get_UseUTF8 write set_UseUTF8;

Default Value

false

Remarks

This property specifies whether UTF8 conversion of filenames is used by the server. It is set automatically according to protocol flow, but user could also set it to the desired value.

Config Method (SFTPServer 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.

DoAction Method (SFTPServer Component)

Performs an additional action.

Syntax

function DoAction(ActionID: String; ActionParams: String): String;

Remarks

DoAction is a generic method available in every component. It is used to perform an additional action introduced after the product major release. The list of actions is not fixed, and may be flexibly extended over time.

The unique identifier (case insensitive) of the action is provided in the ActionID parameter.

ActionParams contains the value of a single parameter, or a list of multiple parameters for the action in the form of PARAM1=VALUE1;PARAM2=VALUE2;....

DropClient Method (SFTPServer Component)

Terminates a client connection.

Syntax

procedure DropClient(ConnectionId: Integer; Forced: Boolean);

Remarks

Call this method to shut down a connected client. Forced indicates whether the connection should be closed in a graceful manner.

GetClientBuffer Method (SFTPServer Component)

Acquires a piece of operation data.

Syntax

function GetClientBuffer(ConnectionID: Int64; Handle: String): TBytes;

Remarks

Use this method to obtain a piece of data relevant to a transfer operation in a thread-safe way.

A typical place to call this method is inside the WriteFile event handler, when implementing customized file transfers.

GetClientFileEntry Method (SFTPServer Component)

Acquires file entry details from the component.

Syntax

procedure GetClientFileEntry(ConnectionID: Int64; Handle: String);

Remarks

Use this method to acquire the details of a file entry from the server in atomic and thread-safe way. After this method completes, the entry details will be propagated in ClientFileEntry property.

When calling this method, pass the client connection ID in ConnectionID property, and the opened file handle (if needed) in Handle property.

ListClients Method (SFTPServer Component)

Enumerates the connected clients.

Syntax

function ListClients(): String;

Remarks

This method enumerates the connected clients. It returns a list of strings, with each string being of 'ConnectionID|Address|Port' format, and representing a single connection.

PinClient Method (SFTPServer Component)

Takes a snapshot of the connection's properties.

Syntax

procedure PinClient(ConnectionId: Integer);

Remarks

Use this method to take a snapshot of a connected client. The captured properties are populated in PinnedClient property.

SetClientBuffer Method (SFTPServer Component)

Commits a data buffer to the server component.

Syntax

procedure SetClientBuffer(ConnectionID: Int64; Handle: String; Value: TBytes);

Remarks

Use this method to commit a data buffer passed via the Value parameter to the server control in a thread-safe way.

One example where you might need to pass your buffer to the server is when customizing upload operations via ReadFile event.

SetClientFileEntry Method (SFTPServer Component)

Commits the file entry details to the component.

Syntax

procedure SetClientFileEntry(ConnectionID: Int64; Handle: String);

Remarks

Use this method to commit the file entry details configured in ClientFileEntry property to the server object in a thread-safe way. Pass the client's connection ID via ConnectionID property, and the file entry's handle via Handle.

Start Method (SFTPServer Component)

Starts SFTP server operation.

Syntax

procedure Start();

Remarks

Call this method to start listening to incoming connections.

Stop Method (SFTPServer Component)

Stops SFTP server.

Syntax

procedure Stop();

Remarks

Call this method to close all connections and stop listening to clients.

Accept Event (SFTPServer Component)

This event is fired when new incoming connection is accepted.

Syntax

type TAcceptEvent = procedure (
  Sender: TObject;
  const RemoteAddress: String;
  RemotePort: Integer;
  var Accept: Boolean
) of Object;

property OnAccept: TAcceptEvent read FOnAccept write FOnAccept;

Remarks

This event is fired by the component before a new incoming connection is accepted. RemoteAddress contains the IP address of the connecting client. Use the Accept parameter to either accept, or reject the connection.

AfterCreateDirectory Event (SFTPServer Component)

This event indicates completion of directory creation request.

Syntax

type TAfterCreateDirectoryEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var OperationStatus: Integer
) of Object;

property OnAfterCreateDirectory: TAfterCreateDirectoryEvent read FOnAfterCreateDirectory write FOnAfterCreateDirectory;

Remarks

This event is fired to report completion of a directory creation request. The ConnectionID parameter specifies in which session the request was received, the Path specifies the directory path, and the OperationStatus contains the operation result.

If needed, you can amend the OperationStatus to return a different operation result:

AfterRemove Event (SFTPServer Component)

This event indicates completion of file removal request.

Syntax

type TAfterRemoveEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var OperationStatus: Integer
) of Object;

property OnAfterRemove: TAfterRemoveEvent read FOnAfterRemove write FOnAfterRemove;

Remarks

This event is fired when a request to delete a file or directory has been processed by the server. The ConnectionID parameter specifies the session in which the request was received. OperationStatus contains the operation result.

If needed, you can amend the OperationStatus to return a different operation result:

AfterRenameFile Event (SFTPServer Component)

This event indicates completion of a file rename operation.

Syntax

type TAfterRenameFileEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const OldPath: String;
  const NewPath: String;
  var OperationStatus: Integer
) of Object;

property OnAfterRenameFile: TAfterRenameFileEvent read FOnAfterRenameFile write FOnAfterRenameFile;

Remarks

This event is fired when a request to rename a file (from OldPath to NewPath) has been processed. The ConnectionID parameter specifies in which session the request was received, and OperationStatus contains the operation result.

If needed, you can amend the OperationStatus to return a different operation result:

AfterRequestAttributes Event (SFTPServer Component)

This event indicates completion of file attributes request.

Syntax

type TAfterRequestAttributesEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var OperationStatus: Integer
) of Object;

property OnAfterRequestAttributes: TAfterRequestAttributesEvent read FOnAfterRequestAttributes write FOnAfterRequestAttributes;

Remarks

This event is fired when a request for get file attributes has been processed by the server. The ConnectionID parameter specifies in which session the request was received. OperationStatus contains the result of the operation.

If needed, you can amend the OperationStatus to return a different operation result:

AfterSetAttributes Event (SFTPServer Component)

This event indicates completion of a set attributes request.

Syntax

type TAfterSetAttributesEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var OperationStatus: Integer
) of Object;

property OnAfterSetAttributes: TAfterSetAttributesEvent read FOnAfterSetAttributes write FOnAfterSetAttributes;

Remarks

This event is fired when a request for set file attributes has been processed. The ConnectionID parameter specifies in which session the request was received. The OperationStatus parameter contains the operation result.

If needed, you can amend the OperationStatus to return a different operation result:

AuthAttempt Event (SFTPServer Component)

Reports a user authentication attempt.

Syntax

type TAuthAttemptEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Username: String;
  AuthType: Integer;
  var Accept: Boolean
) of Object;

property OnAuthAttempt: TAuthAttemptEvent read FOnAuthAttempt write FOnAuthAttempt;

Remarks

ConnectionID identifies the session, Username specifies client's username, and AuthType specifies the authentication type. Use the Accept parameter to accept or decline the attempt.

Supported authentication types:

AuthFailed Event (SFTPServer Component)

Reports user authentication failure.

Syntax

type TAuthFailedEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Username: String;
  AuthType: Integer
) of Object;

property OnAuthFailed: TAuthFailedEvent read FOnAuthFailed write FOnAuthFailed;

Remarks

ConnectionID identifies the session, Username specify client's username, and AuthType specifies what authentication type was used.

Supported authentication types:

AuthPassword Event (SFTPServer Component)

This event is fired on password authentication attempt from a client.

Syntax

type TAuthPasswordEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Username: String;
  const Password: String;
  var Accept: Boolean;
  var ForceChangePassword: Boolean
) of Object;

property OnAuthPassword: TAuthPasswordEvent read FOnAuthPassword write FOnAuthPassword;

Remarks

Parameters Username and Password contain user credentials. If they are correct, set Accept to true. You can request password change by setting ForceChangePassword to true.

AuthPublicKey Event (SFTPServer Component)

This event is fired on public key authentication attempt from a client.

Syntax

type TAuthPublicKeyEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Username: String;
  var Accept: Boolean
) of Object;

property OnAuthPublicKey: TAuthPublicKeyEvent read FOnAuthPublicKey write FOnAuthPublicKey;

Remarks

Username specifies client's username, and Accept is used to accept or reject authentication.

AuthSucceeded Event (SFTPServer Component)

Reports a successful user authentication.

Syntax

type TAuthSucceededEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Username: String;
  AuthType: Integer
) of Object;

property OnAuthSucceeded: TAuthSucceededEvent read FOnAuthSucceeded write FOnAuthSucceeded;

Remarks

ConnectionID identifies the session, Username specify client's username, and AuthType specifies what authentication type was used.

Supported authentication types:

BeforeCreateDirectory Event (SFTPServer Component)

This event is fired when a client requests to create a directory.

Syntax

type TBeforeCreateDirectoryEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var Action: Integer
) of Object;

property OnBeforeCreateDirectory: TBeforeCreateDirectoryEvent read FOnBeforeCreateDirectory write FOnBeforeCreateDirectory;

Remarks

This event is fired when a request to create a directory has been received. The ConnectionID parameter specifies in which session the request was received.

Choose Action as one of the following values:

BeforeDownloadFile Event (SFTPServer Component)

This event is fired when a download file request is received.

Syntax

type TBeforeDownloadFileEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var Action: Integer
) of Object;

property OnBeforeDownloadFile: TBeforeDownloadFileEvent read FOnBeforeDownloadFile write FOnBeforeDownloadFile;

Remarks

This event is fired when a request to download file is received from the client. The ConnectionID parameter specifies in which session the request was received.

Choose Action as one of the following values:

BeforeFind Event (SFTPServer Component)

This event is fired when a client requests to find files and folders in Path.

Syntax

type TBeforeFindEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var Action: Integer
) of Object;

property OnBeforeFind: TBeforeFindEvent read FOnBeforeFind write FOnBeforeFind;

Remarks

This event is fired when a request to find files and folders in Path has been received. The ConnectionID parameter specifies in which session the request was received.

Choose Action as one of the following values:

BeforeRemove Event (SFTPServer Component)

This event is fired when a client requests to delete a file or directory.

Syntax

type TBeforeRemoveEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var Action: Integer
) of Object;

property OnBeforeRemove: TBeforeRemoveEvent read FOnBeforeRemove write FOnBeforeRemove;

Remarks

This event is fired when a request to delete a file or directory is received from the client. The ConnectionID parameter specifies in which session the request was received.

Choose Action as one of the following values:

BeforeRenameFile Event (SFTPServer Component)

This event is fired when a client requests to rename a file.

Syntax

type TBeforeRenameFileEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const OldPath: String;
  const NewPath: String;
  var Action: Integer
) of Object;

property OnBeforeRenameFile: TBeforeRenameFileEvent read FOnBeforeRenameFile write FOnBeforeRenameFile;

Remarks

This event is fired when a request to rename a file (from OldPath to NewPath) is received from the client. The ConnectionID parameter specifies in which session the request was received.

Choose Action as one of the following values:

BeforeRequestAttributes Event (SFTPServer Component)

This event is fired when a client requests to get file attributes.

Syntax

type TBeforeRequestAttributesEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var Action: Integer
) of Object;

property OnBeforeRequestAttributes: TBeforeRequestAttributesEvent read FOnBeforeRequestAttributes write FOnBeforeRequestAttributes;

Remarks

This event is fired when a request to get file attributes has been received. The ConnectionID parameter specifies in which session the request was received.

Choose Action as one of the following values:

BeforeSetAttributes Event (SFTPServer Component)

This event is fired when a client requests to set file attributes.

Syntax

type TBeforeSetAttributesEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var Action: Integer
) of Object;

property OnBeforeSetAttributes: TBeforeSetAttributesEvent read FOnBeforeSetAttributes write FOnBeforeSetAttributes;

Remarks

This event is fired when a request to set file attributes has been received. The ConnectionID parameter specifies in which session the request was received.

Choose Action as one of the following values:

BeforeUploadFile Event (SFTPServer Component)

This event is fired when an upload file request is received.

Syntax

type TBeforeUploadFileEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var Action: Integer
) of Object;

property OnBeforeUploadFile: TBeforeUploadFileEvent read FOnBeforeUploadFile write FOnBeforeUploadFile;

Remarks

This event is fired when an upload file request is received from the client. The ConnectionID parameter specifies in which session the request was received, and Path specifies the location on the server where the file needs to be saved.

Choose Action as one of the following values:

CloseFile Event (SFTPServer Component)

This event instructs the application to close an opened file.

Syntax

type TCloseFileEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Handle: String;
  var OperationStatus: Integer
) of Object;

property OnCloseFile: TCloseFileEvent read FOnCloseFile write FOnCloseFile;

Remarks

This event is fired upon receipt of a close-file packet from a client. Servers implementing virtualized transfers must close the previously opened local file referenced by Handle in this event handler. No further operations are allowed with the closed file.

Set OperationStatus to one of the following values to report the result of this operation to the client:

Connect Event (SFTPServer Component)

This event is fired when a remote connection has been established.

Syntax

type TConnectEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const RemoteAddress: String;
  RemotePort: Integer
) of Object;

property OnConnect: TConnectEvent read FOnConnect write FOnConnect;

Remarks

ConnectionID contains a session identifier, and RemoteAddress specifies the client's IP address.

CreateDirectory Event (SFTPServer Component)

This event instructs the application to create a directory.

Syntax

type TCreateDirectoryEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var OperationStatus: Integer
) of Object;

property OnCreateDirectory: TCreateDirectoryEvent read FOnCreateDirectory write FOnCreateDirectory;

Remarks

This event is fired when a request to create a directory has been received and needs to be served (virtualized) by the application. The ConnectionID parameter specifies the session that has communicated the request, and Path contains the name of the directory to be created.

Set OperationStatus to one of the below values according to the outcome of the request processing:

Disconnect Event (SFTPServer Component)

This event is fired when a client has disconnected.

Syntax

type TDisconnectEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64
) of Object;

property OnDisconnect: TDisconnectEvent read FOnDisconnect write FOnDisconnect;

Remarks

This event reports loss of connection to the client within the session specified by ConnectionID.

Error Event (SFTPServer Component)

Information 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 event is fired in case of exceptional conditions during message processing.

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

ExternalSign Event (SFTPServer Component)

Handles remote or external signing initiated by the server protocol.

Syntax

type TExternalSignEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const OperationId: String;
  const HashAlgorithm: String;
  const Pars: String;
  const Data: String;
  var SignedData: String
) of Object;

property OnExternalSign: TExternalSignEvent read FOnExternalSign write FOnExternalSign;

Remarks

Assign a handler to this event if you need to delegate a low-level signing operation to an external, remote, or custom signing engine. Depending on the settings, the handler will receive a hashed or unhashed value to be signed.

The event handler must pass the value of Data to the signer, obtain the signature, and pass it back to the component via the SignedData parameter.

OperationId provides a comment about the operation and its origin. It depends on the exact component being used, and may be empty. HashAlgorithm specifies the hash algorithm being used for the operation, and Pars contains algorithm-dependent parameters.

The component uses base16 (hex) encoding for the Data, SignedData, and Pars parameters. If your signing engine uses a different input and output encoding, you may need to decode and/or encode the data before and/or after the signing.

A sample MD5 hash encoded in base16: a0dee2a0382afbb09120ffa7ccd8a152 - lower case base16 A0DEE2A0382AFBB09120FFA7CCD8A152 - upper case base16

A sample event handler that uses the .NET RSACryptoServiceProvider class may look like the following: signer.OnExternalSign += (s, e) => { var cert = new X509Certificate2("cert.pfx", "", X509KeyStorageFlags.Exportable); var key = (RSACryptoServiceProvider)cert.PrivateKey; var dataToSign = e.Data.FromBase16String(); var signedData = key.SignHash(dataToSign, "2.16.840.1.101.3.4.2.1"); e.SignedData = signedData.ToBase16String(); };

FindClose Event (SFTPServer Component)

This event signifies the completion of a custom file listing operation.

Syntax

type TFindCloseEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Handle: String;
  var OperationStatus: Integer
) of Object;

property OnFindClose: TFindCloseEvent read FOnFindClose write FOnFindClose;

Remarks

FindClose notifies your code about the completion of a custom file listing request. Use it in conjunction with FindFirst and FindNext to handle file listing requests manually.

See FindFirst topic for the details on implementing customized file listing request processing.

Set OperationStatus to one of the below values according to the outcome of the request processing:

FindFirst Event (SFTPServer Component)

This event signifies the start of the custom file listing retrieval mechanism.

Syntax

type TFindFirstEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var OperationStatus: Integer;
  var Handle: String
) of Object;

property OnFindFirst: TFindFirstEvent read FOnFindFirst write FOnFindFirst;

Remarks

FindFirst, FindNext, and FindClose events represent a mechanism for providing customized file listings to component. They are only fired if Action parameter of the preceding BeforeFind event was set to fraCustom.

The behaviour of these events mimics that of the standard FindFirst/FindNext/FindClose functions found in many operating systems/frameworks. FindFirst fires once to request the first list entry; FindNext then fires continuously in a loop to request all subsequent entries. To indicate that the listing is over, set OperationStatus parameter to ostEOF. Not doing so may lead to an endless loop and session freeze, as the component would continue firing FindNext infinitely waiting for the EOF marker.

The handlers for both FindFirst and FindNext events should be implemented in the following way: if there are more entries in the directory to pass back to the server component,

• set OperationStatus to ostOK,
• fill in ClientFileEntry with the details of the next entry,
• commit the entry to the server using SetClientFileEntry method.

When all the entries from the requested directory have been passed to the server component, set OperationStatus to ostEOF. The server will then fire FindClose event to notify your code that the file listing is completed.

Use the by-ref Handle parameter to assign a handle (a unique identifier) to the file listing procedure inside the FindFirst event handler. This identifier will then be passed to all subsequent FindNext and FindClose calls to let your code chain the events together.

The ConnectionID parameter specifies in which SFTP session the request was received, and Path indicates the requested directory.

The following operation status constants are available, besides the ones referenced above:

FindNext Event (SFTPServer Component)

This event retrieves the next entry of a custom file listing.

Syntax

type TFindNextEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Handle: String;
  var OperationStatus: Integer
) of Object;

property OnFindNext: TFindNextEvent read FOnFindNext write FOnFindNext;

Remarks

This event is fired repeatedly after FindFirst to retrieve the directory contents entry-by-entry. Please see the FindFirst topic for more details about implementing a handler of this event.

Remember to set OperationStatus to ostEOF when there are no more entries left to close the listing operation. If there are more entries to pass, set it to ostOK. Other possible values are given in the table below:

Notification Event (SFTPServer Component)

This event notifies the application about an underlying control flow event.

Syntax

type TNotificationEvent = procedure (
  Sender: TObject;
  const EventID: String;
  const EventParam: String
) of Object;

property OnNotification: TNotificationEvent read FOnNotification write FOnNotification;

Remarks

The component fires this event to let the application know about some event, occurrence, or milestone in the component. For example, it may fire to report completion of the document processing. The list of events being reported is not fixed, and may be flexibly extended over time.

The unique identifier of the event is provided in the EventID parameter. EventParam contains any parameters accompanying the occurrence. Depending on the type of the component, the exact action it is performing, or the document being processed, one or both may be omitted.

This component can fire this event with the following EventID values:

OpenFile Event (SFTPServer Component)

This event instructs the application to handle the file open request.

Syntax

type TOpenFileEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  Modes: Integer;
  Access: Integer;
  var OperationStatus: Integer;
  var Handle: String
) of Object;

property OnOpenFile: TOpenFileEvent read FOnOpenFile write FOnOpenFile;

Remarks

This event is fired when a file open request is received from the client and needs to be handled (virtualized) by the server. The ConnectionID parameter specifies in which session the request was received, and Path specifies the location of the file.

Modes can be a combination of one or several file open mode flags:

Different client applications may provide different selections of mode flags. For example, some clients specify (cfmCreate + cfmTruncate) when overwriting files, whereas others would specify cfmOpenOrCreate. Please make sure your code is prepared to receive different combinations of flags here and handles them gracefully.

The Access parameter provides additional file access modifiers:

These parameter may also contain a combination of the above flags. Access modifiers are only supported in SFTPv6, and in practice are rarely used by client applications.

The Handle string represents a unique identifier of the opened file, similar to file handles used in Windows or Unix APIs. Handles are unique across all files opened at the same time. Component generates handles automatically, but you can update the auto-generated values with your own in this event handler (just remember to keep them unique).

Set OperationStatus parameter in accordance with the outcome of the operation to one of the values given below:

ReadFile Event (SFTPServer Component)

This event is fired when a file read request is received.

Syntax

type TReadFileEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Handle: String;
  Offset: Int64;
  Size: Integer;
  var OperationStatus: Integer
) of Object;

property OnReadFile: TReadFileEvent read FOnReadFile write FOnReadFile;

Remarks

This event is fired when a request to read block from a file is received from the client. The ConnectionID parameter specifies in which session the request was received, and Handle indicates an opened file handle. Offset and Size denote the location and size of the file piece.

Inside the event handler, pass the appropriate file chunk to the component via SetClientBuffer method.

Set OperationStatus to one of the below values according to the outcome of the request processing:

Remove Event (SFTPServer Component)

This event is fired when a client requests to delete a file or directory.

Syntax

type TRemoveEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var OperationStatus: Integer
) of Object;

property OnRemove: TRemoveEvent read FOnRemove write FOnRemove;

Remarks

This event is fired when a request to delete a file or directory is received from the client. The ConnectionID parameter specifies in which session the request was received.

Set OperationStatus to one of the below values according to the outcome of the request processing:

RenameFile Event (SFTPServer Component)

This event is fired when a client requests to rename a file.

Syntax

type TRenameFileEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const OldPath: String;
  const NewPath: String;
  var OperationStatus: Integer
) of Object;

property OnRenameFile: TRenameFileEvent read FOnRenameFile write FOnRenameFile;

Remarks

This event is fired when a request to rename a file (from OldPath to NewPath) is received from the client. The ConnectionID parameter specifies in which session the request was received.

Set OperationStatus to one of the below values according to the outcome of the request processing:

RequestAttributes Event (SFTPServer Component)

This event is fired when a get file attributes request is received.

Syntax

type TRequestAttributesEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  const Handle: String;
  var OperationStatus: Integer
) of Object;

property OnRequestAttributes: TRequestAttributesEvent read FOnRequestAttributes write FOnRequestAttributes;

Remarks

This event is fired when a request to get file attributes is received from the client. The ConnectionID parameter specifies in which session the request was received, and Path specifies the file location where the attributes need to be retrieved.

Set OperationStatus to one of the below values according to the outcome of the request processing:

SessionClosed Event (SFTPServer Component)

Reports session closure.

Syntax

type TSessionClosedEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64
) of Object;

property OnSessionClosed: TSessionClosedEvent read FOnSessionClosed write FOnSessionClosed;

Remarks

This event is fired when a connection identified by ConnectionID has been gracefully closed.

SessionEstablished Event (SFTPServer Component)

This event is fired when a new session is established.

Syntax

type TSessionEstablishedEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64
) of Object;

property OnSessionEstablished: TSessionEstablishedEvent read FOnSessionEstablished write FOnSessionEstablished;

Remarks

This event is fired when a new connection identified by ConnectionID has been established with a client.

SetAttributes Event (SFTPServer Component)

This event is fired when an set file attributes request is received.

Syntax

type TSetAttributesEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  const Handle: String;
  var OperationStatus: Integer
) of Object;

property OnSetAttributes: TSetAttributesEvent read FOnSetAttributes write FOnSetAttributes;

Remarks

This event is fired when a request to set file attributes is received from the client. The ConnectionID parameter specifies in which session the request was received, and Path specifies the file location which the attributes needs to be set.

Set OperationStatus to one of the below values according to the outcome of the request processing:

TranslatePath Event (SFTPServer Component)

This event is fired when a client requests the server to translate a path to its absolute form.

Syntax

type TTranslatePathEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Path: String;
  var AbsolutePath: String;
  var Action: Integer
) of Object;

property OnTranslatePath: TTranslatePathEvent read FOnTranslatePath write FOnTranslatePath;

Remarks

This event is fired when a request to translate a relative path to the corresponding absolute path is received. The ConnectionID parameter specifies the session in which the request was received.

You can let the server do the translation automatically according to the default file system rules, or take care of it yourself. Use the Action parameter to specify who is responsible for the translation. If doing the translation manually, return the translated path via the AbsolutePath parameter. Action can take one of the following values:

WriteFile Event (SFTPServer Component)

This event is fired when a file write request is received.

Syntax

type TWriteFileEvent = procedure (
  Sender: TObject;
  ConnectionID: Int64;
  const Handle: String;
  Offset: Int64;
  var OperationStatus: Integer
) of Object;

property OnWriteFile: TWriteFileEvent read FOnWriteFile write FOnWriteFile;

Remarks

This event is fired when a request to write a data block to a file is received from the client. The ConnectionID parameter specifies the session the request originates from. The Handle parameter references the opened file where the block should be written to. Offset references the position in the file where the block of data should be written.

Use GetClientBuffer method to obtain the piece of data that should be written to the file.

Set OperationStatus to one of the below values according to the outcome of the request processing:

ExternalCrypto Type

Specifies the parameters of external cryptographic calls.

Remarks

External cryptocalls are used in a Distributed Cryptography (DC) subsystem, which allows the delegation of security operations to the remote agent. For instance, it can be used to compute the signature value on the server, while retaining the client's private key locally.

Fields

Constructors

>

constructor Create();

Creates a new ExternalCrypto object with default field values.

SFTPListEntry Type

A container for filesystem element's attributes.

Remarks

This type contains attributes of a single entry returned by a ListDir command.

The contents of this container may differ for different servers (not all servers support all attributes).

Fields

Constructors

>

constructor Create();

Creates a new SFTPListEntry object.

SocketSettings Type

A container for the socket settings.

Remarks

This type is a container for socket-layer parameters.

Fields

Constructors

>

constructor Create();

Creates a new SocketSettings object.

SSHClientEntry Type

Contains information about an accepted SSH connection.

Remarks

SSHClientEntry object contains information about one accepted SSH connection.

Fields

Constructors

>

constructor Create();

Creates an empty object representing a SSH connection entry.

SSHKey Type

SSHKey is used to store information about single compound public-key algorithm (such as RSA or DSA) key.

Remarks

SSH keys are used to secure the SSH protocol flow. They support different algorithms and key lengths, a very typical example being RSA-2048 bits.

Fields

Constructors

>

constructor Create();

Creates a new key.

SSHSettings Type

A container for various SSH protocol settings.

Remarks

SSHSettings stores various settings of SSH client or server.

Fields

Constructors

>

constructor Create();

Creates a new object with default settings.

UserAccount Type

A container for user account information.

Remarks

UserAccount objects are used to store user account information, such as logins and passwords.

Fields

Constructors

>

constructor Create();

Creates a new UserAccount object.

Config Settings (SFTPServer 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.

SFTPServer Config Settings

Base Config Settings

Trappable Errors (SFTPServer Component)

SFTPServer Errors

	1048577   Invalid parameter value (SB_ERROR_INVALID_PARAMETER)
	1048578   Component is configured incorrectly (SB_ERROR_INVALID_SETUP)
	1048579   Operation cannot be executed in the current state (SB_ERROR_INVALID_STATE)
	1048580   Attempt to set an invalid value to a property (SB_ERROR_INVALID_VALUE)
	1048581   Certificate does not have its private key loaded (SB_ERROR_NO_PRIVATE_KEY)
	1048581   Cancelled by the user (SB_ERROR_CANCELLED_BY_USER) 
	31457281   Unsupported file operation (SB_ERROR_SFTP_UNSUPPORTED_FILEOPERATION)