ch.ethz.ssh2

Class SFTPv3Client

java.lang.Object

ch.ethz.ssh2.SFTPv3Client

public class SFTPv3Client
extends Object

A SFTPv3Client represents a SFTP (protocol version 3) client connection tunnelled over a SSH-2 connection. This is a very simple (synchronous) implementation.

Basically, most methods in this class map directly to one of the packet types described in draft-ietf-secsh-filexfer-02.txt.

Note: this is experimental code.

Error handling: the methods of this class throw IOExceptions. However, unless there is catastrophic failure, exceptions of the type SFTPv3Client will be thrown (a subclass of IOException). Therefore, you can implement more verbose behavior by checking if a thrown exception if of this type. If yes, then you can cast the exception and access detailed information about the failure.

Notes about file names, directory names and paths, copy-pasted from the specs:

• SFTP v3 represents file names as strings. File names are assumed to use the slash ('/') character as a directory separator.
• File names starting with a slash are "absolute", and are relative to the root of the file system. Names starting with any other character are relative to the user's default directory (home directory).
• Servers SHOULD interpret a path name component ".." as referring to the parent directory, and "." as referring to the current directory. If the server implementation limits access to certain parts of the file system, it must be extra careful in parsing file names when enforcing such restrictions. There have been numerous reported security bugs where a ".." in a path name has allowed access outside the intended area.
• An empty path name is valid, and it refers to the user's default directory (usually the user's home directory).

If you are still not tired then please go on and read the comment for setCharset(String).

Version:

$Id: SFTPv3Client.java 99 2014-04-10 09:04:31Z dkocher@sudo.ch $

Author:

Christian Plattner, plattner@inf.ethz.ch

Field Summary

Fields

Modifier and Type	Field and Description
static int	SSH_FXF_APPEND Force all writes to append data at the end of the file.
static int	SSH_FXF_CREAT If this flag is specified, then a new file will be created if one does not alread exist (if O_TRUNC is specified, the new file will be truncated to zero length if it previously exists).
static int	SSH_FXF_EXCL Causes the request to fail if the named file already exists.
static int	SSH_FXF_READ Open the file for reading.
static int	SSH_FXF_TRUNC Forces an existing file with the same name to be truncated to zero length when creating a file by specifying SSH_FXF_CREAT.
static int	SSH_FXF_WRITE Open the file for writing.

Constructor Summary

Constructors

Constructor and Description
SFTPv3Client(Connection conn) Create a SFTP v3 client.
SFTPv3Client(Connection conn, PacketListener listener) Create a SFTP v3 client.

Method Summary

Methods

Modifier and Type	Method and Description
String	canonicalPath(String path) Have the server canonicalize any given path name to an absolute path.
void	close() Close this SFTP session.
void	closeFile(SFTPv3FileHandle handle) Close a file.
SFTPv3FileHandle	createFile(String fileName) Create a file and open it for reading and writing.
SFTPv3FileHandle	createFile(String fileName, SFTPv3FileAttributes attr) Create a file and open it for reading and writing.
SFTPv3FileHandle	createFileTruncate(String fileName) Create a file (truncate it if it already exists) and open it for writing.
SFTPv3FileHandle	createFileTruncate(String fileName, SFTPv3FileAttributes attr) reate a file (truncate it if it already exists) and open it for writing.
void	createSymlink(String src, String target) Create a symbolic link on the server.
void	fsetstat(SFTPv3FileHandle handle, SFTPv3FileAttributes attr) Modify the attributes of a file.
SFTPv3FileAttributes	fstat(SFTPv3FileHandle handle) Retrieve the file attributes of an open file.
String	getCharset() The currently used charset for filename encoding/decoding.
int	getProtocolVersion() Returns the negotiated SFTP protocol version between the client and the server.
boolean	isConnected() Queries the channel state
List<SFTPv3DirectoryEntry>	ls(String dirName) List the contents of a directory.
SFTPv3FileAttributes	lstat(String path) Retrieve the file attributes of a file.
void	mkdir(String dirName, int posixPermissions) Create a new directory.
void	mv(String oldPath, String newPath) Move a file or directory.
SFTPv3FileHandle	openDirectory(String path)
SFTPv3FileHandle	openFile(String fileName, int flags, SFTPv3FileAttributes attr)
SFTPv3FileHandle	openFileRO(String fileName) Open a file for reading.
SFTPv3FileHandle	openFileRW(String fileName) Open a file for reading and writing.
SFTPv3FileHandle	openFileRWAppend(String fileName) Open a file in append mode.
SFTPv3FileHandle	openFileWAppend(String fileName) Open a file in append mode.
int	read(SFTPv3FileHandle handle, long fileOffset, byte[] dst, int dstoff, int len) Read bytes from a file in a parallel fashion.
String	readLink(String path) Read the target of a symbolic link.
void	rm(String fileName) Remove a file.
void	rmdir(String dirName) Remove an empty directory.
void	setCharset(String charset) Set the charset used to convert between Java Unicode Strings and byte encodings used by the server for paths and file names.
void	setRequestParallelism(int parallelism)
void	setstat(String path, SFTPv3FileAttributes attr) Modify the attributes of a file.
SFTPv3FileAttributes	stat(String path) Retrieve the file attributes of a file.
void	write(SFTPv3FileHandle handle, long fileOffset, byte[] src, int srcoff, int len) Write bytes to a file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SSH_FXF_READ

public static final int SSH_FXF_READ

Open the file for reading.

See Also:

Constant Field Values

SSH_FXF_WRITE

public static final int SSH_FXF_WRITE

Open the file for writing. If both this and SSH_FXF_READ are specified, the file is opened for both reading and writing.

See Also:

Constant Field Values

SSH_FXF_APPEND

public static final int SSH_FXF_APPEND

Force all writes to append data at the end of the file.

See Also:

Constant Field Values

SSH_FXF_CREAT

public static final int SSH_FXF_CREAT

If this flag is specified, then a new file will be created if one does not alread exist (if O_TRUNC is specified, the new file will be truncated to zero length if it previously exists).

See Also:

Constant Field Values

SSH_FXF_TRUNC

public static final int SSH_FXF_TRUNC

Forces an existing file with the same name to be truncated to zero length when creating a file by specifying SSH_FXF_CREAT. SSH_FXF_CREAT MUST also be specified if this flag is used.

See Also:

Constant Field Values

SSH_FXF_EXCL

public static final int SSH_FXF_EXCL

Causes the request to fail if the named file already exists.

See Also:

Constant Field Values

Constructor Detail

SFTPv3Client

public SFTPv3Client(Connection conn,
            PacketListener listener)
             throws IOException

Create a SFTP v3 client.

Parameters:

conn - The underlying SSH-2 connection to be used.

Throws:

IOException

SFTPv3Client

public SFTPv3Client(Connection conn)
             throws IOException

Create a SFTP v3 client.

Parameters:

conn - The underlying SSH-2 connection to be used.

Throws:

IOException

Method Detail

setCharset

public void setCharset(String charset)
                throws IOException

Set the charset used to convert between Java Unicode Strings and byte encodings used by the server for paths and file names. Unfortunately, the SFTP v3 draft says NOTHING about such conversions (well, with the exception of error messages which have to be in UTF-8). Newer drafts specify to use UTF-8 for file names (if I remember correctly). However, a quick test using OpenSSH serving a EXT-3 filesystem has shown that UTF-8 seems to be a bad choice for SFTP v3 (tested with filenames containing german umlauts). "windows-1252" seems to work better for Europe. Luckily, "windows-1252" is the platform default in my case =).

If you don't set anything, then the platform default will be used (this is the default behavior).

Parameters:

charset - the name of the charset to be used or null to use the platform's default encoding.

Throws:

IOException

See Also:

getCharset()

getCharset

public String getCharset()

The currently used charset for filename encoding/decoding.

Returns:

The name of the charset (null if the platform's default charset is being used)

See Also:

setCharset(String)

fstat

public SFTPv3FileAttributes fstat(SFTPv3FileHandle handle)
                           throws IOException

Retrieve the file attributes of an open file.

Parameters:

handle - a SFTPv3FileHandle handle.

Returns:

a SFTPv3FileAttributes object.

Throws:

IOException

stat

public SFTPv3FileAttributes stat(String path)
                          throws IOException

Retrieve the file attributes of a file. This method follows symbolic links on the server.

Parameters:

path - See the comment for the class for more details.

Returns:

a SFTPv3FileAttributes object.

Throws:

IOException

See Also:

lstat(String)

lstat

public SFTPv3FileAttributes lstat(String path)
                           throws IOException

Retrieve the file attributes of a file. This method does NOT follow symbolic links on the server.

Parameters:

path - See the comment for the class for more details.

Returns:

a SFTPv3FileAttributes object.

Throws:

IOException

See Also:

stat(String)

readLink

public String readLink(String path)
                throws IOException

Read the target of a symbolic link. Note: OpenSSH (as of version 4.4) gets very upset (SSH_FX_BAD_MESSAGE error) if you want to read the target of a file that is not a symbolic link. Better check first with lstat(String).

Parameters:

path - See the comment for the class for more details.

Returns:

The target of the link.

Throws:

IOException

setstat

public void setstat(String path,
           SFTPv3FileAttributes attr)
             throws IOException

Modify the attributes of a file. Used for operations such as changing the ownership, permissions or access times, as well as for truncating a file.

Parameters:

path - See the comment for the class for more details.

attr - A SFTPv3FileAttributes object. Specifies the modifications to be made to the attributes of the file. Empty fields will be ignored.

Throws:

IOException

fsetstat

public void fsetstat(SFTPv3FileHandle handle,
            SFTPv3FileAttributes attr)
              throws IOException

Modify the attributes of a file. Used for operations such as changing the ownership, permissions or access times, as well as for truncating a file.

Parameters:

handle - a SFTPv3FileHandle handle

attr - A SFTPv3FileAttributes object. Specifies the modifications to be made to the attributes of the file. Empty fields will be ignored.

Throws:

IOException

createSymlink

public void createSymlink(String src,
                 String target)
                   throws IOException

Create a symbolic link on the server. Creates a link "src" that points to "target".

Parameters:

src - See the comment for the class for more details.

target - See the comment for the class for more details.

Throws:

IOException

canonicalPath

public String canonicalPath(String path)
                     throws IOException

Have the server canonicalize any given path name to an absolute path. This is useful for converting path names containing ".." components or relative pathnames without a leading slash into absolute paths.

Parameters:

path - See the comment for the class for more details.

Returns:

An absolute path.

Throws:

IOException

openDirectory

public final SFTPv3FileHandle openDirectory(String path)
                                     throws IOException

Throws:

IOException

getProtocolVersion

public int getProtocolVersion()

Returns the negotiated SFTP protocol version between the client and the server.

Returns:

SFTP protocol version, i.e., "3".

isConnected

public boolean isConnected()

Queries the channel state

Returns:

True if the underlying session is in open state

close

public void close()

Close this SFTP session. NEVER forget to call this method to free up resources - even if you got an exception from one of the other methods. Sometimes these other methods may throw an exception, saying that the underlying channel is closed (this can happen, e.g., if the other server sent a close message.) However, as long as you have not called the close() method, you are likely wasting resources.

ls

public List<SFTPv3DirectoryEntry> ls(String dirName)
                              throws IOException

List the contents of a directory.

Parameters:

dirName - See the comment for the class for more details.

Returns:

A Vector containing SFTPv3DirectoryEntry objects.

Throws:

IOException

mkdir

public void mkdir(String dirName,
         int posixPermissions)
           throws IOException

Create a new directory.

Parameters:

dirName - See the comment for the class for more details.

posixPermissions - the permissions for this directory, e.g., "0700" (remember that this is octal noation). The server will likely apply a umask.

Throws:

IOException

rm

public void rm(String fileName)
        throws IOException

Remove a file.

Parameters:

fileName - See the comment for the class for more details.

Throws:

IOException

rmdir

public void rmdir(String dirName)
           throws IOException

Remove an empty directory.

Parameters:

dirName - See the comment for the class for more details.

Throws:

IOException

mv

public void mv(String oldPath,
      String newPath)
        throws IOException

Move a file or directory.

Parameters:

oldPath - See the comment for the class for more details.

newPath - See the comment for the class for more details.

Throws:

IOException

openFileRO

public SFTPv3FileHandle openFileRO(String fileName)
                            throws IOException

Open a file for reading.

Parameters:

fileName - See the comment for the class for more details.

Returns:

a SFTPv3FileHandle handle

Throws:

IOException

openFileRW

public SFTPv3FileHandle openFileRW(String fileName)
                            throws IOException

Open a file for reading and writing.

Parameters:

fileName - See the comment for the class for more details.

Returns:

a SFTPv3FileHandle handle

Throws:

IOException

openFileRWAppend

public SFTPv3FileHandle openFileRWAppend(String fileName)
                                  throws IOException

Open a file in append mode. The SFTP v3 draft says nothing but assuming normal POSIX behavior, all writes will be appendend to the end of the file, no matter which offset one specifies.

A side note for the curious: OpenSSH does an lseek() to the specified writing offset before each write(), even for writes to files opened in O_APPEND mode. However, bear in mind that when working in the O_APPEND mode, each write() includes an implicit lseek() to the end of the file (well, this is what the newsgroups say).

Parameters:

fileName - See the comment for the class for more details.

Returns:

a SFTPv3FileHandle handle

Throws:

IOException

openFileWAppend

public SFTPv3FileHandle openFileWAppend(String fileName)
                                 throws IOException

Open a file in append mode. The SFTP v3 draft says nothing but assuming normal POSIX behavior, all writes will be appendend to the end of the file, no matter which offset one specifies.

A side note for the curious: OpenSSH does an lseek() to the specified writing offset before each write(), even for writes to files opened in O_APPEND mode. However, bear in mind that when working in the O_APPEND mode, each write() includes an implicit lseek() to the end of the file (well, this is what the newsgroups say).

Parameters:

fileName - See the comment for the class for more details.

Returns:

a SFTPv3FileHandle handle

Throws:

IOException

createFile

public SFTPv3FileHandle createFile(String fileName)
                            throws IOException

Create a file and open it for reading and writing. Same as createFile(fileName, null).

Parameters:

fileName - See the comment for the class for more details.

Returns:

a SFTPv3FileHandle handle

Throws:

IOException

createFile

public SFTPv3FileHandle createFile(String fileName,
                          SFTPv3FileAttributes attr)
                            throws IOException

Create a file and open it for reading and writing. You can specify the default attributes of the file (the server may or may not respect your wishes).

Parameters:

fileName - See the comment for the class for more details.

attr - may be null to use server defaults. Probably only the uid, gid and permissions (remember the server may apply a umask) entries of the SFTPv3FileHandle structure make sense. You need only to set those fields where you want to override the server's defaults.

Returns:

a SFTPv3FileHandle handle

Throws:

IOException

createFileTruncate

public SFTPv3FileHandle createFileTruncate(String fileName)
                                    throws IOException

Create a file (truncate it if it already exists) and open it for writing. Same as createFileTruncate(fileName, null).

Parameters:

fileName - See the comment for the class for more details.

Returns:

a SFTPv3FileHandle handle

Throws:

IOException

createFileTruncate

public SFTPv3FileHandle createFileTruncate(String fileName,
                                  SFTPv3FileAttributes attr)
                                    throws IOException

reate a file (truncate it if it already exists) and open it for writing. You can specify the default attributes of the file (the server may or may not respect your wishes).

Parameters:

fileName - See the comment for the class for more details.

attr - may be null to use server defaults. Probably only the uid, gid and permissions (remember the server may apply a umask) entries of the SFTPv3FileHandle structure make sense. You need only to set those fields where you want to override the server's defaults.

Returns:

a SFTPv3FileHandle handle

Throws:

IOException

openFile

public SFTPv3FileHandle openFile(String fileName,
                        int flags,
                        SFTPv3FileAttributes attr)
                          throws IOException

Throws:

IOException

setRequestParallelism

public void setRequestParallelism(int parallelism)

Parameters:

parallelism -

read

public int read(SFTPv3FileHandle handle,
       long fileOffset,
       byte[] dst,
       int dstoff,
       int len)
         throws IOException

Read bytes from a file in a parallel fashion. As many bytes as you want will be read.

• The server will read as many bytes as it can from the file (up to len), and return them.
• If EOF is encountered before reading any data, -1 is returned.
• If an error occurs, an exception is thrown
.
• For normal disk files, it is guaranteed that the server will return the specified number of bytes, or up to end of file. For, e.g., device files this may return fewer bytes than requested.

Parameters:

handle - a SFTPv3FileHandle handle

fileOffset - offset (in bytes) in the file

dst - the destination byte array

dstoff - offset in the destination byte array

len - how many bytes to read, 0 < len

Returns:

the number of bytes that could be read, may be less than requested if the end of the file is reached, -1 is returned in case of EOF

Throws:

IOException

write

public void write(SFTPv3FileHandle handle,
         long fileOffset,
         byte[] src,
         int srcoff,
         int len)
           throws IOException

Write bytes to a file. If len > 32768, then the write operation will be split into multiple writes.

Parameters:

handle - a SFTPv3FileHandle handle.

fileOffset - offset (in bytes) in the file.

src - the source byte array.

srcoff - offset in the source byte array.

len - how many bytes to write.

Throws:

IOException

closeFile

public void closeFile(SFTPv3FileHandle handle)
               throws IOException

Close a file.

Parameters:

handle - a SFTPv3FileHandle handle

Throws:

IOException