promise-sftp is an SFTP client module for node.js that provides an asynchronous interface for communicating with an SFTP server.

This module is a wrapper the SFTP client functionality from ssh2, and provides some additional features as well as a convenient promise-based API. The API is semi-interchangeable with the promise-ftp module, an idea that was inspired by sftpjs.

This library is written primarily in CoffeeScript, but may be used just as easily in a Node app using Javascript or CoffeeScript. Promises in this module are provided by Bluebird.

• v0.9.0: Added PromiseSftp.ERROR_CODES
• v0.8.0: Most features are in place.

• node.js -- v0.8.7 or newer

npm install promise-sftp

TODO: examples

For the most part, this module's API mirrors ssh2's SFTPStream API, except that it returns promises which resolve or reject, rather than emitting events or calling callbacks. However, there are some minor differences and some additional features, including attempts to make this API as interchangeable as possible with promise-ftp's.

Most errors generated by this module will be instances of one of the following:

• FtpConnectionError: Indicates the connection status was not appropriate for the method called; e.g. connect() or reconnect() was called when the connection was not in a disconnected state, end() was called when the connection has already closed, etc.

• FtpReconnectError: Only possible when the autoReconnect option is set true, this indicates a reconnect was attempted and failed. It includes information about both the original disconnect error (if any) as well as the error while attempting to reconnect.

In addition, errors from the underlying node-ftp library may be rejected unchanged through method calls. These errors may contain a code property that references the SFTP error code. This code may be translated into a (generic) human-readable text explanation by referencing the map PromiseSftp.ERROR_CODES. TODO: investigate and document ssh-level errors and the level property of errors.

• [constructor](): Creates and returns a new PromiseSftp client instance.

• connect(config <object>): Connects to an SFTP server; returned promise resolves to the server's greeting message. If multiple authentication methods are available based on the passed config, they are attempted in the following order: Password > Private Key > Agent > keyboard-interactive (if tryKeyboard is set) > Host-based > None. NOTE: many of the config properties below are NOT relevant for promise-ftp. However, all promise-ftp connect options will work here, except for secure, secureOptions, and preserveCwd. Valid config properties are:

  • host <string>: The hostname or IP address of the SFTP server. Default: 'localhost'

  • port <integer>: The port of the SFTP server. Default: 22

  • username <string>: Username for authentication.

  • password <string>: Password for password-based user authentication. Default: (none)

  • changePassword <function>: When using password-based user authentication, set this option to handle password change requests. If this option isn't set, and the server requests a password change, I haven't tested what will happen. The function should behave as described below. Default: (none)

    • changePassword(message <string>, language <string>): This function should return a promise which resolves to the new password.

  • autoReconnect <boolean>: Whether to attempt to automatically reconnect using the existing config if the connection is unexpectedly closed. Auto-reconnection is lazy, and so will wait until a command needs to be issued before attempting to reconnect.

  • forceIPv4 <boolean>: Only connect via resolved IPv4 address for host. Default: false

  • forceIPv6 <boolean>: Only connect via resolved IPv6 address for host. Default: false

  • hostHash <string>: 'md5' or 'sha1'. The host's key is hashed using this method and passed to the hostVerifier function. Default: (none)

  • hostVerifier <function>: Function that is passed a string hex hash of the host's key for verification purposes. Return true to continue with the handshake or false to reject and disconnect. Default: (auto-accept)

  • agent <string>: Path to ssh-agent's UNIX socket for ssh-agent-based user authentication. Windows users: set to 'pageant' for authenticating with Pageant or (actual) path to a cygwin "UNIX socket." Default: (none)

  • privateKey <mixed>: Buffer or string that contains a private key for either key-based or host-based user authentication (OpenSSH format). Default: (none)

  • privateKeyFile <string>: Path and name of a file containing a private key as would be passed to the privateKey option. If privateKey is also set, priority is given to the privateKey option. Default: (none)

  • passphrase <string>: For an encrypted private key, this is the passphrase used to decrypt it. Default: (none)

  • localHostname <string>: Along with localUsername and privateKey, set this to a non-empty string for host-based user authentication. Default: (none)

  • localUsername <string>: Along with localHostname and privateKey, set this to a non-empty string for host-based user authentication. Default: (none)

  • tryKeyboard <function>: Set this option to a function to try keyboard-interactive user authentication if primary user authentication method fails. The function should behave as described below. Default: (none)

    • tryKeyboard(name <string>, instructions <string>, instructionsLang <string>, prompts <array>): The goal of this function is to acquire responses to the given prompts.

    • name is generally what you'd use as a header or GUI window title to describe the purpose of the prompts.

    • prompts is an array of objects containing the fields prompt (the query to <string> pose to the user) and echo (a indicating <boolean> whether the user's input should be displayed on-screen).

    • The function's return value should be one of the following: an array of response strings, a promise to an array of response strings, or an array of promises to response strings.

    • NOTE: This function may be called more than once, with the same or different prompts.

  • keepaliveInterval <integer>: How often (in milliseconds) to send SSH-level keepalive packets to the server (in a similar way as OpenSSH's ServerAliveInterval config option). Set to 0 to disable. Default: 0

  • keepaliveCountMax <integer>: How many consecutive, unanswered SSH-level keepalive packets that can be sent to the server before disconnection (similar to OpenSSH's ServerAliveCountMax config option). Default: 3

  • readyTimeout <integer>: How long (in milliseconds) to wait for the SSH handshake to complete. Default: 20000

  • strictVendor <boolean>: Performs a strict server vendor check before sending vendor-specific requests, etc. (e.g. check for OpenSSH server when using openssh_noMoreSessions()) Default: true

  • sock <ReadableStream>: A ReadableStream to use for communicating with the server instead of creating and using a new TCP connection (useful for connection hopping).

  • agentForward <boolean>: Set to true to use OpenSSH agent forwarding (auth-agent@openssh.com) for the life of the connection. agent must also be set to use this feature. Default: false

  • debug <function>: Set this to a function that receives a single string argument to get detailed (local) debug information. Default: (none)

  • the additional promise-ftp-style option aliases below are used for compatibility purposes. The aliases are only used if the actual option is not set:

    • user <string>: alias for username

    • connTimeout <integer>: alias for readyTimeout

    • pasvTimeout <integer>: alias for readyTimeout; if both this and connTimeout are given truthy values, connTimeout will be given priority.

    • keepalive <integer>: alias for keepaliveInterval

• reconnect(): Connects to an SFTP server using the config from the most recent call to connect(). Returned promise resolves to the server's greeting message.

• end(): Closes the connection to the server after any/all enqueued commands have been executed; returned promise resolves to a boolean indicating whether there was an error associated with closing the connection.

• destroy(): Closes the connection to the server immediately. Returns a boolean indicating whether the connection was connected prior to the call to destroy().

• getConnectionStatus(): Returns a string describing the current connection state. Possible strings are enumerated in PromiseSftp.STATUSES, as well as below:

  • not yet connected

  • connecting

  • connected

  • logging out

  • disconnecting

  • disconnected

  • reconnecting

• list([path <string>]): Retrieves the directory listing of path. path defaults to '.'. Returned promise resolves to an array of objects with these properties:

  * type <_string_>: A single character denoting the entry type: 'd' for directory, '-' for file (or 'l' for
  symlink on **\*NIX only**).
  
  * name <_string_>: The name of the entry.
  
  * size <_string_>: The size of the entry in bytes.
  
  * date <_Date_>: The last modified date of the entry.
  
  * rights <_object_>: The various permissions for this entry **(*NIX only)**.
  
      * user <_string_>: An empty string or any combination of 'r', 'w', 'x'.
  
      * group <_string_>: An empty string or any combination of 'r', 'w', 'x'.
  
      * other <_string_>: An empty string or any combination of 'r', 'w', 'x'.
  
  * owner <_string_>: The user name or ID that this entry belongs to **(*NIX only)**.
  
  * group <_string_>: The group name or ID that this entry belongs to **(*NIX only)**.
  
  * target <_string_>: _null_  **TODO**: For symlink entries, this is the symlink's target **(*NIX only)**.
  
  * sticky <_boolean_>: _null_  **TODO**: True if the sticky bit is set for this entry **(*NIX only)**.
  

• get(path <string>): Retrieves a file at path from the server. Returned promise resolves to a ReadableStream.

• put(input <mixed>, destPath <string>): Sends data to the server to be stored as destPath. input can be a ReadableStream, a Buffer, or a path to a local file. Returned promise resolves to undefined.

• append(input <mixed>, destPath <string>): Same as put(), except if destPath already exists, it will be appended to instead of overwritten.

• logout(): Alias to end().

• delete(path <string>): Alias for unlink()

• rename(oldPath <string>, newPath <string>): Renames/moves oldPath to newPath on the server. Returned promise resolves to undefined.

• mkdir(path <string>[, recursive <boolean>][, attributes <ATTRS>]): Creates a new directory on the server at path. recursive is for enabling a 'mkdir -p' algorithm and defaults to false. attributes sets the ATTRS used when creating directories. Returned promise resolves to undefined. TODO: The recursive option here may not work as desired currently -- fix it.

• rmdir(path <string>): Removes the directory on the server at path. Returned promise resolves to undefined. TODO: Test whether this deletes directory contents recursively, and document and/or add recursive option to behave like promise-ftp

• listSafe([path <string>]): Alias to list().

• size(path <string>): Retrieves the size of path. Returned promise resolves to number of bytes.

• lastMod(path <string>): Retrieves the last modified date and time for path. Returned promise resolves an instance of Date.

• restart(byteOffset <integer>): Sets the file byte offset for the next file transfer action initiated via get() or put() to byteOffset. Returned promise resolves to undefined.

• fastGet(remotePath <string>, localPath <string>[, options <object>]): Downloads a file at remotePath to localPath using parallel reads for faster throughput. Returned promise resolves to undefined. options can have the following properties:

  • concurrency <integer>: Number of concurrent reads Default: 25

  • chunkSize <integer>: Size of each read in bytes Default: 32768

  • step - <function(total_transferred <integer>, chunk <integer>, total <integer>)>: Called every time a part of a file was transferred

• fastPut(localPath <string>, remotePath <string>[, options <object>]): Uploads a file from localPath to remotePath using parallel reads for faster throughput. Returned promise resolves to undefined. options can have the following properties:

  • concurrency <integer>: Number of concurrent reads Default: 25

  • chunkSize <integer>: Size of each read in bytes Default: 32768

  • step - <function(total_transferred <integer>, chunk <integer>, total <integer>)>: Called every time a part of a file was transferred

• createReadStream(path <string>[, options <object>]): Returned promise resolves to a new readable stream for path. options has the following defaults:

  {
    flags: 'r',
    encoding: null,
    handle: null,
    mode: 0666,
    autoClose: true
  }

  options can include start and end values to read a range of bytes from the file instead of the entire file. Both start and end are inclusive and 0-indexed. The encoding can be 'utf8', 'ascii', or 'base64'.

  If autoClose is false, then the file handle won't be closed, even if there's an error. It is your responsibility to close it and make sure there's no file handle leak. If autoClose is set to true (default behavior), on error or end the file handle will be closed automatically.

  An example to read the last 10 bytes of a file which is 100 bytes long:

  sftp.createReadStream('sample.txt', {start: 90, end: 99});

• createWriteStream(path <string>[, options <object>]): Returned promise resolves to a new readable stream for path. options has the following defaults:

  { 
    flags: 'w',
    encoding: null,
    mode: 0666
  }

  options may also include a start option to allow writing data at some position past the beginning of the file. Modifying a file rather than replacing it may require a flags mode of 'r+' rather than the default mode 'w'.

  If 'autoClose' is set to false and you pipe to this stream, this stream will not automatically close after there is no more data upstream -- allowing future pipes and/or manual writes.

• open(filename <string>, mode <string>[, attributes <ATTRS>]): Opens a file filename for mode with optional attributes (in case open() creates a file). mode is any of the modes supported by fs.open (except sync mode). Returned promise resolves to a Buffer containing a handle to the file.

• close(handle <Buffer>): Closes the resource associated with handle given by open() or opendir(). Returned promise resolves to undefined.

• read(handle <Buffer>, buffer <Buffer>, offset <integer>, length <integer>, position <integer>): Reads length bytes from the resource associated with handle starting at position and stores the bytes in buffer starting at offset. Returned promise resolves to an object with the following properties:

  • bytesRead <integer>: bytes successfully read

  • buffer <_Buffer>: the buffer passed to read(), but offset-adjusted

  • position <integer>: the position passed to read()

• write(handle <Buffer>, buffer <Buffer>, offset <integer>, length <integer>, position <integer>): Writes length bytes from buffer starting at offset to the resource associated with handle starting at position. Returned promise resolves to undefined.

• fstat(handle <Buffer>): Retrieves attributes for the resource associated with handle. Returned promise resolves to a Stats object.

• fsetstat(handle <Buffer>, attributes <ATTRS>): Sets the attributes for the resource associated with handle. Returned promise resolves to undefined.

• futimes(handle <Buffer>, atime <mixed>, mtime <mixed>): Sets the access time and modified time for the resource associated with handle. atime and mtime can be Date instances or UNIX timestamp integers. Returned promise resolves to undefined.

• fchown(handle <Buffer>, uid <integer>, gid <integer>): Sets the owner for the resource associated with handle. Returned promise resolves to undefined.

• fchmod(handle <Buffer>, mode <mixed>): Sets the mode for the resource associated with handle. mode can be an integer or a string containing an octal number. Returned promise resolves to undefined.

• opendir(path <string>): Opens a directory path. Returned promise resolves to a Buffer containing a directory handle.

• readdir(location <mixed>): Retrieves a directory listing. location can either be a Buffer containing a valid directory handle from opendir() or a string containing the path to a directory. Returned promise resolves to an Array of { filename: <_string_>, longname: <_string_>, attrs: [ATTRS](#attrs) } style objects. NOTE: If location is a directory handle, this function may need to be called multiple times until it resolves to boolean false, which indicates that no more directory entries are available for that directory handle.

• unlink(path <string>): Removes the file/symlink at path. Returned promise resolves to undefined.

• stat(path <string>): Retrieves attributes for path. Returned promise resolves to a Stats object.

• lstat(path <string>): Retrieves attributes for path. If path is a symlink, the link itself is stat'ed instead of the resource it refers to. Returned promise resolves to a Stats object.

• setstat(path <string>, attributes <ATTRS>): Sets the attributes defined in attributes for path. Returned promise resolves to undefined.

• utimes(path <string>, atime <mixed>, mtime <mixed>): Sets the access time and modified time for path. atime and mtime can be Date instances or UNIX timestamp integers. Returned promise resolves to undefined.

• chown(path <string>, uid <integer>, gid <integer>): Sets the owner and group for path. Returned promise resolves to undefined.

• chmod(path <string>, mode <mixed>): Sets the mode for path. mode can be an integer or a string containing an octal number. Returned promise resolves to undefined.

• readlink(path <string>): Returned promise resolves to the target for a symlink at path.

• symlink(targetPath <string>, linkPath <string>): Creates a symlink at linkPath to targetPath. Returned promise resolves to undefined.

• realpath(path <string>): Returned promise resolves to the absolute path corresponding to path.

• ext_openssh_rename(srcPath <string>, destPath <string>): OpenSSH extension Performs POSIX rename(3) from srcPath to destPath. Returned promise resolves to undefined.

• ext_openssh_statvfs(path <string>): OpenSSH extension Performs POSIX statvfs(2) on path. Returned promise resolves to an object containing the same fields as found in the statvfs struct.

• ext_openssh_fstatvfs(handle <Buffer>): OpenSSH extension Performs POSIX fstatvfs(2) on open handle handle. Returned promise resolves to an object containing the same fields as found in the statvfs struct.

• ext_openssh_hardlink(targetPath <string>, linkPath <string>): OpenSSH extension Performs POSIX link(2) to create a hard link to targetPath at linkPath. Returned promise resolves to undefined.

• ext_openssh_fsync(handle <Buffer>): OpenSSH extension Performs POSIX fsync(3) on the open handle handle. Returned promise resolves to undefined.

• wait(): Waits for any previously-issued commands to complete.

TODO: document

TODO: document

• implement additional FTP commands:
  • cwd
  • cdup
  • pwd
  • abort
  • site
  • status
  • ascii
  • binary
  • system
• investigate and document (and maybe enhance) the way the level property of underlying errors works
• investigate and document (and maybe enhance) the way the code property of underlying errors works, especially re: ssh errors vs sftp errors vs socket errors (?)
• properly handle the target and sticky attributes on the list() command
• fix mkdir() recursive option
• add recursive option to rmdir
• improve 'continue' handling to account for parallel promises