HrrRbSftp

hrr_rb_sftp is a pure Ruby SFTP server implementation. hrr_rb_sftp now supports SFTP protocol version 1, 2, and 3.

hrr_rb_sftp can be run on SSH 2.0 server like OpenSSH or hrr_rb_ssh.

Installation
Usage
- hrr_rb_ssh's SFTP subsystem
- OpenSSH's SFTP subsystem
Note
Supported extensions
Development
Contributing
License
Code of Conduct

Installation

Add this line to your application's Gemfile:

gem 'hrr_rb_sftp'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install hrr_rb_sftp

Usage

Here, some typical usage is described, but is not limited to.

hrr_rb_ssh's SFTP subsystem

hrr_rb_sftp is written in Ruby, so it is straightforward to implement SFTP server on SSH 2.0 server library written in Ruby like hrr_rb_ssh.

There are two ways to work with hrr_rb_ssh, on same process or spawning child process. On both cases, hrr_rb_ssh's request handler mechanism is used.

To run hrr_rb_sftp server on the same process as hrr_rb_ssh is running, the hrr_rb_ssh's request handler is as follows.

subsys = HrrRbSsh::Connection::RequestHandler.new { |ctx|
  ctx.chain_proc { |chain|
    case ctx.subsystem_name
    when 'sftp'
      begin
        sftp_server = HrrRbSftp::Server.new(logger: nil)
        sftp_server.start(ctx.io[0], ctx.io[1], ctx.io[2])
        exitstatus = 0
      rescue
        exitstatus = 1
      end
    else
      # Do something for other subsystem, or just return exitstatus
      exitstatus = 0
    end
    exitstatus
  }
}

options['connection_channel_request_subsystem']  = subsys

On the other hand, because the arguments for the hrr_rb_sftp server can be standard input, output, and error, so hrr_rb_sftp can be a independent program and be spawned as a child process.

subsys = HrrRbSsh::Connection::RequestHandler.new { |ctx|
  ctx.chain_proc { |chain|
    case ctx.subsystem_name
    when 'sftp'
      pid = spawn("/path/to/hrr_rb_sftp_server.rb", {in: ctx.io[0], out: ctx.io[1], err: ctx.io[2]})
      exitstatus = Process.waitpid(pid).to_i
    else
      # Do something for other subsystem, or just return exitstatus
      exitstatus = 0
    end
    exitstatus
  }
}

options['connection_channel_request_subsystem']  = subsys

Where, the /path/to/hrr_rb_sftp_server.rb is as follows.

#!/usr/bin/env ruby

require "hrr_rb_sftp"

server = HrrRbSftp::Server.new(logger: nil)
server.start($stdin, $stdout, $stderr)

OpenSSH's SFTP subsystem

OpenSSH has capability to run user-defined subsystems. Subsystems that the OpenSSH server recognizes are listed in /etc/ssh/sshd_config file. Usually SFTP subsystem is defined by default to use OpenSSH's SFTP server implementation.

$ cat /etc/ssh/sshd_config | grep Subsystem
Subsystem   sftp    /usr/lib/openssh/sftp-server

hrr_rb_sftp can be an alternative with replacing the line in the config file. (After editing the config, reloading or restarting sshd is required.)

$ cat /etc/ssh/sshd_config | grep Subsystem
#Subsystem  sftp    /usr/lib/openssh/sftp-server    # Comment out the original line
Subsystem   sftp    /path/to/hrr_rb_sftp_server.rb

Where, the /path/to/hrr_rb_sftp_server.rb code is the same as shown above.

Note

Reversal of SSH_FXP_SYMLINK arguments
Because OpenSSH's sftp-server implementation takes SSH_FXP_SYMLINK request linkpath and targetpath arguments in reverse order, this library follows it.
The SSH_FXP_SYMLINK request format is as follows:
```
uint32          id
string          targetpath
string          linkpath
```

Supported extensions

The following extensions are supported.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/hirura/hrr_rb_sftp. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the HrrRbSftp project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

hirura / hrr_rb_sftp