Enhancing the FTP protocol

[RomanRII]

What was done

• Modified nxc/protocols/ftp.py
  • Modified the --ls flag to allow for listing the current directory and sub-directories. Default now lists .. If an argument is provided, it will list the provided sub-directory
  • Added the --get flag to download a file on the server. If the file exists and is successfully downloaded, it will be written to the users cwd with the remote file's filename.
  • Added the --put flag to upload files onto the server.
• Modified nxc/protocols/ftp/proto_args.py to reflect the added features
  • Modified the --ls flag to allow for a default directory listing (.) or use a provided directory
  • Added the --get and --put flags
• Modified nxc/protocols/ftp.py#L83 to comply with RFC 1635

Test environment used

• During testing, different permissions were used to account for edge cases.

from pyftpdlib.authorizers import DummyAuthorizer
from pyftpdlib.handlers import FTPHandler
from pyftpdlib.servers import FTPServer

def start_ftp_server():
    # Instantiate an authorizer object responsible for managing authentication and authorization
    authorizer = DummyAuthorizer()

    # Allow anonymous access with read-only permissions
    authorizer.add_anonymous("./FTP_Folder/", perm="erlw")

    # Instantiate an FTP handler object and link it to the authorizer
    handler = FTPHandler
    handler.authorizer = authorizer

    # Create the FTP server on the desired address and port, and link it to the handler
    server = FTPServer(("127.0.0.1", 21), handler)

    # Start the FTP server
    server.serve_forever()

if __name__ == "__main__":
    start_ftp_server()

[RomanRII]

RFC 1635 Compliance

Traditionally, this special anonymous user account accepts any string
as a password, although it is common to use either the password
"guest" or one's electronic mail (e-mail) address.  Some archive
sites now explicitly ask for the user's e-mail address and will not
allow login with the "guest" password.  Providing an e-mail address
is a courtesy that allows archive site operators to get some idea of
who is using their services.

--ls

• Standard usage
  
• If permissions are not granted
  

--get

• Standard usage
  
• If the file does not exist
  

--put

• Standard usage
  
• If a local file does not exist
  
• Permissions error
  

[RomanRII]

Couple things to mind about this merge, it currently doesn't allow the following:

--put

• If a user attempts to upload a file like --put example.txt ., it will fail with Failed to upload file. Response: (550 Is a directory.)

The user will need to specify the filename or dir + filename to save to
--put example.txt example.txt or --put example.txt Sub/Dir/example.txt

If this current implementation is not prefered, let me know and I can make some adjustments to allow users to upload using either . or Sub/ and upload to the directory using the local_name

[Marshall-Hallenbeck]

@RomanRII can you add these new flags to the e2e tests commands file under the FTP section (tests/e2e_commands.txt)?

[RomanRII]

@Marshall-Hallenbeck you got it. will get that done

[RomanRII]

• Added new flags to (tests/e2e_commands.txt)
• Added test file to test upload/download functions (tests/data/test_file.txt)

[NeffIsBack]

Really good PR! Clean code and very nice documentation of the changes! Love to see that

[Marshall-Hallenbeck]

Reviewed and tested this. It all works. Great code and feature, thank you!