Next File Transfer Protocol
===========================

Introduction
------------

Next File Transfer uses a simple protocol where a 2 character code defines
a message type. 

The following are standard compents of a message:

    +------------+------------------------------------------------------+
    | <NNNNNN>   | 6 ASCII digits making up a zero-padded number        |
    +------------+------------------------------------------------------+
    | <N bytes>  | A stream of N bytes                                  |
    +------------+------------------------------------------------------+


Put File
--------

The format of the message from the client is:

    +------------+------------------------------------------------------+
    | PF         | Put file command                                     |
    +------------+------------------------------------------------------+
    | <NNNNNN>   | Length of filename                                   |
    +------------+------------------------------------------------------+
    | <N bytes>  | The filename                                         |
    +------------+------------------------------------------------------+
    | <NNNNNN>   | Length of the data for the file                      |
    +------------+------------------------------------------------------+
    | <N bytes>  | The data                                             |
    +------------+------------------------------------------------------+

The server responds with either:

    +------------+------------------------------------------------------+
    | OK         | The command completed OK                             |
    +------------+------------------------------------------------------+

or:

    +------------+------------------------------------------------------+
    | !E         | There was an error writing the file                  |
    +------------+------------------------------------------------------+


Get File
--------

The format of the message from the client is:

    +------------+------------------------------------------------------+
    | GF         | Get file command                                     |
    +------------+------------------------------------------------------+
    | <NNNNNN>   | Length of filename                                   |
    +------------+------------------------------------------------------+
    | <N bytes>  | The filename                                         |
    +------------+------------------------------------------------------+

The server responds with either:

    +------------+------------------------------------------------------+
    | OK         | The command completed OK.  The file contents will    |
    |            | follow.                                              |
    +------------+------------------------------------------------------+
    | <NNNNNN>   | Length of the following data                         |
    +------------+------------------------------------------------------+
    | <N bytes>  | The data from from the file                          |
    +------------+------------------------------------------------------+

or:

    +------------+------------------------------------------------------+
    | !E         | There was an error reading the file                  |
    +------------+------------------------------------------------------+


Change Directory
----------------

The format of the message from the client is:

    +------------+------------------------------------------------------+
    | CD         | Change directory command                             |
    +------------+------------------------------------------------------+
    | <NNNNNN>   | Length of pathname                                   |
    +------------+------------------------------------------------------+
    | <N bytes>  | The pathname                                         |
    +------------+------------------------------------------------------+

The server responds with either:

    +------------+------------------------------------------------------+
    | OK         | The command completed OK                             |
    +------------+------------------------------------------------------+

or:

    +------------+------------------------------------------------------+
    | !E         | There was an error changing to the directory         |
    +------------+------------------------------------------------------+


Create Directory
----------------

The format of the message from the client is:

    +------------+------------------------------------------------------+
    | MD         | Create directory command                             |
    +------------+------------------------------------------------------+
    | <NNNNNN>   | Length of pathname                                   |
    +------------+------------------------------------------------------+
    | <N bytes>  | The pathname                                         |
    +------------+------------------------------------------------------+

The server responds with either:

    +------------+------------------------------------------------------+
    | OK         | The command completed OK                             |
    +------------+------------------------------------------------------+

or:

    +------------+------------------------------------------------------+
    | !E         | There was an error creating the directory            |
    +------------+------------------------------------------------------+


List Files
----------

The format of the message from the client is:

    +------------+------------------------------------------------------+
    | LS         | List files command                                   |
    +------------+------------------------------------------------------+

The server responds with either:

    +------------+------------------------------------------------------+
    | OK         | The command completed OK                             |
    +------------+------------------------------------------------------+
    | <NNNNNN>   | The number of filenames                              |
    +------------+------------------------------------------------------+
    | <NNNNNN>   | Length of filename 1                                 |
    +------------+------------------------------------------------------+
    | <N bytes>  | Filename 1                                           |
    +------------+------------------------------------------------------+
    ... above 2 fields repeated ...
    +------------+------------------------------------------------------+
    | <NNNNNN>   | Length of filename N                                 |
    +------------+------------------------------------------------------+
    | <N bytes>  | Filename N                                           |
    +------------+------------------------------------------------------+

or:

    +------------+------------------------------------------------------+
    | !E         | There was an error reading the directory             |
    +------------+------------------------------------------------------+