Whitespace in the configuration file is ignored (the indents in the example file are purely cosmetic), as are empty lines and lines starting with "#". The following settings are valid:

motd FILE
Defines a file that contains the message of the day, which will be printed on logon.

logfile FILE
Defines the name of a file to store log messages in.

loglevel LEVEL
Only messages with a loglevel below LEVEL will be printed / logged to file. LEVEL ranges from 0 (critical) to 5 (informational).

masquerade NAME
Specifies that the server masquerades as the host NAME. This is very useful if the server is behind a NAT gateway, and its actual IP address is not visible to the world. In this case, for clients using PASV instead of EPSV for the passive mode, the reply to PASV will contain the IP address for NAME, not the actual server's IP.
Note: Do not use this if you're not behind a NAT gateway and the server is not actually reachable under the given name. It won't work.

timeout SECONDS
Specifies that the server will close the data connection after the given period of inactivity. Default is 60 seconds.

portrangestart NUM / portrangeend NUM
Specifies what port range to use for passive connections. If these aren't given, the portrange goes from 1024 to INT_MAX.

screensaver SECONDS
Specifies the timeout for the screen saver. Can also be the string "off", which disables the screen saver altogether. Default is 60 seconds.

wakeonlog BOOL
If this is "true", the screensaver will wake up on every log entry. Default is true.

user NAME
Starts a new user block, which must be finished by "end user". Only users named by a user block will be accepted for login. Exception: If no users at all are specified, a default user and pass are generated automatically and displayed in the log.
Settings valid in the user block are:

pass PASSWORD
Set the password for the current user, stored in cleartext. If the user's name is "anonymous", this will be ignored, and the user will be asked to specify his email address for a password.

root DIR
Restrict the user to the directory hierarchy below DIR.

home DIR
Upon logon, set the current directory to DIR (relative to the user's root dir).

write BOOL
Grant the user write permission (including permission to rename and delete!) for everything below his root dir.

boot BOOL
Grant the user permission to boot files and to power down the DS.

Protocol Additions
DSFTP defines the additional command "BOOT", with the filename to be booted as an argument. Since the "BOOT" command is not in the official protocol, the FTP client doesn't know it. For text-based ftp, the "quote" prefix allows you to send it anyway, like this:

quote BOOT /mydsfile.nds

Possible reply codes to the BOOT command are 530 (No permission to boot) and 250 (Booting file). Booting currently only works on Supercard CF. No checks are performed; it is legal to boot a ".txt" file, which will most likely crash your DS. On a successful boot, the data connection to the client is closed. Since booting doesn't return on success, a success message is always printed. If the file to boot could not be found, nothing is reported to the FTP client, but the connection remains intact.

DSFTP defines the additional command "POWR", which can be used to power the DS off. Possible reply codes are 530 (No permission to power off) and 250 (Powering off). DSFTP defines the additional command "UNZP" to uncompress files compressed with GNU zip. Usage is: quote UNZP /zipfile.gz

This will create a file named /zipfile (without the .gz ending). The original, zipped file will not be removed. Possible reply codes are 530 (Unable to open file or error unpacking) and 226 (unpacking succeeded.
Using DSFTP for development
This section describes how you can use libDSFTP to add an FTP server to your own applications. For all of these steps, you can use the included source for DSFTP as an example.
Preliminaries
Adding an FTP server is very easy. First, you should make sure that the following components are added to your build process. That means their include files must be accessible, and their libraries/object files must be linked with your program.

* gba_nds_fat (either chishm's FAT lib or REIN's)
* dswifi
* libDSFTP

Then, you initialize the Wifi and FAT libraries as usual. Please refer to their respective examples for info on how to do it, or to the DSFTP source.
Creating the server
Next, you create an instance of BFTPServer somewhere in your program, like so:

BFTPServer server;


If you want to, you can also create an instance of BFTPConfigurator to configure the server. This is not mandatory, but it allows you to configure the FTP server via config file. This would look as follows.

BFTPConfigurator configurator(&server);
configurator.configureFromFile("/data/settings/ftp.conf");


...or wherever you want the config file to be.

If you do not use a BFTPConfigurator, you must add users to the FTP server manually. Otherwise, you won't be able to log in. The simplest way to do this is like this:

server.addUser("myusername", "mypassword");


Please refer to BFTPServer.h for other arguments to this command.

Letting it do its work
That's it, your FTP server is ready! Now, whenever your program is idle (e.g. from the main loop), you should let the server do its work, like this:

server.handle();


Wrapping it up
And that's all you have to do. All the code inside of a nice little mainloop function would look like this:

void mainloop(void)
{
BFTPServer server;
BFTPConfigurator configurator(&server);
configurator.configureFromFile("/data/settings/ftp.conf");
while(true)
{
server.handle();
swiWaitForVBlank();
}
}



Please refer to the source code of DSFTP and the header files of libDSFTP for other possible settings and features.
Known Bugs and Limitations
The following bugs and limitations are known at the time of writing:

* Sometimes sockets seem not to be reaped correctly.

If any bugs pop up, please send me the log output with a full description to bjoern@giesler.de. Thank you and have fun!