README

libcli

libcli emulates a cisco style telnet command-line interface.

To compile:

	make
	make install

This will install libcli.so into /usr/local/lib. If you want to change
the location, edit Makefile.

There is a test application built called clitest. Run this and telnet
to port 8000.

By default, a single username and password combination is enabled.

Username: fred
Password: nerk

Get help by entering "help" or hitting ?.

libcli provides support for using the arrow keys for command-line editing. Up
and Down arrows will cycle through the command history, and Left & Right can be
used for editing the current command line.
libcli also works out the shortest way of entering a command, so if you have a
command "show users grep foobar" defined, you can enter "sh us g foobar" if that
is the shortest possible way of doing it.

Enter "sh?" at the command line to get a list of commands starting with "sh"

A few commands are defined in every libcli program:
help
quit
exit
logout
history




Use in your own code:

First of all, make sure you #include <libcli.h> in your C code, and link
with -lcli.

If you have any trouble with this, have a look at clitest.c for a
demonstration.

Start your program off with a cli_init().
This sets up the internal data structures required.

When a user connects, they are presented with a greeting if one is set using the
cli_set_banner(banner) function.


By default, the command-line session is not authenticated, which means users
will get full access as soon as they connect. As this may not be always the best
thing, 2 methods of authentication are available.

First, you can add username / password combinations with the
cli_allow_user(username, password) function. When a user connects, they can
connect with any of these username / password combinations.

Secondly, you can add a callback using the cli_set_auth_callback(callback)
function. This function is passed the username and password as char *, and must
return CLI_OK if the user is to have access and CLI_ERROR if they are not.

The library itself will take care of prompting the user for credentials.




Commands are built using a tree-like structure. You define commands with the
cli_register_command(parent, command, callback, privilege, mode, help) function.

parent is a cli_command * reference to a previously added command. Using a
parent you can build up complex commands.
e.g. to provide commands "show users", "show sessions" and "show people", use
the following sequence:

cli_command *c = cli_register_command(NULL, "show", NULL, PRIVILEGE_UNPRIVILEGED, MODE_EXEC, NULL);
cli_register_command(c, "sessions", fn_sessions, PRIVILEGE_UNPRIVILEGED, MODE_EXEC, "Show the sessions connected");
cli_register_command(c, "users", fn_users, PRIVILEGE_UNPRIVILEGED, MODE_EXEC, "Show the users connected");
cli_register_command(c, "people", fn_people, PRIVILEGE_UNPRIVILEGED, MODE_EXEC, "Show a list of the people I like");


If callback is NULL, the command can be used as part of a tree, but cannot be
individually run. 


If you decide later that you don't want a command to be run, you can call
cli_unregister_command(command).
You can use this to build dynamic command trees.


It is possible to carry along a user-defined context to all command callbacks
using cli_set_context(cli, context) and cli_get_context(cli) functions.


You are responsible for accepting a TCP connection, and for creating a
process or thread to run the cli.  Once you are ready to process the
connection, call cli_loop(cli, sock) to interact with the user on the
given socket.

This function will return when the user exits the cli, either by breaking the
connection or entering "quit".

Call cli_done() to free the data structures.


- David Parrish (david@dparrish.com)