Turtle library

Turtle library is a command line interpreter to rapidly build simple shells. Its typical use can be for testing, debugging and interacting with server daemons. It allows you to call C functions with different arguments just by passing strings to the library. The library will parse the string and call the command's function with the appropriate arguments.

Its goal is to provide a rapid way to create a simple and safe shell interface to daemons. It can very easily be wrapped to accept commands over a localhost-bound tcp/udp socket to remotely execute commands. It uses libffi to dynamically build a callstack and call methods with the arguments provided and uses an adaptive radix tree for fast and efficient lookup of commands.

Example

#include "turtle.h"

#include <stdio.h>
#include <stdint.h>

static void _list_connections(void)
{
    printf("list clients connected...\n");
}

static void _show_connection(uint32_t id)
{
    printf("connection details for conn id %u...\n", id);
    /* look up connection using id and then print packets, bytes etc... */
}

static void _start_statsd_connection(uint32_t ip, uint16_t port)
{    
    printf("initializing statsd connection...\n");
    
    // open tcp socket to ip and port
    //statsd_init(ip, port);    
}

turtle_cmd_list_t cmds = {
    TURTLE_CMD_NP("listconn", "show list of connections", _list_connections),
    TURTLE_CMD("showconn", "%d", "show details of connection", _show_connection),
    TURTLE_CMD("statsd_connect", "%I %d", "initialize the statsd connection", _start_statsd_connection),
    { NULL, },
};

int main()
{
    turtle_init(cmds);

    turtle_execute("statsd_connect 192.168.1.2 8125");
    turtle_execute("listconn");
    turtle_execute("showconn 4");
    turtle_execute("showconn 12");
    
    return 0;
}

Command format specifiers

Directive	Meaning	Notes
%b	boolean
%c	char
%f	double
%d	int64_t
%I	IPv4 address string	Will be converted to network ordered 32-bit integer for method invocation
%s	char *

Building

This project requires CMake to build. libffi is required but a copy is maintained in the repository as of now. I have wrapped the CMake build calls in a Makefile for ease.

git clone --recurse-submodules https://github.com/rishid/turtle
cd turtle
make
make test

TODO

There are a lot of features I want to add to the library over time

• Implement extended parameter validations features
• Add support for optional parameters
• Add support for switch params (e.g. '-n %d')
• Add support for key=value params
• Allow switch and key=value params to be in entered in any order
• Benchmark radix tree vs linear search for small set of commands

License

MIT © Rishi Dhupar