javiermon

# dns server using dnslib and gevent
# based on https://bitbucket.org/paulc/dnslib/src/80d85555aae4/src/server/gevent_server.py
# set the key as
# set IP:name ip_addr
# set TXT:name txtfield
# fallback on gevent's dns resolver
# gleicon 2011


import gevent

javiermon

#!/usr/bin/env python

"""
A sample Mongo server that handles enough of the commands to connect
with the mongo shell.

Requires: https://github.com/chergert/mongo-async-python-driver
"""

from collections      import OrderedDict

javiermon

#!/usr/bin/perl -w
#
#  This script was developed by Robin Barker (Robin.Barker@npl.co.uk),
#  from Larry Wall's original script eg/rename from the perl source.
#
#  This script is free software; you can redistribute it and/or modify it
#  under the same terms as Perl itself.
#
# Larry(?)'s RCS header:
#  RCSfile: rename,v   Revision: 4.1   Date: 92/08/07 17:20:30 

javiermon

# (unset) mask = 0xff - (1 << offset) if (nibble == 'lower') else 0xff - (4 << (4 - offset)); operation = &
# (set) mask = 1 << offset if (nibble == 'lower') else 4 << (4 - offset); operation = |
#
# (read) result = (current_values & 0x0F) if (nibble == 'lower') else (current_values & 0xF0) >> 4
# (write) mask = (offset - 1) & 0xf0 if (nibble == 'lower') else 4 << (offset - 1) & 0x0f; operation = |

def getNibbles(int_type):
  """ getNibbles() returns the byte nibbles for a given integer (upper, lower) """
    return((int_type & 0xF0) >> 4, (int_type & 0x0F))

javiermon

/*
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 */

#include <arpa/inet.h>
#include <linux/if_packet.h>
#include <stdio.h>

javiermon

/*
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 */

#include <arpa/inet.h>
#include <linux/if_packet.h>
#include <linux/ip.h>

javiermon

// derived from http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Parallel_algorithm

function map() {
    emit(1, // Or put a GROUP BY key here
         {sum: this.value, // the field you want stats for
          min: this.value,
          max: this.value,
          count:1,
          diff: 0, // M2,n:  sum((val-mean)^2)
    });

javiermon

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

javiermon

#include <stdio.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/connector.h>
#include <linux/cn_proc.h>
#include <stdlib.h>
#include <errno.h>

struct __attribute__ ((aligned(NLMSG_ALIGNTO))) nlcn_msg {
  struct nlmsghdr nl_hdr;

javiermon

High-level

I want to write about why GDB is a great tool for learning C. At least part of the difficulty in learning C is that the language isn’t as interactive as using Python or Ruby.

TL;DR You can kinda use gdb as a repl for c

What’s the smallest possible program we could debug to learn about pointers?