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@interface NSData (CRC32)

-(NSUInteger) crc32;

@end

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Let's Encrypt with Nginx

Here's how I set up a tiny Nginx/Rails server that uses HTTPS via a Let's Encrypt issued certificate.

https://letsencrypt.paddd.de/

Server

I use the smallest DigitalOcean droplet (512 MB) here, which is built from the "Ubuntu Ruby on Rails on 14.04" image provided by them.

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OpenVPN on Ubuntu 12.10 at DigitalOcean

Install OpenVPN

sudo apt-get install openvpn

Generate Server Certificates

sudo cp -r /usr/share/doc/openvpn/examples/easy-rsa/2.0 /etc/openvpn/easy-rsa2

cd /etc/openvpn/easy-rsa2

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iex> <<first, rest::binary>> = "☺ how dare you, unicode!"
"☺ how dare you, unicode!"

iex> <<first>>
<<226>>

iex> rest
<<152, 186, 32, 104, 111, 119, 32, 100, 97, 114, 101, 32, 121, 111, 117, 44, 32, 117, 110, 105, 99, 111, 100, 101, 33>>

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# Chained comparisons in Ruby
# inspired by http://coffeescript.org/#comparisons
# as well as http://refactormycode.com/codes/1284

[:<, :>, :<=, :>=].each do |operator|
  [Float, Fixnum, Rational, Comparable].each do |klass|
    klass.class_eval do
      alias_method "_#{operator}", operator
      define_method operator do |rhs|
        send("_#{operator}", rhs) && rhs

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defmodule MyEnum do
  defmacro filter_matching(collection, pattern) do
    quote do
      Enum.filter unquote(collection), fn
        unquote(pattern) -> true
        _ -> false
      end
    end
  end
end

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*.aux
*.glo
*.idx
*.log
*.toc
*.ist
*.acn
*.acr
*.alg
*.bbl

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def typekit_include_tag apikey
  javascript_include_tag("http://use.typekit.com/#{apikey}.js") +
  javascript_tag("try{Typekit.load()}catch(e){}")
end

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#!/usr/bin/env sh

# Automatically renew all installed letsencrypt certificates on this server

service nginx stop
/root/letsencrypt/letsencrypt-auto renew -nvv --standalone > /var/log/letsencrypt/renew.log 2>&1
RESULT=$?
service nginx start

# optional: notify yourself of succeeded/failed renewals

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defmodule MyStream do
  def mutate(enum, user_acc, user) do
    step = fn val, _acc -> {:suspend, val} end
    next = &Enumerable.reduce(enum, &1, step)
    &do_mutate([], user_acc, user, next, &1, &2)
  end

  defp do_mutate(values, user_acc, user, next, {:suspend, acc}, fun) do
    {:suspended, acc, &do_mutate(values, user_acc, user, next, &1, fun)}
  end