monokuma

monokuma

This is Sandy's custom URL shortener that works through Redis.

Motivation

I wanted to learn how to use custom TLS Redis and I wanted to make a URL shortener. So I did both.

Done. hah. See nagito, which is a program that talks to this server to generate short URLs.

Well, on my website, I also have many gallery pages, which are powered by OneDrive that have really long URLs. I wanted to shorten them so that I can share them more easily.

Setting up Redis

First, you need to have Redis installed and running through one of the modified redis config files in the redis folder. There are two config files, one for a secure TLS connection and one for a non-secure connection. You can use either one, but I recommend using the secure one.

Please update the username and password in the config file to your own username and password. You can generate a password by running openssl rand -base64 32 in your terminal.

When it comes to SSL certificates, you can either use a self-signed certificate or you can use a certificate from a certificate authority. You can use my commands for generating yourself a custom CA, server certificate, and client certificate for two-way authentication. See thecsw/certificates.

Setting up the server

First, build the golang binary by running go build in the root directory of this repository. Then, you can run the binary by running ./monokuma in the root directory of this repository.

Here is the list of command-line flags that you can use:

Usage of ./monokuma:
  -alphabet string
    	alphabet used for key gen (default "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
  -auth string
    	auth token (empty for no auth)
  -gen-tries int
    	unique key gen number of tries (default 100)
  -key-size int
    	size of the short url keys (default 3)
  -port int
    	port at which to open the server (default 11037)
  -redis-ca string
    	CA certificate (in DER) (default "ca.der")
  -redis-cert string
    	client certificate (default "client.crt")
  -redis-db int
    	redis database
  -redis-host string
    	redis host (default "localhost")
  -redis-key string
    	client key (default "client.key")
  -redis-port int
    	redis port (default 6379)
  -redis-tls
    	use TLS
  -url string
    	the url with short urls (default "https://photos.sandyuraz.com/")

Redis credentials

You will have to set up environment variables for the Redis credentials:

• MONOKUMA_REDIS_USER - the username for Redis (default: user)
• MONOKUMA_REDIS_PASS - the password for Redis (default: pass)

An example is included in the script monokuma.example.sh. You can copy this script and modify it to your needs.

Secure Redis

These are all "sensible" defaults, so you don't need to change them unless you want to. If you use TLS, you will need to provide the CA certificate, client certificate, and client key. If you don't use TLS, you don't need to provide any of those.

Don't forget to enable secure monokuma through -redi-tls flag.

See other redis flags to change the host, port, and database.

Server flags

You can change the port that the server runs on through the -port flag. You can also change the URL that the short URLs redirect to through the -url flag.

You can also change the alphabet used for generating the short URLs through the -alphabet flag. The default is abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.

You can also change the size of the short URLs through the -key-size flag. The default is 3. This means that the short URLs will be 3 characters long. If you want to change the number of tries for generating a unique key, you can use the -gen-tries flag. The default is 100.

You can also set an auth token through the -auth flag. This will require you to provide the auth token in the URL Authorization header (Bearer AUTH_VALUE). The default is no auth.

Using the server

You can use the server by sending a POST request to the /create endpoint with the url to shorten in the body of the request. The server will return a raw string of the shortened URL.

Custom short URLs

You can also create custom short URLs by sending a POST request to the /create endpoint with the url to shorten in the body of the request and the custom short name with a query parameter key. The server will return a raw string of the shortened URL.

So, like this: /create?key=custom_short_name with the url to shorten in the body.

Caveats

Each unique URL will have a unique key. This means that if you shorten the same URL twice, you will get the same shortened URL. This is because the server will check if the URL already exists in the database and if it does, it will return the same shortened URL.

LICENSE

Apache License. Go wild.