clink

Dead-simple URL shortener written in pure C with Mongoose

Maintenance Note

This project is still maintained! Occasional certificate expirations may occur, this is due to disputes between my ISP and I regarding server hosting and certificate renewal. Please be patient, I have a life. :)

Differences from link

• Much smaller executable size
• Longer, more "secure" deletion keys
• No external libraries
• Speedier
• Smaller resource footprint

Self-Hosting

You can host this yourself.

Note: all commands here are done as root.

Building & Installing

To build this project, you'll need a libc implementation (only tested with glibc), optionally a separate libcrypt implementation, and Git. Most Linux distributions should have all of these by default, but in case yours doesn't:

• pacman -S glibc libxcrypt git
• emerge --ask sys-libs/glibc dev-vcs/git
• apt install glibc git

1. Clone this repository:

git clone https://git.swurl.xyz/swirl/clink && cd clink

2. Compile:

make

3. Now, you need to install. NGINX and systemd files are provided in this project; you may choose not to install them.

For all install commands, you may optionally provide prefix and DESTDIR options. This is useful for packagers; i.e. for a PKGBUILD: make prefix=/usr DESTDIR=${pkgdir} install.

Available install commands are as follows:

• make install installs the executable, NGINX, and systemd files.
• make install-bin installs the executable file.
• make install-systemd installs the systemd file, as well as its environment file.
• make install-nginx installs the NGINX file.

For example, on a non-systemd system using NGINX, you would run make install-bin install-nginx.

4. If using systemd, change the environment file to reflect your desired options:

vim /etc/clink.conf

5. You can now enable and start the service:

systemctl enable --now clink

The server should now be running on localhost at port 8080.

NGINX Reverse Proxy

An NGINX file is provided with this project.

For this, you'll need NGINX (obviously), certbot, and its NGINX plugin. Most Linux distributions should have these in their repositories, i.e.:

• pacman -S nginx certbot-nginx
• emerge --ask www-servers/nginx app-crypt/certbot-nginx
• apt install nginx python-certbot-nginx

This section assumes you've already followed the last.

1. Change the domain in the NGINX file:

sed -i 's/your.doma.in/[DOMAIN HERE]' /etc/nginx/sites-available/clink

2. Enable the site:

ln -s /etc/nginx/sites-{available,enabled}/clink

3. Enable HTTPS for the site:

certbot --nginx -d [DOMAIN HERE]

4. Enable and start NGINX:

systemctl enable --now nginx

If it's already running, reload:

systemctl reload nginx

Your site should be running at https://your.doma.in. Test it by going there, and trying the examples. If they don't work, open an issue.

Contributions

Contributions are always welcome.

clinkctl

clink contains an additional clinkctl utility.

Run clinkctl for commands and syntax help.

FAQ

A user has made a link to a bad site! What do I do?

Deleting a link can be done simply by running:

rm /srv/clink/*/BADLINKHERE

Replace /srv/clink with whatever your data directory is.

Can I prevent users from making links to specific sites (i.e. illegal content)? Can I blacklist certain words from being used in short links?

No. While it might be possible through some NGINX stuff, this is not supported nor it is encouraged.

Is this an IP grabber?

No, unless someone links to grabify or something. If access logs are turned on, then the server administrator can see your IP, but management of access logs is up to them.

Can I use this without a reverse proxy?

Probably, I don't know. Won't have HTTPS though, so either way, I heavily recommend you use a reverse proxy.

What's the seed for?

The seed is used for generating deletion keys. Do not share it whatsoever.

What operating systems are supported?

I've only tested it on my Arch Linux server, but it should work perfectly fine on all Linux distributions. Probably doesn't work on Windows.

Can I run this in a subdirectory of my site?

Yes. Simply put the proxy_pass directive in a subdirectory, i.e.:

location /shortener {
    proxy_pass http://localhost:8080;
}

Why'd you make this?

While the original link was by far the best link shortener I could find, it had a few problems:

• No query-string support: had to make POST requests
• Didn't decode URLs
• SQLite is not the greatest storage method out there
• No pre-provided systemd or NGINX files
• No install target for the makefile

The first two are mostly problems when using them with specific services; i.e. PrivateBin, which expects to be able to use query-strings and encoded URLs.

So, seeing those problems, I decided to fork it. However, Go is absolute anal cancer (~300 line file results in a 8MB executable), so I decided to write it in C (and now, it's ~270 lines and results in a ~60KB executable). Also, I like C.