Campus Planner Open Backend

Since the https://campus-planer.com/ domain hasn't been renewed, the "Campus Planer" app by the TH Köln does not work anymore. The goal of this project is to provide an open reverse-engineered backend to make the app usable again.

Installation

To compile the project, you will need shards and the crystal compiler, as well as the libraries bdwgc, openssl, pcre, pcre2 and libc (including their development headers).

If you meet these prequisites, simply run the following command: shards build --release --production

The resulting server binary will be located in the bin directory. This binary is the only file needed to run the server (aside from the aforementioned libraries).

Usage

Starting the web service

To start the web service, just execute the server binary. Optionally, you can set the CPOB_SERVER_HOST and CPOB_SERVER_PORT environment variables to set the application host (default: 0.0.0.0) and port (default: 3000).

CPOB_SERVER_HOST="0.0.0.0" CPOB_SERVER_PORT="3000" ./campus_planner_open_backend

Connecting the android app

Since the android app tries to communicate with the domain https://campus-planer.com, it will not magically connect to the web service. To do that, the android app will be patched.

This will require apktool (for patching), jdk (for signing) and adb (for installing). Also, you will need an https-enabled domain to reach your computer. For development purposes, you can use a service like ngrok (using command ngrok http 3000).

First, download the Campus Planer apk (for example from apkpure). To follow this guide, rename the file to CampusPlaner.apk.

Decode the downloaded apk into a folder using apktool:

apktool d CampusPlaner.apk

Replace all occurrences of the string "api.campus-planer.com" with your local domain:

sed -i "s/api.campus-planer.com/your-domain.net/g" ./CampusPlaner/smali/de/mdxdave/campusplaner/utils/Utils.smali

Encode the apk again using apktool:

apktool b ./CampusPlaner

To sign the final apk, a keystore first needs to be created:

keytool -genkey -v -keystore my-release-key.keystore -alias keystore -keyalg RSA -keysize 4096 -validity 10000000

You will be asked for a password (just use "password", you will only need it once again). Also, you will be asked for various information (name, city, ...). Just click enter until the question Is CN=Unknown, OU=Unknown, O=Unknown, L=Unknown, ST=Unknown, C=Unknown correct? comes up - which you need to answer with yes.

Finally, sign the resulting apk file:

jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore my-release-key.keystore CampusPlaner/dist/CampusPlaner.apk keystore

Here, you only need to type in your previously assigned password.

The final apk can now be installed on an android phone, but since it was signed with a self-signed certificate it must be installed through adb. The easiest way to do this is using adb-over-wifi. After you have connected to your device using adb, run:

adb install ./CampusPlaner/dist/CampusPlaner.apk

Development

TODO: Write development instructions here

Contributing

1. Fork it (https://gitlab.com/campus-verplaner/campus_planner_open_backend/-/forks/new)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• David Keller - creator and maintainer