MeLaan

This is a small project that makes it easier for me to open the apartment door when someone is delivering a package and I am not at home. There is a Raspberry Pi Pico W that is wired to the door buzzer circuit, which makes a persistent TLS connection to a small Golang server running on a VPS, which proxies door opening requests submitted via Tasker on Android and exposes status monitoring.

It has some problems.

Usage

Create some files in the repository:

• CONTROLLER_PASSWORD: a randomly generated password
• SERVER_ADDRESS: IPv4 address and port separated by colon
• WIFI_CREDENTIALS: wireless SSID and password separated by colon
• melaan-ca.crt: Self-signed certificate authority, PEM
• melaan-server.crt: Leaf certificate, PEM
• melaan-server.key: Leaf private key, PEM
• melaan-ca.der: DER version of the CA
• .env: values for CONTROLLER_PASSWORD, REMOTE_PASSWORD, and REMOTE_PASSWORD_READONLY (all randomly generated passwords) as well as SERVER_PORT (probably >=1025)

Here's an example, though you would certainly have to adjust the IP/port and wifi credentials at least:

head -c20 /dev/urandom | xxd -p > CONTROLLER_PASSWORD
echo "$(curl -4 https://icanhazip.com):52739" > SERVER_ADDRESS
echo xfinitywifi:password > WIFI_CREDENTIALS
step certificate create melaan-ca melaan-ca.crt melaan-ca.key --profile root-ca --no-password --insecure --not-after 876000h
step certificate create melaan-server melaan-server.crt melaan-server.key --profile leaf --ca melaan-ca.crt --ca-key melaan-ca.key --no-password --insecure --not-after 876000h
step certificate format melaan-ca.crt > melaan-ca.der
echo CONTROLLER_PASSWORD="$(< CONTROLLER_PASSWORD)" >> .env
echo REMOTE_PASSWORD="$(head -c20 /dev/urandom | xxd -p)" >> .env
echo REMOTE_PASSWORD_READONLY="$(head -c20 /dev/urandom | xxd -p)" >> .env
echo SERVER_PORT="$(awk -F: '{print $2}' SERVER_ADDRESS)" >> .env

The controller will run on the Raspberry Pi and connect to a local wireless network, then contact the server at the provided IPv4 address. The controller uses CONTROLLER_PASSWORD to authenticate to the server, while door-opening and health-check clients use REMOTE_PASSWORD and REMOTE_PASSWORD_READONLY to authenticate to the server.

You can run server.go on a standard Linux server. Copy the .env file as well as the leaf cert and key to it first.

You can run controller.py using a standard Linux Python installation, for testing. To install onto the Raspberry Pi, install MicroPython to the board via UF2, then once you have make shell working (install picocom and udev rules, make sure you have a data-capable microUSB cable), run make install to copy the script and necessary files onto the filesystem. Then terminate the shell to restart into the controller code.

To update the code, interrupt with ctrl-C so that you get back to the shell, then make install and restart again. If it gets completely bricked, see wiping flash from UF2 and reinstall MicroPython.