Replace custom python connector with ncat (#42)

* Replace custom made daemon with nmap-ncat

* Use stderr to log ncat output

* Refresh the branch

connector/Dockerfile

@@ -0,0 +1,9 @@
+FROM alpine:edge
+
+RUN apk add --no-cache coreutils nmap-ncat
+
+EXPOSE 2560/tcp
+
+SHELL ["/bin/ash", "-c"]
+CMD stty -F /dev/arduino -echo 115200 && \
+    ncat -n -k -l 2560 </dev/arduino >/dev/arduino

connector/README.md

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+# Use a container to implement a serial to net bridge
+
+This uses `ncat` by [namp](https://nmap.org/ncat/) to bridge a serial port to a network port. The serial port is passed to the Podman command (eg. `/dev/ttyUSB0`) and the network port is `2560`.
+
+> [!IMPORTANT]
+> Other variants of `nc` or `ncat` may not work as expected.
+
+## Build and run the container
+
+```bash
+$ podman buil -t dcc/bridge .
+$ podman run -d --device=/dev/ttyUSB0:/dev/arduino -p 2560:2560 --name dcc-bridge dcc/bridge
+```
+
+It can be tested with `telnet`:
+
+```bash
+$ telnet localhost 2560
+```

connector/simulator/Dockerfile

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+FROM dcc/bridge
+
+RUN apk update && apk add --no-cache qemu-system-avr \
+    && mkdir /io
+ADD start.sh /usr/local/bin
+ADD CommandStation-EX*.elf /io
+
+ENTRYPOINT ["/usr/local/bin/start.sh"]

connector/simulator/README.md

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+# Connector and AVR simulator
+
+> [!WARNING]
+> The simulator is intended for light development and testing purposes only and far from being a complete replacement for a real hardware.
+
+`qemu-system-avr` tries to use all the CPU cycles (leaving a CPU core stuck at 100%; limit CPU core usage to 10% via `--cpus 0.1`. It can be adjusted on slower machines.
+
+```bash
+$ podman build -t dcc/connector:sim .
+$ podman run --init --cpus 0.1 -d -p 2560:2560 dcc/connector:sim
+```
+
+All traffic will be collected on the container's `stderr` for debugging purposes.

connector/simulator/start.sh

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+#!/bin/sh
+
+PTY=0
+
+# if container is run with -ti pts/0 is already taken
+if [ -c /dev/pts/0 ]; then
+    PTY=1
+fi
+
+qemu-system-avr -machine uno -bios /io/CommandStation-EX*.elf -serial pty -daemonize
+ncat -n -k -l 2560 -o /dev/stderr </dev/pts/${PTY} >/dev/pts/${PTY}