Initial commit

.gitignore

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+mqtt2exec

Makefile

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+all: mqtt2exec
+.PHONY: mqtt2exec
+
+mqtt2exec:
+	GOOS=linux GOARCH=arm go build -o mqtt2exec
+	arm-linux-gnueabihf-strip mqtt2exec

README.md

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+# Setup
+
+Root android with magisk
+
+Install busybox
+
+Create init script at `/data/adb/service.d/mqtt2exec.sh`
+
+```shell
+#!/system/bin/sh
+/system/xbin/start-stop-daemon -S -b /system/xbin/mqtt2exec -- tcp://ENDPOINT:1883 CLIENT_ID USERNAME PASSWORD
+exit 0
+```
+
+Set it as executable: `chmod +x /data/adb/service.d/mqtt2exec.sh`
+
+Install binary:
+
+```shell
+adb push mqtt2exec /storage/emulated/0/mqtt2exec
+adb shell
+su
+mv /storage/emulated/0/mqtt2exec /system/xbin/mqtt2exec
+chmod +x /system/xbin/mqtt2exec
+```
+
+Reboot :)

go.mod

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+module mqtt2exec
+
+go 1.23
+
+require (
+	github.com/eclipse/paho.mqtt.golang v1.5.0 // indirect
+	github.com/gorilla/websocket v1.5.3 // indirect
+	golang.org/x/net v0.27.0 // indirect
+	golang.org/x/sync v0.7.0 // indirect
+)

go.sum

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+github.com/eclipse/paho.mqtt.golang v1.5.0 h1:EH+bUVJNgttidWFkLLVKaQPGmkTUfQQqjOsyvMGvD6o=
+github.com/eclipse/paho.mqtt.golang v1.5.0/go.mod h1:du/2qNQVqJf/Sqs4MEL77kR8QTqANF7XU7Fk0aOTAgk=
+github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
+github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+golang.org/x/net v0.27.0 h1:5K3Njcw06/l2y9vpGCSdcxWOYHOUk3dVNGDXN+FvAys=
+golang.org/x/net v0.27.0/go.mod h1:dDi0PyhWNoiUOrAS8uXv/vnScO4wnHQO4mj9fn/RytE=
+golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M=
+golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=

main.go

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+package main
+
+import (
+	"encoding/json"
+	mqtt "github.com/eclipse/paho.mqtt.golang"
+	"log"
+	"os"
+	"os/exec"
+	"time"
+)
+
+type Result struct {
+	Command string
+	Output  string
+	Error   string
+}
+
+func main() {
+
+	var msgchan = make(chan mqtt.Message, 4)
+
+	if len(os.Args) < 5 {
+		log.Fatalf("Usage: %s <broker> <client_id> <username> <password>", os.Args[0])
+	}
+	opts := mqtt.NewClientOptions()
+	opts.AddBroker(os.Args[1])
+	opts.SetClientID(os.Args[2])
+	opts.SetUsername(os.Args[3])
+	opts.SetPassword(os.Args[4])
+	opts.SetDefaultPublishHandler(func(client mqtt.Client, msg mqtt.Message) {
+		msgchan <- msg
+	})
+	opts.OnConnect = connectHandler
+	opts.SetKeepAlive(20 * time.Second)
+	opts.SetAutoReconnect(true)
+	opts.SetWill("mqtt2exec/"+os.Args[2]+"/state", "offline", 1, false)
+	client := mqtt.NewClient(opts)
+	sleep := 1 * time.Second
+	for {
+		if token := client.Connect(); token.Wait() && token.Error() != nil {
+			log.Printf("Initial connection failed: %s", token.Error())
+			sleep *= 2
+			time.Sleep(sleep)
+		} else {
+			log.Printf("Connected to broker: %s", os.Args[1])
+			break
+		}
+	}
+	for {
+		msg := <-msgchan
+		if msg.Topic() == "mqtt2exec/"+os.Args[2]+"/run" {
+			cmd := exec.Command("/system/xbin/busybox", "ash", "-c", string(msg.Payload()))
+			cmd.Stdin = nil
+			out, err := cmd.CombinedOutput()
+			result := Result{
+				Command: string(msg.Payload()),
+				Output:  string(out),
+			}
+			if err != nil {
+				result.Error = err.Error()
+			}
+			resultJSON, _ := json.Marshal(result)
+			client.Publish("mqtt2exec/"+os.Args[2]+"/result", 0, false, resultJSON)
+		}
+	}
+
+}
+
+func connectHandler(c mqtt.Client) {
+	token := c.Subscribe("mqtt2exec/"+os.Args[2]+"/run", 2, nil)
+	token.Wait()
+	if token.Error() != nil {
+		log.Printf("mqtt2exec: Error subscribing to topic: %s", token.Error())
+	}
+	c.Publish("mqtt2exec/"+os.Args[2]+"/state", 1, false, "online")
+}