From 3f739baab456c2cc977f11090381d1f61eb023c4 Mon Sep 17 00:00:00 2001
From: xengineering <mail2xengineering@protonmail.com>
Date: Thu, 15 Oct 2020 12:48:30 +0200
Subject: Split Executable to reduce root-priviledged Code Execution

---
 .gitignore                 |  1 -
 README.md                  | 32 ++++++++++++++++++++++++++++----
 barcode_scanner_daemon.py  | 42 ++++++++++++++++++++++++++++++++++++++++++
 barcode_transmit_daemon.py | 38 ++++++++++++++++++++++++++++++++++++++
 config.json                |  6 +++++-
 main.py                    | 29 -----------------------------
 6 files changed, 113 insertions(+), 35 deletions(-)
 create mode 100755 barcode_scanner_daemon.py
 create mode 100644 barcode_transmit_daemon.py
 delete mode 100755 main.py

diff --git a/.gitignore b/.gitignore
index 0f4de50..bee8a64 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1 @@
-first_test.py
 __pycache__
diff --git a/README.md b/README.md
index c1f49b8..96b137f 100644
--- a/README.md
+++ b/README.md
@@ -5,9 +5,33 @@
 A service that makes barcode scanners available on the network for IoT use.
 
 
+## Usage
+
+1. Adapt config.json file if needed.
+2. Run ```sudo python barcode_scanner_daemon.py```
+3. Run ```python barcode_transmit_daemon.py```
+4. Listen to MQTT output (e.g. with ```mosquitto_sub -h localhost -t "xengineering.eu/iot-barcode-scanner"```)
+
+
 ## Milestones
 
-- MVP: Forward keyboard/scanner input to MQTT topic
-- Read MQTT connection details from config file
-- Disable scanner as regular input source and bind it only to the service
-- Package it for Arch Linux
+- [x] MVP: Forward keyboard/scanner input to MQTT topic
+- [x] Use config file
+- [x] Disable scanner as regular input source and bind it only to the service
+- [x] Split into two executables to reduce root-priviledged code
+- [ ] Implement systemd services
+- [ ] Write Makefile for easy installation
+- [ ] Implement auto discovery of barcode scanners
+- [ ] Package it for Arch Linux
+
+
+## Dependencies
+
+- ```python-paho-mqtt```
+- ```python-evdev```
+
+
+## Links
+
+- [python-evdev documentation](https://python-evdev.readthedocs.io/en/latest/index.html)
+- [Please answer this guy!](https://stackoverflow.com/questions/49850238/redirect-usb-hid-barcode-output-to-dev-tty-device)
diff --git a/barcode_scanner_daemon.py b/barcode_scanner_daemon.py
new file mode 100755
index 0000000..38f0514
--- /dev/null
+++ b/barcode_scanner_daemon.py
@@ -0,0 +1,42 @@
+#!/usr/bin/python3
+
+
+"""Executable to read the Key Events from the Barcode Scanner (root Priviledges necessary)"""
+
+
+import evdev
+import os
+
+import iot_barcode_scanner.config as config
+
+
+def main():
+
+    try:
+        # read config
+        cfg = config.get_config()
+        fifo_path = cfg["scanner"]["fifo_path"]
+        event_device_path = cfg["scanner"]["evdev_path"]
+
+        # prepare fifo
+        os.makedirs(os.path.dirname(fifo_path), exist_ok=True)
+        os.mkfifo(fifo_path)
+
+        barcode_scanner = evdev.InputDevice(event_device_path)
+        with barcode_scanner.grab_context():
+            for event in barcode_scanner.read_loop():
+                if event.type == evdev.ecodes.EV_KEY:
+                    eventdata = evdev.categorize(event)
+                    if eventdata.keystate:
+                        with open(fifo_path, "a") as fifo:
+                            fifo.append(eventdata.keycode)
+
+    except KeyboardInterrupt:
+        pass
+
+    finally:
+        os.remove(fifo_path)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/barcode_transmit_daemon.py b/barcode_transmit_daemon.py
new file mode 100644
index 0000000..4edb72d
--- /dev/null
+++ b/barcode_transmit_daemon.py
@@ -0,0 +1,38 @@
+#!/usr/bin/python3
+
+
+"""Executable to transmit the Barcode Data to MQTT without root Priviledges"""
+
+
+import iot_barcode_scanner.config as config
+from iot_barcode_scanner.mqtt import MqttService
+
+
+def main():
+    try:
+
+        # read config
+        cfg = config.get_config()
+        fifo_path = cfg["scanner"]["fifo_path"]
+        topic = cfg["mqtt"]["topic"]
+
+        # setup mqtt
+        mqtt_service = MqttService(cfg)
+        mqtt_service.run()
+
+        while True:
+            with open(fifo_path, "r") as fifo:
+                text = fifo.read()
+            mqtt_service.client.publish(
+                topic,
+                payload=text,
+                qos=0,
+                retain=False
+            )
+
+    except KeyboardInterrupt:
+        pass
+
+
+if __name__ == "__main__":
+    main()
diff --git a/config.json b/config.json
index 3f046a3..223dbcf 100644
--- a/config.json
+++ b/config.json
@@ -2,6 +2,10 @@
     "mqtt":{
         "broker":"127.0.0.1",
         "port":1883,
-        "topic":"eu/xengineering/iot-barcode-scanner"
+        "topic":"xengineering.eu/iot-barcode-scanner"
+    },
+    "scanner":{
+        "evdev_path":"/dev/input/event4",
+        "fifo_path":"/tmp/xengineering.eu/iot-barcode-scanner/scanner_fifo"
     }
 }
diff --git a/main.py b/main.py
deleted file mode 100755
index b50962a..0000000
--- a/main.py
+++ /dev/null
@@ -1,29 +0,0 @@
-#!/usr/bin/python3
-
-
-"""Main executable for the Package / Service"""
-
-
-import iot_barcode_scanner as ibs
-
-
-def main():
-    try:
-        config = ibs.get_config()
-        mqtt_service = ibs.MqttService(config)
-        mqtt_service.run()
-        print("Starting Service")
-        while True:
-            text = input()
-            mqtt_service.client.publish(
-                config["mqtt"]["topic"],
-                payload=text,
-                qos=0,
-                retain=False
-            )
-    except KeyboardInterrupt:
-        print("Service stopped")
-
-
-if __name__ == "__main__":
-    main()
-- 
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