feat: add barcode-websocket-server, webextension-tabfocus

LICENSE

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+Copyright 2024 s3lph
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+associated documentation files (the "Software"), to deal in the Software without restriction,
+including without limitation the rights to use, copy, modify, merge, publish, distribute,
+sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or
+substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
+OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# barcode-utils
+
+Collection of tools for our beverage POS kiosk system with barcode scanner:
+
+## barcode-websocket-server
+
+Service that binds to the USBHID barcode scanner and provides scan events via a websocket to web clients.
+
+Can also wake the screen via ydotool.
+
+## webextension-tabfocus
+
+Web Extension that injects a `window.extension_tabfocus()` function into browser tabs' Javscript context.
+
+When called, this function will cause the browser to switch to the calling tab.

barcode-websocket-server

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+#!/usr/bin/env python3
+
+import argparse
+import select
+import os
+import socket
+import struct
+import sys
+import time
+import webbrowser
+import queue
+from threading import Thread, Event
+from websockets.sync.server import serve
+
+import hid
+
+
+# struct input_event data to move the mouse
+# the timeval header uses native types, the event data uses platform-independent types
+# struct timeval { tv_sec = 0, tv_usec = 0 }
+evhdr = struct.pack('@LL', 0, 0)
+# struct input_event { time = evhdr, type = EV_REL(2), code = REL_X(0), value = 1/-1 }
+moveleft = evhdr + struct.pack('=HHi', 2, 0, -1)
+moveright = evhdr + struct.pack('=HHi', 2, 0, 1)
+# struct input_event { time = evhdr, type = EV_SYN(0), code = 0, value = 0 }
+evsyn = evhdr + struct.pack('=HHi', 0, 0, 0)
+
+
+class BarcodeServer:
+
+    def __init__(self, ns):
+        self.vid = int(ns.vid, 16)
+        self.pid = int(ns.pid, 16)
+        self.url = ns.url
+        self.aim = ns.aim
+        self.chars = ns.chars
+        self.q = queue.Queue()
+        self.e = Event()
+        self.shutdown = Event()
+
+        self.sock = None
+        if ns.ydotool_socket:
+            self.ydotool_socket = ns.ydotool_socket
+            self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
+
+        self.wshost = ns.websocket_host
+        self.wsport = ns.websocket_port
+
+    def start(self):
+        self.t_ws = Thread(target=self.serve, args=[])
+        self.t_ws.start()
+        self.t_bc = Thread(target=self.loop, args=[])
+        self.t_bc.start()
+        try:
+            self.t_ws.join()
+            self.t_bc.join()
+        except KeyboardInterrupt:
+            print('Shutting down...')
+            self.shutdown.set()
+            self.t_ws.join()
+            self.t_bc.join()
+
+    def ws_handler(self, websocket):
+        a = websocket.remote_address
+        if self.e.is_set():
+            return
+        self.e.set()
+        print(f'websocket connected: {a}')
+        try:
+            while not self.shutdown.is_set():
+                try:
+                    code = self.q.get(timeout=1)
+                    print(f'sending code {code} via ws {a}')
+                    try:
+                        websocket.send(code)
+                        self.q.task_done()
+                    except:
+                        self.q.put(code)
+                    finally:
+                        websocket.close()
+                        break
+                except queue.Empty:
+                    websocket.ping()
+        finally:
+            self.e.clear()
+            print(f'websocket {a} disconnected')
+
+    def serve(self):
+        with serve(self.ws_handler, self.wshost, self.wsport) as server:
+            server.serve_forever()
+
+    def loop(self):
+        while not self.shutdown.is_set():
+            try:
+                h = hid.device()
+                h.open(self.vid, self.pid)
+                print(f'Device manufacturer: {h.get_manufacturer_string()}')
+                print(f'Product: {h.get_product_string()}')
+                print(f'Serial Number: {h.get_serial_number_string()}')
+                while not self.shutdown.is_set():
+                    # Line from Honeywell scanner consists of:
+                    # - 0x02 (magic?)
+                    # - 1 byte payload length (without AIM, so 13 for EAN-13)
+                    # - 3 bytes AIM, e.g. "]E0" for EAN-13
+                    # - payload bytes
+                    # - Rest is filled with zeros
+                    hidmsg = h.read(255, 1000)
+                    try:
+                        flag = hidmsg.index(ord(']'))
+                    except ValueError:
+                        continue
+                    if len(hidmsg) < flag+3:
+                        continue
+                    try:
+                        end = hidmsg[flag:].index(0)
+                        end += flag
+                    except ValueError:
+                        continue
+                    aim = bytes(hidmsg[flag:flag+3]).decode()
+                    data = bytes(hidmsg[flag+3:end]).decode().strip()
+                    print(aim, hidmsg[flag+3:end], data)
+                    if not aim.startswith(self.aim):
+                        print('aim mismatch')
+                        continue
+                    if any(filter(lambda c: c not in self.chars, data)):
+                        print('chars mismatch')
+                        continue
+                    url = self.url.format(data)
+                    if self.sock:
+                        try:
+                            print(f'Moving mouse via ydotoold')
+                            self.sock.sendto(moveleft, self.ydotool_socket)
+                            self.sock.sendto(evsyn, self.ydotool_socket)
+                            self.sock.sendto(moveright, self.ydotool_socket)
+                            self.sock.sendto(evsyn, self.ydotool_socket)
+                        except Exception as e:
+                            print(e)
+                    if not self.e.is_set():
+                        with self.q.mutex:
+                            print('clearing queue')
+                            self.q.queue.clear()
+                        print(f'Opening URL {url}')
+                        webbrowser.open(url, new=2)
+                    self.q.put(data)
+                    print(f'enqued {data}')
+            except Exception as e:
+                print(e)
+                time.sleep(5)
+
+
+def main():
+    ap = argparse.ArgumentParser(sys.argv[0], description='Opens a website when a barcode is scanned with an USB-HID barcode scanner.')
+    ap.add_argument('--url', '-u', type=str, help='The URL to open. "{}" is replaced by the barcode data. Default: http://localhost/?ean={}', default='http://localhost/?ean={}')
+    ap.add_argument('--vid', '-v', type=str, help='The USB vendor ID. Default: 0c2e', default='0c2e')
+    ap.add_argument('--pid', '-p', type=str, help='The USB product ID. Default: 0b07', default='0b07')
+    ap.add_argument('--aim', '-A', type=str, help='AIM filter prefix, e.g. "]E0" for EAN13, "]E" for all EAN variants, or "]" for all barcodes. Default: "]E"', default=']E')
+    ap.add_argument('--chars', '-C', type=str, help='Permitted characters.  Defaults to "0123456789"', default='0123456789')
+    ap.add_argument('--ydotool-socket', '-Y', type=str, help='If provided, the ydotool socket to wake the screen.')
+    ap.add_argument('--websocket-host', '-w', type=str, help='Websocket host to listen on.  Defaults to "localhost"', default='localhost')
+    ap.add_argument('--websocket-port', '-W', type=int, help='Websocket port to listen on.  Defaults to 47808', default=47808)
+    ns = ap.parse_args()
+
+    BarcodeServer(ns).start()
+
+
+if __name__ == '__main__':
+    main()

webextension-tabfocus/manifest.json

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+{
+    "manifest_version": 2,
+    "name": "tabfocus",
+    "version": "0.1",
+    "description": "Allow tabs to request focus",
+    "permissions": [
+	"tabs",
+	"<all_urls>"
+    ],
+    "content_scripts": [
+	{
+	    "matches": ["<all_urls>"],
+	    "js": ["tabfocus_content.js"]
+	}
+    ],
+    "background": {
+	"scripts": ["tabfocus_background.js"],
+	"persistent": false,
+	"type": "module"
+    },
+    "applications": {
+	"gecko": {
+	    "id": "tabfocus@ccc-basel.ch",
+	    "strict_min_version": "1.0"
+	}
+    }
+}

webextension-tabfocus/tabfocus_background.js

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+browser.runtime.onMessage.addListener((request, sender, responsewi) => {
+    browser.tabs.update(sender.tab.id, {active: true});
+    browser.windows.update(sender.tab.windowId, {focused: true});
+});

webextension-tabfocus/tabfocus_content.js

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+function tabfocus() {
+    browser.runtime.sendMessage({focus: 1});
+}
+exportFunction(tabfocus, window, { defineAs: "extension_tabfocus" });