Update README.md

NfcReaderService.py

@@ -10,98 +10,69 @@ from pynput.keyboard import Controller
 
 from card_reader import read_card
 
-GET_UID = [0xFF, 0xCA, 0x00, 0x00, 0x00]
 
 class NfcReaderService:
     def __init__(self) -> None:
         self._is_running = True
         self._last_uid = None
         self._keyboard = Controller()
-        self._last_write = datetime.min
+        self._last_write = datetime(1900, 1, 1)
 
     def run(self) -> None:
         print("Reader ready.")
 
         while self._is_running:
             try:
-                self._poll_card()
+                time.sleep(0.1)
+                card_request = CardRequest(timeout=None)
+                print("Waiting for card...")
+                card_service = card_request.waitforcard()
+                connection = card_service.connection
+                print("Connected to card!")
+
+                try:
+                    connection.connect(CardConnection.T1_protocol)
+
+                    GET_UID = [0xFF, 0xCA, 0x00, 0x00, 0x00]
+                    uid, sw1, sw2 = connection.transmit(GET_UID)
+
+                    if sw1 != 0x90:
+                        raise CardConnectionException("UID read failed")
+
+                    uid_hex = toHexString(uid)
+
+                    if uid_hex == self._last_uid:
+                        connection.disconnect()
+                        time.sleep(0.5)
+                        self._last_uid = None
+                        continue
+
+                    self._last_uid = uid_hex
+
+                    user_id = read_card(connection)
+                    if user_id is not None:
+                        now = datetime.now()
+                        if now - self._last_write > timedelta(seconds=2):
+                            self._keyboard.type(str(user_id))
+                            self._last_write = now
+
+                except (CardConnectionException, NoCardException):
+                    pass
+
+                finally:
+                    try:
+                        connection.disconnect()
+                    except:
+                        pass
+
+                time.sleep(0.5)
 
             except (KeyboardInterrupt, SystemExit):
                 self.stop()
 
-            except Exception as e:
-                print(f"[ERROR] Unexpected failure: {e}")
-                time.sleep(1)
-
-    def _poll_card(self) -> None:
-        card_request = CardRequest(timeout=1)
-
-        try:
-            card_service = card_request.waitforcard()
-        except NoCardException:
-            self._last_uid = None
-            return
-
-        connection = card_service.connection
-
-        try:
-            connection.connect(CardConnection.T1_protocol)
-
-            uid_hex = self._read_uid(connection)
-            if uid_hex is None:
-                return
-
-            # Card still present and unchanged -> ignore
-            if uid_hex == self._last_uid:
-                return
-
-            self._last_uid = uid_hex
-
-            self._handle_card(connection)
-
-        except (CardConnectionException, NoCardException) as e:
-            print(f"[CARD ERROR] {e}")
-
-        finally:
-            try:
-                connection.disconnect()
-            except Exception:
-                pass
-
-    def _read_uid(self, connection) -> Optional[str]:
-        uid, sw1, sw2 = connection.transmit(GET_UID)
-
-        if sw1 != 0x90:
-            raise CardConnectionException("UID read failed")
-
-        return toHexString(uid)
-
-    def _handle_card(self, connection) -> None:
-        user_id = read_card(connection)
-
-        if user_id is None:
-            return
-
-        now = datetime.now()
-
-        # debounce keyboard output
-        if now - self._last_write < timedelta(seconds=2):
-            return
-
-        self._send_to_keyboard(user_id)
-        self._last_write = now
-
-    def _send_to_keyboard(self, user_id: str) -> None:
-        try:
-            self._keyboard.type(f"{user_id}\n")
-        except Exception as e:
-            print(f"[KEYBOARD ERROR] {e}")
-
     def stop(self) -> None:
-        print("Stopping NFC service.")
         self._is_running = False
 
-
 if __name__ == "__main__":
     service = NfcReaderService()
-    service.run()
+    service.run()

README.md

@@ -4,6 +4,14 @@ This repository contains the tooling around NFC readers/writers.
 
 Currently supported NFC Device: ACR 1252U
 
+## Installation
+
+Make sure you have the apt packages `python3-dev` and `libpcsclite-dev` installed before installing the dependencies from `requirements.txt`.
+
+## Configuration
+
+The root path of the installation (next to `NfcReaderService.py`) needs to contain the `hmac_key.txt`. The correct key can be retrieved from sys admin.
+
 ## Tools:
 
 - card_reader
@@ -17,6 +25,6 @@ Currently supported NFC Device: ACR 1252U
 ## Intended usage
 
 Start `NfcReaderService` on terminals where LAN team needs to verify guest identity, EZGG LAN manager then reads user ID from clipboard.
-`NfcReaderService` may be used as part of a systemd unit, to automate the startup process.
+`NfcReaderService` may be used as part of a systemd unit, to automate the startup process. See service file for additional info.
 
 Run `card_writer` when preparing tickets.

nfc-reader.service

@@ -1,10 +1,15 @@
+# THIS IS A USER-LEVEL SERVICE
+# ~/.config/systemd/user
+# systemctl --user daemon-reload
+# systemctl --user enable nfc-reader.service
+# systemctl --user start nfc-reader.service
+
 [Unit]
 Description=NFC Reader Service
-After=network.target
+After=graphical-session.target
 
 [Service]
 Type=simple
-User=ezgg
 WorkingDirectory=/opt/nfc
 
 ExecStart=/opt/nfc/venv/bin/python /opt/nfc/NfcReaderService.py
@@ -14,5 +19,8 @@ RestartSec=2
 
 Environment=PYTHONUNBUFFERED=1
 
+Environment=DISPLAY=:0
+Environment=XAUTHORITY=%h/.Xauthority
+
 [Install]
-WantedBy=multi-user.target
+WantedBy=default.target