feat: lora_bridge.py — two-way LoRa bridge over TCP (Tailscale, WireGuard, etc.)

lora_bridge.py

@@ -0,0 +1,155 @@
+#!/usr/bin/env python3
+"""Two-way LoRa bridge over TCP — relay packets between two DongLoRa dongles
+across any IP network (LAN, Tailscale, WireGuard, internet).
+
+Architecture:
+    [Radio A] <-USB-> [DongLoRa A] <-TCP-> [DongLoRa B] <-USB-> [Radio B]
+
+Usage:
+    # Machine A (server):
+    uv run examples/lora_bridge.py --mode server --port 9100
+
+    # Machine B (client):
+    uv run examples/lora_bridge.py --mode client --host machineA --port 9100
+
+Both sides:
+    - Open local DongLoRa, configure radio, start RX
+    - Forward received LoRa packets -> TCP -> remote side -> TX
+    - Bidirectional: both sides receive AND transmit
+"""
+# /// script
+# requires-python = ">=3.10"
+# dependencies = ["cobs", "pyserial"]
+# ///
+
+import argparse
+import serial
+import socket
+import struct
+import sys
+import threading
+import time
+
+sys.path.insert(0, __import__("pathlib").Path(__file__).parent.as_posix())
+import donglora as dl  # noqa: E402
+
+
+def tcp_send(sock: socket.socket, payload: bytes):
+    """Send a length-prefixed message over TCP."""
+    sock.sendall(struct.pack("<I", len(payload)) + payload)
+
+
+def tcp_recv(sock: socket.socket) -> bytes | None:
+    """Receive a length-prefixed message from TCP. Returns None on disconnect."""
+    header = b""
+    while len(header) < 4:
+        chunk = sock.recv(4 - len(header))
+        if not chunk:
+            return None
+        header += chunk
+    length = struct.unpack("<I", header)[0]
+    if length > 65536:
+        return None  # sanity check
+    data = b""
+    while len(data) < length:
+        chunk = sock.recv(length - len(data))
+        if not chunk:
+            return None
+        data += chunk
+    return data
+
+
+def radio_to_tcp(ser: serial.Serial, sock: socket.socket):
+    """Thread: forward LoRa RX packets to TCP."""
+    ser.timeout = 1
+    while True:
+        try:
+            data = dl.read_frame(ser)
+            if data is None:
+                continue
+            resp = dl.decode_response(data)
+            if resp["type"] == "RxPacket":
+                payload = resp["payload"]
+                print(f"  RX→TCP  len:{len(payload):3d}  rssi:{resp['rssi']}dBm")
+                tcp_send(sock, payload)
+        except (serial.SerialException, OSError) as e:
+            print(f"  [radio→tcp error: {e}]")
+            break
+
+
+def tcp_to_radio(ser: serial.Serial, sock: socket.socket):
+    """Thread: forward TCP packets to LoRa TX."""
+    while True:
+        try:
+            payload = tcp_recv(sock)
+            if payload is None:
+                print("  [TCP disconnected]")
+                break
+            print(f"  TCP→TX  len:{len(payload):3d}")
+            dl.send(ser, "Transmit", payload=payload)
+        except (serial.SerialException, OSError) as e:
+            print(f"  [tcp→radio error: {e}]")
+            break
+
+
+def run_bridge(ser: serial.Serial, sock: socket.socket):
+    """Run bidirectional bridge between serial and TCP."""
+    print("Bridge active — forwarding packets bidirectionally\n")
+
+    t1 = threading.Thread(target=radio_to_tcp, args=(ser, sock), daemon=True)
+    t2 = threading.Thread(target=tcp_to_radio, args=(ser, sock), daemon=True)
+    t1.start()
+    t2.start()
+
+    try:
+        while t1.is_alive() and t2.is_alive():
+            time.sleep(0.5)
+    except KeyboardInterrupt:
+        pass
+    print("\nBridge stopped.")
+
+
+def main():
+    parser = argparse.ArgumentParser(description="DongLoRa two-way LoRa bridge over TCP")
+    parser.add_argument("--mode", choices=["server", "client"], required=True)
+    parser.add_argument("--host", default="localhost", help="Remote host (client mode)")
+    parser.add_argument("--port", type=int, default=9100, help="TCP port")
+    parser.add_argument("--serial", default=None, help="Serial port (auto-detect if omitted)")
+    args = parser.parse_args()
+
+    try:
+        # Open DongLoRa
+        ser = dl.connect(args.serial)
+        print(dl.send(ser, "SetConfig", config=dl.DEFAULT_CONFIG))
+        print(dl.send(ser, "StartRx"))
+
+        # Establish TCP connection
+        if args.mode == "server":
+            print(f"Listening on port {args.port}...")
+            srv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            srv.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+            srv.bind(("0.0.0.0", args.port))
+            srv.listen(1)
+            sock, addr = srv.accept()
+            print(f"Connected from {addr}")
+            srv.close()
+        else:
+            print(f"Connecting to {args.host}:{args.port}...")
+            sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            sock.connect((args.host, args.port))
+            print("Connected")
+
+        run_bridge(ser, sock)
+
+    except KeyboardInterrupt:
+        print("\nInterrupted.")
+    except serial.SerialException as e:
+        print(f"\nSerial error: {e}", file=sys.stderr)
+        sys.exit(1)
+    except OSError as e:
+        print(f"\nNetwork error: {e}", file=sys.stderr)
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()