Vehicle Identification & Routing

import socket, struct

# DoIP VehicleIdentificationRequest: broadcast on UDP 13400
# Tester sends; all DoIP entities (ECU gateway) respond

def discover_doip_entities(broadcast_ip="255.255.255.255", timeout=2.0):
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
    sock.settimeout(timeout)

    # VehicleIdentificationRequest (payload type 0x0001, no payload)
    request = struct.pack(">BBHI", 0x02, 0xFD, 0x0001, 0)
    sock.sendto(request, (broadcast_ip, 13400))

    entities = []
    try:
        while True:
            data, addr = sock.recvfrom(65535)
            entity = parse_vehicle_id_response(data, addr[0])
            if entity:
                entities.append(entity)
    except socket.timeout:
        pass
    finally:
        sock.close()
    return entities

def parse_vehicle_id_response(data: bytes, src_ip: str) -> dict:
    if len(data) < 8: return None
    ver, inv_ver, ptype, plen = struct.unpack(">BBHI", data[:8])
    if ptype != 0x0004: return None   # not VehicleIdentificationResponse
    payload = data[8:8+plen]
    if len(payload) < 33: return None
    vin  = payload[0:17].decode('ascii', errors='replace')
    la   = struct.unpack(">H", payload[17:19])[0]
    eid  = payload[19:25].hex(':')   # Entity ID (MAC address)
    gid  = payload[25:31].hex(':')   # Group ID
    return {"vin": vin, "logical_addr": f"0x{la:04X}", "eid": eid, "ip": src_ip}

# Typical output for a test ECU:
# {"vin": "WVWZZZ1JZYW000001", "logical_addr": "0x0001", "eid": "00:1a:2b:3c:4d:01", "ip": "169.254.1.100"}