93 lines
3.4 KiB
Python
93 lines
3.4 KiB
Python
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#!/usr/bin/env python3
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"""抓 SOEM 自己发的 EtherCAT 帧，对照裸帧格式。
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另开 pcap 句柄抓包，同时在同进程里跑 pysoem eeprom_read，hexdump 收发帧。
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用法：ecat_sniff.py [adapter-substr]"""
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import ctypes
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import struct
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import sys
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import threading
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import time
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import pysoem
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ECAT = b"\x88\xa4"
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class PcapPktHdr(ctypes.Structure):
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_fields_ = [("tv_sec", ctypes.c_long), ("tv_usec", ctypes.c_long),
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("caplen", ctypes.c_uint32), ("len", ctypes.c_uint32)]
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def main():
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substr = sys.argv[1] if len(sys.argv) > 1 else "I226"
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adapter = None
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for a in pysoem.find_adapters():
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desc = a.desc.decode() if isinstance(a.desc, bytes) else a.desc
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if substr.lower() in desc.lower():
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adapter = a
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break
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if adapter is None:
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raise SystemExit("适配器未找到")
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name = adapter.name.decode() if isinstance(adapter.name, bytes) else adapter.name
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wpcap = ctypes.WinDLL("wpcap.dll")
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wpcap.pcap_open_live.restype = ctypes.c_void_p
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wpcap.pcap_open_live.argtypes = [ctypes.c_char_p] + [ctypes.c_int] * 3 + [ctypes.c_char_p]
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wpcap.pcap_next_ex.restype = ctypes.c_int
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wpcap.pcap_next_ex.argtypes = [ctypes.c_void_p,
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ctypes.POINTER(ctypes.POINTER(PcapPktHdr)),
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ctypes.POINTER(ctypes.POINTER(ctypes.c_ubyte))]
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wpcap.pcap_close.restype = None
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wpcap.pcap_close.argtypes = [ctypes.c_void_p]
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errbuf = ctypes.create_string_buffer(256)
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handle = wpcap.pcap_open_live(name.encode(), 65535, 1, 50, errbuf)
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if not handle:
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raise SystemExit(f"pcap_open_live 失败: {errbuf.value.decode(errors='replace')}")
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def soem_work():
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try:
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master = pysoem.Master()
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master.open(adapter.name)
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master.config_init()
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slave = master.slaves[0]
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slave.eeprom_read(0)
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master.close()
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except Exception as e:
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print(f"soem_work: {type(e).__name__}: {e}")
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t = threading.Thread(target=soem_work, daemon=True)
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t.start()
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frames = []
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deadline = time.time() + 4.0
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ph = ctypes.POINTER(PcapPktHdr)()
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pd = ctypes.POINTER(ctypes.c_ubyte)()
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while time.time() < deadline and len(frames) < 8:
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r = wpcap.pcap_next_ex(handle, ctypes.byref(ph), ctypes.byref(pd))
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if r != 1:
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continue
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data = bytes(bytearray(pd[:ph.contents.caplen]))
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if len(data) >= 14 and data[12:14] == ECAT:
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frames.append(data)
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wpcap.pcap_close(handle)
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print(f"抓到 {len(frames)} 个 EtherCAT 帧")
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for i, f in enumerate(frames):
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src = ":".join(f"{b:02X}" for b in f[6:12])
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print(f"\n[{i}] len={len(f)} src={src}")
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for off in range(14, min(len(f), 14 + 48), 16):
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chunk = f[off:off + 16]
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print(f" +{off - 14:02d}: " + " ".join(f"{b:02X}" for b in chunk))
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# 解析前两个 datagram 头字段，确定头部布局
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elen = struct.unpack_from("<H", f, 14)[0] & 0x7FF
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print(f" ecat_hdr.len={elen} type={struct.unpack_from('<H', f, 14)[0] >> 12}")
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d = f[16:]
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if len(d) >= 12:
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cmd, idx, adp, ado, ln = struct.unpack_from("<BBHHH", d, 0)
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print(f" dgram: cmd=0x{cmd:02X} idx={idx} adp=0x{adp:04X} "
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f"ado=0x{ado:04X} len_field={ln} (len={ln & 0x7FF})")
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if __name__ == "__main__":
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main()
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