catarrh
7d8dca1ffd
GsmtapListener.stop() closed the UDP socket permanently, but start() only set _running=True without recreating it. Second capture session would silently spin on the dead socket (OSError → None → continue). - Add _closed flag to GsmtapReceiver, set in close() - Store bind_port in GsmtapListener for socket recreation - start() recreates GsmtapReceiver only if previous one was closed - Uses getattr for backward compat with test fakes
114 lines
3.7 KiB
Python
114 lines
3.7 KiB
Python
"""GSMTAP UDP sender for Wireshark integration.
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GSMTAP header format (big-endian, 16 bytes). Based on libosmocore's gsmtap.h.
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"""
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import struct
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import socket
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GSMTAP_VERSION = 0x02
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GSMTAP_HDR_LEN = 4 # in 32-bit words (16 bytes)
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GSMTAP_TYPE_SIM = 0x04
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GSMTAP_SIM_APDU = 0x00
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GSMTAP_SIM_ATR = 0x01
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GSMTAP_SIM_PPS_REQ = 0x02
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GSMTAP_SIM_PPS_RSP = 0x03
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# Custom sub-types from the sigrok-iso7816-stream decoder
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# (github.com/anttro/sigrok_iso7816_stream): line-level events.
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GSMTAP_SIM_RST_EVENT = 0x10
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GSMTAP_SIM_VCC_EVENT = 0x11
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# Per-packet flags carried in the GSMTAP header `res` byte (libosmocore
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# gsmtap.h). sigrok-iso7816-stream sets BAD_FCS on a desynced TPDU.
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GSMTAP_FLAG_BAD_FCS = 0x01
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GSMTAP_UDP_PORT = 4729
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_GSMTAP_HDR_FMT = '!BBBBHBBIBBBB' # 16 bytes, big-endian
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_GSMTAP_HDR_SIZE = struct.calcsize(_GSMTAP_HDR_FMT)
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def build_gsmtap_packet(sub_type, data, slot_nr=0):
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"""Build a GSMTAP packet as bytes.
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Returns *gsmtap_hdr* + *data* as a single bytes object.
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"""
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hdr = struct.pack(
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_GSMTAP_HDR_FMT,
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GSMTAP_VERSION, # version
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GSMTAP_HDR_LEN, # hdr_len (in 32-bit words)
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GSMTAP_TYPE_SIM, # type
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0, # timeslot
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0, # arfcn
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0, # noise_db
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0, # signal_db
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0, # frame_number
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sub_type, # sub_type
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0, # antenna_nr
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slot_nr, # sub_slot
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0, # res
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)
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return hdr + data
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class GsmtapSender:
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"""Send ATR/APDU data as GSMTAP UDP packets."""
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def __init__(self, host='127.0.0.1', port=GSMTAP_UDP_PORT):
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self._addr = (host, port)
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self._sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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def send_atr(self, data, slot_nr=0):
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packet = build_gsmtap_packet(GSMTAP_SIM_ATR, data, slot_nr)
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self._sock.sendto(packet, self._addr)
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def send_apdu(self, data, slot_nr=0):
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packet = build_gsmtap_packet(GSMTAP_SIM_APDU, data, slot_nr)
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self._sock.sendto(packet, self._addr)
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def close(self):
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self._sock.close()
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class GsmtapReceiver:
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"""Receive GSMTAP-SIM packets over UDP (compatible with simtrace2-sniff)."""
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def __init__(self, bind_ip='127.0.0.1', bind_port=GSMTAP_UDP_PORT):
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self._sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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self._sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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self._sock.bind((bind_ip, bind_port))
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self._sock.settimeout(1.0)
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self._closed = False
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def read_packet(self):
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"""Block until a GSMTAP-SIM packet arrives.
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Returns ``(sub_type, data, flags)`` on success or ``(None, None, 0)``
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on timeout. *sub_type* is ``GSMTAP_SIM_ATR``/``GSMTAP_SIM_APDU`` or
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a custom sub-type; *flags* are the per-packet bits from the GSMTAP
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header ``res`` byte (see ``GSMTAP_FLAG_*``).
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Raises ``ValueError`` for non-SIM or unknown GSMTAP packets.
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"""
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try:
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packet, addr = self._sock.recvfrom(65536)
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except (socket.timeout, OSError):
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return None, None, 0
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if len(packet) < _GSMTAP_HDR_SIZE:
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raise ValueError(f'GSMTAP packet too short: {len(packet)} bytes')
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(version, hdr_len, pkt_type, _timeslot, _arfcn, _noise, _signal,
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_frame, sub_type, _antenna, sub_slot, res) = \
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struct.unpack(_GSMTAP_HDR_FMT, packet[:_GSMTAP_HDR_SIZE])
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if pkt_type != GSMTAP_TYPE_SIM:
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raise ValueError(f'Not a GSMTAP SIM packet (type={pkt_type})')
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data = packet[_GSMTAP_HDR_SIZE:]
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return sub_type, data, res
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def close(self):
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self._sock.close()
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self._closed = True
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