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"""Libknot probe interface wrapper.
## Example ##
import libknot.probe
#import libknot
#libknot.Knot("/usr/lib/libknot.so")
probe = libknot.probe.KnotProbe("/run/knot")
data = libknot.probe.KnotProbeDataArray(8)
while (True):
if probe.consume(data) > 0:
for item in data:
print(item)
"""
import ctypes
import enum
import socket
import libknot
class KnotProbeDataProto(enum.IntEnum):
"""Libknot probe transport protocol types."""
UDP = 0
TCP = 1
TLS = 2
HTTPS = 3
QUIC = 4
class KnotProbeDataDNSHdr(ctypes.BigEndianStructure):
"""DNS message header."""
_fields_ = [('id', ctypes.c_ushort),
('flag_qr', ctypes.c_ubyte, 1),
('opcode', ctypes.c_ubyte, 4),
('flag_aa', ctypes.c_ubyte, 1),
('flag_tc', ctypes.c_ubyte, 1),
('flag_rd', ctypes.c_ubyte, 1),
('flag_ra', ctypes.c_ubyte, 1),
('flag_z', ctypes.c_ubyte, 1),
('flag_ad', ctypes.c_ubyte, 1),
('flag_cd', ctypes.c_ubyte, 1),
('rcode', ctypes.c_ubyte, 4),
('questions', ctypes.c_ushort),
('answers', ctypes.c_ushort),
('authorities', ctypes.c_ushort),
('additionals', ctypes.c_ushort)]
class KnotProbeData(ctypes.Structure):
"""Libknot probe data unit."""
ADDR_MAX_SIZE = 16
QNAME_MAX_SIZE = 255
EDE_NONE = 65535
_fields_ = [('ip', ctypes.c_ubyte),
('proto', ctypes.c_ubyte),
('local_addr', ctypes.c_ubyte * ADDR_MAX_SIZE),
('local_port', ctypes.c_ushort),
('remote_addr', ctypes.c_ubyte * ADDR_MAX_SIZE),
('remote_port', ctypes.c_ushort),
('reply_hdr', KnotProbeDataDNSHdr),
('reply_size', ctypes.c_ushort),
('reply_rcode', ctypes.c_ushort),
('reply_ede', ctypes.c_ushort),
('tcp_rtt', ctypes.c_uint),
('edns_options', ctypes.c_uint),
('edns_payload', ctypes.c_ushort),
('edns_version', ctypes.c_ubyte),
('edns_present', ctypes.c_ubyte, 1),
('edns_flag_do', ctypes.c_ubyte, 1),
('_reserved_', ctypes.c_ubyte, 6),
('query_hdr', KnotProbeDataDNSHdr),
('query_size', ctypes.c_ushort),
('query_class', ctypes.c_ushort),
('query_type', ctypes.c_ushort),
('query_name_len', ctypes.c_ubyte),
('query_name', ctypes.c_ubyte * (QNAME_MAX_SIZE))]
def addr_str(self, addr: ctypes.c_ubyte * ADDR_MAX_SIZE) -> str:
"""Converts IPv4 or IPv6 address from binary to text form."""
if self.ip == 4:
buffer = ctypes.create_string_buffer(4)
ctypes.memmove(buffer, ctypes.addressof(addr), 4)
return socket.inet_ntop(socket.AF_INET, buffer)
else:
return socket.inet_ntop(socket.AF_INET6, addr)
def qname_str(self) -> str:
"""Returns QNAME in text form."""
string = str()
pos = 0
while pos < self.query_name_len:
label_len = self.query_name[pos]
if label_len == 0:
if self.query_name_len == 1:
string += "."
break
pos += 1
label_end = pos + label_len
while pos < label_end:
string += chr(self.query_name[pos])
pos += 1
string += "."
return string
def __str__(self) -> str:
"""Returns data unit in pre-formatted simple text form."""
string = str()
string += "%s@%u > " % (self.addr_str(self.remote_addr), self.remote_port)
string += "%s@%u " % (self.addr_str(self.local_addr), self.local_port)
string += "%s, " % ("UDP" if self.proto == 0 else "TCP")
string += "%s %s" % (self.qname_str(), libknot.Knot.rtype_str(self.query_type))
if self.edns_present == 1 and self.edns_flag_do == 1:
string += " DO"
string += ", %s" % libknot.Knot.rcode_str(self.reply_rcode)
return string
class KnotProbeDataArray(object):
"""Libknot probe data unit array."""
def __init__(self, size: int = 1) -> None:
"""Creates a data array of a given size."""
if size < 1 or size > 255:
raise ValueError
data_array = KnotProbeData * size
self.data = data_array()
self.capacity = size
self.used = 0
self.pos = 0
def __getitem__(self, i: int) -> KnotProbeData:
"""Returns a data unit at a specified position."""
if i < 0 or i >= self.capacity:
raise ValueError
return self.data[i]
def __len__(self) -> int:
"""Returns currently used size of the array."""
return self.used
def __iter__(self):
"""Initializes the array iterator."""
self.pos = 0
return self
def __next__(self) -> KnotProbeData:
"""Increments the array iterator."""
if self.used == 0 or self.pos == self.used:
raise StopIteration
else:
data = self.data[self.pos]
self.pos += 1
return data
class KnotProbe(object):
"""Libknot probe consumer interface."""
ALLOC = None
FREE = None
CONSUME = None
SET_CONSUMER = None
def __init__(self, path: str = "/run/knot", idx: int = 1) -> None:
"""Initializes a probe channel at a specified path with a channel index."""
if not KnotProbe.ALLOC:
libknot.Knot()
KnotProbe.ALLOC = libknot.Knot.LIBKNOT.knot_probe_alloc
KnotProbe.ALLOC.restype = ctypes.c_void_p
KnotProbe.FREE = libknot.Knot.LIBKNOT.knot_probe_free
KnotProbe.FREE.argtypes = [ctypes.c_void_p]
KnotProbe.CONSUME = libknot.Knot.LIBKNOT.knot_probe_consume
KnotProbe.CONSUME.restype = ctypes.c_int
KnotProbe.CONSUME.argtypes = [ctypes.c_void_p, ctypes.c_void_p, \
ctypes.c_ubyte, ctypes.c_int]
KnotProbe.SET_CONSUMER = libknot.Knot.LIBKNOT.knot_probe_set_consumer
KnotProbe.SET_CONSUMER.restype = ctypes.c_int
KnotProbe.SET_CONSUMER.argtypes = [ctypes.c_void_p, ctypes.c_char_p, \
ctypes.c_ushort]
self.obj = KnotProbe.ALLOC()
ret = KnotProbe.SET_CONSUMER(self.obj, path.encode(), idx)
if ret != 0:
err = libknot.Knot.STRERROR(ret)
raise RuntimeError(err.decode())
def __del__(self) -> None:
"""Deinitializes a probe channel."""
KnotProbe.FREE(self.obj)
def consume(self, data: KnotProbeDataArray, timeout: int = 1000) -> int:
'''Consumes data units from a channel and stores them in data array.
Returns the number of consumed data units.
'''
ret = KnotProbe.CONSUME(self.obj, data.data, data.capacity, timeout)
if ret < 0:
err = libknot.Knot.STRERROR(ret)
raise RuntimeError(err.decode())
data.used = ret
return ret
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