def from_wire(rdclass, rdtype, wire, current, rdlen, origin=None):
"""Build an rdata object from wire format
This function attempts to dynamically load a class which
implements the specified rdata class and type. If there is no
class-and-type-specific implementation, the GenericRdata class
is used.
Once a class is chosen, its from_wire() class method is called
with the parameters to this function.
@param rdclass: The rdata class
@type rdclass: int
@param rdtype: The rdata type
@type rdtype: int
@param wire: The wire-format message
@type wire: string
@param current: The offet in wire of the beginning of the rdata.
@type current: int
@param rdlen: The length of the wire-format rdata
@type rdlen: int
@param origin: The origin to use for relative names
@type origin: name.Name
@rtype: rdata.Rdata instance"""
wire = wiredata.maybe_wrap(wire)
cls = get_rdata_class(rdclass, rdtype)
return cls.from_wire(rdclass, rdtype, wire, current, rdlen, origin)
def from_wire(rdclass, rdtype, wire, current, rdlen, origin=None):
"""Build an rdata object from wire format
This function attempts to dynamically load a class which
implements the specified rdata class and type. If there is no
class-and-type-specific implementation, the GenericRdata class
is used.
Once a class is chosen, its from_wire() class method is called
with the parameters to this function.
@param rdclass: The rdata class
@type rdclass: int
@param rdtype: The rdata type
@type rdtype: int
@param wire: The wire-format message
@type wire: string
@param current: The offet in wire of the beginning of the rdata.
@type current: int
@param rdlen: The length of the wire-format rdata
@type rdlen: int
@param origin: The origin to use for relative names
@type origin: name.Name
@rtype: rdata.Rdata instance"""
wire = wiredata.maybe_wrap(wire)
cls = get_rdata_class(rdclass, rdtype)
return cls.from_wire(rdclass, rdtype, wire, current, rdlen, origin)
def __init__(self, wire, message, question_only=False,
one_rr_per_rrset=False, ignore_trailing=False):
self.wire = wiredata.maybe_wrap(wire)
self.message = message
self.current = 0
self.updating = False
self.zone_rdclass = rdataclass.IN
self.question_only = question_only
self.one_rr_per_rrset = one_rr_per_rrset
self.ignore_trailing = ignore_trailing
def __init__(self,
wire,
message,
question_only=False,
one_rr_per_rrset=False,
ignore_trailing=False):
self.wire = wiredata.maybe_wrap(wire)
self.message = message
self.current = 0
self.updating = False
self.zone_rdclass = rdataclass.IN
self.question_only = question_only
self.one_rr_per_rrset = one_rr_per_rrset
self.ignore_trailing = ignore_trailing
def from_wire(message, current):
"""Convert possibly compressed wire format into a Name.
@param message: the entire DNS message
@type message: string
@param current: the offset of the beginning of the name from the start
of the message
@type current: int
@raises name.BadPointer: a compression pointer did not point backwards
in the message
@raises name.BadLabelType: an invalid label type was encountered.
@returns: a tuple consisting of the name that was read and the number
of bytes of the wire format message which were consumed reading it
@rtype: (name.Name object, int) tuple
"""
if not isinstance(message, str):
raise ValueError("input to from_wire() must be a byte string")
message = wiredata.maybe_wrap(message)
labels = []
biggest_pointer = current
hops = 0
count = ord(message[current])
current += 1
cused = 1
while count != 0:
if count < 64:
labels.append(message[current : current + count].unwrap())
current += count
if hops == 0:
cused += count
elif count >= 192:
current = (count & 0x3f) * 256 + ord(message[current])
if hops == 0:
cused += 1
if current >= biggest_pointer:
raise BadPointer
biggest_pointer = current
hops += 1
else:
raise BadLabelType
count = ord(message[current])
current += 1
if hops == 0:
cused += 1
labels.append('')
return (Name(labels), cused)
def from_wire(message, current):
"""Convert possibly compressed wire format into a Name.
@param message: the entire DNS message
@type message: string
@param current: the offset of the beginning of the name from the start
of the message
@type current: int
@raises name.BadPointer: a compression pointer did not point backwards
in the message
@raises name.BadLabelType: an invalid label type was encountered.
@returns: a tuple consisting of the name that was read and the number
of bytes of the wire format message which were consumed reading it
@rtype: (name.Name object, int) tuple
"""
if not isinstance(message, str):
raise ValueError("input to from_wire() must be a byte string")
message = wiredata.maybe_wrap(message)
labels = []
biggest_pointer = current
hops = 0
count = ord(message[current])
current += 1
cused = 1
while count != 0:
if count < 64:
labels.append(message[current:current + count].unwrap())
current += count
if hops == 0:
cused += count
elif count >= 192:
current = (count & 0x3f) * 256 + ord(message[current])
if hops == 0:
cused += 1
if current >= biggest_pointer:
raise BadPointer
biggest_pointer = current
hops += 1
else:
raise BadLabelType
count = ord(message[current])
current += 1
if hops == 0:
cused += 1
labels.append('')
return (Name(labels), cused)
