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################################################################################
#
# Copyright (c) 2007-2008 Christopher J. Stawarz
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#
################################################################################
"""
Pure-Python interface to Apple Bonjour and compatible DNS-SD libraries
pybonjour provides a pure-Python interface (via ctypes) to Apple
Bonjour and compatible DNS-SD libraries (such as Avahi). It allows
Python scripts to take advantage of Zero Configuration Networking
(Zeroconf) to register, discover, and resolve services on both local
and wide-area networks. Since pybonjour is implemented in pure
Python, scripts that use it can easily be ported to Mac OS X, Windows,
Linux, and other systems that run Bonjour.
Note on strings: Internally, all strings used in DNS-SD are UTF-8
strings. String arguments passed to the DNS-SD functions provided by
pybonjour must be either unicode instances or str instances that can
be converted to unicode using the default encoding. (Passing a
non-convertible str will result in an exception.) Strings returned
from pybonjour (either directly from API functions or passed to
application callbacks) are always unicode instances.
"""
__author__ = 'Christopher Stawarz <cstawarz@gmail.com>'
__version__ = '1.1.1'
import ctypes
import os
import re
import socket
import sys
################################################################################
#
# Global setup
#
################################################################################
class _DummyLock(object):
@staticmethod
def acquire():
pass
@staticmethod
def release():
pass
_global_lock = _DummyLock()
if sys.platform == 'win32':
# Need to use the stdcall variants
_libdnssd = ctypes.windll.dnssd
_CFunc = ctypes.WINFUNCTYPE
else:
if sys.platform == 'darwin':
_libdnssd = 'libSystem.B.dylib'
else:
_libdnssd = 'libdns_sd.so.1'
# If libdns_sd is actually Avahi's Bonjour compatibility
# layer, silence its annoying warning messages, and use a real
# RLock as the global lock, since the compatibility layer
# isn't thread safe.
try:
ctypes.cdll.LoadLibrary('libavahi-client.so.3')
except OSError:
pass
else:
os.environ['AVAHI_COMPAT_NOWARN'] = '1'
import threading
_global_lock = threading.RLock()
_libdnssd = ctypes.cdll.LoadLibrary(_libdnssd)
_CFunc = ctypes.CFUNCTYPE
################################################################################
#
# Constants
#
################################################################################
#
# General flags
#
kDNSServiceFlagsMoreComing = 0x1
kDNSServiceFlagsAdd = 0x2
kDNSServiceFlagsDefault = 0x4
kDNSServiceFlagsNoAutoRename = 0x8
kDNSServiceFlagsShared = 0x10
kDNSServiceFlagsUnique = 0x20
kDNSServiceFlagsBrowseDomains = 0x40
kDNSServiceFlagsRegistrationDomains = 0x80
kDNSServiceFlagsLongLivedQuery = 0x100
kDNSServiceFlagsAllowRemoteQuery = 0x200
kDNSServiceFlagsForceMulticast = 0x400
kDNSServiceFlagsReturnCNAME = 0x800
#
# Service classes
#
kDNSServiceClass_IN = 1
#
# Service types
#
kDNSServiceType_A = 1
kDNSServiceType_NS = 2
kDNSServiceType_MD = 3
kDNSServiceType_MF = 4
kDNSServiceType_CNAME = 5
kDNSServiceType_SOA = 6
kDNSServiceType_MB = 7
kDNSServiceType_MG = 8
kDNSServiceType_MR = 9
kDNSServiceType_NULL = 10
kDNSServiceType_WKS = 11
kDNSServiceType_PTR = 12
kDNSServiceType_HINFO = 13
kDNSServiceType_MINFO = 14
kDNSServiceType_MX = 15
kDNSServiceType_TXT = 16
kDNSServiceType_RP = 17
kDNSServiceType_AFSDB = 18
kDNSServiceType_X25 = 19
kDNSServiceType_ISDN = 20
kDNSServiceType_RT = 21
kDNSServiceType_NSAP = 22
kDNSServiceType_NSAP_PTR = 23
kDNSServiceType_SIG = 24
kDNSServiceType_KEY = 25
kDNSServiceType_PX = 26
kDNSServiceType_GPOS = 27
kDNSServiceType_AAAA = 28
kDNSServiceType_LOC = 29
kDNSServiceType_NXT = 30
kDNSServiceType_EID = 31
kDNSServiceType_NIMLOC = 32
kDNSServiceType_SRV = 33
kDNSServiceType_ATMA = 34
kDNSServiceType_NAPTR = 35
kDNSServiceType_KX = 36
kDNSServiceType_CERT = 37
kDNSServiceType_A6 = 38
kDNSServiceType_DNAME = 39
kDNSServiceType_SINK = 40
kDNSServiceType_OPT = 41
kDNSServiceType_TKEY = 249
kDNSServiceType_TSIG = 250
kDNSServiceType_IXFR = 251
kDNSServiceType_AXFR = 252
kDNSServiceType_MAILB = 253
kDNSServiceType_MAILA = 254
kDNSServiceType_ANY = 255
#
# Error codes
#
kDNSServiceErr_NoError = 0
kDNSServiceErr_Unknown = -65537
kDNSServiceErr_NoSuchName = -65538
kDNSServiceErr_NoMemory = -65539
kDNSServiceErr_BadParam = -65540
kDNSServiceErr_BadReference = -65541
kDNSServiceErr_BadState = -65542
kDNSServiceErr_BadFlags = -65543
kDNSServiceErr_Unsupported = -65544
kDNSServiceErr_NotInitialized = -65545
kDNSServiceErr_AlreadyRegistered = -65547
kDNSServiceErr_NameConflict = -65548
kDNSServiceErr_Invalid = -65549
kDNSServiceErr_Firewall = -65550
kDNSServiceErr_Incompatible = -65551
kDNSServiceErr_BadInterfaceIndex = -65552
kDNSServiceErr_Refused = -65553
kDNSServiceErr_NoSuchRecord = -65554
kDNSServiceErr_NoAuth = -65555
kDNSServiceErr_NoSuchKey = -65556
kDNSServiceErr_NATTraversal = -65557
kDNSServiceErr_DoubleNAT = -65558
kDNSServiceErr_BadTime = -65559
#
# Other constants
#
kDNSServiceMaxServiceName = 64
kDNSServiceMaxDomainName = 1005
kDNSServiceInterfaceIndexAny = 0
kDNSServiceInterfaceIndexLocalOnly = -1
################################################################################
#
# Error handling
#
################################################################################
class BonjourError(Exception):
"""
Exception representing an error returned by the DNS-SD library.
The errorCode attribute contains the actual integer error code
returned.
"""
_errmsg = {
kDNSServiceErr_NoSuchName: 'no such name',
kDNSServiceErr_NoMemory: 'no memory',
kDNSServiceErr_BadParam: 'bad param',
kDNSServiceErr_BadReference: 'bad reference',
kDNSServiceErr_BadState: 'bad state',
kDNSServiceErr_BadFlags: 'bad flags',
kDNSServiceErr_Unsupported: 'unsupported',
kDNSServiceErr_NotInitialized: 'not initialized',
kDNSServiceErr_AlreadyRegistered: 'already registered',
kDNSServiceErr_NameConflict: 'name conflict',
kDNSServiceErr_Invalid: 'invalid',
kDNSServiceErr_Firewall: 'firewall',
kDNSServiceErr_Incompatible: 'incompatible',
kDNSServiceErr_BadInterfaceIndex: 'bad interface index',
kDNSServiceErr_Refused: 'refused',
kDNSServiceErr_NoSuchRecord: 'no such record',
kDNSServiceErr_NoAuth: 'no auth',
kDNSServiceErr_NoSuchKey: 'no such key',
kDNSServiceErr_NATTraversal: 'NAT traversal',
kDNSServiceErr_DoubleNAT: 'double NAT',
kDNSServiceErr_BadTime: 'bad time',
}
@classmethod
def _errcheck(cls, result, func, args):
if result != kDNSServiceErr_NoError:
raise cls(result)
return args
def __init__(self, errorCode):
self.errorCode = errorCode
Exception.__init__(self,
(errorCode, self._errmsg.get(errorCode, 'unknown')))
################################################################################
#
# Data types
#
################################################################################
class _utf8_char_p(ctypes.c_char_p):
@classmethod
def from_param(cls, obj):
if (obj is not None) and (not isinstance(obj, cls)):
if not isinstance(obj, basestring):
raise TypeError('parameter must be a string type instance')
if not isinstance(obj, unicode):
obj = unicode(obj)
obj = obj.encode('utf-8')
return ctypes.c_char_p.from_param(obj)
def decode(self):
if self.value is None:
return None
return self.value.decode('utf-8')
class _utf8_char_p_non_null(_utf8_char_p):
@classmethod
def from_param(cls, obj):
if obj is None:
raise ValueError('parameter cannot be None')
return _utf8_char_p.from_param(obj)
_DNSServiceFlags = ctypes.c_uint32
_DNSServiceErrorType = ctypes.c_int32
class DNSRecordRef(ctypes.c_void_p):
"""
A DNSRecordRef pointer. DO NOT CREATE INSTANCES OF THIS CLASS!
Only instances returned by the DNS-SD library are valid. Using
others will likely cause the Python interpreter to crash.
Application code should not use any of the methods of this class.
The only valid use of a DNSRecordRef instance is as an argument to
a DNS-SD function.
To compare two DNSRecordRef instances for equality, use '=='
rather than 'is'.
"""
@classmethod
def from_param(cls, obj):
if type(obj) is not cls:
raise TypeError("expected '%s', got '%s'" %
(cls.__name__, type(obj).__name__))
if obj.value is None:
raise ValueError('invalid %s instance' % cls.__name__)
return obj
def __eq__(self, other):
return ((type(other) is type(self)) and (other.value == self.value))
def __ne__(self, other):
return not (other == self)
def _invalidate(self):
self.value = None
def _valid(self):
return (self.value is not None)
class _DNSRecordRef_or_null(DNSRecordRef):
@classmethod
def from_param(cls, obj):
if obj is None:
return obj
return DNSRecordRef.from_param(obj)
class DNSServiceRef(DNSRecordRef):
"""
A DNSServiceRef pointer. DO NOT CREATE INSTANCES OF THIS CLASS!
Only instances returned by the DNS-SD library are valid. Using
others will likely cause the Python interpreter to crash.
An instance of this class represents an active connection to the
mDNS daemon. The connection remains open until the close() method
is called (which also terminates the associated browse, resolve,
etc.). Note that this method is *not* called automatically when
the instance is deallocated; therefore, application code must be
certain to call close() when the connection is no longer needed.
The primary use of a DNSServiceRef instance is in conjunction with
select() or poll() to determine when a response from the daemon is
available. When the file descriptor returned by fileno() is ready
for reading, a reply from the daemon is available and should be
processed by passing the DNSServiceRef instance to
DNSServiceProcessResult(), which will invoke the appropriate
application callback function. (Note that the file descriptor
should never be read from or written to directly.)
The DNSServiceRef class supports the context management protocol
introduced in Python 2.5, meaning applications can use the 'with'
statement to ensure that DNSServiceRef instances are closed
regardless of whether an exception occurs, e.g.
sdRef = DNSServiceBrowse(...)
with sdRef:
# sdRef will be closed regardless of how this block is
# exited
...
To compare two DNSServiceRef instances for equality, use '=='
rather than 'is'.
"""
def __init__(self, *args, **kwargs):
DNSRecordRef.__init__(self, *args, **kwargs)
# Since callback functions are called asynchronously, we need
# to hold onto references to them for as long as they're in
# use. Otherwise, Python could deallocate them before we call
# DNSServiceProcessResult(), meaning the Bonjour library would
# dereference freed memory when it tried to invoke the
# callback.
self._callbacks = []
# A DNSRecordRef is invalidated if DNSServiceRefDeallocate()
# is called on the corresponding DNSServiceRef, so we need to
# keep track of all our record refs and invalidate them when
# we're closed.
self._record_refs = []
def __enter__(self):
return self
def __exit__(self, type, value, traceback):
self.close()
def _add_callback(self, cb):
self._callbacks.append(cb)
def _add_record_ref(self, ref):
self._record_refs.append(ref)
def close(self):
"""
Close the connection to the mDNS daemon and terminate any
associated browse, resolve, etc. operations.
"""
if self._valid():
for ref in self._record_refs:
ref._invalidate()
del self._record_refs
_global_lock.acquire()
try:
_DNSServiceRefDeallocate(self)
finally:
_global_lock.release()
self._invalidate()
del self._callbacks
def fileno(self):
"""
Return the file descriptor associated with this connection.
This descriptor should never be read from or written to
directly. It should only be passed to select() or poll() to
determine when a response from the mDNS daemon is available.
"""
_global_lock.acquire()
try:
fd = _DNSServiceRefSockFD(self)
finally:
_global_lock.release()
return fd
_DNSServiceDomainEnumReply = _CFunc(
None,
DNSServiceRef, # sdRef
_DNSServiceFlags, # flags
ctypes.c_uint32, # interfaceIndex
_DNSServiceErrorType, # errorCode
_utf8_char_p, # replyDomain
ctypes.c_void_p, # context
)
_DNSServiceRegisterReply = _CFunc(
None,
DNSServiceRef, # sdRef
_DNSServiceFlags, # flags
_DNSServiceErrorType, # errorCode
_utf8_char_p, # name
_utf8_char_p, # regtype
_utf8_char_p, # domain
ctypes.c_void_p, # context
)
_DNSServiceBrowseReply = _CFunc(
None,
DNSServiceRef, # sdRef
_DNSServiceFlags, # flags
ctypes.c_uint32, # interfaceIndex
_DNSServiceErrorType, # errorCode
_utf8_char_p, # serviceName
_utf8_char_p, # regtype
_utf8_char_p, # replyDomain
ctypes.c_void_p, # context
)
_DNSServiceResolveReply = _CFunc(
None,
DNSServiceRef, # sdRef
_DNSServiceFlags, # flags
ctypes.c_uint32, # interfaceIndex
_DNSServiceErrorType, # errorCode
_utf8_char_p, # fullname
_utf8_char_p, # hosttarget
ctypes.c_uint16, # port
ctypes.c_uint16, # txtLen
ctypes.c_void_p, # txtRecord (not null-terminated, so c_void_p)
ctypes.c_void_p, # context
)
_DNSServiceRegisterRecordReply = _CFunc(
None,
DNSServiceRef, # sdRef
DNSRecordRef, # RecordRef
_DNSServiceFlags, # flags
_DNSServiceErrorType, # errorCode
ctypes.c_void_p, # context
)
_DNSServiceQueryRecordReply = _CFunc(
None,
DNSServiceRef, # sdRef
_DNSServiceFlags, # flags
ctypes.c_uint32, # interfaceIndex
_DNSServiceErrorType, # errorCode
_utf8_char_p, # fullname
ctypes.c_uint16, # rrtype
ctypes.c_uint16, # rrclass
ctypes.c_uint16, # rdlen
ctypes.c_void_p, # rdata
ctypes.c_uint32, # ttl
ctypes.c_void_p, # context
)
################################################################################
#
# Low-level function bindings
#
################################################################################
def _create_function_bindings():
ERRCHECK = True
NO_ERRCHECK = False
OUTPARAM = (lambda index: index)
NO_OUTPARAM = None
specs = {
#'funcname':
#(
# return_type,
# errcheck,
# outparam,
# (
# param_1_type,
# param_2_type,
# ...
# param_n_type,
# )),
'DNSServiceRefSockFD':
(
ctypes.c_int,
NO_ERRCHECK,
NO_OUTPARAM,
(
DNSServiceRef, # sdRef
)),
'DNSServiceProcessResult':
(
_DNSServiceErrorType,
ERRCHECK,
NO_OUTPARAM,
(
DNSServiceRef, # sdRef
)),
'DNSServiceRefDeallocate':
(
None,
NO_ERRCHECK,
NO_OUTPARAM,
(
DNSServiceRef, # sdRef
)),
'DNSServiceEnumerateDomains':
(
_DNSServiceErrorType,
ERRCHECK,
OUTPARAM(0),
(
ctypes.POINTER(DNSServiceRef), # sdRef
_DNSServiceFlags, # flags
ctypes.c_uint32, # interfaceIndex
_DNSServiceDomainEnumReply, # callBack
ctypes.c_void_p, # context
)),
'DNSServiceRegister':
(
_DNSServiceErrorType,
ERRCHECK,
OUTPARAM(0),
(
ctypes.POINTER(DNSServiceRef), # sdRef
_DNSServiceFlags, # flags
ctypes.c_uint32, # interfaceIndex
_utf8_char_p, # name
_utf8_char_p_non_null, # regtype
_utf8_char_p, # domain
_utf8_char_p, # host
ctypes.c_uint16, # port
ctypes.c_uint16, # txtLen
ctypes.c_void_p, # txtRecord
_DNSServiceRegisterReply, # callBack
ctypes.c_void_p, # context
)),
'DNSServiceAddRecord':
(
_DNSServiceErrorType,
ERRCHECK,
OUTPARAM(1),
(
DNSServiceRef, # sdRef
ctypes.POINTER(DNSRecordRef), # RecordRef
_DNSServiceFlags, # flags
ctypes.c_uint16, # rrtype
ctypes.c_uint16, # rdlen
ctypes.c_void_p, # rdata
ctypes.c_uint32, # ttl
)),
'DNSServiceUpdateRecord':
(
_DNSServiceErrorType,
ERRCHECK,
NO_OUTPARAM,
(
DNSServiceRef, # sdRef
_DNSRecordRef_or_null, # RecordRef
_DNSServiceFlags, # flags
ctypes.c_uint16, # rdlen
ctypes.c_void_p, # rdata
ctypes.c_uint32, # ttl
)),
'DNSServiceRemoveRecord':
(
_DNSServiceErrorType,
ERRCHECK,
NO_OUTPARAM,
(
DNSServiceRef, # sdRef
DNSRecordRef, # RecordRef
_DNSServiceFlags, # flags
)),
'DNSServiceBrowse':
(
_DNSServiceErrorType,
ERRCHECK,
OUTPARAM(0),
(
ctypes.POINTER(DNSServiceRef), # sdRef
_DNSServiceFlags, # flags
ctypes.c_uint32, # interfaceIndex
_utf8_char_p_non_null, # regtype
_utf8_char_p, # domain
_DNSServiceBrowseReply, # callBack
ctypes.c_void_p, # context
)),
'DNSServiceResolve':
(
_DNSServiceErrorType,
ERRCHECK,
OUTPARAM(0),
(
ctypes.POINTER(DNSServiceRef), # sdRef
_DNSServiceFlags, # flags
ctypes.c_uint32, # interfaceIndex
_utf8_char_p_non_null, # name
_utf8_char_p_non_null, # regtype
_utf8_char_p_non_null, # domain
_DNSServiceResolveReply, # callBack
ctypes.c_void_p, # context
)),
'DNSServiceCreateConnection':
(
_DNSServiceErrorType,
ERRCHECK,
OUTPARAM(0),
(
ctypes.POINTER(DNSServiceRef), # sdRef
)),
'DNSServiceRegisterRecord':
(
_DNSServiceErrorType,
ERRCHECK,
OUTPARAM(1),
(
DNSServiceRef, # sdRef
ctypes.POINTER(DNSRecordRef), # RecordRef
_DNSServiceFlags, # flags
ctypes.c_uint32, # interfaceIndex
_utf8_char_p_non_null, # fullname
ctypes.c_uint16, # rrtype
ctypes.c_uint16, # rrclass
ctypes.c_uint16, # rdlen
ctypes.c_void_p, # rdata
ctypes.c_uint32, # ttl
_DNSServiceRegisterRecordReply, # callBack
ctypes.c_void_p, # context
)),
'DNSServiceQueryRecord':
(
_DNSServiceErrorType,
ERRCHECK,
OUTPARAM(0),
(
ctypes.POINTER(DNSServiceRef), # sdRef
_DNSServiceFlags, # flags
ctypes.c_uint32, # interfaceIndex
_utf8_char_p_non_null, # fullname
ctypes.c_uint16, # rrtype
ctypes.c_uint16, # rrclass
_DNSServiceQueryRecordReply, # callBack
ctypes.c_void_p, # context
)),
'DNSServiceReconfirmRecord':
(
None, # _DNSServiceErrorType in more recent versions
NO_ERRCHECK,
NO_OUTPARAM,
(
_DNSServiceFlags, # flags
ctypes.c_uint32, # interfaceIndex
_utf8_char_p_non_null, # fullname
ctypes.c_uint16, # rrtype
ctypes.c_uint16, # rrclass
ctypes.c_uint16, # rdlen
ctypes.c_void_p, # rdata
)),
'DNSServiceConstructFullName':
(
ctypes.c_int,
ERRCHECK,
OUTPARAM(0),
(
ctypes.c_char * kDNSServiceMaxDomainName, # fullName
_utf8_char_p, # service
_utf8_char_p_non_null, # regtype
_utf8_char_p_non_null, # domain
)),
}
for name, (restype, errcheck, outparam, argtypes) in specs.iteritems():
prototype = _CFunc(restype, *argtypes)
paramflags = [1] * len(argtypes)
if outparam is not None:
paramflags[outparam] = 2
paramflags = tuple((val,) for val in paramflags)
func = prototype((name, _libdnssd), paramflags)
if errcheck:
func.errcheck = BonjourError._errcheck
globals()['_' + name] = func
# Only need to do this once
_create_function_bindings()
del _create_function_bindings
################################################################################
#
# Internal utility types and functions
#
################################################################################
class _NoDefault(object):
def __repr__(self):
return '<NO DEFAULT>'
def check(self, obj):
if obj is self:
raise ValueError('required parameter value missing')
_NO_DEFAULT = _NoDefault()
def _string_to_length_and_void_p(string):
if isinstance(string, TXTRecord):
string = str(string)
void_p = ctypes.cast(ctypes.c_char_p(string), ctypes.c_void_p)
return len(string), void_p
def _length_and_void_p_to_string(length, void_p):
char_p = ctypes.cast(void_p, ctypes.POINTER(ctypes.c_char))
return ''.join(char_p[i] for i in xrange(length))
################################################################################
#
# High-level functions
#
################################################################################
def DNSServiceProcessResult(
sdRef,
):
"""
Read a reply from the daemon, calling the appropriate application
callback. This call will block until the daemon's response is
received. Use sdRef in conjunction with select() or poll() to
determine the presence of a response from the server before
calling this function to process the reply without blocking. Call
this function at any point if it is acceptable to block until the
daemon's response arrives. Note that the client is responsible
for ensuring that DNSServiceProcessResult() is called whenever
there is a reply from the daemon; the daemon may terminate its
connection with a client that does not process the daemon's
responses.
sdRef:
A DNSServiceRef returned by any of the DNSService calls that
take a callback parameter.
"""
_global_lock.acquire()
try:
_DNSServiceProcessResult(sdRef)
finally:
_global_lock.release()
def DNSServiceEnumerateDomains(
flags,
interfaceIndex = kDNSServiceInterfaceIndexAny,
callBack = None,
):
"""
Asynchronously enumerate domains available for browsing and
registration.
The enumeration MUST be cancelled by closing the returned
DNSServiceRef when no more domains are to be found.
flags:
Possible values are:
kDNSServiceFlagsBrowseDomains to enumerate domains
recommended for browsing.
kDNSServiceFlagsRegistrationDomains to enumerate domains
recommended for registration.
interfaceIndex:
If non-zero, specifies the interface on which to look for
domains. Most applications will pass
kDNSServiceInterfaceIndexAny (0) to enumerate domains on all
interfaces.
callBack:
The function to be called when a domain is found or the call
asynchronously fails. Its signature should be
callBack(sdRef, flags, interfaceIndex, errorCode, replyDomain).
return value:
A DNSServiceRef instance.
Callback Parameters:
sdRef:
The DNSServiceRef returned by DNSServiceEnumerateDomains().
flags:
Possible values are:
kDNSServiceFlagsMoreComing
kDNSServiceFlagsAdd
kDNSServiceFlagsDefault
interfaceIndex:
Specifies the interface on which the domain exists.
errorCode:
Will be kDNSServiceErr_NoError (0) on success, otherwise
indicates the failure that occurred (in which case other
parameters are undefined).
replyDomain:
The name of the domain.
"""
@_DNSServiceDomainEnumReply
def _callback(sdRef, flags, interfaceIndex, errorCode, replyDomain,
context):
if callBack is not None:
callBack(sdRef, flags, interfaceIndex, errorCode,
replyDomain.decode())
_global_lock.acquire()
try:
sdRef = _DNSServiceEnumerateDomains(flags,
interfaceIndex,
_callback,
None)
finally:
_global_lock.release()
sdRef._add_callback(_callback)
return sdRef
def DNSServiceRegister(
flags = 0,
interfaceIndex = kDNSServiceInterfaceIndexAny,
name = None,
regtype = _NO_DEFAULT,
domain = None,
host = None,
port = _NO_DEFAULT,
txtRecord = '',
callBack = None,
):
"""
Register a service that is discovered via DNSServiceBrowse() and
DNSServiceResolve() calls.
flags:
Indicates the renaming behavior on name conflict. Most
applications will pass 0.
interfaceIndex:
If non-zero, specifies the interface on which to register the
service. Most applications will pass
kDNSServiceInterfaceIndexAny (0) to register on all available
interfaces.
name:
If not None, specifies the service name to be registered.
Most applications will not specify a name, in which case the
computer name is used. (This name is communicated to the
client via the callback.) If a name is specified, it must be
1-63 bytes of UTF-8 text. If the name is longer than 63
bytes, it will be automatically truncated to a legal length,
unless the flag kDNSServiceFlagsNoAutoRename is set, in which
case a BonjourError exception will be thrown.
regtype:
The service type followed by the protocol, separated by a dot
(e.g. "_ftp._tcp"). The service type must be an underscore,
followed by 1-14 characters, which may be letters, digits, or
hyphens. The transport protocol must be "_tcp" or "_udp". New
service types should be registered at
<http://www.dns-sd.org/ServiceTypes.html>.
domain:
If not None, specifies the domain on which to advertise the
service. Most applications will not specify a domain, instead
automatically registering in the default domain(s).
host:
If not None, specifies the SRV target host name. Most
applications will not specify a host, instead automatically
using the machine's default host name(s). Note that
specifying a host name does NOT create an address record for
that host; the application is responsible for ensuring that
the appropriate address record exists, or creating it via
DNSServiceRegisterRecord().
port:
The port, in host (not network) byte order, on which the
service accepts connections. Pass 0 for a "placeholder"
service (i.e. a service that will not be discovered by
browsing, but will cause a name conflict if another client
tries to register that same name). Most clients will not use
placeholder services.
txtRecord:
The TXT record rdata. If not None, txtRecord must be either a
TXTRecord instance or a string containing a properly formatted
DNS TXT record, i.e.
<length byte> <data> <length byte> <data> ...
callBack:
The function to be called when the registration completes or
asynchronously fails. Its signature should be
callBack(sdRef, flags, errorCode, name, regtype, domain).
The client MAY pass None for the callback, in which case the
client will NOT be notified of the default values picked on
its behalf, and the client will NOT be notified of any
asynchronous errors (e.g. out of memory errors, etc.) that may
prevent the registration of the service. The client may NOT
pass the flag kDNSServiceFlagsNoAutoRename if the callback is
None. The client may still deregister the service at any time
by closing the returned DNSServiceRef.
return value:
A DNSServiceRef instance. The registration will remain active
indefinitely until the client terminates it by closing the
DNSServiceRef.
Callback Parameters:
sdRef:
The DNSServiceRef returned by DNSServiceRegister().
flags:
Currently unused, reserved for future use.
errorCode:
Will be kDNSServiceErr_NoError on success, otherwise will
indicate the failure that occurred (including name conflicts,
if the kDNSServiceFlagsNoAutoRename flag was used when
registering). Other parameters are undefined if an error
occurred.
name:
The service name registered. (If the application did not
specify a name in DNSServiceRegister(), this indicates what
name was automatically chosen.)
regtype:
The type of service registered, as it was passed to the
callout.
domain:
The domain on which the service was registered. (If the
application did not specify a domain in DNSServiceRegister(),
this indicates the default domain on which the service was
registered.)
"""
_NO_DEFAULT.check(regtype)
_NO_DEFAULT.check(port)
port = socket.htons(port)
if not txtRecord:
txtLen, txtRecord = 1, '\0'
else:
txtLen, txtRecord = _string_to_length_and_void_p(txtRecord)
@_DNSServiceRegisterReply
def _callback(sdRef, flags, errorCode, name, regtype, domain, context):
if callBack is not None:
callBack(sdRef, flags, errorCode, name.decode(), regtype.decode(),
domain.decode())
_global_lock.acquire()
try:
sdRef = _DNSServiceRegister(flags,
interfaceIndex,
name,
regtype,
domain,
host,
port,
txtLen,
txtRecord,
_callback,
None)
finally:
_global_lock.release()
sdRef._add_callback(_callback)
return sdRef
def DNSServiceAddRecord(
sdRef,
flags = 0,
rrtype = _NO_DEFAULT,
rdata = _NO_DEFAULT,
ttl = 0,
):
"""
Add a record to a registered service. The name of the record will
be the same as the registered service's name. The record can
later be updated or deregistered by passing the DNSRecordRef
returned by this function to DNSServiceUpdateRecord() or
DNSServiceRemoveRecord().
Note that DNSServiceAddRecord/UpdateRecord/RemoveRecord are NOT
thread-safe with respect to a single DNSServiceRef. If you plan
to have multiple threads in your program simultaneously add,
update, or remove records from the same DNSServiceRef, then it's
the caller's responsibility to use a lock or take similar
appropriate precautions to serialize those calls.
sdRef:
A DNSServiceRef returned by DNSServiceRegister().
flags:
Currently ignored, reserved for future use.
rrtype:
The type of the record (e.g. kDNSServiceType_TXT,
kDNSServiceType_SRV, etc.).
rdata:
A string containing the raw rdata to be contained in the added
resource record.
ttl:
The time to live of the resource record, in seconds. Pass 0
to use a default value.
return value:
A DNSRecordRef instance, which may be passed to
DNSServiceUpdateRecord() or DNSServiceRemoveRecord(). If
sdRef is closed, the DNSRecordRef is also invalidated and may
not be used further.
"""
_NO_DEFAULT.check(rrtype)
_NO_DEFAULT.check(rdata)
rdlen, rdata = _string_to_length_and_void_p(rdata)
_global_lock.acquire()
try:
RecordRef = _DNSServiceAddRecord(sdRef,
flags,
rrtype,
rdlen,
rdata,
ttl)
finally:
_global_lock.release()
sdRef._add_record_ref(RecordRef)
return RecordRef
def DNSServiceUpdateRecord(
sdRef,
RecordRef = None,
flags = 0,
rdata = _NO_DEFAULT,
ttl = 0,
):
"""
Update a registered resource record. The record must either be:
- The primary txt record of a service registered via
DNSServiceRegister(), or
- A record added to a registered service via
DNSServiceAddRecord(), or
- An individual record registered by DNSServiceRegisterRecord()
sdRef:
A DNSServiceRef returned by DNSServiceRegister() or
DNSServiceCreateConnection().
RecordRef:
A DNSRecordRef returned by DNSServiceAddRecord(), or None to
update the service's primary txt record.
flags:
Currently ignored, reserved for future use.
rdata:
A string containing the new rdata to be contained in the
updated resource record.
ttl:
The time to live of the updated resource record, in seconds.
"""
_NO_DEFAULT.check(rdata)
rdlen, rdata = _string_to_length_and_void_p(rdata)
_global_lock.acquire()
try:
_DNSServiceUpdateRecord(sdRef,
RecordRef,
flags,
rdlen,
rdata,
ttl)
finally:
_global_lock.release()
def DNSServiceRemoveRecord(
sdRef,
RecordRef,
flags = 0,
):
"""
Remove a record previously added to a service record set via
DNSServiceAddRecord(), or deregister a record registered
individually via DNSServiceRegisterRecord().
sdRef:
A DNSServiceRef returned by DNSServiceRegister() (if the
record being removed was registered via DNSServiceAddRecord())
or by DNSServiceCreateConnection() (if the record being
removed was registered via DNSServiceRegisterRecord()).
recordRef:
A DNSRecordRef returned by DNSServiceAddRecord() or
DNSServiceRegisterRecord().
flags:
Currently ignored, reserved for future use.
"""
_global_lock.acquire()
try:
_DNSServiceRemoveRecord(sdRef,
RecordRef,
flags)
finally:
_global_lock.release()
RecordRef._invalidate()
def DNSServiceBrowse(
flags = 0,
interfaceIndex = kDNSServiceInterfaceIndexAny,
regtype = _NO_DEFAULT,
domain = None,
callBack = None,
):
"""
Browse for instances of a service.
flags:
Currently ignored, reserved for future use.
interfaceIndex:
If non-zero, specifies the interface on which to browse for
services. Most applications will pass
kDNSServiceInterfaceIndexAny (0) to browse on all available
interfaces.
regtype:
The service type being browsed for followed by the protocol,
separated by a dot (e.g. "_ftp._tcp"). The transport protocol
must be "_tcp" or "_udp".
domain:
If not None, specifies the domain on which to browse for
services. Most applications will not specify a domain,
instead browsing on the default domain(s).
callBack:
The function to be called when an instance of the service
being browsed for is found, or if the call asynchronously
fails. Its signature should be
callBack(sdRef, flags, interfaceIndex, errorCode,
serviceName, regtype, replyDomain).
return value:
A DNSServiceRef instance. The browse operation will run
indefinitely until the client terminates it by closing the
DNSServiceRef.
Callback Parameters:
sdRef:
The DNSServiceRef returned by DNSServiceBrowse().
flags:
Possible values are kDNSServiceFlagsMoreComing and
kDNSServiceFlagsAdd.
interfaceIndex:
The interface on which the service is advertised. This index
should be passed to DNSServiceResolve() when resolving the
service.
errorCode:
Will be kDNSServiceErr_NoError (0) on success, otherwise will
indicate the failure that occurred. Other parameters are
undefined if an error occurred.
serviceName:
The discovered service name. This name should be displayed to
the user and stored for subsequent use in the
DNSServiceResolve() call.
regtype:
The service type, which is usually (but not always) the same
as was passed to DNSServiceBrowse(). One case where the
discovered service type may not be the same as the requested
service type is when using subtypes: The client may want to
browse for only those ftp servers that allow anonymous
connections. The client will pass the string
"_ftp._tcp,_anon" to DNSServiceBrowse(), but the type of the
service that's discovered is simply "_ftp._tcp". The regtype
for each discovered service instance should be stored along
with the name, so that it can be passed to DNSServiceResolve()
when the service is later resolved.
replyDomain:
The domain of the discovered service instance. This may or
may not be the same as the domain that was passed to
DNSServiceBrowse(). The domain for each discovered service
instance should be stored along with the name, so that it can
be passed to DNSServiceResolve() when the service is later
resolved.
"""
_NO_DEFAULT.check(regtype)
@_DNSServiceBrowseReply
def _callback(sdRef, flags, interfaceIndex, errorCode, serviceName, regtype,
replyDomain, context):
if callBack is not None:
callBack(sdRef, flags, interfaceIndex, errorCode,
serviceName.decode(), regtype.decode(),
replyDomain.decode())
_global_lock.acquire()
try:
sdRef = _DNSServiceBrowse(flags,
interfaceIndex,
regtype,
domain,
_callback,
None)
finally:
_global_lock.release()
sdRef._add_callback(_callback)
return sdRef
def DNSServiceResolve(
flags = 0,
interfaceIndex = _NO_DEFAULT,
name = _NO_DEFAULT,
regtype = _NO_DEFAULT,
domain = _NO_DEFAULT,
callBack = None,
):
"""
Resolve a service name discovered via DNSServiceBrowse() to a
target host name, port number, and txt record.
Note: Applications should NOT use DNSServiceResolve() solely for
txt record monitoring; use DNSServiceQueryRecord() instead, as it
is more efficient for this task.
Note: When the desired results have been returned, the client MUST
terminate the resolve by closing the returned DNSServiceRef.
Note: DNSServiceResolve() behaves correctly for typical services
that have a single SRV record and a single TXT record. To resolve
non-standard services with multiple SRV or TXT records,
DNSServiceQueryRecord() should be used.
flags:
Currently ignored, reserved for future use.
interfaceIndex:
The interface on which to resolve the service. If this
resolve call is as a result of a currently active
DNSServiceBrowse() operation, then the interfaceIndex should
be the index reported in the browse callback. If this resolve
call is using information previously saved (e.g. in a
preference file) for later use, then use
kDNSServiceInterfaceIndexAny (0), because the desired service
may now be reachable via a different physical interface.
name:
The name of the service instance to be resolved, as reported
to the DNSServiceBrowse() callback.
regtype:
The type of the service instance to be resolved, as reported
to the DNSServiceBrowse() callback.
domain:
The domain of the service instance to be resolved, as reported
to the DNSServiceBrowse() callback.
callBack:
The function to be called when a result is found, or if the
call asynchronously fails. Its signature should be
callBack(sdRef, flags, interfaceIndex, errorCode, fullname,
hosttarget, port, txtRecord).
return value:
A DNSServiceRef instance. The resolve operation will run
indefinitely until the client terminates it by closing the
DNSServiceRef.
Callback Parameters:
sdRef:
The DNSServiceRef returned by DNSServiceResolve().
flags:
Currently unused, reserved for future use.
interfaceIndex:
The interface on which the service was resolved.
errorCode:
Will be kDNSServiceErr_NoError (0) on success, otherwise will
indicate the failure that occurred. Other parameters are
undefined if an error occurred.
fullname:
The full service domain name, in the form
<servicename>.<protocol>.<domain>.
hosttarget:
The target hostname of the machine providing the service.
port:
The port, in host (not network) byte order, on which
connections are accepted for this service.
txtRecord:
A string containing the service's primary txt record, in
standard txt record format.
"""
_NO_DEFAULT.check(interfaceIndex)
_NO_DEFAULT.check(name)
_NO_DEFAULT.check(regtype)
_NO_DEFAULT.check(domain)
@_DNSServiceResolveReply
def _callback(sdRef, flags, interfaceIndex, errorCode, fullname, hosttarget,
port, txtLen, txtRecord, context):
if callBack is not None:
port = socket.ntohs(port)
txtRecord = _length_and_void_p_to_string(txtLen, txtRecord)
callBack(sdRef, flags, interfaceIndex, errorCode, fullname.decode(),
hosttarget.decode(), port, txtRecord)
_global_lock.acquire()
try:
sdRef = _DNSServiceResolve(flags,
interfaceIndex,
name,
regtype,
domain,
_callback,
None)
finally:
_global_lock.release()
sdRef._add_callback(_callback)
return sdRef
def DNSServiceCreateConnection():
"""
Create a connection to the daemon allowing efficient registration
of multiple individual records.
return value:
A DNSServiceRef instance. Closing it severs the connection
and deregisters all records registered on this connection.
"""
_global_lock.acquire()
try:
sdRef = _DNSServiceCreateConnection()
finally:
_global_lock.release()
return sdRef
def DNSServiceRegisterRecord(
sdRef,
flags,
interfaceIndex = kDNSServiceInterfaceIndexAny,
fullname = _NO_DEFAULT,
rrtype = _NO_DEFAULT,
rrclass = kDNSServiceClass_IN,
rdata = _NO_DEFAULT,
ttl = 0,
callBack = None,
):
"""
Register an individual resource record on a connected
DNSServiceRef.
Note that name conflicts occurring for records registered via this
call must be handled by the client in the callback.
sdRef:
A DNSServiceRef returned by DNSServiceCreateConnection().
flags:
Possible values are kDNSServiceFlagsShared or
kDNSServiceFlagsUnique.
interfaceIndex:
If non-zero, specifies the interface on which to register the
record. Passing kDNSServiceInterfaceIndexAny (0) causes the
record to be registered on all interfaces.
fullname:
The full domain name of the resource record.
rrtype:
The numerical type of the resource record
(e.g. kDNSServiceType_PTR, kDNSServiceType_SRV, etc.).
rrclass:
The class of the resource record (usually
kDNSServiceClass_IN).
rdata:
A string containing the raw rdata, as it is to appear in the
DNS record.
ttl:
The time to live of the resource record, in seconds. Pass 0
to use a default value.
callBack:
The function to be called when a result is found, or if the
call asynchronously fails (e.g. because of a name conflict).
Its signature should be
callBack(sdRef, RecordRef, flags, errorCode).
return value:
A DNSRecordRef instance, which may be passed to
DNSServiceUpdateRecord() or DNSServiceRemoveRecord(). (To
deregister ALL records registered on a single connected
DNSServiceRef and deallocate each of their corresponding
DNSRecordRefs, close the DNSServiceRef.)
Callback Parameters:
sdRef:
The connected DNSServiceRef returned by
DNSServiceCreateConnection().
RecordRef:
The DNSRecordRef returned by DNSServiceRegisterRecord().
flags:
Currently unused, reserved for future use.
errorCode:
Will be kDNSServiceErr_NoError on success, otherwise will
indicate the failure that occurred (including name conflicts).
Other parameters are undefined if an error occurred.
"""
_NO_DEFAULT.check(fullname)
_NO_DEFAULT.check(rrtype)
_NO_DEFAULT.check(rdata)
rdlen, rdata = _string_to_length_and_void_p(rdata)
@_DNSServiceRegisterRecordReply
def _callback(sdRef, RecordRef, flags, errorCode, context):
if callBack is not None:
callBack(sdRef, RecordRef, flags, errorCode)
_global_lock.acquire()
try:
RecordRef = _DNSServiceRegisterRecord(sdRef,
flags,
interfaceIndex,
fullname,
rrtype,
rrclass,
rdlen,
rdata,
ttl,
_callback,
None)
finally:
_global_lock.release()
sdRef._add_callback(_callback)
sdRef._add_record_ref(RecordRef)
return RecordRef
def DNSServiceQueryRecord(
flags = 0,
interfaceIndex = kDNSServiceInterfaceIndexAny,
fullname = _NO_DEFAULT,
rrtype = _NO_DEFAULT,
rrclass = kDNSServiceClass_IN,
callBack = None,
):
"""
Query for an arbitrary DNS record.
flags:
Pass kDNSServiceFlagsLongLivedQuery to create a "long-lived"
unicast query in a non-local domain. Without setting this
flag, unicast queries will be one-shot; that is, only answers
available at the time of the call will be returned. By
setting this flag, answers (including Add and Remove events)
that become available after the initial call is made will
generate callbacks. This flag has no effect on link-local
multicast queries.
interfaceIndex:
If non-zero, specifies the interface on which to issue the
query. Passing kDNSServiceInterfaceIndexAny (0) causes the
name to be queried for on all interfaces.
fullname:
The full domain name of the resource record to be queried for.
rrtype:
The numerical type of the resource record to be queried for
(e.g. kDNSServiceType_PTR, kDNSServiceType_SRV, etc.).
rrclass:
The class of the resource record (usually
kDNSServiceClass_IN).
callBack:
The function to be called when a result is found, or if the
call asynchronously fails. Its signature should be
callBack(sdRef, flags, interfaceIndex, errorCode, fullname,
rrtype, rrclass, rdata, ttl).
return value:
A DNSServiceRef instance. The query operation will run
indefinitely until the client terminates it by closing the
DNSServiceRef.
Callback Parameters:
sdRef:
The DNSServiceRef returned by DNSServiceQueryRecord().
flags:
Possible values are kDNSServiceFlagsMoreComing and
kDNSServiceFlagsAdd. The Add flag is NOT set for PTR records
with a ttl of 0, i.e. "Remove" events.
interfaceIndex:
The interface on which the query was resolved.
errorCode:
Will be kDNSServiceErr_NoError on success, otherwise will
indicate the failure that occurred. Other parameters are
undefined if an error occurred.
fullname:
The resource record's full domain name.
rrtype:
The resource record's type (e.g. kDNSServiceType_PTR,
kDNSServiceType_SRV, etc.).
rrclass:
The class of the resource record (usually
kDNSServiceClass_IN).
rdata:
A string containing the raw rdata of the resource record.
ttl:
The resource record's time to live, in seconds.
"""
_NO_DEFAULT.check(fullname)
_NO_DEFAULT.check(rrtype)
@_DNSServiceQueryRecordReply
def _callback(sdRef, flags, interfaceIndex, errorCode, fullname, rrtype,
rrclass, rdlen, rdata, ttl, context):
if callBack is not None:
rdata = _length_and_void_p_to_string(rdlen, rdata)
callBack(sdRef, flags, interfaceIndex, errorCode, fullname.decode(),
rrtype, rrclass, rdata, ttl)
_global_lock.acquire()
try:
sdRef = _DNSServiceQueryRecord(flags,
interfaceIndex,
fullname,
rrtype,
rrclass,
_callback,
None)
finally:
_global_lock.release()
sdRef._add_callback(_callback)
return sdRef
def DNSServiceReconfirmRecord(
flags = 0,
interfaceIndex = kDNSServiceInterfaceIndexAny,
fullname = _NO_DEFAULT,
rrtype = _NO_DEFAULT,
rrclass = kDNSServiceClass_IN,
rdata = _NO_DEFAULT,
):
"""
Instruct the daemon to verify the validity of a resource record
that appears to be out of date (e.g. because tcp connection to a
service's target failed). Causes the record to be flushed from
the daemon's cache (as well as all other daemons' caches on the
network) if the record is determined to be invalid.
flags:
Currently unused, reserved for future use.
interfaceIndex:
If non-zero, specifies the interface of the record in
question. Passing kDNSServiceInterfaceIndexAny (0) causes all
instances of this record to be reconfirmed.
fullname:
The resource record's full domain name.
rrtype:
The resource record's type (e.g. kDNSServiceType_PTR,
kDNSServiceType_SRV, etc.).
rrclass:
The class of the resource record (usually
kDNSServiceClass_IN).
rdata:
A string containing the raw rdata of the resource record.
"""
_NO_DEFAULT.check(fullname)
_NO_DEFAULT.check(rrtype)
_NO_DEFAULT.check(rdata)
rdlen, rdata = _string_to_length_and_void_p(rdata)
_global_lock.acquire()
try:
_DNSServiceReconfirmRecord(flags,
interfaceIndex,
fullname,
rrtype,
rrclass,
rdlen,
rdata)
finally:
_global_lock.release()
def DNSServiceConstructFullName(
service = None,
regtype = _NO_DEFAULT,
domain = _NO_DEFAULT,
):
"""
Concatenate a three-part domain name (as returned by a callback
function) into a properly-escaped full domain name. Note that
callback functions already escape strings where necessary.
service:
The service name; any dots or backslashes must NOT be escaped.
May be None (to construct a PTR record name, e.g.
"_ftp._tcp.apple.com.").
regtype:
The service type followed by the protocol, separated by a dot
(e.g. "_ftp._tcp").
domain:
The domain name, e.g. "apple.com.". Literal dots or
backslashes, if any, must be escaped,
e.g. "1st\. Floor.apple.com."
return value:
The resulting full domain name.
"""
_NO_DEFAULT.check(regtype)
_NO_DEFAULT.check(domain)
_global_lock.acquire()
try:
fullName = _DNSServiceConstructFullName(service, regtype, domain)
finally:
_global_lock.release()
return fullName.value.decode('utf-8')
################################################################################
#
# TXTRecord class
#
################################################################################
class TXTRecord(object):
"""
A mapping representing a DNS TXT record. The TXT record's
name=value entries are stored as key/value pairs in the mapping.
Although keys can be accessed in a case-insensitive fashion
(meaning txt['foo'] and txt['FoO'] refer to the same value), key
case is preserved in the wire representation of the record (so
txt['FoO'] = 'bar' will generate a FoO=bar entry in the TXT
record). Key order is also preserved, so keys appear in the wire
format in the order in which they were created.
Note that in addition to being valid as a txtRecord parameter to
DNSServiceRegister(), a TXTRecord instance can be used in place of
a resource record data string (i.e. rdata parameter) with any
function that accepts one.
"""
def __init__(self, items={}, strict=True):
"""
Create a new TXTRecord instance, initializing it with the
contents of items. If strict is true, then strict conformance
to the DNS TXT record format will be enforced, and attempts to
add a name containing invalid characters or a name/value pair
whose wire representation is longer than 255 bytes will raise
a ValueError exception.
"""
self.strict = strict
self._names = []
self._items = {}
for name, value in items.iteritems():
self[name] = value
def __contains__(self, name):
'Return True if name is a key in the record, False otherwise'
return (name.lower() in self._items)
def __iter__(self):
'Return an iterator over name/value pairs'
for name in self._names:
yield self._items[name]
def __len__(self):
'Return the number of name/value pairs'
return len(self._names)
def __nonzero__(self):
'Return False if the record is empty, True otherwise'
return bool(self._items)
def __str__(self):
"""
Return the wire representation of the TXT record as a string.
If self.strict is false, any name/value pair whose wire length
if greater than 255 bytes will be truncated to 255 bytes. If
the record is empty, '\\0' is returned.
"""
if not self:
return '\0'
parts = []
for name, value in self:
if value is None:
item = name
else:
item = '%s=%s' % (name, value)
if (not self.strict) and (len(item) > 255):
item = item[:255]
parts.append(chr(len(item)))
parts.append(item)
return ''.join(parts)
def __getitem__(self, name):
"""
Return the value associated with name. The value is either
None (meaning name has no associated value) or an str instance
(which may be of length 0). Raises KeyError if name is not a
key.
"""
return self._items[name.lower()][1]
# Require one or more printable ASCII characters (0x20-0x7E),
# excluding '=' (0x3D)
_valid_name_re = re.compile(r'^[ -<>-~]+$')
def __setitem__(self, name, value):
"""
Add a name/value pair to the record. If value is None, then
name will have no associated value. If value is a unicode
instance, it will be encoded as a UTF-8 string. Otherwise,
value will be converted to an str instance.
"""
stored_name = name
name = name.lower()
length = len(name)
if value is not None:
if isinstance(value, unicode):
value = value.encode('utf-8')
else:
value = str(value)
length += 1 + len(value)
if self.strict and (length > 255):
raise ValueError('name=value string must be 255 bytes or less')
if name not in self._items:
if self.strict and (self._valid_name_re.match(stored_name) is None):
raise ValueError("invalid name: '%s'" % stored_name)
self._names.append(name)
self._items[name] = (stored_name, value)
def __delitem__(self, name):
"""
Remove name and its corresponding value from the record.
Raises KeyError if name is not a key.
"""
name = name.lower()
del self._items[name]
self._names.remove(name)
@classmethod
def parse(cls, data, strict=False):
"""
Given a string data containing the wire representation of a
DNS TXT record, parse it and return a TXTRecord instance. The
strict parameter is passed to the TXTRecord constructor.
"""
txt = cls(strict=strict)
while data:
length = ord(data[0])
item = data[1:length+1].split('=', 1)
# Add the item only if the name is non-empty and there are
# no existing items with the same name
if item[0] and (item[0] not in txt):
if len(item) == 1:
txt[item[0]] = None
else:
txt[item[0]] = item[1]
data = data[length+1:]
return txt
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