diff --git a/sipsimple/account/bonjour/_bonjour.py b/sipsimple/account/bonjour/_bonjour.py index 63231b40..8e4dffb9 100644 --- a/sipsimple/account/bonjour/_bonjour.py +++ b/sipsimple/account/bonjour/_bonjour.py @@ -1,2109 +1,2109 @@ ################################################################################ # # 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 ' __version__ = '1.1.1' __revision__ = int('$Revision: 6125 $'.split()[1]) import ctypes import os import re import socket import sys from application.python import Null ################################################################################ # # 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 try: _libdnssd = ctypes.windll.dnssd except: _libdnssd = _CFunc = Null available = False else: _CFunc = ctypes.WINFUNCTYPE available = True 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' from eventlib.green.threading import RLock _global_lock = RLock() try: _libdnssd = ctypes.cdll.LoadLibrary(_libdnssd) except: _libdnssd = _CFunc = Null available = False else: _CFunc = ctypes.CFUNCTYPE available = True ################################################################################ # # 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, str): raise TypeError('parameter must be a string type instance') if not isinstance(obj, str): obj = str(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 __hash__(self): return hash(self.value) 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 list(specs.items()): 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 # preset these so that pyflakes doesn't complain _DNSServiceRefDeallocate = None _DNSServiceRefSockFD = None _DNSServiceProcessResult = None _DNSServiceEnumerateDomains = None _DNSServiceRegister = None _DNSServiceAddRecord = None _DNSServiceUpdateRecord = None _DNSServiceRemoveRecord = None _DNSServiceBrowse = None _DNSServiceResolve = None _DNSServiceCreateConnection = None _DNSServiceRegisterRecord = None _DNSServiceQueryRecord = None _DNSServiceReconfirmRecord = None _DNSServiceConstructFullName = None # 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 '' 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.encode()), 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].decode() for i in range(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 . 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. ... 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 ... 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 list(items.items()): 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 __bool__(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) + item = '%s=%s' % (name, value.decode() if isinstance(value, bytes) else 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, str): 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) def get(self, name, default=None): return self._items.get(name.lower(), (name, default))[1] @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