1573 lines
45 KiB
Python
1573 lines
45 KiB
Python
""" Multicast DNS Service Discovery for Python, v0.12
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Copyright (C) 2003, Paul Scott-Murphy
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This module provides a framework for the use of DNS Service Discovery
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using IP multicast. It has been tested against the JRendezvous
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implementation from <a href="http://strangeberry.com">StrangeBerry</a>,
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and against the mDNSResponder from Mac OS X 10.3.8.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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"""
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"""0.12 update - allow selection of binding interface
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typo fix - Thanks A. M. Kuchlingi
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removed all use of word 'Rendezvous' - this is an API change"""
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"""0.11 update - correction to comments for addListener method
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support for new record types seen from OS X
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- IPv6 address
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- hostinfo
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ignore unknown DNS record types
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fixes to name decoding
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works alongside other processes using port 5353 (e.g. on Mac OS X)
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tested against Mac OS X 10.3.2's mDNSResponder
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corrections to removal of list entries for service browser"""
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"""0.10 update - Jonathon Paisley contributed these corrections:
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always multicast replies, even when query is unicast
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correct a pointer encoding problem
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can now write records in any order
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traceback shown on failure
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better TXT record parsing
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server is now separate from name
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can cancel a service browser
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modified some unit tests to accommodate these changes"""
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"""0.09 update - remove all records on service unregistration
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fix DOS security problem with readName"""
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"""0.08 update - changed licensing to LGPL"""
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"""0.07 update - faster shutdown on engine
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pointer encoding of outgoing names
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ServiceBrowser now works
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new unit tests"""
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"""0.06 update - small improvements with unit tests
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added defined exception types
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new style objects
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fixed hostname/interface problem
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fixed socket timeout problem
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fixed addServiceListener() typo bug
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using select() for socket reads
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tested on Debian unstable with Python 2.2.2"""
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"""0.05 update - ensure case insensitivty on domain names
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support for unicast DNS queries"""
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"""0.04 update - added some unit tests
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added __ne__ adjuncts where required
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ensure names end in '.local.'
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timeout on receiving socket for clean shutdown"""
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__author__ = "Paul Scott-Murphy"
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__email__ = "paul at scott dash murphy dot com"
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__version__ = "0.12"
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import string
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import time
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import struct
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import socket
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import threading
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import select
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import traceback
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__all__ = ["Zeroconf", "ServiceInfo", "ServiceBrowser"]
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# hook for threads
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globals()['_GLOBAL_DONE'] = 0
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# Some timing constants
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_UNREGISTER_TIME = 125
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_CHECK_TIME = 175
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_REGISTER_TIME = 225
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_LISTENER_TIME = 200
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_BROWSER_TIME = 500
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# Some DNS constants
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_MDNS_ADDR = '224.0.0.251'
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_MDNS_PORT = 5353;
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_DNS_PORT = 53;
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_DNS_TTL = 60 * 60; # one hour default TTL
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_MAX_MSG_TYPICAL = 1460 # unused
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_MAX_MSG_ABSOLUTE = 8972
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_FLAGS_QR_MASK = 0x8000 # query response mask
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_FLAGS_QR_QUERY = 0x0000 # query
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_FLAGS_QR_RESPONSE = 0x8000 # response
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_FLAGS_AA = 0x0400 # Authorative answer
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_FLAGS_TC = 0x0200 # Truncated
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_FLAGS_RD = 0x0100 # Recursion desired
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_FLAGS_RA = 0x8000 # Recursion available
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_FLAGS_Z = 0x0040 # Zero
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_FLAGS_AD = 0x0020 # Authentic data
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_FLAGS_CD = 0x0010 # Checking disabled
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_CLASS_IN = 1
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_CLASS_CS = 2
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_CLASS_CH = 3
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_CLASS_HS = 4
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_CLASS_NONE = 254
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_CLASS_ANY = 255
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_CLASS_MASK = 0x7FFF
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_CLASS_UNIQUE = 0x8000
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_TYPE_A = 1
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_TYPE_NS = 2
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_TYPE_MD = 3
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_TYPE_MF = 4
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_TYPE_CNAME = 5
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_TYPE_SOA = 6
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_TYPE_MB = 7
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_TYPE_MG = 8
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_TYPE_MR = 9
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_TYPE_NULL = 10
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_TYPE_WKS = 11
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_TYPE_PTR = 12
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_TYPE_HINFO = 13
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_TYPE_MINFO = 14
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_TYPE_MX = 15
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_TYPE_TXT = 16
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_TYPE_AAAA = 28
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_TYPE_SRV = 33
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_TYPE_ANY = 255
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# Mapping constants to names
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_CLASSES = { _CLASS_IN : "in",
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_CLASS_CS : "cs",
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_CLASS_CH : "ch",
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_CLASS_HS : "hs",
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_CLASS_NONE : "none",
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_CLASS_ANY : "any" }
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_TYPES = { _TYPE_A : "a",
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_TYPE_NS : "ns",
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_TYPE_MD : "md",
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_TYPE_MF : "mf",
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_TYPE_CNAME : "cname",
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_TYPE_SOA : "soa",
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_TYPE_MB : "mb",
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_TYPE_MG : "mg",
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_TYPE_MR : "mr",
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_TYPE_NULL : "null",
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_TYPE_WKS : "wks",
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_TYPE_PTR : "ptr",
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_TYPE_HINFO : "hinfo",
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_TYPE_MINFO : "minfo",
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_TYPE_MX : "mx",
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_TYPE_TXT : "txt",
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_TYPE_AAAA : "quada",
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_TYPE_SRV : "srv",
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_TYPE_ANY : "any" }
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# utility functions
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def currentTimeMillis():
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"""Current system time in milliseconds"""
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return time.time() * 1000
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# Exceptions
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class NonLocalNameException(Exception):
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pass
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class NonUniqueNameException(Exception):
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pass
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class NamePartTooLongException(Exception):
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pass
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class AbstractMethodException(Exception):
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pass
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class BadTypeInNameException(Exception):
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pass
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# implementation classes
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class DNSEntry(object):
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"""A DNS entry"""
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def __init__(self, name, type, clazz):
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self.key = string.lower(name)
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self.name = name
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self.type = type
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self.clazz = clazz & _CLASS_MASK
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self.unique = (clazz & _CLASS_UNIQUE) != 0
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def __eq__(self, other):
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"""Equality test on name, type, and class"""
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if isinstance(other, DNSEntry):
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return self.name == other.name and self.type == other.type and self.clazz == other.clazz
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return 0
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def __ne__(self, other):
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"""Non-equality test"""
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return not self.__eq__(other)
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def getClazz(self, clazz):
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"""Class accessor"""
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try:
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return _CLASSES[clazz]
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except:
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return "?(%s)" % (clazz)
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def getType(self, type):
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"""Type accessor"""
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try:
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return _TYPES[type]
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except:
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return "?(%s)" % (type)
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def toString(self, hdr, other):
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"""String representation with additional information"""
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result = "%s[%s,%s" % (hdr, self.getType(self.type), self.getClazz(self.clazz))
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if self.unique:
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result += "-unique,"
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else:
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result += ","
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result += self.name
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if other is not None:
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result += ",%s]" % (other)
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else:
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result += "]"
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return result
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class DNSQuestion(DNSEntry):
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"""A DNS question entry"""
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def __init__(self, name, type, clazz):
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if not name.endswith(".local."):
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raise NonLocalNameException(name)
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DNSEntry.__init__(self, name, type, clazz)
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def answeredBy(self, rec):
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"""Returns true if the question is answered by the record"""
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return self.clazz == rec.clazz and (self.type == rec.type or self.type == _TYPE_ANY) and self.name == rec.name
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def __repr__(self):
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"""String representation"""
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return DNSEntry.toString(self, "question", None)
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class DNSRecord(DNSEntry):
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"""A DNS record - like a DNS entry, but has a TTL"""
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def __init__(self, name, type, clazz, ttl):
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DNSEntry.__init__(self, name, type, clazz)
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self.ttl = ttl
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self.created = currentTimeMillis()
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def __eq__(self, other):
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"""Tests equality as per DNSRecord"""
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if isinstance(other, DNSRecord):
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return DNSEntry.__eq__(self, other)
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return 0
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def suppressedBy(self, msg):
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"""Returns true if any answer in a message can suffice for the
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information held in this record."""
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for record in msg.answers:
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if self.suppressedByAnswer(record):
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return 1
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return 0
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def suppressedByAnswer(self, other):
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"""Returns true if another record has same name, type and class,
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and if its TTL is at least half of this record's."""
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if self == other and other.ttl > (self.ttl / 2):
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return 1
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return 0
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def getExpirationTime(self, percent):
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"""Returns the time at which this record will have expired
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by a certain percentage."""
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return self.created + (percent * self.ttl * 10)
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def getRemainingTTL(self, now):
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"""Returns the remaining TTL in seconds."""
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return max(0, (self.getExpirationTime(100) - now) / 1000)
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def isExpired(self, now):
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"""Returns true if this record has expired."""
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return self.getExpirationTime(100) <= now
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def isStale(self, now):
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"""Returns true if this record is at least half way expired."""
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return self.getExpirationTime(50) <= now
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def resetTTL(self, other):
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"""Sets this record's TTL and created time to that of
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another record."""
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self.created = other.created
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self.ttl = other.ttl
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def write(self, out):
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"""Abstract method"""
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raise AbstractMethodException
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def toString(self, other):
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"""String representation with addtional information"""
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arg = "%s/%s,%s" % (self.ttl, self.getRemainingTTL(currentTimeMillis()), other)
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return DNSEntry.toString(self, "record", arg)
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class DNSAddress(DNSRecord):
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"""A DNS address record"""
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def __init__(self, name, type, clazz, ttl, address):
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DNSRecord.__init__(self, name, type, clazz, ttl)
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self.address = address
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def write(self, out):
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"""Used in constructing an outgoing packet"""
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out.writeString(self.address, len(self.address))
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def __eq__(self, other):
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"""Tests equality on address"""
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if isinstance(other, DNSAddress):
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return self.address == other.address
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return 0
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def __repr__(self):
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"""String representation"""
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try:
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return socket.inet_ntoa(self.address)
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except:
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return self.address
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class DNSHinfo(DNSRecord):
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"""A DNS host information record"""
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def __init__(self, name, type, clazz, ttl, cpu, os):
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DNSRecord.__init__(self, name, type, clazz, ttl)
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self.cpu = cpu
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self.os = os
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def write(self, out):
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"""Used in constructing an outgoing packet"""
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out.writeString(self.cpu, len(self.cpu))
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out.writeString(self.os, len(self.os))
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def __eq__(self, other):
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"""Tests equality on cpu and os"""
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if isinstance(other, DNSHinfo):
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return self.cpu == other.cpu and self.os == other.os
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return 0
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def __repr__(self):
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"""String representation"""
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return self.cpu + " " + self.os
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class DNSPointer(DNSRecord):
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"""A DNS pointer record"""
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def __init__(self, name, type, clazz, ttl, alias):
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DNSRecord.__init__(self, name, type, clazz, ttl)
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self.alias = alias
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def write(self, out):
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"""Used in constructing an outgoing packet"""
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out.writeName(self.alias)
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def __eq__(self, other):
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"""Tests equality on alias"""
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if isinstance(other, DNSPointer):
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return self.alias == other.alias
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return 0
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def __repr__(self):
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"""String representation"""
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return self.toString(self.alias)
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class DNSText(DNSRecord):
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"""A DNS text record"""
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def __init__(self, name, type, clazz, ttl, text):
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DNSRecord.__init__(self, name, type, clazz, ttl)
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self.text = text
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def write(self, out):
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"""Used in constructing an outgoing packet"""
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out.writeString(self.text, len(self.text))
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def __eq__(self, other):
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"""Tests equality on text"""
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if isinstance(other, DNSText):
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return self.text == other.text
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return 0
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def __repr__(self):
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"""String representation"""
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if len(self.text) > 10:
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return self.toString(self.text[:7] + "...")
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else:
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return self.toString(self.text)
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class DNSService(DNSRecord):
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"""A DNS service record"""
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def __init__(self, name, type, clazz, ttl, priority, weight, port, server):
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DNSRecord.__init__(self, name, type, clazz, ttl)
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self.priority = priority
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self.weight = weight
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self.port = port
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self.server = server
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def write(self, out):
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"""Used in constructing an outgoing packet"""
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out.writeShort(self.priority)
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out.writeShort(self.weight)
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out.writeShort(self.port)
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out.writeName(self.server)
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def __eq__(self, other):
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"""Tests equality on priority, weight, port and server"""
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if isinstance(other, DNSService):
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return self.priority == other.priority and self.weight == other.weight and self.port == other.port and self.server == other.server
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return 0
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def __repr__(self):
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"""String representation"""
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return self.toString("%s:%s" % (self.server, self.port))
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class DNSIncoming(object):
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"""Object representation of an incoming DNS packet"""
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def __init__(self, data):
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"""Constructor from string holding bytes of packet"""
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self.offset = 0
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self.data = data
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self.questions = []
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self.answers = []
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self.numQuestions = 0
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self.numAnswers = 0
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self.numAuthorities = 0
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self.numAdditionals = 0
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self.readHeader()
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self.readQuestions()
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self.readOthers()
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def readHeader(self):
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"""Reads header portion of packet"""
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format = '!HHHHHH'
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length = struct.calcsize(format)
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info = struct.unpack(format, self.data[self.offset:self.offset+length])
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self.offset += length
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self.id = info[0]
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self.flags = info[1]
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self.numQuestions = info[2]
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self.numAnswers = info[3]
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self.numAuthorities = info[4]
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self.numAdditionals = info[5]
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def readQuestions(self):
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"""Reads questions section of packet"""
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format = '!HH'
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length = struct.calcsize(format)
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for i in range(0, self.numQuestions):
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name = self.readName()
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info = struct.unpack(format, self.data[self.offset:self.offset+length])
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self.offset += length
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try:
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question = DNSQuestion(name, info[0], info[1])
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self.questions.append(question)
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except NonLocalNameException:
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pass
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def readInt(self):
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"""Reads an integer from the packet"""
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format = '!I'
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length = struct.calcsize(format)
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info = struct.unpack(format, self.data[self.offset:self.offset+length])
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self.offset += length
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return info[0]
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def readCharacterString(self):
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"""Reads a character string from the packet"""
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length = ord(self.data[self.offset])
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self.offset += 1
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return self.readString(length)
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def readString(self, len):
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"""Reads a string of a given length from the packet"""
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format = '!' + str(len) + 's'
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length = struct.calcsize(format)
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info = struct.unpack(format, self.data[self.offset:self.offset+length])
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self.offset += length
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return info[0]
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def readUnsignedShort(self):
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"""Reads an unsigned short from the packet"""
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format = '!H'
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length = struct.calcsize(format)
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info = struct.unpack(format, self.data[self.offset:self.offset+length])
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self.offset += length
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return info[0]
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def readOthers(self):
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"""Reads the answers, authorities and additionals section of the packet"""
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format = '!HHiH'
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length = struct.calcsize(format)
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n = self.numAnswers + self.numAuthorities + self.numAdditionals
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for i in range(0, n):
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domain = self.readName()
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info = struct.unpack(format, self.data[self.offset:self.offset+length])
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self.offset += length
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|
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rec = None
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if info[0] == _TYPE_A:
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rec = DNSAddress(domain, info[0], info[1], info[2], self.readString(4))
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elif info[0] == _TYPE_CNAME or info[0] == _TYPE_PTR:
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rec = DNSPointer(domain, info[0], info[1], info[2], self.readName())
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elif info[0] == _TYPE_TXT:
|
|
rec = DNSText(domain, info[0], info[1], info[2], self.readString(info[3]))
|
|
elif info[0] == _TYPE_SRV:
|
|
rec = DNSService(domain, info[0], info[1], info[2], self.readUnsignedShort(), self.readUnsignedShort(), self.readUnsignedShort(), self.readName())
|
|
elif info[0] == _TYPE_HINFO:
|
|
rec = DNSHinfo(domain, info[0], info[1], info[2], self.readCharacterString(), self.readCharacterString())
|
|
elif info[0] == _TYPE_AAAA:
|
|
rec = DNSAddress(domain, info[0], info[1], info[2], self.readString(16))
|
|
else:
|
|
# Try to ignore types we don't know about
|
|
# this may mean the rest of the name is
|
|
# unable to be parsed, and may show errors
|
|
# so this is left for debugging. New types
|
|
# encountered need to be parsed properly.
|
|
#
|
|
#print "UNKNOWN TYPE = " + str(info[0])
|
|
#raise BadTypeInNameException
|
|
pass
|
|
|
|
if rec is not None:
|
|
self.answers.append(rec)
|
|
|
|
def isQuery(self):
|
|
"""Returns true if this is a query"""
|
|
return (self.flags & _FLAGS_QR_MASK) == _FLAGS_QR_QUERY
|
|
|
|
def isResponse(self):
|
|
"""Returns true if this is a response"""
|
|
return (self.flags & _FLAGS_QR_MASK) == _FLAGS_QR_RESPONSE
|
|
|
|
def readUTF(self, offset, len):
|
|
"""Reads a UTF-8 string of a given length from the packet"""
|
|
result = self.data[offset:offset+len].decode('utf-8')
|
|
return result
|
|
|
|
def readName(self):
|
|
"""Reads a domain name from the packet"""
|
|
result = ''
|
|
off = self.offset
|
|
next = -1
|
|
first = off
|
|
|
|
while 1:
|
|
len = ord(self.data[off])
|
|
off += 1
|
|
if len == 0:
|
|
break
|
|
t = len & 0xC0
|
|
if t == 0x00:
|
|
result = ''.join((result, self.readUTF(off, len) + '.'))
|
|
off += len
|
|
elif t == 0xC0:
|
|
if next < 0:
|
|
next = off + 1
|
|
off = ((len & 0x3F) << 8) | ord(self.data[off])
|
|
if off >= first:
|
|
raise "Bad domain name (circular) at " + str(off)
|
|
first = off
|
|
else:
|
|
raise "Bad domain name at " + str(off)
|
|
|
|
if next >= 0:
|
|
self.offset = next
|
|
else:
|
|
self.offset = off
|
|
|
|
return result
|
|
|
|
|
|
class DNSOutgoing(object):
|
|
"""Object representation of an outgoing packet"""
|
|
|
|
def __init__(self, flags, multicast = 1):
|
|
self.finished = 0
|
|
self.id = 0
|
|
self.multicast = multicast
|
|
self.flags = flags
|
|
self.names = {}
|
|
self.data = []
|
|
self.size = 12
|
|
|
|
self.questions = []
|
|
self.answers = []
|
|
self.authorities = []
|
|
self.additionals = []
|
|
|
|
def addQuestion(self, record):
|
|
"""Adds a question"""
|
|
self.questions.append(record)
|
|
|
|
def addAnswer(self, inp, record):
|
|
"""Adds an answer"""
|
|
if not record.suppressedBy(inp):
|
|
self.addAnswerAtTime(record, 0)
|
|
|
|
def addAnswerAtTime(self, record, now):
|
|
"""Adds an answer if if does not expire by a certain time"""
|
|
if record is not None:
|
|
if now == 0 or not record.isExpired(now):
|
|
self.answers.append((record, now))
|
|
|
|
def addAuthorativeAnswer(self, record):
|
|
"""Adds an authoritative answer"""
|
|
self.authorities.append(record)
|
|
|
|
def addAdditionalAnswer(self, record):
|
|
"""Adds an additional answer"""
|
|
self.additionals.append(record)
|
|
|
|
def writeByte(self, value):
|
|
"""Writes a single byte to the packet"""
|
|
format = '!c'
|
|
self.data.append(struct.pack(format, chr(value)))
|
|
self.size += 1
|
|
|
|
def insertShort(self, index, value):
|
|
"""Inserts an unsigned short in a certain position in the packet"""
|
|
format = '!H'
|
|
self.data.insert(index, struct.pack(format, value))
|
|
self.size += 2
|
|
|
|
def writeShort(self, value):
|
|
"""Writes an unsigned short to the packet"""
|
|
format = '!H'
|
|
self.data.append(struct.pack(format, value))
|
|
self.size += 2
|
|
|
|
def writeInt(self, value):
|
|
"""Writes an unsigned integer to the packet"""
|
|
format = '!I'
|
|
self.data.append(struct.pack(format, int(value)))
|
|
self.size += 4
|
|
|
|
def writeString(self, value, length):
|
|
"""Writes a string to the packet"""
|
|
format = '!' + str(length) + 's'
|
|
self.data.append(struct.pack(format, value))
|
|
self.size += length
|
|
|
|
def writeUTF(self, s):
|
|
"""Writes a UTF-8 string of a given length to the packet"""
|
|
utfstr = s.encode('utf-8')
|
|
length = len(utfstr)
|
|
if length > 64:
|
|
raise NamePartTooLongException
|
|
self.writeByte(length)
|
|
self.writeString(utfstr, length)
|
|
|
|
def writeName(self, name):
|
|
"""Writes a domain name to the packet"""
|
|
|
|
try:
|
|
# Find existing instance of this name in packet
|
|
#
|
|
index = self.names[name]
|
|
except KeyError:
|
|
# No record of this name already, so write it
|
|
# out as normal, recording the location of the name
|
|
# for future pointers to it.
|
|
#
|
|
self.names[name] = self.size
|
|
parts = name.split('.')
|
|
if parts[-1] == '':
|
|
parts = parts[:-1]
|
|
for part in parts:
|
|
self.writeUTF(part)
|
|
self.writeByte(0)
|
|
return
|
|
|
|
# An index was found, so write a pointer to it
|
|
#
|
|
self.writeByte((index >> 8) | 0xC0)
|
|
self.writeByte(index)
|
|
|
|
def writeQuestion(self, question):
|
|
"""Writes a question to the packet"""
|
|
self.writeName(question.name)
|
|
self.writeShort(question.type)
|
|
self.writeShort(question.clazz)
|
|
|
|
def writeRecord(self, record, now):
|
|
"""Writes a record (answer, authoritative answer, additional) to
|
|
the packet"""
|
|
self.writeName(record.name)
|
|
self.writeShort(record.type)
|
|
if record.unique and self.multicast:
|
|
self.writeShort(record.clazz | _CLASS_UNIQUE)
|
|
else:
|
|
self.writeShort(record.clazz)
|
|
if now == 0:
|
|
self.writeInt(record.ttl)
|
|
else:
|
|
self.writeInt(record.getRemainingTTL(now))
|
|
index = len(self.data)
|
|
# Adjust size for the short we will write before this record
|
|
#
|
|
self.size += 2
|
|
record.write(self)
|
|
self.size -= 2
|
|
|
|
length = len(''.join(self.data[index:]))
|
|
self.insertShort(index, length) # Here is the short we adjusted for
|
|
|
|
def packet(self):
|
|
"""Returns a string containing the packet's bytes
|
|
|
|
No further parts should be added to the packet once this
|
|
is done."""
|
|
if not self.finished:
|
|
self.finished = 1
|
|
for question in self.questions:
|
|
self.writeQuestion(question)
|
|
for answer, time in self.answers:
|
|
self.writeRecord(answer, time)
|
|
for authority in self.authorities:
|
|
self.writeRecord(authority, 0)
|
|
for additional in self.additionals:
|
|
self.writeRecord(additional, 0)
|
|
|
|
self.insertShort(0, len(self.additionals))
|
|
self.insertShort(0, len(self.authorities))
|
|
self.insertShort(0, len(self.answers))
|
|
self.insertShort(0, len(self.questions))
|
|
self.insertShort(0, self.flags)
|
|
if self.multicast:
|
|
self.insertShort(0, 0)
|
|
else:
|
|
self.insertShort(0, self.id)
|
|
return ''.join(self.data)
|
|
|
|
|
|
class DNSCache(object):
|
|
"""A cache of DNS entries"""
|
|
|
|
def __init__(self):
|
|
self.cache = {}
|
|
|
|
def add(self, entry):
|
|
"""Adds an entry"""
|
|
try:
|
|
list = self.cache[entry.key]
|
|
except:
|
|
list = self.cache[entry.key] = []
|
|
list.append(entry)
|
|
|
|
def remove(self, entry):
|
|
"""Removes an entry"""
|
|
try:
|
|
list = self.cache[entry.key]
|
|
list.remove(entry)
|
|
except:
|
|
pass
|
|
|
|
def get(self, entry):
|
|
"""Gets an entry by key. Will return None if there is no
|
|
matching entry."""
|
|
try:
|
|
list = self.cache[entry.key]
|
|
return list[list.index(entry)]
|
|
except:
|
|
return None
|
|
|
|
def getByDetails(self, name, type, clazz):
|
|
"""Gets an entry by details. Will return None if there is
|
|
no matching entry."""
|
|
entry = DNSEntry(name, type, clazz)
|
|
return self.get(entry)
|
|
|
|
def entriesWithName(self, name):
|
|
"""Returns a list of entries whose key matches the name."""
|
|
try:
|
|
return self.cache[name]
|
|
except:
|
|
return []
|
|
|
|
def entries(self):
|
|
"""Returns a list of all entries"""
|
|
def add(x, y): return x+y
|
|
try:
|
|
return reduce(add, self.cache.values())
|
|
except:
|
|
return []
|
|
|
|
|
|
class Engine(threading.Thread):
|
|
"""An engine wraps read access to sockets, allowing objects that
|
|
need to receive data from sockets to be called back when the
|
|
sockets are ready.
|
|
|
|
A reader needs a handle_read() method, which is called when the socket
|
|
it is interested in is ready for reading.
|
|
|
|
Writers are not implemented here, because we only send short
|
|
packets.
|
|
"""
|
|
|
|
def __init__(self, zeroconf):
|
|
threading.Thread.__init__(self)
|
|
self.zeroconf = zeroconf
|
|
self.readers = {} # maps socket to reader
|
|
self.timeout = 5
|
|
self.condition = threading.Condition()
|
|
self.start()
|
|
|
|
def run(self):
|
|
while not globals()['_GLOBAL_DONE']:
|
|
rs = self.getReaders()
|
|
if len(rs) == 0:
|
|
# No sockets to manage, but we wait for the timeout
|
|
# or addition of a socket
|
|
#
|
|
self.condition.acquire()
|
|
self.condition.wait(self.timeout)
|
|
self.condition.release()
|
|
else:
|
|
try:
|
|
rr, wr, er = select.select(rs, [], [], self.timeout)
|
|
for socket in rr:
|
|
try:
|
|
self.readers[socket].handle_read()
|
|
except:
|
|
traceback.print_exc()
|
|
except:
|
|
pass
|
|
|
|
def getReaders(self):
|
|
self.condition.acquire()
|
|
result = self.readers.keys()
|
|
self.condition.release()
|
|
return result
|
|
|
|
def addReader(self, reader, socket):
|
|
self.condition.acquire()
|
|
self.readers[socket] = reader
|
|
self.condition.notify()
|
|
self.condition.release()
|
|
|
|
def delReader(self, socket):
|
|
self.condition.acquire()
|
|
del(self.readers[socket])
|
|
self.condition.notify()
|
|
self.condition.release()
|
|
|
|
def notify(self):
|
|
self.condition.acquire()
|
|
self.condition.notify()
|
|
self.condition.release()
|
|
|
|
class Listener(object):
|
|
"""A Listener is used by this module to listen on the multicast
|
|
group to which DNS messages are sent, allowing the implementation
|
|
to cache information as it arrives.
|
|
|
|
It requires registration with an Engine object in order to have
|
|
the read() method called when a socket is availble for reading."""
|
|
|
|
def __init__(self, zeroconf):
|
|
self.zeroconf = zeroconf
|
|
self.zeroconf.engine.addReader(self, self.zeroconf.socket)
|
|
|
|
def handle_read(self):
|
|
data, (addr, port) = self.zeroconf.socket.recvfrom(_MAX_MSG_ABSOLUTE)
|
|
self.data = data
|
|
msg = DNSIncoming(data)
|
|
if msg.isQuery():
|
|
# Always multicast responses
|
|
#
|
|
if port == _MDNS_PORT:
|
|
self.zeroconf.handleQuery(msg, _MDNS_ADDR, _MDNS_PORT)
|
|
# If it's not a multicast query, reply via unicast
|
|
# and multicast
|
|
#
|
|
elif port == _DNS_PORT:
|
|
self.zeroconf.handleQuery(msg, addr, port)
|
|
self.zeroconf.handleQuery(msg, _MDNS_ADDR, _MDNS_PORT)
|
|
else:
|
|
self.zeroconf.handleResponse(msg)
|
|
|
|
|
|
class Reaper(threading.Thread):
|
|
"""A Reaper is used by this module to remove cache entries that
|
|
have expired."""
|
|
|
|
def __init__(self, zeroconf):
|
|
threading.Thread.__init__(self)
|
|
self.zeroconf = zeroconf
|
|
self.start()
|
|
|
|
def run(self):
|
|
while 1:
|
|
self.zeroconf.wait(10 * 1000)
|
|
if globals()['_GLOBAL_DONE']:
|
|
return
|
|
now = currentTimeMillis()
|
|
for record in self.zeroconf.cache.entries():
|
|
if record.isExpired(now):
|
|
self.zeroconf.updateRecord(now, record)
|
|
self.zeroconf.cache.remove(record)
|
|
|
|
|
|
class ServiceBrowser(threading.Thread):
|
|
"""Used to browse for a service of a specific type.
|
|
|
|
The listener object will have its addService() and
|
|
removeService() methods called when this browser
|
|
discovers changes in the services availability."""
|
|
|
|
def __init__(self, zeroconf, type, listener):
|
|
"""Creates a browser for a specific type"""
|
|
threading.Thread.__init__(self)
|
|
self.zeroconf = zeroconf
|
|
self.type = type
|
|
self.listener = listener
|
|
self.services = {}
|
|
self.nextTime = currentTimeMillis()
|
|
self.delay = _BROWSER_TIME
|
|
self.list = []
|
|
|
|
self.done = 0
|
|
|
|
self.zeroconf.addListener(self, DNSQuestion(self.type, _TYPE_PTR, _CLASS_IN))
|
|
self.start()
|
|
|
|
def updateRecord(self, zeroconf, now, record):
|
|
"""Callback invoked by Zeroconf when new information arrives.
|
|
|
|
Updates information required by browser in the Zeroconf cache."""
|
|
if record.type == _TYPE_PTR and record.name == self.type:
|
|
expired = record.isExpired(now)
|
|
try:
|
|
oldrecord = self.services[record.alias.lower()]
|
|
if not expired:
|
|
oldrecord.resetTTL(record)
|
|
else:
|
|
del(self.services[record.alias.lower()])
|
|
callback = lambda x: self.listener.removeService(x, self.type, record.alias)
|
|
self.list.append(callback)
|
|
return
|
|
except:
|
|
if not expired:
|
|
self.services[record.alias.lower()] = record
|
|
callback = lambda x: self.listener.addService(x, self.type, record.alias)
|
|
self.list.append(callback)
|
|
|
|
expires = record.getExpirationTime(75)
|
|
if expires < self.nextTime:
|
|
self.nextTime = expires
|
|
|
|
def cancel(self):
|
|
self.done = 1
|
|
self.zeroconf.notifyAll()
|
|
|
|
def run(self):
|
|
while 1:
|
|
event = None
|
|
now = currentTimeMillis()
|
|
if len(self.list) == 0 and self.nextTime > now:
|
|
self.zeroconf.wait(self.nextTime - now)
|
|
if globals()['_GLOBAL_DONE'] or self.done:
|
|
return
|
|
now = currentTimeMillis()
|
|
|
|
if self.nextTime <= now:
|
|
out = DNSOutgoing(_FLAGS_QR_QUERY)
|
|
out.addQuestion(DNSQuestion(self.type, _TYPE_PTR, _CLASS_IN))
|
|
for record in self.services.values():
|
|
if not record.isExpired(now):
|
|
out.addAnswerAtTime(record, now)
|
|
self.zeroconf.send(out)
|
|
self.nextTime = now + self.delay
|
|
self.delay = min(20 * 1000, self.delay * 2)
|
|
|
|
if len(self.list) > 0:
|
|
event = self.list.pop(0)
|
|
|
|
if event is not None:
|
|
event(self.zeroconf)
|
|
|
|
|
|
class ServiceInfo(object):
|
|
"""Service information"""
|
|
|
|
def __init__(self, type, name, address=None, port=None, weight=0, priority=0, properties=None, server=None):
|
|
"""Create a service description.
|
|
|
|
type: fully qualified service type name
|
|
name: fully qualified service name
|
|
address: IP address as unsigned short, network byte order
|
|
port: port that the service runs on
|
|
weight: weight of the service
|
|
priority: priority of the service
|
|
properties: dictionary of properties (or a string holding the bytes for the text field)
|
|
server: fully qualified name for service host (defaults to name)"""
|
|
|
|
if not name.endswith(type):
|
|
raise BadTypeInNameException
|
|
self.type = type
|
|
self.name = name
|
|
self.address = address
|
|
self.port = port
|
|
self.weight = weight
|
|
self.priority = priority
|
|
if server:
|
|
self.server = server
|
|
else:
|
|
self.server = name
|
|
self.setProperties(properties)
|
|
|
|
def setProperties(self, properties):
|
|
"""Sets properties and text of this info from a dictionary"""
|
|
if isinstance(properties, dict):
|
|
self.properties = properties
|
|
list = []
|
|
result = ''
|
|
for key in properties:
|
|
value = properties[key]
|
|
if value is None:
|
|
suffix = ''.encode('utf-8')
|
|
elif isinstance(value, str):
|
|
suffix = value.encode('utf-8')
|
|
elif isinstance(value, int):
|
|
if value:
|
|
suffix = 'true'
|
|
else:
|
|
suffix = 'false'
|
|
else:
|
|
suffix = ''.encode('utf-8')
|
|
list.append('='.join((key, suffix)))
|
|
for item in list:
|
|
result = ''.join((result, struct.pack('!c', chr(len(item))), item))
|
|
self.text = result
|
|
else:
|
|
self.text = properties
|
|
|
|
def setText(self, text):
|
|
"""Sets properties and text given a text field"""
|
|
self.text = text
|
|
try:
|
|
result = {}
|
|
end = len(text)
|
|
index = 0
|
|
strs = []
|
|
while index < end:
|
|
length = ord(text[index])
|
|
index += 1
|
|
strs.append(text[index:index+length])
|
|
index += length
|
|
|
|
for s in strs:
|
|
eindex = s.find('=')
|
|
if eindex == -1:
|
|
# No equals sign at all
|
|
key = s
|
|
value = 0
|
|
else:
|
|
key = s[:eindex]
|
|
value = s[eindex+1:]
|
|
if value == 'true':
|
|
value = 1
|
|
elif value == 'false' or not value:
|
|
value = 0
|
|
|
|
# Only update non-existent properties
|
|
if key and result.get(key) == None:
|
|
result[key] = value
|
|
|
|
self.properties = result
|
|
except:
|
|
traceback.print_exc()
|
|
self.properties = None
|
|
|
|
def getType(self):
|
|
"""Type accessor"""
|
|
return self.type
|
|
|
|
def getName(self):
|
|
"""Name accessor"""
|
|
if self.type is not None and self.name.endswith("." + self.type):
|
|
return self.name[:len(self.name) - len(self.type) - 1]
|
|
return self.name
|
|
|
|
def getAddress(self):
|
|
"""Address accessor"""
|
|
return self.address
|
|
|
|
def getPort(self):
|
|
"""Port accessor"""
|
|
return self.port
|
|
|
|
def getPriority(self):
|
|
"""Pirority accessor"""
|
|
return self.priority
|
|
|
|
def getWeight(self):
|
|
"""Weight accessor"""
|
|
return self.weight
|
|
|
|
def getProperties(self):
|
|
"""Properties accessor"""
|
|
return self.properties
|
|
|
|
def getText(self):
|
|
"""Text accessor"""
|
|
return self.text
|
|
|
|
def getServer(self):
|
|
"""Server accessor"""
|
|
return self.server
|
|
|
|
def updateRecord(self, zeroconf, now, record):
|
|
"""Updates service information from a DNS record"""
|
|
if record is not None and not record.isExpired(now):
|
|
if record.type == _TYPE_A:
|
|
#if record.name == self.name:
|
|
if record.name == self.server:
|
|
self.address = record.address
|
|
elif record.type == _TYPE_SRV:
|
|
if record.name == self.name:
|
|
self.server = record.server
|
|
self.port = record.port
|
|
self.weight = record.weight
|
|
self.priority = record.priority
|
|
#self.address = None
|
|
self.updateRecord(zeroconf, now, zeroconf.cache.getByDetails(self.server, _TYPE_A, _CLASS_IN))
|
|
elif record.type == _TYPE_TXT:
|
|
if record.name == self.name:
|
|
self.setText(record.text)
|
|
|
|
def request(self, zeroconf, timeout):
|
|
"""Returns true if the service could be discovered on the
|
|
network, and updates this object with details discovered.
|
|
"""
|
|
now = currentTimeMillis()
|
|
delay = _LISTENER_TIME
|
|
next = now + delay
|
|
last = now + timeout
|
|
result = 0
|
|
try:
|
|
zeroconf.addListener(self, DNSQuestion(self.name, _TYPE_ANY, _CLASS_IN))
|
|
while self.server is None or self.address is None or self.text is None:
|
|
if last <= now:
|
|
return 0
|
|
if next <= now:
|
|
out = DNSOutgoing(_FLAGS_QR_QUERY)
|
|
out.addQuestion(DNSQuestion(self.name, _TYPE_SRV, _CLASS_IN))
|
|
out.addAnswerAtTime(zeroconf.cache.getByDetails(self.name, _TYPE_SRV, _CLASS_IN), now)
|
|
out.addQuestion(DNSQuestion(self.name, _TYPE_TXT, _CLASS_IN))
|
|
out.addAnswerAtTime(zeroconf.cache.getByDetails(self.name, _TYPE_TXT, _CLASS_IN), now)
|
|
if self.server is not None:
|
|
out.addQuestion(DNSQuestion(self.server, _TYPE_A, _CLASS_IN))
|
|
out.addAnswerAtTime(zeroconf.cache.getByDetails(self.server, _TYPE_A, _CLASS_IN), now)
|
|
zeroconf.send(out)
|
|
next = now + delay
|
|
delay = delay * 2
|
|
|
|
zeroconf.wait(min(next, last) - now)
|
|
now = currentTimeMillis()
|
|
result = 1
|
|
finally:
|
|
zeroconf.removeListener(self)
|
|
|
|
return result
|
|
|
|
def __eq__(self, other):
|
|
"""Tests equality of service name"""
|
|
if isinstance(other, ServiceInfo):
|
|
return other.name == self.name
|
|
return 0
|
|
|
|
def __ne__(self, other):
|
|
"""Non-equality test"""
|
|
return not self.__eq__(other)
|
|
|
|
def __repr__(self):
|
|
"""String representation"""
|
|
result = "service[%s,%s:%s," % (self.name, socket.inet_ntoa(self.getAddress()), self.port)
|
|
if self.text is None:
|
|
result += "None"
|
|
else:
|
|
if len(self.text) < 20:
|
|
result += self.text
|
|
else:
|
|
result += self.text[:17] + "..."
|
|
result += "]"
|
|
return result
|
|
|
|
|
|
class Zeroconf(object):
|
|
"""Implementation of Zeroconf Multicast DNS Service Discovery
|
|
|
|
Supports registration, unregistration, queries and browsing.
|
|
"""
|
|
def __init__(self, bindaddress=None):
|
|
"""Creates an instance of the Zeroconf class, establishing
|
|
multicast communications, listening and reaping threads."""
|
|
globals()['_GLOBAL_DONE'] = 0
|
|
if bindaddress is None:
|
|
self.intf = socket.gethostbyname(socket.gethostname())
|
|
else:
|
|
self.intf = bindaddress
|
|
self.group = ('', _MDNS_PORT)
|
|
self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
|
|
try:
|
|
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
|
|
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
|
|
except:
|
|
# SO_REUSEADDR should be equivalent to SO_REUSEPORT for
|
|
# multicast UDP sockets (p 731, "TCP/IP Illustrated,
|
|
# Volume 2"), but some BSD-derived systems require
|
|
# SO_REUSEPORT to be specified explicity. Also, not all
|
|
# versions of Python have SO_REUSEPORT available. So
|
|
# if you're on a BSD-based system, and haven't upgraded
|
|
# to Python 2.3 yet, you may find this library doesn't
|
|
# work as expected.
|
|
#
|
|
pass
|
|
self.socket.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_TTL, 255)
|
|
self.socket.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_LOOP, 1)
|
|
try:
|
|
self.socket.bind(self.group)
|
|
except:
|
|
# Some versions of linux raise an exception even though
|
|
# the SO_REUSE* options have been set, so ignore it
|
|
#
|
|
pass
|
|
#self.socket.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_IF, socket.inet_aton(self.intf) + socket.inet_aton('0.0.0.0'))
|
|
self.socket.setsockopt(socket.SOL_IP, socket.IP_ADD_MEMBERSHIP, socket.inet_aton(_MDNS_ADDR) + socket.inet_aton('0.0.0.0'))
|
|
|
|
self.listeners = []
|
|
self.browsers = []
|
|
self.services = {}
|
|
self.servicetypes = {}
|
|
|
|
self.cache = DNSCache()
|
|
|
|
self.condition = threading.Condition()
|
|
|
|
self.engine = Engine(self)
|
|
self.listener = Listener(self)
|
|
self.reaper = Reaper(self)
|
|
|
|
def isLoopback(self):
|
|
return self.intf.startswith("127.0.0.1")
|
|
|
|
def isLinklocal(self):
|
|
return self.intf.startswith("169.254.")
|
|
|
|
def wait(self, timeout):
|
|
"""Calling thread waits for a given number of milliseconds or
|
|
until notified."""
|
|
self.condition.acquire()
|
|
self.condition.wait(timeout/1000)
|
|
self.condition.release()
|
|
|
|
def notifyAll(self):
|
|
"""Notifies all waiting threads"""
|
|
self.condition.acquire()
|
|
self.condition.notifyAll()
|
|
self.condition.release()
|
|
|
|
def getServiceInfo(self, type, name, timeout=3000):
|
|
"""Returns network's service information for a particular
|
|
name and type, or None if no service matches by the timeout,
|
|
which defaults to 3 seconds."""
|
|
info = ServiceInfo(type, name)
|
|
if info.request(self, timeout):
|
|
return info
|
|
return None
|
|
|
|
def addServiceListener(self, type, listener):
|
|
"""Adds a listener for a particular service type. This object
|
|
will then have its updateRecord method called when information
|
|
arrives for that type."""
|
|
self.removeServiceListener(listener)
|
|
self.browsers.append(ServiceBrowser(self, type, listener))
|
|
|
|
def removeServiceListener(self, listener):
|
|
"""Removes a listener from the set that is currently listening."""
|
|
for browser in self.browsers:
|
|
if browser.listener == listener:
|
|
browser.cancel()
|
|
del(browser)
|
|
|
|
def registerService(self, info, ttl=_DNS_TTL):
|
|
"""Registers service information to the network with a default TTL
|
|
of 60 seconds. Zeroconf will then respond to requests for
|
|
information for that service. The name of the service may be
|
|
changed if needed to make it unique on the network."""
|
|
self.checkService(info)
|
|
self.services[info.name.lower()] = info
|
|
if self.servicetypes.has_key(info.type):
|
|
self.servicetypes[info.type]+=1
|
|
else:
|
|
self.servicetypes[info.type]=1
|
|
now = currentTimeMillis()
|
|
nextTime = now
|
|
i = 0
|
|
while i < 3:
|
|
if now < nextTime:
|
|
self.wait(nextTime - now)
|
|
now = currentTimeMillis()
|
|
continue
|
|
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
|
|
out.addAnswerAtTime(DNSPointer(info.type, _TYPE_PTR, _CLASS_IN, ttl, info.name), 0)
|
|
out.addAnswerAtTime(DNSService(info.name, _TYPE_SRV, _CLASS_IN, ttl, info.priority, info.weight, info.port, info.server), 0)
|
|
out.addAnswerAtTime(DNSText(info.name, _TYPE_TXT, _CLASS_IN, ttl, info.text), 0)
|
|
if info.address:
|
|
out.addAnswerAtTime(DNSAddress(info.server, _TYPE_A, _CLASS_IN, ttl, info.address), 0)
|
|
self.send(out)
|
|
i += 1
|
|
nextTime += _REGISTER_TIME
|
|
|
|
def unregisterService(self, info):
|
|
"""Unregister a service."""
|
|
try:
|
|
del(self.services[info.name.lower()])
|
|
if self.servicetypes[info.type]>1:
|
|
self.servicetypes[info.type]-=1
|
|
else:
|
|
del self.servicetypes[info.type]
|
|
except:
|
|
pass
|
|
now = currentTimeMillis()
|
|
nextTime = now
|
|
i = 0
|
|
while i < 3:
|
|
if now < nextTime:
|
|
self.wait(nextTime - now)
|
|
now = currentTimeMillis()
|
|
continue
|
|
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
|
|
out.addAnswerAtTime(DNSPointer(info.type, _TYPE_PTR, _CLASS_IN, 0, info.name), 0)
|
|
out.addAnswerAtTime(DNSService(info.name, _TYPE_SRV, _CLASS_IN, 0, info.priority, info.weight, info.port, info.name), 0)
|
|
out.addAnswerAtTime(DNSText(info.name, _TYPE_TXT, _CLASS_IN, 0, info.text), 0)
|
|
if info.address:
|
|
out.addAnswerAtTime(DNSAddress(info.server, _TYPE_A, _CLASS_IN, 0, info.address), 0)
|
|
self.send(out)
|
|
i += 1
|
|
nextTime += _UNREGISTER_TIME
|
|
|
|
def unregisterAllServices(self):
|
|
"""Unregister all registered services."""
|
|
if len(self.services) > 0:
|
|
now = currentTimeMillis()
|
|
nextTime = now
|
|
i = 0
|
|
while i < 3:
|
|
if now < nextTime:
|
|
self.wait(nextTime - now)
|
|
now = currentTimeMillis()
|
|
continue
|
|
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
|
|
for info in self.services.values():
|
|
out.addAnswerAtTime(DNSPointer(info.type, _TYPE_PTR, _CLASS_IN, 0, info.name), 0)
|
|
out.addAnswerAtTime(DNSService(info.name, _TYPE_SRV, _CLASS_IN, 0, info.priority, info.weight, info.port, info.server), 0)
|
|
out.addAnswerAtTime(DNSText(info.name, _TYPE_TXT, _CLASS_IN, 0, info.text), 0)
|
|
if info.address:
|
|
out.addAnswerAtTime(DNSAddress(info.server, _TYPE_A, _CLASS_IN, 0, info.address), 0)
|
|
self.send(out)
|
|
i += 1
|
|
nextTime += _UNREGISTER_TIME
|
|
|
|
def checkService(self, info):
|
|
"""Checks the network for a unique service name, modifying the
|
|
ServiceInfo passed in if it is not unique."""
|
|
now = currentTimeMillis()
|
|
nextTime = now
|
|
i = 0
|
|
while i < 3:
|
|
for record in self.cache.entriesWithName(info.type):
|
|
if record.type == _TYPE_PTR and not record.isExpired(now) and record.alias == info.name:
|
|
if (info.name.find('.') < 0):
|
|
info.name = info.name + ".[" + info.address + ":" + info.port + "]." + info.type
|
|
self.checkService(info)
|
|
return
|
|
raise NonUniqueNameException
|
|
if now < nextTime:
|
|
self.wait(nextTime - now)
|
|
now = currentTimeMillis()
|
|
continue
|
|
out = DNSOutgoing(_FLAGS_QR_QUERY | _FLAGS_AA)
|
|
self.debug = out
|
|
out.addQuestion(DNSQuestion(info.type, _TYPE_PTR, _CLASS_IN))
|
|
out.addAuthorativeAnswer(DNSPointer(info.type, _TYPE_PTR, _CLASS_IN, _DNS_TTL, info.name))
|
|
self.send(out)
|
|
i += 1
|
|
nextTime += _CHECK_TIME
|
|
|
|
def addListener(self, listener, question):
|
|
"""Adds a listener for a given question. The listener will have
|
|
its updateRecord method called when information is available to
|
|
answer the question."""
|
|
now = currentTimeMillis()
|
|
self.listeners.append(listener)
|
|
if question is not None:
|
|
for record in self.cache.entriesWithName(question.name):
|
|
if question.answeredBy(record) and not record.isExpired(now):
|
|
listener.updateRecord(self, now, record)
|
|
self.notifyAll()
|
|
|
|
def removeListener(self, listener):
|
|
"""Removes a listener."""
|
|
try:
|
|
self.listeners.remove(listener)
|
|
self.notifyAll()
|
|
except:
|
|
pass
|
|
|
|
def updateRecord(self, now, rec):
|
|
"""Used to notify listeners of new information that has updated
|
|
a record."""
|
|
for listener in self.listeners:
|
|
listener.updateRecord(self, now, rec)
|
|
self.notifyAll()
|
|
|
|
def handleResponse(self, msg):
|
|
"""Deal with incoming response packets. All answers
|
|
are held in the cache, and listeners are notified."""
|
|
now = currentTimeMillis()
|
|
for record in msg.answers:
|
|
expired = record.isExpired(now)
|
|
if record in self.cache.entries():
|
|
if expired:
|
|
self.cache.remove(record)
|
|
else:
|
|
entry = self.cache.get(record)
|
|
if entry is not None:
|
|
entry.resetTTL(record)
|
|
record = entry
|
|
else:
|
|
self.cache.add(record)
|
|
|
|
self.updateRecord(now, record)
|
|
|
|
def handleQuery(self, msg, addr, port):
|
|
"""Deal with incoming query packets. Provides a response if
|
|
possible."""
|
|
out = None
|
|
|
|
# Support unicast client responses
|
|
#
|
|
if port != _MDNS_PORT:
|
|
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA, 0)
|
|
for question in msg.questions:
|
|
out.addQuestion(question)
|
|
|
|
for question in msg.questions:
|
|
if question.type == _TYPE_PTR:
|
|
if question.name == "_services._dns-sd._udp.local.":
|
|
for stype in self.servicetypes.keys():
|
|
if out is None:
|
|
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
|
|
out.addAnswer(msg, DNSPointer("_services._dns-sd._udp.local.", _TYPE_PTR, _CLASS_IN, _DNS_TTL, stype))
|
|
for service in self.services.values():
|
|
if question.name == service.type:
|
|
if out is None:
|
|
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
|
|
out.addAnswer(msg, DNSPointer(service.type, _TYPE_PTR, _CLASS_IN, _DNS_TTL, service.name))
|
|
else:
|
|
try:
|
|
if out is None:
|
|
out = DNSOutgoing(_FLAGS_QR_RESPONSE | _FLAGS_AA)
|
|
|
|
# Answer A record queries for any service addresses we know
|
|
if question.type == _TYPE_A or question.type == _TYPE_ANY:
|
|
for service in self.services.values():
|
|
if service.server == question.name.lower():
|
|
out.addAnswer(msg, DNSAddress(question.name, _TYPE_A, _CLASS_IN | _CLASS_UNIQUE, _DNS_TTL, service.address))
|
|
|
|
service = self.services.get(question.name.lower(), None)
|
|
if not service: continue
|
|
|
|
if question.type == _TYPE_SRV or question.type == _TYPE_ANY:
|
|
out.addAnswer(msg, DNSService(question.name, _TYPE_SRV, _CLASS_IN | _CLASS_UNIQUE, _DNS_TTL, service.priority, service.weight, service.port, service.server))
|
|
if question.type == _TYPE_TXT or question.type == _TYPE_ANY:
|
|
out.addAnswer(msg, DNSText(question.name, _TYPE_TXT, _CLASS_IN | _CLASS_UNIQUE, _DNS_TTL, service.text))
|
|
if question.type == _TYPE_SRV:
|
|
out.addAdditionalAnswer(DNSAddress(service.server, _TYPE_A, _CLASS_IN | _CLASS_UNIQUE, _DNS_TTL, service.address))
|
|
except:
|
|
traceback.print_exc()
|
|
|
|
if out is not None and out.answers:
|
|
out.id = msg.id
|
|
self.send(out, addr, port)
|
|
|
|
def send(self, out, addr = _MDNS_ADDR, port = _MDNS_PORT):
|
|
"""Sends an outgoing packet."""
|
|
# This is a quick test to see if we can parse the packets we generate
|
|
#temp = DNSIncoming(out.packet())
|
|
try:
|
|
self.socket.sendto(out.packet(), 0, (addr, port))
|
|
except:
|
|
# Ignore this, it may be a temporary loss of network connection
|
|
pass
|
|
|
|
def close(self):
|
|
"""Ends the background threads, and prevent this instance from
|
|
servicing further queries."""
|
|
if globals()['_GLOBAL_DONE'] == 0:
|
|
globals()['_GLOBAL_DONE'] = 1
|
|
self.notifyAll()
|
|
self.engine.notify()
|
|
self.unregisterAllServices()
|
|
self.socket.setsockopt(socket.SOL_IP, socket.IP_DROP_MEMBERSHIP, socket.inet_aton(_MDNS_ADDR) + socket.inet_aton('0.0.0.0'))
|
|
self.socket.close()
|
|
|
|
# Test a few module features, including service registration, service
|
|
# query (for Zoe), and service unregistration.
|
|
|
|
if __name__ == '__main__':
|
|
print "Multicast DNS Service Discovery for Python, version", __version__
|
|
r = Zeroconf()
|
|
print "1. Testing registration of a service..."
|
|
desc = {'version':'0.10','a':'test value', 'b':'another value'}
|
|
info = ServiceInfo("_http._tcp.local.", "My Service Name._http._tcp.local.", socket.inet_aton("127.0.0.1"), 1234, 0, 0, desc)
|
|
print " Registering service..."
|
|
r.registerService(info)
|
|
print " Registration done."
|
|
print "2. Testing query of service information..."
|
|
print " Getting ZOE service:", str(r.getServiceInfo("_http._tcp.local.", "ZOE._http._tcp.local."))
|
|
print " Query done."
|
|
print "3. Testing query of own service..."
|
|
print " Getting self:", str(r.getServiceInfo("_http._tcp.local.", "My Service Name._http._tcp.local."))
|
|
print " Query done."
|
|
print "4. Testing unregister of service information..."
|
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r.unregisterService(info)
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print " Unregister done."
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r.close()
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