zeroconf: Python 3 porting of vendored library

A quick glance through this module reveals that most of it "just works"
on Python 3 with the source transformer active. There are a few
places where we need to ensure we're using str.

Differential Revision: https://phab.mercurial-scm.org/D5804

hgext/zeroconf/Zeroconf.py

@@ -84,7 +84,6 b' import errno'
 import itertools
 import select
 import socket
-import string
 import struct
 import threading
 import time
@@ -106,7 +105,7 b" globals()['_GLOBAL_DONE'] = 0"
 
 # Some DNS constants
 
-_MDNS_ADDR = '224.0.0.251'
+_MDNS_ADDR = r'224.0.0.251'
 _MDNS_PORT = 5353
 _DNS_PORT = 53
 _DNS_TTL = 60 * 60 # one hour default TTL
@@ -221,7 +220,7 b' class DNSEntry(object):'
     """A DNS entry"""
 
     def __init__(self, name, type, clazz):
-        self.key = string.lower(name)
+        self.key = name.lower()
         self.name = name
         self.type = type
         self.clazz = clazz & _CLASS_MASK
@@ -620,7 +619,7 b' class DNSIncoming(object):'
         first = off
 
         while True:
-            len = ord(self.data[off])
+            len = ord(self.data[off:off + 1])
             off += 1
             if len == 0:
                 break
@@ -631,7 +630,7 b' class DNSIncoming(object):'
             elif t == 0xC0:
                 if next < 0:
                     next = off + 1
-                off = ((len & 0x3F) << 8) | ord(self.data[off])
+                off = ((len & 0x3F) << 8) | ord(self.data[off:off + 1])
                 if off >= first:
                     raise BadDomainNameCircular(off)
                 first = off
@@ -1333,7 +1332,7 b' class Zeroconf(object):'
             # SO_REUSEADDR and SO_REUSEPORT have been set, so ignore it
             pass
         self.socket.setsockopt(socket.SOL_IP, socket.IP_ADD_MEMBERSHIP,
-            socket.inet_aton(_MDNS_ADDR) + socket.inet_aton('0.0.0.0'))
+            socket.inet_aton(_MDNS_ADDR) + socket.inet_aton(r'0.0.0.0'))
 
         self.listeners = []
         self.browsers = []
@@ -1657,7 +1656,7 b' class Zeroconf(object):'
             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'))
+                socket.inet_aton(_MDNS_ADDR) + socket.inet_aton(r'0.0.0.0'))
             self.socket.close()
 
 # Test a few module features, including service registration, service