def get_resolver():
resolver = dns.resolver.Resolver()
resolver.reset()
# Configure our test resolver to resolve against localhost
resolver.read_resolv_conf(StringIO.StringIO('nameserver 127.0.0.1'))
return resolver
def get_resolver():
resolver = dns.resolver.Resolver()
resolver.reset()
# Configure our test resolver to resolve against localhost
resolver.read_resolv_conf(StringIO.StringIO('nameserver 127.0.0.1'))
return resolver
def query_dns(self, address, resolver):
'''
Will query for a dns record. Checks for an SRV dns record first, if found
it will return a random record from the highest priority.
If no SRV record is found, the domain of the jid will be used.
'''
ret_addr = address
# call res_init to refresh name resolution is necessary:
try:
Socket.getaddrinfo(ret_addr[0], ret_addr[1])
except Socket.gaierror as e:
if e.errno == 2: # name resolution error
logging.warn("Name resolution error; calling res_init()")
try:
import ctypes
libresolv = ctypes.CDLL('libresolv.so.2')
result = getattr(libresolv,'__res_init')()
if result != 0:
logging.warn( "res_init() call returned " + result )
except:
logging.exception( "Error while calling res_init" )
try:
resolver.nameservers = []
resolver.read_resolv_conf(f='/etc/resolv.conf')
logging.debug(resolver.nameservers)
xmpp_srv = "_xmpp-client._tcp.%s" % address[0]
answers = dns.resolver.query(xmpp_srv, dns.rdatatype.SRV)
except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer, dns.exception.Timeout):
log.debug("No appropriate SRV record found." + \
" Using %s" %self.address[0])
else:
# Pick a random server, weighted by priority.
addresses = {}
intmax = 0
for answer in answers:
intmax += answer.priority
addresses[intmax] = (answer.target.to_text()[:-1],
answer.port)
#python3 returns a generator for dictionary keys
priorities = [x for x in addresses.keys()]
priorities.sort()
picked = random.randint(0, intmax)
for priority in priorities:
if picked <= priority:
ret_addr = (addresses[priority][0], addresses[priority][1])
break
return ret_addr
