openstack/swift
Code Issues Proposed changes

better cname lookups

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This commit is contained in:
John Dickinson 2010-11-05 13:37:54 -05:00
parent d122e5e98f
commit b6cee3e0c5
1 changed files with 22 additions and 9 deletions
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31
swift/common/middleware/cname_lookup.py
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@ -16,8 +16,9 @@
from webob import Request
from webob.exc import HTTPBadRequest
import dns.resolver
from dns.exception import DNSException
from swift.common.utils import cache_from_env
from swift.common.utils import cache_from_env, get_logger
def lookup_cname(domain): # pragma: no cover
@ -27,10 +28,14 @@ def lookup_cname(domain): # pragma: no cover
:param domain: domain to query on
:returns: (ttl, result)
"""
answer = dns.resolver.query(domain, 'CNAME').rrset
ttl = answer.ttl
result = answer.name.to_text()
return ttl, result
try:
answer = dns.resolver.query(domain, 'CNAME').rrset
ttl = answer.ttl
result = answer.items[0].to_text()
result = result.rstrip('.')
return ttl, result
except DNSException:
return 0, domain
class CNAMELookupMiddleware(object):
@ -47,6 +52,7 @@ class CNAMELookupMiddleware(object):
self.storage_domain = '.' + self.storage_domain
self.lookup_depth = int(conf.get('lookup_depth', '1'))
self.memcache = None
self.logger = get_logger(conf)
def __call__(self, env, start_response):
if not self.storage_domain:
@ -55,16 +61,19 @@ class CNAMELookupMiddleware(object):
port = ''
if ':' in given_domain:
given_domain, port = given_domain.rsplit(':', 1)
if not given_domain.endswith(self.storage_domain):
if given_domain == self.storage_domain[1:]: # strip initial '.'
return self.app(env, start_response)
a_domain = given_domain
if not a_domain.endswith(self.storage_domain):
if self.memcache is None:
self.memcache = cache_from_env(env)
error = True
for tries in xrange(self.lookup_depth):
found_domain = None
if self.memcache:
found_domain = self.memcache.get(given_domain)
found_domain = self.memcache.get(a_domain)
if not found_domain:
ttl, found_domain = lookup_cname(given_domain)
ttl, found_domain = lookup_cname(a_domain)
if self.memcache:
self.memcache.set(given_domain, found_domain,
timeout=ttl)
@ -79,6 +88,8 @@ class CNAMELookupMiddleware(object):
break
elif found_domain.endswith(self.storage_domain):
# Found it!
self.logger.info('Mapped %s to %s' % (given_domain,
found_domain))
if port:
env['HTTP_HOST'] = ':'.join([found_domain, port])
else:
@ -87,7 +98,9 @@ class CNAMELookupMiddleware(object):
break
else:
# try one more deep in the chain
given_domain = found_domain
self.logger.debug('Following CNAME chain for %s to %s' %
(given_domain, found_domain))
a_domain = found_domain
if error:
if found_domain:
msg = 'CNAME lookup failed after %d tries' % \