freeipa/ipatests/test_ipapython/test_dnsutil.py
Christian Heimes f90e137a17 Sort and shuffle SRV record by priority and weight
On multiple occasions, SRV query answers were not properly sorted by
priority. Records with same priority weren't randomized and shuffled.
This caused FreeIPA to contact the same remote peer instead of
distributing the load across all available servers.

Two new helper functions now take care of SRV queries. sort_prio_weight()
sorts SRV and URI records. query_srv() combines SRV lookup with
sort_prio_weight().

Fixes: https://pagure.io/freeipa/issue/7475
Signed-off-by: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>
2018-06-19 08:56:46 +02:00

107 lines
3.1 KiB
Python

#
# Copyright (C) 2018 FreeIPA Contributors. See COPYING for license
#
import dns.name
import dns.rdataclass
import dns.rdatatype
from dns.rdtypes.IN.SRV import SRV
from dns.rdtypes.ANY.URI import URI
from ipapython import dnsutil
import pytest
def mksrv(priority, weight, port, target):
return SRV(
rdclass=dns.rdataclass.IN,
rdtype=dns.rdatatype.SRV,
priority=priority,
weight=weight,
port=port,
target=dns.name.from_text(target)
)
def mkuri(priority, weight, target):
return URI(
rdclass=dns.rdataclass.IN,
rdtype=dns.rdatatype.URI,
priority=priority,
weight=weight,
target=target
)
class TestSortSRV(object):
def test_empty(self):
assert dnsutil.sort_prio_weight([]) == []
def test_one(self):
h1 = mksrv(1, 0, 443, u"host1")
assert dnsutil.sort_prio_weight([h1]) == [h1]
h2 = mksrv(10, 5, 443, u"host2")
assert dnsutil.sort_prio_weight([h2]) == [h2]
def test_prio(self):
h1 = mksrv(1, 0, 443, u"host1")
h2 = mksrv(2, 0, 443, u"host2")
h3 = mksrv(3, 0, 443, u"host3")
assert dnsutil.sort_prio_weight([h3, h2, h1]) == [h1, h2, h3]
assert dnsutil.sort_prio_weight([h3, h3, h3]) == [h3]
assert dnsutil.sort_prio_weight([h2, h2, h1, h1]) == [h1, h2]
h380 = mksrv(4, 0, 80, u"host3")
assert dnsutil.sort_prio_weight([h1, h3, h380]) == [h1, h3, h380]
hs = mksrv(-1, 0, 443, u"special")
assert dnsutil.sort_prio_weight([h1, h2, hs]) == [hs, h1, h2]
def assert_permutations(self, answers, permutations):
seen = set()
for _unused in range(1000):
result = tuple(dnsutil.sort_prio_weight(answers))
assert result in permutations
seen.add(result)
if seen == permutations:
break
else:
pytest.fail("sorting didn't exhaust all permutations.")
def test_sameprio(self):
h1 = mksrv(1, 0, 443, u"host1")
h2 = mksrv(1, 0, 443, u"host2")
permutations = {
(h1, h2),
(h2, h1),
}
self.assert_permutations([h1, h2], permutations)
def test_weight(self):
h1 = mksrv(1, 0, 443, u"host1")
h2_w15 = mksrv(2, 15, 443, u"host2")
h3_w10 = mksrv(2, 10, 443, u"host3")
permutations = {
(h1, h2_w15, h3_w10),
(h1, h3_w10, h2_w15),
}
self.assert_permutations([h1, h2_w15, h3_w10], permutations)
def test_large(self):
records = tuple(
mksrv(1, i, 443, "host{}".format(i)) for i in range(1000)
)
assert len(dnsutil.sort_prio_weight(records)) == len(records)
class TestSortURI(object):
def test_prio(self):
h1 = mkuri(1, 0, u"https://host1/api")
h2 = mkuri(2, 0, u"https://host2/api")
h3 = mkuri(3, 0, u"https://host3/api")
assert dnsutil.sort_prio_weight([h3, h2, h1]) == [h1, h2, h3]
assert dnsutil.sort_prio_weight([h3, h3, h3]) == [h3]
assert dnsutil.sort_prio_weight([h2, h2, h1, h1]) == [h1, h2]