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/**
* Copyright (C) 2017 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/util/dns_query.h"
#include "mongo/unittest/unittest.h"
using namespace std::literals::string_literals;
namespace {
std::string getFirstARecord(const std::string& service) {
auto res = mongo::dns::lookupARecords(service);
if (res.empty())
return "";
return res.front();
}
TEST(MongoDnsQuery, basic) {
// We only require 50% of the records to pass, because it is possible that some large scale
// outages could cause some of these records to fail.
const double kPassingPercentage = 0.50;
std::size_t resolution_count = 0;
const struct {
std::string dns;
std::string ip;
} tests[] =
// The reason for a vast number of tests over basic DNS query calls is to provide a
// redundancy in testing. We'd like to make sure that this test always passes. Lazy
// maintanance will cause some references to be commented out. Our belief is that all 13
// root servers and both of Google's public servers will all be unresolvable (when
// connections are available) only when a major problem occurs. This test only fails if
// more than half of the resolved names fail.
{
// These can be kept up to date by checking the root-servers.org listings. Note that
// root name servers are located in the `root-servers.net.` domain, NOT in the
// `root-servers.org.` domain. The `.org` domain is for webpages with statistics on
// these servers. The `.net` domain is the domain with the canonical addresses for
// these servers.
{"a.root-servers.net.", "198.41.0.4"},
{"b.root-servers.net.", "199.9.14.201"},
{"c.root-servers.net.", "192.33.4.12"},
{"d.root-servers.net.", "199.7.91.13"},
{"e.root-servers.net.", "192.203.230.10"},
{"f.root-servers.net.", "192.5.5.241"},
{"g.root-servers.net.", "192.112.36.4"},
{"h.root-servers.net.", "198.97.190.53"},
{"i.root-servers.net.", "192.36.148.17"},
{"j.root-servers.net.", "192.58.128.30"},
{"k.root-servers.net.", "193.0.14.129"},
{"l.root-servers.net.", "199.7.83.42"},
{"m.root-servers.net.", "202.12.27.33"},
// These can be kept up to date by checking with Google's public dns service.
{"google-public-dns-a.google.com.", "8.8.8.8"},
{"google-public-dns-b.google.com.", "8.8.4.4"},
};
for (const auto& test : tests) {
try {
const auto witness = getFirstARecord(test.dns);
std::cout << "Resolved " << test.dns << " to: " << witness << std::endl;
const bool resolution = (witness == test.ip);
if (!resolution)
std::cerr << "Warning: Did not correctly resolve " << test.dns << std::endl;
resolution_count += resolution;
}
// Failure to resolve is okay, but not great -- print a warning
catch (const mongo::DBException& ex) {
std::cerr << "Warning: Did not resolve " << test.dns << " at all: " << ex.what()
<< std::endl;
}
}
// As long as enough tests pass, we're okay -- this means that a single DNS name server drift
// won't cause a BF -- when enough fail, then we can rebuild the list in one pass.
const std::size_t kPassingRate = sizeof(tests) / sizeof(tests[0]) * kPassingPercentage;
ASSERT_GTE(resolution_count, kPassingRate);
}
TEST(MongoDnsQuery, srvRecords) {
const auto kMongodbSRVPrefix = "_mongodb._tcp."s;
const struct {
std::string query;
std::vector<mongo::dns::SRVHostEntry> result;
} tests[] = {
{"test1.test.build.10gen.cc.",
{
{"localhost.test.build.10gen.cc.", 27017}, {"localhost.test.build.10gen.cc.", 27018},
}},
{"test2.test.build.10gen.cc.",
{
{"localhost.test.build.10gen.cc.", 27018}, {"localhost.test.build.10gen.cc.", 27019},
}},
{"test3.test.build.10gen.cc.",
{
{"localhost.test.build.10gen.cc.", 27017},
}},
// Test case 4 does not exist in the expected DNS records.
{"test4.test.build.10gen.cc.", {}},
{"test5.test.build.10gen.cc.",
{
{"localhost.test.build.10gen.cc.", 27017},
}},
{"test6.test.build.10gen.cc.",
{
{"localhost.test.build.10gen.cc.", 27017},
}},
};
for (const auto& test : tests) {
const auto& expected = test.result;
if (expected.empty()) {
ASSERT_THROWS_CODE(mongo::dns::lookupSRVRecords(kMongodbSRVPrefix + test.query),
mongo::DBException,
mongo::ErrorCodes::DNSHostNotFound);
continue;
}
auto witness = mongo::dns::lookupSRVRecords(kMongodbSRVPrefix + test.query);
std::sort(begin(witness), end(witness));
for (const auto& entry : witness) {
std::cout << "Entry: " << entry << std::endl;
}
for (std::size_t i = 0; i < witness.size() && i < expected.size(); ++i) {
std::cout << "Expected: " << expected.at(i) << std::endl;
std::cout << "Witness: " << witness.at(i) << std::endl;
ASSERT_EQ(witness.at(i), expected.at(i));
}
ASSERT_TRUE(std::equal(begin(witness), end(witness), begin(expected), end(expected)));
ASSERT_TRUE(witness.size() == expected.size());
}
}
TEST(MongoDnsQuery, txtRecords) {
const struct {
std::string query;
std::vector<std::string> result;
} tests[] = {
// Test case 4 does not exist in the expected DNS records.
{"test4.test.build.10gen.cc.", {}},
{"test5.test.build.10gen.cc",
{
"replicaSet=repl0&authSource=thisDB",
}},
{"test6.test.build.10gen.cc",
{
"authSource=otherDB", "replicaSet=repl0",
}},
};
for (const auto& test : tests) {
try {
auto witness = mongo::dns::getTXTRecords(test.query);
std::sort(begin(witness), end(witness));
const auto& expected = test.result;
ASSERT_TRUE(std::equal(begin(witness), end(witness), begin(expected), end(expected)));
ASSERT_EQ(witness.size(), expected.size());
} catch (const mongo::DBException& ex) {
if (ex.code() != mongo::ErrorCodes::DNSHostNotFound)
throw;
ASSERT_TRUE(test.result.empty());
}
}
}
} // namespace
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