Improve query sleep time for getaddrinfo parallel lookup am: 5b30e710dc am: 241d8d35ed (313038b9) · Commits · e / os / android_packages_modules_DnsResolver

getaddrinfo.cpp

+13 −7

Original line number	Diff line number	Diff line
		@@ -53,6 +53,7 @@
		#include <sys/un.h>
		#include <unistd.h>

		#include <chrono>
		#include <future>

		#include <android-base/logging.h>
		@@ -1607,7 +1608,8 @@ struct QueryResult {
		NetworkDnsEventReported event;
		};

		QueryResult doQuery(const char* name, res_target* t, res_state res) {
		QueryResult doQuery(const char* name, res_target* t, res_state res,
		std::chrono::milliseconds sleepTimeMs) {
		HEADER* hp = (HEADER)(void)t->answer.data();

		hp->rcode = NOERROR; // default
		@@ -1643,7 +1645,7 @@ QueryResult doQuery(const char* name, res_target* t, res_state res) {
		ResState res_temp = fromResState(*res, &event);

		int rcode = NOERROR;
		n = res_nsend(&res_temp, buf, n, t->answer.data(), anslen, &rcode, 0);
		n = res_nsend(&res_temp, buf, n, t->answer.data(), anslen, &rcode, 0, sleepTimeMs);
		if (n < 0 \|\| hp->rcode != NOERROR \|\| ntohs(hp->ancount) == 0) {
		// if the query choked with EDNS0, retry without EDNS0
		if ((res_temp.netcontext_flags &
		@@ -1671,13 +1673,17 @@ QueryResult doQuery(const char* name, res_target* t, res_state res) {
		static int res_queryN_parallel(const char* name, res_target* target, res_state res, int* herrno) {
		std::vector<std::future<QueryResult>> results;
		results.reserve(2);
		std::chrono::milliseconds sleepTimeMs{};
		for (res_target* t = target; t; t = t->next) {
		results.emplace_back(std::async(std::launch::async, doQuery, name, t, res));
		results.emplace_back(std::async(std::launch::async, doQuery, name, t, res, sleepTimeMs));
		// Avoiding gateways drop packets if queries are sent too close together
		int sleepTime = android::net::Experiments::getInstance()->getFlag(
		// Only needed if we have multiple queries in a row.
		if (t->next) {
		int sleepFlag = android::net::Experiments::getInstance()->getFlag(
		"parallel_lookup_sleep_time", SLEEP_TIME_MS);
		if (sleepTime > 1000) sleepTime = 1000;
		if (t->next) usleep(sleepTime * 1000);
		if (sleepFlag > 1000) sleepFlag = 1000;
		sleepTimeMs = std::chrono::milliseconds(sleepFlag);
		}
		}

		int ancount = 0;

res_send.cpp

+9 −1

Original line number	Diff line number	Diff line
		@@ -76,6 +76,8 @@

		#define LOG_TAG "resolv"

		#include <chrono>

		#include <sys/param.h>
		#include <sys/socket.h>
		#include <sys/time.h>
		@@ -115,6 +117,7 @@
		#include "stats.pb.h"
		#include "util.h"

		using namespace std::chrono_literals;
		// TODO: use the namespace something like android::netd_resolv for libnetd_resolv
		using android::base::ErrnoError;
		using android::base::Result;
		@@ -408,7 +411,7 @@ static DnsQueryEvent* addDnsQueryEvent(NetworkDnsEventReported* event) {
		}

		int res_nsend(res_state statp, const uint8_t* buf, int buflen, uint8_t* ans, int anssiz, int* rcode,
		uint32_t flags) {
		uint32_t flags, std::chrono::milliseconds sleepTimeMs) {
		LOG(DEBUG) << __func__;

		// Should not happen
		@@ -448,6 +451,11 @@ int res_nsend(res_state statp, const uint8_t* buf, int buflen, uint8_t* ans, int
		return -ESRCH;
		}

		// If parallel_lookup is enabled, it might be required to wait some time to avoid
		// gateways drop packets if queries are sent too close together
		if (sleepTimeMs != 0ms) {
		std::this_thread::sleep_for(sleepTimeMs);
		}
		// DoT
		if (!(statp->netcontext_flags & NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS)) {
		bool fallback = false;

resolv_private.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -140,7 +140,8 @@ int res_nsearch(res_state, const char, int, int, uint8_t, int, int*);
		int res_nquerydomain(res_state, const char, const char, int, int, uint8_t, int, int);
		int res_nmkquery(int op, const char* qname, int cl, int type, const uint8_t* data, int datalen,
		uint8_t* buf, int buflen, int netcontext_flags);
		int res_nsend(res_state, const uint8_t, int, uint8_t, int, int*, uint32_t);
		int res_nsend(res_state statp, const uint8_t* buf, int buflen, uint8_t* ans, int anssiz, int* rcode,
		uint32_t flags, std::chrono::milliseconds sleepTimeMs = {});
		int res_nopt(res_state, int, uint8_t*, int, int);

		int getaddrinfo_numeric(const char* hostname, const char* servname, addrinfo hints,

tests/resolv_integration_test.cpp

+47 −0

Original line number	Diff line number	Diff line
		@@ -4779,6 +4779,8 @@ TEST_F(ResolverTest, GetAddrInfoParallelLookupTimeout) {
		StartDns(neverRespondDns, records);
		ScopedSystemProperties scopedSystemProperties(
		"persist.device_config.netd_native.parallel_lookup", "1");
		// The default value of parallel_lookup_sleep_time should be very small
		// that we can ignore in this test case.
		// Re-setup test network to make experiment flag take effect.
		resetNetwork();

		@@ -4797,3 +4799,48 @@ TEST_F(ResolverTest, GetAddrInfoParallelLookupTimeout) {
		<< "took time should approximate equal timeout";
		EXPECT_EQ(2U, GetNumQueries(neverRespondDns, host_name));
		}

		TEST_F(ResolverTest, GetAddrInfoParallelLookupSleepTime) {
		constexpr char listen_addr[] = "127.0.0.4";
		constexpr int TIMING_TOLERANCE_MS = 200;
		const std::vector<DnsRecord> records = {
		{kHelloExampleCom, ns_type::ns_t_a, kHelloExampleComAddrV4},
		{kHelloExampleCom, ns_type::ns_t_aaaa, kHelloExampleComAddrV6},
		};
		const std::vector<int> params = {300, 25, 8, 8, 1000 /* BASE_TIMEOUT_MSEC */,
		1 /* retry count */};
		test::DNSResponder dns(listen_addr);
		StartDns(dns, records);
		ScopedSystemProperties scopedSystemProperties1(
		"persist.device_config.netd_native.parallel_lookup", "1");
		constexpr int PARALLEL_LOOKUP_SLEEP_TIME_MS = 500;
		ScopedSystemProperties scopedSystemProperties2(
		"persist.device_config.netd_native.parallel_lookup_sleep_time",
		std::to_string(PARALLEL_LOOKUP_SLEEP_TIME_MS));
		// Re-setup test network to make experiment flag take effect.
		resetNetwork();

		ASSERT_TRUE(mDnsClient.SetResolversForNetwork({listen_addr}, kDefaultSearchDomains, params));
		dns.clearQueries();

		// Expect the safe_getaddrinfo_time_taken() might take ~500ms to return because we set
		// parallel_lookup_sleep_time to 500ms.
		const addrinfo hints = {.ai_family = AF_UNSPEC, .ai_socktype = SOCK_DGRAM};
		auto [result, timeTakenMs] = safe_getaddrinfo_time_taken(kHelloExampleCom, nullptr, hints);

		EXPECT_NE(nullptr, result);
		EXPECT_THAT(ToStrings(result), testing::UnorderedElementsAreArray(
		{kHelloExampleComAddrV4, kHelloExampleComAddrV6}));
		EXPECT_NEAR(PARALLEL_LOOKUP_SLEEP_TIME_MS, timeTakenMs, TIMING_TOLERANCE_MS)
		<< "took time should approximate equal timeout";
		EXPECT_EQ(2U, GetNumQueries(dns, kHelloExampleCom));

		// Expect the PARALLEL_LOOKUP_SLEEP_TIME_MS won't affect the query under cache hit case.
		dns.clearQueries();
		std::tie(result, timeTakenMs) = safe_getaddrinfo_time_taken(kHelloExampleCom, nullptr, hints);
		EXPECT_NE(nullptr, result);
		EXPECT_THAT(ToStrings(result), testing::UnorderedElementsAreArray(
		{kHelloExampleComAddrV4, kHelloExampleComAddrV6}));
		EXPECT_GT(PARALLEL_LOOKUP_SLEEP_TIME_MS, timeTakenMs);
		EXPECT_EQ(0U, GetNumQueries(dns, kHelloExampleCom));
		}