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Commit 426803e1 authored by Ken Chen's avatar Ken Chen
Browse files

Add skip_4a_query_on_v6_linklocal_addr flag 

Add a default ON flag so that the "don't send AAAA query when there is
only v6 link-local address with default route" feature can be disabled
by server push.

Bug: 256507503
Test: atest & manually set flag and check log
Change-Id: I46421fa8b2218be32ca2d25e9b37d6a67738dcb2
parent f25e363d

Experiments.h

+1 −0
Original line number Diff line number Diff line
@@ -70,6 +70,7 @@ class Experiments { 
            "parallel_lookup_sleep_time",

            "retransmission_time_interval",

            "retry_count",

            "skip_4a_query_on_v6_linklocal_addr",

            "sort_nameservers",

    };

    // This value is used in updateInternal as the default value if any flags can't be found.

getaddrinfo.cpp

+3 −1
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ 


#define ANY 0



using android::net::Experiments;

using android::net::NetworkDnsEventReported;



const char in_addrany[] = {0, 0, 0, 0};
@@ -1312,7 +1313,8 @@ static int _find_src_addr(const struct sockaddr* addr, struct sockaddr* src_addr 
        return -1;

    }



    if (src_addr->sa_family == AF_INET6) {

    if (Experiments::getInstance()->getFlag("skip_4a_query_on_v6_linklocal_addr", 1) &&

        src_addr->sa_family == AF_INET6) {

        sockaddr_in6* sin6 = reinterpret_cast<sockaddr_in6*>(src_addr);

        if (!allow_v6_linklocal && IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {

            return 0;

tests/resolv_integration_test.cpp

+42 −0
Original line number Diff line number Diff line
@@ -7666,6 +7666,48 @@ TEST_F(ResolverMultinetworkTest, IPv6LinkLocalWithDefaultRoute) { 
    EXPECT_EQ(GetNumQueriesForType(*dnsPair->dnsServer, ns_type::ns_t_aaaa, host_name), 1U);

}



// Test if the "do not send AAAA query when IPv6 address is link-local with a default route" feature

// can be toggled by flag.

TEST_F(ResolverMultinetworkTest, IPv6LinkLocalWithDefaultRouteFlag) {

    constexpr char host_name[] = "ohayou.example.com.";

    const struct TestConfig {

        std::string flagValue;

        std::vector<std::string> ips;

        unsigned numOfQuadAQuery;

    } TestConfigs[]{{"0", {"192.0.2.0", "2001:db8:cafe:d00d::31"}, 1U}, {"1", {"192.0.2.0"}, 0U}};



    for (const auto& config : TestConfigs) {

        SCOPED_TRACE(fmt::format("flagValue = {}, numOfQuadAQuery = {}", config.flagValue,

                                 config.numOfQuadAQuery));



        ScopedSystemProperties sp1(kSkip4aQueryOnV6LinklocalAddrFlag, config.flagValue);

        ScopedPhysicalNetwork network = CreateScopedPhysicalNetwork(ConnectivityType::V4);

        ASSERT_RESULT_OK(network.init());



        // Add IPv6 default route

        ASSERT_TRUE(mDnsClient.netdService()

                            ->networkAddRoute(network.netId(), network.ifname(), "::/0", "")

                            .isOk());



        const Result<DnsServerPair> dnsPair = network.addIpv4Dns();

        ASSERT_RESULT_OK(dnsPair);

        StartDns(*dnsPair->dnsServer, {{host_name, ns_type::ns_t_a, "192.0.2.0"},

                                       {host_name, ns_type::ns_t_aaaa, "2001:db8:cafe:d00d::31"}});



        ASSERT_TRUE(network.setDnsConfiguration());

        ASSERT_TRUE(network.startTunForwarder());



        auto result = android_getaddrinfofornet_wrapper(host_name, network.netId());

        ASSERT_RESULT_OK(result);

        ScopedAddrinfo ai_results(std::move(result.value()));

        std::vector<std::string> result_strs = ToStrings(ai_results);

        EXPECT_THAT(result_strs, testing::UnorderedElementsAreArray(config.ips));

        EXPECT_EQ(GetNumQueriesForType(*dnsPair->dnsServer, ns_type::ns_t_a, host_name), 1U);

        EXPECT_EQ(GetNumQueriesForType(*dnsPair->dnsServer, ns_type::ns_t_aaaa, host_name),

                  config.numOfQuadAQuery);

    }

}



// v6 mdns is expected to be sent when the IPv6 address is a link-local with a default route.

TEST_F(ResolverMultinetworkTest, MdnsIPv6LinkLocalWithDefaultRoute) {

    // Kernel 4.4 does not provide an IPv6 link-local address when an interface is added to a

tests/resolv_test_utils.h

+2 −0
Original line number Diff line number Diff line
@@ -140,6 +140,8 @@ const std::string kDotValidationLatencyOffsetMsFlag(kFlagPrefix + 
                                                    "dot_validation_latency_offset_ms");

const std::string kRetransIntervalFlag(kFlagPrefix + "retransmission_time_interval");

const std::string kRetryCountFlag(kFlagPrefix + "retry_count");

const std::string kSkip4aQueryOnV6LinklocalAddrFlag(kFlagPrefix +

                                                    "skip_4a_query_on_v6_linklocal_addr");

const std::string kSortNameserversFlag(kFlagPrefix + "sort_nameservers");



static constexpr char kLocalHost[] = "localhost";