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Commit 71d075fe authored by chenbruce's avatar chenbruce Committed by Automerger Merge Worker
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Subsampling DNS event for mDNS am: 52cf009b am: 67e70742 am: d5a56ff6 am: 82b0b9e2 

Original change: https://android-review.googlesource.com/c/platform/packages/modules/DnsResolver/+/1799848

Change-Id: I702bf892ddbccb5125991fbbf1bfa8f66bd32684
parents b62ff770 82b0b9e2

DnsProxyListener.cpp

+9 −3
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ 
#include <sysutils/SocketClient.h>



#include "DnsResolver.h"

#include "Experiments.h"

#include "NetdPermissions.h"

#include "OperationLimiter.h"

#include "PrivateDnsConfiguration.h"
@@ -305,8 +306,8 @@ void initDnsEvent(NetworkDnsEventReported* event, const android_net_context& net 


// Return 0 if the event should not be logged.

// Otherwise, return subsampling_denom

uint32_t getDnsEventSubsamplingRate(int netid, int returnCode) {

    uint32_t subsampling_denom = resolv_cache_get_subsampling_denom(netid, returnCode);

uint32_t getDnsEventSubsamplingRate(int netid, int returnCode, bool isMdns) {

    uint32_t subsampling_denom = resolv_cache_get_subsampling_denom(netid, returnCode, isMdns);

    if (subsampling_denom == 0) return 0;

    // Sample the event with a chance of 1 / denom.

    return (arc4random_uniform(subsampling_denom) == 0) ? subsampling_denom : 0;
@@ -333,7 +334,12 @@ void maybeLogQuery(int eventType, const android_net_context& netContext, 
void reportDnsEvent(int eventType, const android_net_context& netContext, int latencyUs,

                    int returnCode, NetworkDnsEventReported& event, const std::string& query_name,

                    const std::vector<std::string>& ip_addrs = {}, int total_ip_addr_count = 0) {

    if (uint32_t rate = getDnsEventSubsamplingRate(netContext.dns_netid, returnCode)) {

    uint32_t rate = (query_name.ends_with(".local") &&

                     android::net::Experiments::getInstance()->getFlag("mdns_resolution", 1))

                            ? getDnsEventSubsamplingRate(netContext.dns_netid, returnCode, true)

                            : getDnsEventSubsamplingRate(netContext.dns_netid, returnCode, false);



    if (rate) {

        const std::string& dnsQueryStats = event.dns_query_events().SerializeAsString();

        stats::BytesField dnsQueryBytesField{dnsQueryStats.c_str(), dnsQueryStats.size()};

        event.set_return_code(static_cast<ReturnCode>(returnCode));

ResolverController.cpp

+3 −1
Original line number Diff line number Diff line
@@ -319,7 +319,9 @@ void ResolverController::dump(DumpWriter& dw, unsigned netId) { 
            dw.println("No DNS servers defined");

        } else {

            dw.println("DnsEvent subsampling map: " +

                       android::base::Join(resolv_cache_dump_subsampling_map(netId), ' '));

                       android::base::Join(resolv_cache_dump_subsampling_map(netId, false), ' '));

            dw.println("DnsEvent subsampling map for MDNS: " +

                       android::base::Join(resolv_cache_dump_subsampling_map(netId, true), ' '));

            dw.println(

                    "DNS servers: # IP (total, successes, errors, timeouts, internal errors, "

                    "RTT avg, last sample)");

res_cache.cpp

+21 −13
Original line number Diff line number Diff line
@@ -909,17 +909,19 @@ namespace { 
// Sampling rate varies by return code; events to log are chosen randomly, with a

// probability proportional to the sampling rate.

constexpr const char DEFAULT_SUBSAMPLING_MAP[] = "default:8 0:400 2:110 7:110";

constexpr const char DEFAULT_MDNS_SUBSAMPLING_MAP[] = "default:1";



std::unordered_map<int, uint32_t> resolv_get_dns_event_subsampling_map() {

std::unordered_map<int, uint32_t> resolv_get_dns_event_subsampling_map(bool isMdns) {

    using android::base::ParseInt;

    using android::base::ParseUint;

    using android::base::Split;

    using server_configurable_flags::GetServerConfigurableFlag;

    std::unordered_map<int, uint32_t> sampling_rate_map{};

    std::vector<std::string> subsampling_vector =

            Split(GetServerConfigurableFlag("netd_native", "dns_event_subsample_map",

                                            DEFAULT_SUBSAMPLING_MAP),

                  " ");

    const char* flag = isMdns ? "mdns_event_subsample_map" : "dns_event_subsample_map";

    const char* defaultMap = isMdns ? DEFAULT_MDNS_SUBSAMPLING_MAP : DEFAULT_SUBSAMPLING_MAP;

    const std::vector<std::string> subsampling_vector =

            Split(GetServerConfigurableFlag("netd_native", flag, defaultMap), " ");



    for (const auto& pair : subsampling_vector) {

        std::vector<std::string> rate_denom = Split(pair, ":");

        int return_code;
@@ -1005,7 +1007,8 @@ struct Cache { 
struct NetConfig {

    explicit NetConfig(unsigned netId) : netid(netId) {

        cache = std::make_unique<Cache>();

        dns_event_subsampling_map = resolv_get_dns_event_subsampling_map();

        dns_event_subsampling_map = resolv_get_dns_event_subsampling_map(false);

        mdns_event_subsampling_map = resolv_get_dns_event_subsampling_map(true);

    }

    int nameserverCount() { return nameserverSockAddrs.size(); }

    int setOptions(const ResolverOptionsParcel& resolverOptions) {
@@ -1036,6 +1039,7 @@ struct NetConfig { 
    int wait_for_pending_req_timeout_count = 0;

    // Map format: ReturnCode:rate_denom

    std::unordered_map<int, uint32_t> dns_event_subsampling_map;

    std::unordered_map<int, uint32_t> mdns_event_subsampling_map;

    DnsStats dnsStats;



    // Customized hostname/address table will be stored in customizedTable.
@@ -1793,17 +1797,20 @@ int android_net_res_stats_get_info_for_net(unsigned netid, int* nscount, 
    return info->revision_id;

}



std::vector<std::string> resolv_cache_dump_subsampling_map(unsigned netid) {

std::vector<std::string> resolv_cache_dump_subsampling_map(unsigned netid, bool is_mdns) {

    std::lock_guard guard(cache_mutex);

    NetConfig* netconfig = find_netconfig_locked(netid);

    if (netconfig == nullptr) return {};

    std::vector<std::string> result;

    for (const auto& pair : netconfig->dns_event_subsampling_map) {

    const auto& subsampling_map = (!is_mdns) ? netconfig->dns_event_subsampling_map

                                             : netconfig->mdns_event_subsampling_map;

    result.reserve(subsampling_map.size());

    for (const auto& [return_code, rate_denom] : subsampling_map) {

        result.push_back(fmt::format("{}:{}",

                                     (pair.first == DNSEVENT_SUBSAMPLING_MAP_DEFAULT_KEY)

                                     (return_code == DNSEVENT_SUBSAMPLING_MAP_DEFAULT_KEY)

                                             ? "default"

                                             : std::to_string(pair.first),

                                     pair.second));

                                             : std::to_string(return_code),

                                     rate_denom));

    }

    return result;

}
@@ -1812,11 +1819,12 @@ std::vector<std::string> resolv_cache_dump_subsampling_map(unsigned netid) { 
// a sampling factor derived from the netid and the return code.

//

// Returns the subsampling rate if the event should be sampled, or 0 if it should be discarded.

uint32_t resolv_cache_get_subsampling_denom(unsigned netid, int return_code) {

uint32_t resolv_cache_get_subsampling_denom(unsigned netid, int return_code, bool is_mdns) {

    std::lock_guard guard(cache_mutex);

    NetConfig* netconfig = find_netconfig_locked(netid);

    if (netconfig == nullptr) return 0;  // Don't log anything at all.

    const auto& subsampling_map = netconfig->dns_event_subsampling_map;

    const auto& subsampling_map = (!is_mdns) ? netconfig->dns_event_subsampling_map

                                             : netconfig->mdns_event_subsampling_map;

    auto search_returnCode = subsampling_map.find(return_code);

    uint32_t denom;

    if (search_returnCode != subsampling_map.end()) {

resolv_cache.h

+2 −2
Original line number Diff line number Diff line
@@ -50,8 +50,8 @@ void resolv_populate_res_for_net(ResState* statp); 


std::vector<unsigned> resolv_list_caches();



std::vector<std::string> resolv_cache_dump_subsampling_map(unsigned netid);

uint32_t resolv_cache_get_subsampling_denom(unsigned netid, int return_code);

std::vector<std::string> resolv_cache_dump_subsampling_map(unsigned netid, bool is_mdns);

uint32_t resolv_cache_get_subsampling_denom(unsigned netid, int return_code, bool is_mdns);



typedef enum {

    RESOLV_CACHE_UNSUPPORTED, /* the cache can't handle that kind of queries */

tests/resolv_cache_unit_test.cpp

+72 −22
Original line number Diff line number Diff line
@@ -910,11 +910,12 @@ namespace { 
constexpr int EAI_OK = 0;

constexpr char DNS_EVENT_SUBSAMPLING_MAP_FLAG[] =

        "persist.device_config.netd_native.dns_event_subsample_map";

constexpr char MDNS_EVENT_SUBSAMPLING_MAP_FLAG[] =

        "persist.device_config.netd_native.mdns_event_subsample_map";



class ScopedCacheCreate {

  public:

    explicit ScopedCacheCreate(unsigned netid, const char* subsampling_map,

                               const char* property = DNS_EVENT_SUBSAMPLING_MAP_FLAG)

    explicit ScopedCacheCreate(unsigned netid, const char* subsampling_map, const char* property)

        : mStoredNetId(netid), mStoredProperty(property) {

        property_get(property, mStoredMap, "");

        property_set(property, subsampling_map);
@@ -936,45 +937,94 @@ class ScopedCacheCreate { 
TEST_F(ResolvCacheTest, DnsEventSubsampling) {

    // Test defaults, default flag is "default:8 0:400 2:110 7:110" if no experiment flag is set

    {

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "");

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_AGAIN), 110U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA), 110U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK), 400U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_BADFLAGS),

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "", DNS_EVENT_SUBSAMPLING_MAP_FLAG);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_AGAIN, false), 110U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA, false), 110U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK, false), 400U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_BADFLAGS, false),

                  8U);  // default

        EXPECT_THAT(resolv_cache_dump_subsampling_map(TEST_NETID),

        EXPECT_THAT(resolv_cache_dump_subsampling_map(TEST_NETID, false),

                    testing::UnorderedElementsAreArray({"default:8", "0:400", "2:110", "7:110"}));

    }

    // Now change the experiment flag to "0:42 default:666"

    {

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "0:42 default:666");

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK), 42U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA),

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "0:42 default:666",

                                            DNS_EVENT_SUBSAMPLING_MAP_FLAG);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK, false), 42U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA, false),

                  666U);  // default

        EXPECT_THAT(resolv_cache_dump_subsampling_map(TEST_NETID),

        EXPECT_THAT(resolv_cache_dump_subsampling_map(TEST_NETID, false),

                    testing::UnorderedElementsAreArray({"default:666", "0:42"}));

    }

    // Now change the experiment flag to something illegal

    {

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "asvaxx");

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "asvaxx", DNS_EVENT_SUBSAMPLING_MAP_FLAG);

        // 0(disable log) is the default value if experiment flag is invalid.

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK), 0U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA), 0U);

        EXPECT_TRUE(resolv_cache_dump_subsampling_map(TEST_NETID).empty());

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK, false), 0U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA, false), 0U);

        EXPECT_TRUE(resolv_cache_dump_subsampling_map(TEST_NETID, false).empty());

    }

    // Test negative and zero denom

    {

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "0:-42 default:-666 7:10 10:0");

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "0:-42 default:-666 7:10 10:0",

                                            DNS_EVENT_SUBSAMPLING_MAP_FLAG);

        // 0(disable log) is the default value if no valid denom is set

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK), 0U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_BADFLAGS), 0U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA), 10U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_SOCKTYPE), 0U);

        EXPECT_THAT(resolv_cache_dump_subsampling_map(TEST_NETID),

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK, false), 0U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_BADFLAGS, false), 0U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA, false), 10U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_SOCKTYPE, false), 0U);

        EXPECT_THAT(resolv_cache_dump_subsampling_map(TEST_NETID, false),

                    testing::UnorderedElementsAreArray({"7:10", "10:0"}));

    }

}



TEST_F(ResolvCacheTest, MdnsEventSubsampling) {

    // Test defaults, DEFAULT_MDNS_SUBSAMPLING_MAP is "default:1" if no experiment flag is set

    {

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "", MDNS_EVENT_SUBSAMPLING_MAP_FLAG);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_AGAIN, true),

                  1U);  // default for all return_code

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA, true), 1U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_BADFLAGS, true), 1U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK, true), 1U);

        // not equal to DEFAULT_SUBSAMPLING_MAP[] = "default:8 0:400 2:110 7:110";

        EXPECT_NE(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_AGAIN, true), 110U);

        EXPECT_NE(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA, true), 110U);

        EXPECT_NE(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK, true), 400U);

        EXPECT_NE(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_BADFLAGS, true), 8U);

        EXPECT_THAT(resolv_cache_dump_subsampling_map(TEST_NETID, true),

                    testing::UnorderedElementsAreArray({"default:1"}));

    }

    // Now change the experiment flag to "default:1 0:10"

    {

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "0:10 default:1",

                                            MDNS_EVENT_SUBSAMPLING_MAP_FLAG);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK, true), 10U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA, true), 1U);  // default

        EXPECT_THAT(resolv_cache_dump_subsampling_map(TEST_NETID, true),

                    testing::UnorderedElementsAreArray({"0:10", "default:1"}));

    }

    // Now change the experiment flag to something illegal

    {

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "asvaxx", MDNS_EVENT_SUBSAMPLING_MAP_FLAG);

        // 0(disable log) is the default value if experiment flag is invalid.

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK, true), 0U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA, true), 0U);

        EXPECT_TRUE(resolv_cache_dump_subsampling_map(TEST_NETID, true).empty());

    }

    // Test negative and zero denom

    {

        ScopedCacheCreate scopedCacheCreate(TEST_NETID, "0:-42 default:-666 7:10 10:0",

                                            MDNS_EVENT_SUBSAMPLING_MAP_FLAG);

        // 0(disable log) is the default value if no valid denom is set

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_OK, true), 0U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_BADFLAGS, true), 0U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_NODATA, true), 10U);

        EXPECT_EQ(resolv_cache_get_subsampling_denom(TEST_NETID, EAI_SOCKTYPE, true), 0U);

        EXPECT_THAT(resolv_cache_dump_subsampling_map(TEST_NETID, true),

                    testing::UnorderedElementsAreArray({"7:10", "10:0"}));

    }

}

// TODO: Tests for NetConfig, including:

//     - res_stats

//         -- _resolv_cache_add_resolver_stats_sample()