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Commit 0765c8d7 authored by Mike Yu's avatar Mike Yu Committed by Gerrit Code Review
Browse files

Merge changes Iae392108,Ib00da89c,Ie8175701,Ia4bc47a0 

* changes:
  Embedding DnsStats instead of using a smart pointer
  Rename resolv_cache_info to NetConfig
  Remove the head node of resolv_cache_info
  Allocate resolv_cache_info with operator new
parents 47c3eb58 15ad2f9b

res_cache.cpp

+125 −173
Original line number Diff line number Diff line
@@ -872,10 +872,53 @@ static int entry_equals(const Entry* e1, const Entry* e2) { 
/* Maximum time for a thread to wait for an pending request */

constexpr int PENDING_REQUEST_TIMEOUT = 20;



// lock protecting everything in the resolve_cache_info structs (next ptr, etc)

// lock protecting everything in NetConfig.

static std::mutex cache_mutex;

static std::condition_variable cv;



namespace {



// Map format: ReturnCode:rate_denom

// if the ReturnCode is not associated with any rate_denom, use default

// 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:1 0:100 7:10";



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

    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),

                  " ");

    for (const auto& pair : subsampling_vector) {

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

        int return_code;

        uint32_t denom;

        if (rate_denom.size() != 2) {

            LOG(ERROR) << __func__ << ": invalid subsampling_pair = " << pair;

            continue;

        }

        if (rate_denom[0] == "default") {

            return_code = DNSEVENT_SUBSAMPLING_MAP_DEFAULT_KEY;

        } else if (!ParseInt(rate_denom[0], &return_code)) {

            LOG(ERROR) << __func__ << ": parse subsampling_pair failed = " << pair;

            continue;

        }

        if (!ParseUint(rate_denom[1], &denom)) {

            LOG(ERROR) << __func__ << ": parse subsampling_pair failed = " << pair;

            continue;

        }

        sampling_rate_map[return_code] = denom;

    }

    return sampling_rate_map;

}



}  // namespace



// Note that Cache is not thread-safe per se, access to its members must be protected

// by an external mutex.

//
@@ -933,22 +976,25 @@ struct Cache { 
    } pending_requests{};

};



// TODO: allocate with new

struct resolv_cache_info {

    unsigned netid;

    Cache* cache;  // TODO: use unique_ptr or embed

    struct resolv_cache_info* next;

    int nscount;

struct NetConfig {

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

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

        dns_event_subsampling_map = resolv_get_dns_event_subsampling_map();

    }



    const unsigned netid;

    std::unique_ptr<Cache> cache;

    int nscount = 0;

    std::vector<std::string> nameservers;

    std::vector<IPSockAddr> nameserverSockAddrs;

    int revision_id;  // # times the nameservers have been replaced

    res_params params;

    struct res_stats nsstats[MAXNS];

    int revision_id = 0;  // # times the nameservers have been replaced

    res_params params{};

    res_stats nsstats[MAXNS]{};

    std::vector<std::string> search_domains;

    int wait_for_pending_req_timeout_count;

    int wait_for_pending_req_timeout_count = 0;

    // Map format: ReturnCode:rate_denom

    std::unordered_map<int, uint32_t> dns_event_subsampling_map;

    std::unique_ptr<DnsStats> dnsStats;

    DnsStats dnsStats;

};



/* gets cache associated with a network, or NULL if none exists */
@@ -1126,8 +1172,8 @@ static void _cache_remove_expired(Cache* cache) { 
    }

}



// gets a resolv_cache_info associated with a network, or NULL if not found

static resolv_cache_info* find_cache_info_locked(unsigned netid) REQUIRES(cache_mutex);

// Get a NetConfig associated with a network, or nullptr if not found.

static NetConfig* find_netconfig_locked(unsigned netid) REQUIRES(cache_mutex);



ResolvCacheStatus resolv_cache_lookup(unsigned netid, const void* query, int querylen, void* answer,

                                      int answersize, int* answerlen, uint32_t flags) {
@@ -1189,7 +1235,7 @@ ResolvCacheStatus resolv_cache_lookup(unsigned netid, const void* query, int que 
                return RESOLV_CACHE_NOTFOUND;

            }

            if (ret == false) {

                resolv_cache_info* info = find_cache_info_locked(netid);

                NetConfig* info = find_netconfig_locked(netid);

                if (info != NULL) {

                    info->wait_for_pending_req_timeout_count++;

                }
@@ -1375,169 +1421,75 @@ bool resolv_gethostbyaddr_from_cache(unsigned netid, char domain_name[], size_t 
    return false;

}



// Head of the list of caches.

static struct resolv_cache_info res_cache_list GUARDED_BY(cache_mutex);

static std::unordered_map<unsigned, std::unique_ptr<NetConfig>> sNetConfigMap

        GUARDED_BY(cache_mutex);



// insert resolv_cache_info into the list of resolv_cache_infos

static void insert_cache_info_locked(resolv_cache_info* cache_info);

// creates a resolv_cache_info

static resolv_cache_info* create_cache_info();

// Clears nameservers set for |cache_info| and clears the stats

static void free_nameservers_locked(resolv_cache_info* cache_info);

// Clears nameservers set for |netconfig| and clears the stats

static void free_nameservers_locked(NetConfig* netconfig);

// Order-insensitive comparison for the two set of servers.

static bool resolv_is_nameservers_equal(const std::vector<std::string>& oldServers,

                                        const std::vector<std::string>& newServers);

// clears the stats samples contained withing the given cache_info

static void res_cache_clear_stats_locked(resolv_cache_info* cache_info);

// clears the stats samples contained withing the given netconfig.

static void res_cache_clear_stats_locked(NetConfig* netconfig);



// public API for netd to query if name server is set on specific netid

bool resolv_has_nameservers(unsigned netid) {

    std::lock_guard guard(cache_mutex);

    resolv_cache_info* info = find_cache_info_locked(netid);

    NetConfig* info = find_netconfig_locked(netid);

    return (info != nullptr) && (info->nscount > 0);

}



namespace {



// Map format: ReturnCode:rate_denom

// if the ReturnCode is not associated with any rate_denom, use default

// 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:1 0:100 7:10";



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

    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),

                  " ");

    for (const auto& pair : subsampling_vector) {

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

        int return_code;

        uint32_t denom;

        if (rate_denom.size() != 2) {

            LOG(ERROR) << __func__ << ": invalid subsampling_pair = " << pair;

            continue;

        }

        if (rate_denom[0] == "default") {

            return_code = DNSEVENT_SUBSAMPLING_MAP_DEFAULT_KEY;

        } else if (!ParseInt(rate_denom[0], &return_code)) {

            LOG(ERROR) << __func__ << ": parse subsampling_pair failed = " << pair;

            continue;

        }

        if (!ParseUint(rate_denom[1], &denom)) {

            LOG(ERROR) << __func__ << ": parse subsampling_pair failed = " << pair;

            continue;

        }

        sampling_rate_map[return_code] = denom;

    }

    return sampling_rate_map;

}



}  // namespace



int resolv_create_cache_for_net(unsigned netid) {

    std::lock_guard guard(cache_mutex);

    Cache* cache = find_named_cache_locked(netid);

    // Should not happen

    if (cache) {

    if (sNetConfigMap.find(netid) != sNetConfigMap.end()) {

        LOG(ERROR) << __func__ << ": Cache is already created, netId: " << netid;

        return -EEXIST;

    }



    resolv_cache_info* cache_info = create_cache_info();

    if (!cache_info) return -ENOMEM;

    cache_info->netid = netid;

    cache_info->cache = new Cache;

    cache_info->dns_event_subsampling_map = resolv_get_dns_event_subsampling_map();

    cache_info->dnsStats.reset(new DnsStats());

    insert_cache_info_locked(cache_info);



    sNetConfigMap[netid] = std::make_unique<NetConfig>(netid);

    return 0;

}



void resolv_delete_cache_for_net(unsigned netid) {

    std::lock_guard guard(cache_mutex);



    struct resolv_cache_info* prev_cache_info = &res_cache_list;



    while (prev_cache_info->next) {

        struct resolv_cache_info* cache_info = prev_cache_info->next;



        if (cache_info->netid == netid) {

            prev_cache_info->next = cache_info->next;

            delete cache_info->cache;

            free_nameservers_locked(cache_info);



            // It won't be necessary after the memory of cache_info can be deallocated by the

            // C++ delete expression.

            cache_info->dnsStats.reset();



            free(cache_info);

            break;

        }



        prev_cache_info = prev_cache_info->next;

    }

    sNetConfigMap.erase(netid);

}



int resolv_flush_cache_for_net(unsigned netid) {

    std::lock_guard guard(cache_mutex);



    resolv_cache_info* cache_info = find_cache_info_locked(netid);

    if (cache_info == nullptr) {

    NetConfig* netconfig = find_netconfig_locked(netid);

    if (netconfig == nullptr) {

        return -ENONET;

    }

    cache_info->cache->flush();

    netconfig->cache->flush();



    // Also clear the NS statistics.

    res_cache_clear_stats_locked(cache_info);

    res_cache_clear_stats_locked(netconfig);

    return 0;

}



std::vector<unsigned> resolv_list_caches() {

    std::lock_guard guard(cache_mutex);

    struct resolv_cache_info* cache_info = res_cache_list.next;

    std::vector<unsigned> result;

    while (cache_info) {

        result.push_back(cache_info->netid);

        cache_info = cache_info->next;

    result.reserve(sNetConfigMap.size());

    for (const auto& [netId, _] : sNetConfigMap) {

        result.push_back(netId);

    }

    return result;

}



static resolv_cache_info* create_cache_info() {

    return (struct resolv_cache_info*) calloc(sizeof(struct resolv_cache_info), 1);

}



// TODO: convert this to a simple and efficient C++ container.

static void insert_cache_info_locked(struct resolv_cache_info* cache_info) {

    struct resolv_cache_info* last;

    for (last = &res_cache_list; last->next; last = last->next) {}

    last->next = cache_info;

}



static Cache* find_named_cache_locked(unsigned netid) {

    resolv_cache_info* info = find_cache_info_locked(netid);

    if (info != nullptr) return info->cache;

    NetConfig* info = find_netconfig_locked(netid);

    if (info != nullptr) return info->cache.get();

    return nullptr;

}



static resolv_cache_info* find_cache_info_locked(unsigned netid) {

    struct resolv_cache_info* cache_info = res_cache_list.next;



    while (cache_info) {

        if (cache_info->netid == netid) {

            break;

        }



        cache_info = cache_info->next;

static NetConfig* find_netconfig_locked(unsigned netid) {

    if (auto it = sNetConfigMap.find(netid); it != sNetConfigMap.end()) {

        return it->second.get();

    }

    return cache_info;

    return nullptr;

}



static void resolv_set_experiment_params(res_params* params) {
@@ -1613,41 +1565,41 @@ int resolv_set_nameservers(unsigned netid, const std::vector<std::string>& serve 
    }



    std::lock_guard guard(cache_mutex);

    resolv_cache_info* cache_info = find_cache_info_locked(netid);

    NetConfig* netconfig = find_netconfig_locked(netid);



    if (cache_info == nullptr) return -ENONET;

    if (netconfig == nullptr) return -ENONET;



    uint8_t old_max_samples = cache_info->params.max_samples;

    cache_info->params = params;

    resolv_set_experiment_params(&cache_info->params);

    if (!resolv_is_nameservers_equal(cache_info->nameservers, nameservers)) {

    uint8_t old_max_samples = netconfig->params.max_samples;

    netconfig->params = params;

    resolv_set_experiment_params(&netconfig->params);

    if (!resolv_is_nameservers_equal(netconfig->nameservers, nameservers)) {

        // free current before adding new

        free_nameservers_locked(cache_info);

        cache_info->nameservers = std::move(nameservers);

        free_nameservers_locked(netconfig);

        netconfig->nameservers = std::move(nameservers);

        for (int i = 0; i < numservers; i++) {

            LOG(INFO) << __func__ << ": netid = " << netid

                      << ", addr = " << cache_info->nameservers[i];

                      << ", addr = " << netconfig->nameservers[i];

        }

        cache_info->nameserverSockAddrs = std::move(ipSockAddrs);

        cache_info->nscount = numservers;

        netconfig->nameserverSockAddrs = std::move(ipSockAddrs);

        netconfig->nscount = numservers;

    } else {

        if (cache_info->params.max_samples != old_max_samples) {

        if (netconfig->params.max_samples != old_max_samples) {

            // If the maximum number of samples changes, the overhead of keeping the most recent

            // samples around is not considered worth the effort, so they are cleared instead.

            // All other parameters do not affect shared state: Changing these parameters does

            // not invalidate the samples, as they only affect aggregation and the conditions

            // under which servers are considered usable.

            res_cache_clear_stats_locked(cache_info);

            res_cache_clear_stats_locked(netconfig);

        }

    }



    // Always update the search paths. Cache-flushing however is not necessary,

    // since the stored cache entries do contain the domain, not just the host name.

    cache_info->search_domains = filter_domains(domains);

    netconfig->search_domains = filter_domains(domains);



    // Setup stats for cleartext dns servers.

    if (!cache_info->dnsStats->setServers(cache_info->nameserverSockAddrs, PROTO_TCP) ||

        !cache_info->dnsStats->setServers(cache_info->nameserverSockAddrs, PROTO_UDP)) {

    if (!netconfig->dnsStats.setServers(netconfig->nameserverSockAddrs, PROTO_TCP) ||

        !netconfig->dnsStats.setServers(netconfig->nameserverSockAddrs, PROTO_UDP)) {

        LOG(WARNING) << __func__ << ": netid = " << netid << ", failed to set dns stats";

        return -EINVAL;

    }
@@ -1668,11 +1620,11 @@ static bool resolv_is_nameservers_equal(const std::vector<std::string>& oldServe 
    return olds == news;

}



static void free_nameservers_locked(resolv_cache_info* cache_info) {

    cache_info->nscount = 0;

    cache_info->nameservers.clear();

    cache_info->nameserverSockAddrs.clear();

    res_cache_clear_stats_locked(cache_info);

static void free_nameservers_locked(NetConfig* netconfig) {

    netconfig->nscount = 0;

    netconfig->nameservers.clear();

    netconfig->nameserverSockAddrs.clear();

    res_cache_clear_stats_locked(netconfig);

}



void resolv_populate_res_for_net(ResState* statp) {
@@ -1682,7 +1634,7 @@ void resolv_populate_res_for_net(ResState* statp) { 
    LOG(INFO) << __func__ << ": netid=" << statp->netid;



    std::lock_guard guard(cache_mutex);

    resolv_cache_info* info = find_cache_info_locked(statp->netid);

    NetConfig* info = find_netconfig_locked(statp->netid);

    if (info == nullptr) return;



    // TODO: Convert nsaddrs[] to c++ container and remove the size-checking.
@@ -1720,17 +1672,17 @@ static void res_cache_add_stats_sample_locked(res_stats* stats, const res_sample 
    }

}



static void res_cache_clear_stats_locked(resolv_cache_info* cache_info) {

static void res_cache_clear_stats_locked(NetConfig* netconfig) {

    for (int i = 0; i < MAXNS; ++i) {

        cache_info->nsstats[i].sample_count = 0;

        cache_info->nsstats[i].sample_next = 0;

        netconfig->nsstats[i].sample_count = 0;

        netconfig->nsstats[i].sample_next = 0;

    }



    // Increment the revision id to ensure that sample state is not written back if the

    // servers change; in theory it would suffice to do so only if the servers or

    // max_samples actually change, in practice the overhead of checking is higher than the

    // cost, and overflows are unlikely.

    ++cache_info->revision_id;

    ++netconfig->revision_id;

}



int android_net_res_stats_get_info_for_net(unsigned netid, int* nscount,
@@ -1741,7 +1693,7 @@ int android_net_res_stats_get_info_for_net(unsigned netid, int* nscount, 
    int revision_id = -1;

    std::lock_guard guard(cache_mutex);



    resolv_cache_info* info = find_cache_info_locked(netid);

    NetConfig* info = find_netconfig_locked(netid);

    if (info) {

        if (info->nscount > MAXNS) {

            LOG(INFO) << __func__ << ": nscount " << info->nscount << " > MAXNS " << MAXNS;
@@ -1779,10 +1731,10 @@ int android_net_res_stats_get_info_for_net(unsigned netid, int* nscount, 
std::vector<std::string> resolv_cache_dump_subsampling_map(unsigned netid) {

    using android::base::StringPrintf;

    std::lock_guard guard(cache_mutex);

    resolv_cache_info* cache_info = find_cache_info_locked(netid);

    if (cache_info == nullptr) return {};

    NetConfig* netconfig = find_netconfig_locked(netid);

    if (netconfig == nullptr) return {};

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

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

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

        result.push_back(StringPrintf("%s:%d",

                                      (pair.first == DNSEVENT_SUBSAMPLING_MAP_DEFAULT_KEY)

                                              ? "default"
@@ -1798,9 +1750,9 @@ std::vector<std::string> resolv_cache_dump_subsampling_map(unsigned netid) { 
// 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) {

    std::lock_guard guard(cache_mutex);

    resolv_cache_info* cache_info = find_cache_info_locked(netid);

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

    const auto& subsampling_map = cache_info->dns_event_subsampling_map;

    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;

    auto search_returnCode = subsampling_map.find(return_code);

    uint32_t denom;

    if (search_returnCode != subsampling_map.end()) {
@@ -1814,7 +1766,7 @@ uint32_t resolv_cache_get_subsampling_denom(unsigned netid, int return_code) { 


int resolv_cache_get_resolver_stats(unsigned netid, res_params* params, res_stats stats[MAXNS]) {

    std::lock_guard guard(cache_mutex);

    resolv_cache_info* info = find_cache_info_locked(netid);

    NetConfig* info = find_netconfig_locked(netid);

    if (info) {

        memcpy(stats, info->nsstats, sizeof(info->nsstats));

        *params = info->params;
@@ -1829,7 +1781,7 @@ void resolv_cache_add_resolver_stats_sample(unsigned netid, int revision_id, con 
    if (max_samples <= 0 || sa == nullptr) return;



    std::lock_guard guard(cache_mutex);

    resolv_cache_info* info = find_cache_info_locked(netid);

    NetConfig* info = find_netconfig_locked(netid);



    if (info && info->revision_id == revision_id) {

        const int serverNum = std::min(MAXNS, static_cast<int>(info->nameserverSockAddrs.size()));
@@ -1884,7 +1836,7 @@ int resolv_cache_get_expiration(unsigned netid, const std::vector<char>& query, 


int resolv_stats_set_servers_for_dot(unsigned netid, const std::vector<std::string>& servers) {

    std::lock_guard guard(cache_mutex);

    const auto info = find_cache_info_locked(netid);

    const auto info = find_netconfig_locked(netid);



    if (info == nullptr) return -ENONET;
@@ -1894,7 +1846,7 @@ int resolv_stats_set_servers_for_dot(unsigned netid, const std::vector<std::stri 
        serverSockAddrs.push_back(IPSockAddr::toIPSockAddr(server, 853));

    }



    if (!info->dnsStats->setServers(serverSockAddrs, android::net::PROTO_DOT)) {

    if (!info->dnsStats.setServers(serverSockAddrs, android::net::PROTO_DOT)) {

        LOG(WARNING) << __func__ << ": netid = " << netid << ", failed to set dns stats";

        return -EINVAL;

    }
@@ -1907,15 +1859,15 @@ bool resolv_stats_add(unsigned netid, const android::netdutils::IPSockAddr& serv 
    if (record == nullptr) return false;



    std::lock_guard guard(cache_mutex);

    if (const auto info = find_cache_info_locked(netid); info != nullptr) {

        return info->dnsStats->addStats(server, *record);

    if (const auto info = find_netconfig_locked(netid); info != nullptr) {

        return info->dnsStats.addStats(server, *record);

    }

    return false;

}



void resolv_stats_dump(DumpWriter& dw, unsigned netid) {

    std::lock_guard guard(cache_mutex);

    if (const auto info = find_cache_info_locked(netid); info != nullptr) {

        info->dnsStats->dump(dw);

    if (const auto info = find_netconfig_locked(netid); info != nullptr) {

        info->dnsStats.dump(dw);

    }

}

resolv_cache_unit_test.cpp

+1 −1
Original line number Diff line number Diff line
@@ -902,7 +902,7 @@ TEST_F(ResolvCacheTest, DnsEventSubsampling) { 
    }

}



// TODO: Tests for struct resolv_cache_info, including:

// TODO: Tests for NetConfig, including:

//     - res_params

//         -- resolv_cache_get_resolver_stats()

//     - res_stats