struct hostent* dest,

const struct hostent* src) {

dest->h_addr_list = nullptr;

dest->h_addrtype = 0;

dest->h_aliases = nullptr;

dest->h_length = 0;

dest->h_name = nullptr;

/* copy `h_name` */

size_t name_size = strlen(src->h_name) + 1;

dest->h_name = node::Malloc<char>(name_size);

memcpy(dest->h_name, src->h_name, name_size);

/* copy `h_aliases` */

size_t alias_count;

for (alias_count = 0;

src->h_aliases[alias_count] != nullptr;

alias_count++) {

}

dest->h_aliases = node::Malloc<char*>(alias_count + 1);

for (size_t i = 0; i < alias_count; i++) {

const size_t cur_alias_size = strlen(src->h_aliases[i]) + 1;

dest->h_aliases[i] = node::Malloc(cur_alias_size);

memcpy(dest->h_aliases[i], src->h_aliases[i], cur_alias_size);

}

dest->h_aliases[alias_count] = nullptr;

/* copy `h_addr_list` */

size_t list_count;

for (list_count = 0;

src->h_addr_list[list_count] != nullptr;

list_count++) {

}

dest->h_addr_list = node::Malloc<char*>(list_count + 1);

for (size_t i = 0; i < list_count; i++) {

dest->h_addr_list[i] = node::Malloc(src->h_length);

memcpy(dest->h_addr_list[i], src->h_addr_list[i], src->h_length);

}

dest->h_addr_list[list_count] = nullptr;

/* work after work */

dest->h_length = src->h_length;

dest->h_addrtype = src->h_addrtype;

ChannelWrap* channel;

ares_socket_t sock;

uv_poll_t poll_watcher;

inline void MemoryInfo(MemoryTracker* trakcer) const override;

SET_MEMORY_INFO_NAME(NodeAresTask)

SET_SELF_SIZE(NodeAresTask)

struct Hash {

inline size_t operator()(NodeAresTask* a) const {

return std::hash<ares_socket_t>()(a->sock);

}

};

struct Equal {

inline bool operator()(NodeAresTask* a, NodeAresTask* b) const {

return a->sock == b->sock;

}

};

static NodeAresTask* Create(ChannelWrap* channel, ares_socket_t sock);

using List = std::unordered_set<NodeAresTask*, Hash, Equal>;

public:

ChannelWrap(

Environment* env,

v8::Local<v8::Object> object,

int timeout,

int tries);

~ChannelWrap() override;

static void New(const v8::FunctionCallbackInfo<v8::Value>& args);

void Setup();

void EnsureServers();

void StartTimer();

void CloseTimer();

void ModifyActivityQueryCount(int count);

inline uv_timer_t* timer_handle() { return timer_handle_; }

inline ares_channel cares_channel() { return channel_; }

inline void set_query_last_ok(bool ok) { query_last_ok_ = ok; }

inline void set_is_servers_default(bool is_default) {

is_servers_default_ = is_default;

}

inline int active_query_count() { return active_query_count_; }

inline NodeAresTask::List* task_list() { return &task_list_; }

void MemoryInfo(MemoryTracker* tracker) const override;

SET_MEMORY_INFO_NAME(ChannelWrap)

SET_SELF_SIZE(ChannelWrap)

static void AresTimeout(uv_timer_t* handle);

private:

uv_timer_t* timer_handle_ = nullptr;

ares_channel channel_ = nullptr;

bool query_last_ok_ = true;

bool is_servers_default_ = true;

bool library_inited_ = false;

int timeout_;

int tries_;

int active_query_count_ = 0;

NodeAresTask::List task_list_;

public:

GetAddrInfoReqWrap(Environment* env,

v8::Local<v8::Object> req_wrap_obj,

uint8_t order);

SET_NO_MEMORY_INFO()

SET_MEMORY_INFO_NAME(GetAddrInfoReqWrap)

SET_SELF_SIZE(GetAddrInfoReqWrap)

uint8_t order() const { return order_; }

private:

const uint8_t order_;

public:

GetNameInfoReqWrap(Environment* env, v8::Local<v8::Object> req_wrap_obj);

SET_NO_MEMORY_INFO()

SET_MEMORY_INFO_NAME(GetNameInfoReqWrap)

SET_SELF_SIZE(GetNameInfoReqWrap)

};

struct ResponseData final {

int status;

bool is_host;

SafeHostEntPointer host;

MallocedBuffer<unsigned char> buf;

};

template <typename Traits>

class QueryWrap final : public AsyncWrap {

public:

QueryWrap(ChannelWrap* channel, v8::Local<v8::Object> req_wrap_obj)

: AsyncWrap(channel->env(), req_wrap_obj, AsyncWrap::PROVIDER_QUERYWRAP),

channel_(channel),

trace_name_(Traits::name) {}

~QueryWrap() {

CHECK_EQ(false, persistent().IsEmpty());

// Let Callback() know that this object no longer exists.

if (callback_ptr_ != nullptr)

*callback_ptr_ = nullptr;

}

int Send(const char* name) {

return Traits::Send(this, name);

}

void AresQuery(const char* name,

ares_dns_class_t dnsclass,

ares_dns_rec_type_t type) {

channel_->EnsureServers();

TRACE_EVENT_NESTABLE_ASYNC_BEGIN1(

TRACING_CATEGORY_NODE2(dns, native), trace_name_, this,

"name", TRACE_STR_COPY(name));

ares_query_dnsrec(channel_->cares_channel(),

name,

dnsclass,

type,

Callback,

MakeCallbackPointer(),

nullptr);

}

void ParseError(int status) {

CHECK_NE(status, ARES_SUCCESS);

v8::HandleScope handle_scope(env()->isolate());

v8::Context::Scope context_scope(env()->context());

const char* code = ToErrorCodeString(status);

v8::Local<v8::Value> arg = OneByteString(env()->isolate(), code);

TRACE_EVENT_NESTABLE_ASYNC_END1(

TRACING_CATEGORY_NODE2(dns, native), trace_name_, this,

"error", status);

MakeCallback(env()->oncomplete_string(), 1, &arg);

}

const BaseObjectPtr<ChannelWrap>& channel() const { return channel_; }

void AfterResponse() {

CHECK(response_data_);

int status = response_data_->status;

if (status != ARES_SUCCESS)

return ParseError(status);

status = Traits::Parse(this, response_data_);

if (status != ARES_SUCCESS)

ParseError(status);

}

void* MakeCallbackPointer() {

CHECK_NULL(callback_ptr_);

callback_ptr_ = new QueryWrap<Traits>*(this);

return callback_ptr_;

}

static QueryWrap<Traits>* FromCallbackPointer(void* arg) {

std::unique_ptr<QueryWrap<Traits>*> wrap_ptr {

static_cast<QueryWrap<Traits>**>(arg)

};

QueryWrap<Traits>* wrap = *wrap_ptr.get();

if (wrap == nullptr) return nullptr;

wrap->callback_ptr_ = nullptr;

return wrap;

}

static void Callback(void* arg,

ares_status_t status,

size_t timeouts,

const ares_dns_record_t* dnsrec) {

QueryWrap<Traits>* wrap = FromCallbackPointer(arg);

if (wrap == nullptr) return;

unsigned char* buf_copy = nullptr;

size_t answer_len = 0;

if (status == ARES_SUCCESS) {

// No need to explicitly call ares_free_string here,

// as it is a wrapper around free, which is already

// invoked when MallocedBuffer is destructed.

ares_dns_write(dnsrec, &buf_copy, &answer_len);

}

wrap->response_data_ = std::make_unique<ResponseData>();

ResponseData* data = wrap->response_data_.get();

data->status = status;

data->is_host = false;

data->buf = MallocedBuffer<unsigned char>(buf_copy, answer_len);

wrap->QueueResponseCallback(status);

}

static void Callback(

void* arg,

int status,

int timeouts,

struct hostent* host) {

QueryWrap<Traits>* wrap = FromCallbackPointer(arg);

if (wrap == nullptr) return;

struct hostent* host_copy = nullptr;

if (status == ARES_SUCCESS) {

host_copy = node::Malloc<hostent>(1);

cares_wrap_hostent_cpy(host_copy, host);

}

wrap->response_data_ = std::make_unique<ResponseData>();

ResponseData* data = wrap->response_data_.get();

data->status = status;

data->host.reset(host_copy);

data->is_host = true;

wrap->QueueResponseCallback(status);

}

void QueueResponseCallback(int status) {

BaseObjectPtr<QueryWrap<Traits>> strong_ref{this};

env()->SetImmediate([this, strong_ref](Environment*) {

AfterResponse();

// Delete once strong_ref goes out of scope.

Detach();

});

channel_->set_query_last_ok(status != ARES_ECONNREFUSED);

channel_->ModifyActivityQueryCount(-1);

}

void CallOnComplete(

v8::Local<v8::Value> answer,

v8::Local<v8::Value> extra = v8::Local<v8::Value>()) {

v8::HandleScope handle_scope(env()->isolate());

v8::Context::Scope context_scope(env()->context());

v8::Local<v8::Value> argv[] = {

v8::Integer::New(env()->isolate(), 0),

answer,

extra

};

const int argc = arraysize(argv) - extra.IsEmpty();

TRACE_EVENT_NESTABLE_ASYNC_END0(

TRACING_CATEGORY_NODE2(dns, native), trace_name_, this);

MakeCallback(env()->oncomplete_string(), argc, argv);

}

void MemoryInfo(MemoryTracker* tracker) const override {

tracker->TrackField("channel", channel_);

if (response_data_) {

tracker->TrackFieldWithSize("response", response_data_->buf.size);

}

}

SET_MEMORY_INFO_NAME(QueryWrap)

SET_SELF_SIZE(QueryWrap<Traits>)

private:

BaseObjectPtr<ChannelWrap> channel_;

std::unique_ptr<ResponseData> response_data_;

const char* trace_name_;

// Pointer to pointer to 'this' that can be reset from the destructor,

// in order to let Callback() know that 'this' no longer exists.

QueryWrap<Traits>** callback_ptr_ = nullptr;

};

struct AnyTraits final {

static constexpr const char* name = "resolveAny";

static int Send(QueryWrap<AnyTraits>* wrap, const char* name);

static int Parse(

QueryWrap<AnyTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct ATraits final {

static constexpr const char* name = "resolve4";

static int Send(QueryWrap<ATraits>* wrap, const char* name);

static int Parse(

QueryWrap<ATraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct AaaaTraits final {

static constexpr const char* name = "resolve6";

static int Send(QueryWrap<AaaaTraits>* wrap, const char* name);

static int Parse(

QueryWrap<AaaaTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct CaaTraits final {

static constexpr const char* name = "resolveCaa";

static int Send(QueryWrap<CaaTraits>* wrap, const char* name);

static int Parse(

QueryWrap<CaaTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct CnameTraits final {

static constexpr const char* name = "resolveCname";

static int Send(QueryWrap<CnameTraits>* wrap, const char* name);

static int Parse(

QueryWrap<CnameTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct MxTraits final {

static constexpr const char* name = "resolveMx";

static int Send(QueryWrap<MxTraits>* wrap, const char* name);

static int Parse(

QueryWrap<MxTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct NsTraits final {

static constexpr const char* name = "resolveNs";

static int Send(QueryWrap<NsTraits>* wrap, const char* name);

static int Parse(

QueryWrap<NsTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct TlsaTraits final {

static constexpr const char* name = "resolveTlsa";

static int Send(QueryWrap<TlsaTraits>* wrap, const char* name);

static int Parse(QueryWrap<TlsaTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct TxtTraits final {

static constexpr const char* name = "resolveTxt";

static int Send(QueryWrap<TxtTraits>* wrap, const char* name);

static int Parse(

QueryWrap<TxtTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct SrvTraits final {

static constexpr const char* name = "resolveSrv";

static int Send(QueryWrap<SrvTraits>* wrap, const char* name);

static int Parse(

QueryWrap<SrvTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct PtrTraits final {

static constexpr const char* name = "resolvePtr";

static int Send(QueryWrap<PtrTraits>* wrap, const char* name);

static int Parse(

QueryWrap<PtrTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct NaptrTraits final {

static constexpr const char* name = "resolveNaptr";

static int Send(QueryWrap<NaptrTraits>* wrap, const char* name);

static int Parse(

QueryWrap<NaptrTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct SoaTraits final {

static constexpr const char* name = "resolveSoa";

static int Send(QueryWrap<SoaTraits>* wrap, const char* name);

static int Parse(

QueryWrap<SoaTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

struct ReverseTraits final {

static constexpr const char* name = "reverse";

static int Send(QueryWrap<ReverseTraits>* wrap, const char* name);

static int Parse(

QueryWrap<ReverseTraits>* wrap,

const std::unique_ptr<ResponseData>& response);

};

using QueryAnyWrap = QueryWrap<AnyTraits>;

using QueryAWrap = QueryWrap<ATraits>;

using QueryAaaaWrap = QueryWrap<AaaaTraits>;

using QueryCaaWrap = QueryWrap<CaaTraits>;

using QueryCnameWrap = QueryWrap<CnameTraits>;

using QueryMxWrap = QueryWrap<MxTraits>;

using QueryNsWrap = QueryWrap<NsTraits>;

using QueryTlsaWrap = QueryWrap<TlsaTraits>;

using QueryTxtWrap = QueryWrap<TxtTraits>;

using QuerySrvWrap = QueryWrap<SrvTraits>;

using QueryPtrWrap = QueryWrap<PtrTraits>;

using QueryNaptrWrap = QueryWrap<NaptrTraits>;

using QuerySoaWrap = QueryWrap<SoaTraits>;

using GetHostByAddrWrap = QueryWrap<ReverseTraits>;