diff --git a/dns/resolver/doh.go b/dns/resolver/doh.go
index 266e4b9..1bce0de 100644
--- a/dns/resolver/doh.go
+++ b/dns/resolver/doh.go
@@ -41,11 +41,7 @@ func NewDOHClient(host string) *DOHResolver {
 }
 
 func (r *DOHResolver) Resolve(ctx context.Context, host string, qTypes []uint16) ([]net.IPAddr, error) {
-	sendMsg := func(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
-		return r.dohExchange(ctx, msg)
-	}
-
-	resultCh := lookup(ctx, host, qTypes, sendMsg)
+	resultCh := lookupAllTypes(ctx, host, qTypes, r.exchange)
 	addrs, err := processResults(ctx, resultCh)
 	return addrs, err
 }
@@ -54,7 +50,7 @@ func (r *DOHResolver) String() string {
 	return fmt.Sprintf("doh resolver(%s)", r.upstream)
 }
 
-func (r *DOHResolver) dohQuery(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
+func (r *DOHResolver) exchange(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
 	pack, err := msg.Pack()
 	if err != nil {
 		return nil, err
@@ -91,18 +87,9 @@ func (r *DOHResolver) dohQuery(ctx context.Context, msg *dns.Msg) (*dns.Msg, err
 		return nil, err
 	}
 
-	return resultMsg, nil
-}
-
-func (r *DOHResolver) dohExchange(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
-	res, err := r.dohQuery(ctx, msg)
-	if err != nil {
-		return nil, err
-	}
-
-	if res.Rcode != dns.RcodeSuccess {
+	if resultMsg.Rcode != dns.RcodeSuccess {
 		return nil, errors.New("doh rcode wasn't successful")
 	}
 
-	return res, nil
+	return resultMsg, nil
 }
diff --git a/dns/resolver/general.go b/dns/resolver/general.go
index 44441c4..2f83ffd 100644
--- a/dns/resolver/general.go
+++ b/dns/resolver/general.go
@@ -26,12 +26,7 @@ func NewGeneralClient(server string) *GeneralResolver {
 }
 
 func (r *GeneralResolver) Resolve(ctx context.Context, host string, qTypes []uint16) ([]net.IPAddr, error) {
-	sendMsg := func(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
-		resp, _, err := r.client.Exchange(msg, r.server)
-		return resp, err
-	}
-
-	resultCh := lookup(ctx, host, qTypes, sendMsg)
+	resultCh := lookupAllTypes(ctx, host, qTypes, r.exchange)
 	addrs, err := processResults(ctx, resultCh)
 	return addrs, err
 }
@@ -39,3 +34,8 @@ func (r *GeneralResolver) Resolve(ctx context.Context, host string, qTypes []uin
 func (c *GeneralResolver) String() string {
 	return fmt.Sprintf("general resolver(%s)", c.server)
 }
+
+func (r *GeneralResolver) exchange(ctx context.Context, msg *dns.Msg) (*dns.Msg, error) {
+	resp, _, err := r.client.Exchange(msg, r.server)
+	return resp, err
+}
diff --git a/dns/resolver/resolver.go b/dns/resolver/resolver.go
index f2033ac..031f73e 100644
--- a/dns/resolver/resolver.go
+++ b/dns/resolver/resolver.go
@@ -12,13 +12,13 @@ import (
 	"github.com/xvzc/SpoofDPI/dns/addrselect"
 )
 
+type exchangeFunc = func(ctx context.Context, msg *dns.Msg) (*dns.Msg, error)
+
 type Resolver interface {
 	Resolve(ctx context.Context, host string, qTypes []uint16) ([]net.IPAddr, error)
 	String() string
 }
 
-type exchangeFunc = func(ctx context.Context, msg *dns.Msg) (*dns.Msg, error)
-
 func recordTypeIDToName(id uint16) string {
 	switch id {
 	case 1:
@@ -47,32 +47,31 @@ func sortAddrs(addrs []net.IPAddr) {
 	addrselect.SortByRFC6724(addrs)
 }
 
-func lookup(ctx context.Context, host string, queryTypes []uint16, sendMsg exchangeFunc) <-chan *DNSResult {
+func lookupAllTypes(ctx context.Context, host string, qTypes []uint16, exchange exchangeFunc) <-chan *DNSResult {
 	var wg sync.WaitGroup
 	resCh := make(chan *DNSResult)
 
-	lookup := func(qType uint16) {
-		defer wg.Done()
-		select {
-		case <-ctx.Done():
-			return
-		case resCh <- query(ctx, host, qType, sendMsg):
-		}
-	}
-
-	for _, queryType := range queryTypes {
+	for _, qType := range qTypes {
 		wg.Add(1)
-		go lookup(queryType)
+		go func(qType uint16) {
+			defer wg.Done()
+			select {
+			case <-ctx.Done():
+				return
+			case resCh <- lookupType(ctx, host, qType, exchange):
+			}
+		}(qType)
 	}
 
 	go func() {
 		wg.Wait()
 		close(resCh)
 	}()
+
 	return resCh
 }
 
-func query(ctx context.Context, host string, queryType uint16, exchange exchangeFunc) *DNSResult {
+func lookupType(ctx context.Context, host string, queryType uint16, exchange exchangeFunc) *DNSResult {
 	msg := newMsg(host, queryType)
 	resp, err := exchange(ctx, msg)
 	if err != nil {
@@ -103,7 +102,7 @@ func processResults(ctx context.Context, resCh <-chan *DNSResult) ([]net.IPAddr,
 	}
 	select {
 	case <-ctx.Done():
-		return nil, errors.New("cancelled")
+		return nil, errors.New("canceled")
 	default:
 		if len(addrs) == 0 {
 			return addrs, errors.Join(errs...)
diff --git a/dns/resolver/system.go b/dns/resolver/system.go
index 5be0b9f..928be7f 100644
--- a/dns/resolver/system.go
+++ b/dns/resolver/system.go
@@ -19,7 +19,7 @@ func (r *SystemResolver) String() string {
 	return "system resolver"
 }
 
-func (r *SystemResolver) Resolve(ctx context.Context, host string, qTypes []uint16) ([]net.IPAddr, error) {
+func (r *SystemResolver) Resolve(ctx context.Context, host string, _ []uint16) ([]net.IPAddr, error) {
 	addrs, err := r.LookupIPAddr(ctx, host)
 	if err != nil {
 		return []net.IPAddr{}, err