Merge from remote branch

dns/doh.go

@@ -3,7 +3,6 @@ package dns
 import (
 	"bytes"
 	"context"
-	"crypto/tls"
 	"io/ioutil"
 	"net"
 	"net/http"
@@ -76,7 +75,6 @@ func newDoHClient(url string, r *Resolver) *dohClient {
 	return &dohClient{
 		url: url,
 		transport: &http.Transport{
-			TLSClientConfig:   &tls.Config{ClientSessionCache: globalSessionCache},
 			ForceAttemptHTTP2: true,
 			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
 				host, port, err := net.SplitHostPort(addr)

dns/resolver.go

@@ -2,7 +2,6 @@ package dns
 
 import (
 	"context"
-	"crypto/tls"
 	"errors"
 	"fmt"
 	"math/rand"
@@ -20,10 +19,6 @@ import (
 	"golang.org/x/sync/singleflight"
 )
 
-var (
-	globalSessionCache = tls.NewLRUClientSessionCache(64)
-)
-
 type dnsClient interface {
 	Exchange(m *D.Msg) (msg *D.Msg, err error)
 	ExchangeContext(ctx context.Context, m *D.Msg) (msg *D.Msg, err error)

dns/util.go

@@ -127,7 +127,6 @@ func transform(servers []NameServer, resolver *Resolver) []dnsClient {
 			Client: &D.Client{
 				Net: s.Net,
 				TLSConfig: &tls.Config{
-					ClientSessionCache: globalSessionCache,
 					// alpn identifier, see https://tools.ietf.org/html/draft-hoffman-dprive-dns-tls-alpn-00#page-6
 					NextProtos: []string{"dns"},
 					ServerName: host,