Feature: support DoH

dns/resolver.go

@@ -0,0 +1,289 @@
+package dns
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"net"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/Dreamacro/clash/common/cache"
+	"github.com/Dreamacro/clash/common/picker"
+	"github.com/Dreamacro/clash/component/fakeip"
+	C "github.com/Dreamacro/clash/constant"
+
+	D "github.com/miekg/dns"
+	geoip2 "github.com/oschwald/geoip2-golang"
+)
+
+var (
+	globalSessionCache = tls.NewLRUClientSessionCache(64)
+
+	mmdb *geoip2.Reader
+	once sync.Once
+)
+
+type resolver interface {
+	Exchange(m *D.Msg) (msg *D.Msg, err error)
+	ExchangeContext(ctx context.Context, m *D.Msg) (msg *D.Msg, err error)
+}
+
+type result struct {
+	Msg   *D.Msg
+	Error error
+}
+
+type Resolver struct {
+	ipv6     bool
+	mapping  bool
+	fakeip   bool
+	pool     *fakeip.Pool
+	fallback []resolver
+	main     []resolver
+	cache    *cache.Cache
+}
+
+// ResolveIP request with TypeA and TypeAAAA, priority return TypeAAAA
+func (r *Resolver) ResolveIP(host string) (ip net.IP, err error) {
+	ch := make(chan net.IP)
+	go func() {
+		ip, err := r.resolveIP(host, D.TypeA)
+		if err != nil {
+			close(ch)
+			return
+		}
+		ch <- ip
+	}()
+
+	ip, err = r.resolveIP(host, D.TypeAAAA)
+	if err == nil {
+		go func() {
+			<-ch
+		}()
+		return
+	}
+
+	ip, closed := <-ch
+	if closed {
+		return nil, errors.New("can't found ip")
+	}
+
+	return ip, nil
+}
+
+// ResolveIPv4 request with TypeA
+func (r *Resolver) ResolveIPv4(host string) (ip net.IP, err error) {
+	ip = net.ParseIP(host)
+	if ip != nil {
+		return ip, nil
+	}
+
+	query := &D.Msg{}
+	query.SetQuestion(D.Fqdn(host), D.TypeA)
+
+	msg, err := r.Exchange(query)
+	if err != nil {
+		return nil, err
+	}
+
+	ips := r.msgToIP(msg)
+	if len(ips) == 0 {
+		return nil, errors.New("can't found ip")
+	}
+
+	ip = ips[0]
+	return
+}
+
+// Exchange a batch of dns request, and it use cache
+func (r *Resolver) Exchange(m *D.Msg) (msg *D.Msg, err error) {
+	if len(m.Question) == 0 {
+		return nil, errors.New("should have one question at least")
+	}
+
+	q := m.Question[0]
+	cache, expireTime := r.cache.GetWithExpire(q.String())
+	if cache != nil {
+		msg = cache.(*D.Msg).Copy()
+		setMsgTTL(msg, uint32(expireTime.Sub(time.Now()).Seconds()))
+		return
+	}
+	defer func() {
+		if msg == nil {
+			return
+		}
+
+		putMsgToCache(r.cache, q.String(), msg)
+		if r.mapping {
+			ips := r.msgToIP(msg)
+			for _, ip := range ips {
+				putMsgToCache(r.cache, ip.String(), msg)
+			}
+		}
+	}()
+
+	isIPReq := isIPRequest(q)
+	if isIPReq {
+		msg, err = r.fallbackExchange(m)
+		return
+	}
+
+	msg, err = r.batchExchange(r.main, m)
+	return
+}
+
+// IPToHost return fake-ip or redir-host mapping host
+func (r *Resolver) IPToHost(ip net.IP) (string, bool) {
+	cache := r.cache.Get(ip.String())
+	if cache == nil {
+		return "", false
+	}
+	fqdn := cache.(*D.Msg).Question[0].Name
+	return strings.TrimRight(fqdn, "."), true
+}
+
+func (r *Resolver) IsMapping() bool {
+	return r.mapping
+}
+
+func (r *Resolver) IsFakeIP() bool {
+	return r.fakeip
+}
+
+func (r *Resolver) batchExchange(clients []resolver, m *D.Msg) (msg *D.Msg, err error) {
+	in := make(chan interface{})
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	fast := picker.SelectFast(ctx, in)
+
+	wg := sync.WaitGroup{}
+	wg.Add(len(clients))
+	for _, r := range clients {
+		go func(r resolver) {
+			defer wg.Done()
+			msg, err := r.ExchangeContext(ctx, m)
+			if err != nil || msg.Rcode != D.RcodeSuccess {
+				return
+			}
+			in <- msg
+		}(r)
+	}
+
+	// release in channel
+	go func() {
+		wg.Wait()
+		close(in)
+	}()
+
+	elm, exist := <-fast
+	if !exist {
+		return nil, errors.New("All DNS requests failed")
+	}
+
+	msg = elm.(*D.Msg)
+	return
+}
+
+func (r *Resolver) fallbackExchange(m *D.Msg) (msg *D.Msg, err error) {
+	msgCh := r.asyncExchange(r.main, m)
+	if r.fallback == nil {
+		res := <-msgCh
+		msg, err = res.Msg, res.Error
+		return
+	}
+	fallbackMsg := r.asyncExchange(r.fallback, m)
+	res := <-msgCh
+	if res.Error == nil {
+		if mmdb == nil {
+			return nil, errors.New("GeoIP can't use")
+		}
+
+		if ips := r.msgToIP(res.Msg); len(ips) != 0 {
+			if record, _ := mmdb.Country(ips[0]); record.Country.IsoCode == "CN" || record.Country.IsoCode == "" {
+				// release channel
+				go func() { <-fallbackMsg }()
+				msg = res.Msg
+				return msg, err
+			}
+		}
+	}
+
+	res = <-fallbackMsg
+	msg, err = res.Msg, res.Error
+	return
+}
+
+func (r *Resolver) resolveIP(host string, dnsType uint16) (ip net.IP, err error) {
+	query := &D.Msg{}
+	query.SetQuestion(D.Fqdn(host), dnsType)
+
+	msg, err := r.Exchange(query)
+	if err != nil {
+		return nil, err
+	}
+
+	ips := r.msgToIP(msg)
+	if len(ips) == 0 {
+		return nil, errors.New("can't found ip")
+	}
+
+	ip = ips[0]
+	return
+}
+
+func (r *Resolver) msgToIP(msg *D.Msg) []net.IP {
+	ips := []net.IP{}
+
+	for _, answer := range msg.Answer {
+		switch ans := answer.(type) {
+		case *D.AAAA:
+			ips = append(ips, ans.AAAA)
+		case *D.A:
+			ips = append(ips, ans.A)
+		}
+	}
+
+	return ips
+}
+
+func (r *Resolver) asyncExchange(client []resolver, msg *D.Msg) <-chan *result {
+	ch := make(chan *result)
+	go func() {
+		res, err := r.batchExchange(client, msg)
+		ch <- &result{Msg: res, Error: err}
+	}()
+	return ch
+}
+
+type NameServer struct {
+	Net  string
+	Addr string
+}
+
+type Config struct {
+	Main, Fallback []NameServer
+	IPv6           bool
+	EnhancedMode   EnhancedMode
+	Pool           *fakeip.Pool
+}
+
+func New(config Config) *Resolver {
+	once.Do(func() {
+		mmdb, _ = geoip2.Open(C.Path.MMDB())
+	})
+
+	r := &Resolver{
+		main:    transform(config.Main),
+		ipv6:    config.IPv6,
+		cache:   cache.New(time.Second * 60),
+		mapping: config.EnhancedMode == MAPPING,
+		fakeip:  config.EnhancedMode == FAKEIP,
+		pool:    config.Pool,
+	}
+	if len(config.Fallback) != 0 {
+		r.fallback = transform(config.Fallback)
+	}
+	return r
+}