dns: switch upstream when dial error occurred

README.md

@@ -52,6 +52,7 @@ we can set up local listeners as proxy servers, and forward requests to internet
 |trojan       | | |√|√|client only
 |vmess        | | |√| |client only
 |redir        |√| | | |linux only
+|redir6        |√| | | |linux only(ipv6)
 |tls          |√| |√| |transport client & server
 |kcp          | |√|√| |transport client & server
 |unix         |√| |√| |transport client & server

dns/client.go

@@ -154,7 +154,10 @@ func (c *Client) exchange(qname string, reqBytes []byte, preferTCP bool) (
 		var rc net.Conn
 		rc, err = dialer.Dial(network, server)
 		if err != nil {
-			log.F("[dns] error in resolving %s, failed to connect to server %v via %s: %v", qname, server, dialer.Addr(), err)
+			newServer := ups.SwitchIf(server)
+			log.F("[dns] error in resolving %s, failed to connect to server %v via %s: %v, switch to %s",
+				qname, server, dialer.Addr(), err, newServer)
+			server = newServer
 			continue
 		}
 		defer rc.Close()
@@ -173,7 +176,7 @@ func (c *Client) exchange(qname string, reqBytes []byte, preferTCP bool) (
 			break
 		}
 
-		newServer := ups.Switch()
+		newServer := ups.SwitchIf(server)
 		log.F("[dns] error in resolving %s, failed to exchange with server %v via %s: %v, switch to %s",
 			qname, server, dialer.Addr(), err, newServer)
 

dns/upstream.go

@@ -23,6 +23,14 @@ func (u *UpStream) Switch() string {
 	return u.servers[atomic.AddUint32(&u.index, 1)%uint32(len(u.servers))]
 }
 
+// SwitchIf switches to the next dns server if needed.
+func (u *UpStream) SwitchIf(server string) string {
+	if u.Server() == server {
+		return u.Switch()
+	}
+	return u.Server()
+}
+
 // Len returns the number of dns servers.
 func (u *UpStream) Len() int {
 	return len(u.servers)

proxy/direct.go

@@ -3,6 +3,7 @@ package proxy
 import (
 	"errors"
 	"net"
+	"time"
 
 	"github.com/nadoo/glider/common/log"
 )
@@ -76,7 +77,7 @@ func dial(network, addr string, localIP net.IP) (net.Conn, error) {
 		la = &net.UDPAddr{IP: localIP}
 	}
 
-	dialer := &net.Dialer{LocalAddr: la}
+	dialer := &net.Dialer{LocalAddr: la, Timeout: time.Second * 3}
 	c, err := dialer.Dial(network, addr)
 	if err != nil {
 		return nil, err

strategy/forward.go

@@ -27,7 +27,7 @@ type Forwarder struct {
 	handlers    []StatusHandler
 }
 
-// ForwarderFromURL parses `forward=` command value and returns a new forwarder
+// ForwarderFromURL parses `forward=` command value and returns a new forwarder.
 func ForwarderFromURL(s, intface string) (f *Forwarder, err error) {
 	f = &Forwarder{}
 
@@ -63,7 +63,7 @@ func ForwarderFromURL(s, intface string) (f *Forwarder, err error) {
 	return f, err
 }
 
-// DirectForwarder returns a direct forwarder
+// DirectForwarder returns a direct forwarder.
 func DirectForwarder(intface string) *Forwarder {
 	d, err := proxy.NewDirect(intface)
 	if err != nil {
@@ -91,12 +91,12 @@ func (f *Forwarder) parseOption(option string) error {
 	return err
 }
 
-// Addr .
+// Addr returns the forwarder's addr.
 func (f *Forwarder) Addr() string {
 	return f.addr
 }
 
-// Dial .
+// Dial dials to addr and returns conn.
 func (f *Forwarder) Dial(network, addr string) (c net.Conn, err error) {
 	c, err = f.Dialer.Dial(network, addr)
 	if err != nil {
@@ -106,12 +106,12 @@ func (f *Forwarder) Dial(network, addr string) (c net.Conn, err error) {
 	return c, err
 }
 
-// Failures returns the failuer count of forwarder
+// Failures returns the failuer count of forwarder.
 func (f *Forwarder) Failures() uint32 {
 	return atomic.LoadUint32(&f.failures)
 }
 
-// IncFailures increase the failuer count by 1
+// IncFailures increase the failuer count by 1.
 func (f *Forwarder) IncFailures() {
 	failures := atomic.AddUint32(&f.failures, 1)
 	log.F("[forwarder] %s recorded %d failures, maxfailures: %d", f.addr, failures, f.MaxFailures())
@@ -122,12 +122,12 @@ func (f *Forwarder) IncFailures() {
 	}
 }
 
-// AddHandler adds a custom handler to handle the status change event
+// AddHandler adds a custom handler to handle the status change event.
 func (f *Forwarder) AddHandler(h StatusHandler) {
 	f.handlers = append(f.handlers, h)
 }
 
-// Enable the forwarder
+// Enable the forwarder.
 func (f *Forwarder) Enable() {
 	if atomic.CompareAndSwapUint32(&f.disabled, 1, 0) {
 		for _, h := range f.handlers {
@@ -137,7 +137,7 @@ func (f *Forwarder) Enable() {
 	atomic.StoreUint32(&f.failures, 0)
 }
 
-// Disable the forwarder
+// Disable the forwarder.
 func (f *Forwarder) Disable() {
 	if atomic.CompareAndSwapUint32(&f.disabled, 0, 1) {
 		for _, h := range f.handlers {
@@ -146,7 +146,7 @@ func (f *Forwarder) Disable() {
 	}
 }
 
-// Enabled returns the status of forwarder
+// Enabled returns the status of forwarder.
 func (f *Forwarder) Enabled() bool {
 	return !isTrue(atomic.LoadUint32(&f.disabled))
 }
@@ -155,32 +155,32 @@ func isTrue(n uint32) bool {
 	return n&1 == 1
 }
 
-// Priority returns the priority of forwarder
+// Priority returns the priority of forwarder.
 func (f *Forwarder) Priority() uint32 {
 	return atomic.LoadUint32(&f.priority)
 }
 
-// SetPriority sets the priority of forwarder
+// SetPriority sets the priority of forwarder.
 func (f *Forwarder) SetPriority(l uint32) {
 	atomic.StoreUint32(&f.priority, l)
 }
 
-// MaxFailures returns the maxFailures of forwarder
+// MaxFailures returns the maxFailures of forwarder.
 func (f *Forwarder) MaxFailures() uint32 {
 	return atomic.LoadUint32(&f.maxFailures)
 }
 
-// SetMaxFailures sets the maxFailures of forwarder
+// SetMaxFailures sets the maxFailures of forwarder.
 func (f *Forwarder) SetMaxFailures(l uint32) {
 	atomic.StoreUint32(&f.maxFailures, l)
 }
 
-// Latency returns the latency of forwarder
+// Latency returns the latency of forwarder.
 func (f *Forwarder) Latency() int64 {
 	return atomic.LoadInt64(&f.latency)
 }
 
-// SetLatency sets the latency of forwarder
+// SetLatency sets the latency of forwarder.
 func (f *Forwarder) SetLatency(l int64) {
 	atomic.StoreInt64(&f.latency, l)
 }