Move `DomainStrategy` & `DialerProxy` to `DialSystem`

Fix https://github.com/XTLS/Xray-core/issues/608

app/dns/server.go

@@ -22,7 +22,6 @@ import (
 	"github.com/xtls/xray-core/features"
 	"github.com/xtls/xray-core/features/dns"
 	"github.com/xtls/xray-core/features/routing"
-	"github.com/xtls/xray-core/transport/internet"
 )
 
 // Server is a DNS rely server.
@@ -307,7 +306,7 @@ func (s *Server) queryIPTimeout(idx int, client Client, domain string, option dn
 			Tag: s.tag,
 		})
 	}
-	ctx = internet.ContextWithLookupDomain(ctx, domain)
+
 	ips, err := client.QueryIP(ctx, domain, option)
 	cancel()
 

app/dns/udpns.go

@@ -2,7 +2,6 @@ package dns
 
 import (
 	"context"
-	"github.com/xtls/xray-core/transport/internet"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -192,7 +191,7 @@ func (s *ClassicNameServer) sendQuery(ctx context.Context, domain string, option
 		if inbound := session.InboundFromContext(ctx); inbound != nil {
 			udpCtx = session.ContextWithInbound(udpCtx, inbound)
 		}
-		udpCtx = internet.ContextWithLookupDomain(udpCtx, internet.LookupDomainFromContext(ctx))
+
 		udpCtx = session.ContextWithContent(udpCtx, &session.Content{
 			Protocol: "dns",
 		})

transport/internet/dialer.go

@@ -3,8 +3,15 @@ package internet
 import (
 	"context"
 
+	"github.com/xtls/xray-core/common"
+	"github.com/xtls/xray-core/common/dice"
 	"github.com/xtls/xray-core/common/net"
+	"github.com/xtls/xray-core/common/net/cnc"
 	"github.com/xtls/xray-core/common/session"
+	"github.com/xtls/xray-core/features/dns"
+	"github.com/xtls/xray-core/features/outbound"
+	"github.com/xtls/xray-core/transport"
+	"github.com/xtls/xray-core/transport/pipe"
 )
 
 // Dialer is the interface for dialing outbound connections.
@@ -62,11 +69,99 @@ func Dial(ctx context.Context, dest net.Destination, streamSettings *MemoryStrea
 	return nil, newError("unknown network ", dest.Network)
 }
 
+var (
+	dnsClient dns.Client
+	obm       outbound.Manager
+)
+
+func lookupIP(domain string, strategy DomainStrategy, localAddr net.Address) ([]net.IP, error) {
+	if dnsClient == nil {
+		return nil, nil
+	}
+
+	var option = dns.IPOption{
+		IPv4Enable: true,
+		IPv6Enable: true,
+		FakeEnable: false,
+	}
+
+	switch {
+	case strategy == DomainStrategy_USE_IP4 || (localAddr != nil && localAddr.Family().IsIPv4()):
+		option = dns.IPOption{
+			IPv4Enable: true,
+			IPv6Enable: false,
+			FakeEnable: false,
+		}
+	case strategy == DomainStrategy_USE_IP6 || (localAddr != nil && localAddr.Family().IsIPv6()):
+		option = dns.IPOption{
+			IPv4Enable: false,
+			IPv6Enable: true,
+			FakeEnable: false,
+		}
+	case strategy == DomainStrategy_AS_IS:
+		return nil, nil
+	}
+
+	return dnsClient.LookupIP(domain, option)
+}
+
+func canLookupIP(ctx context.Context, dst net.Destination, sockopt *SocketConfig) bool {
+	if dst.Address.Family().IsIP() || dnsClient == nil {
+		return false
+	}
+	return sockopt.DomainStrategy != DomainStrategy_AS_IS
+}
+
+func redirect(ctx context.Context, dst net.Destination, obt string) net.Conn {
+	newError("redirecting request " + dst.String() + " to " + obt).WriteToLog(session.ExportIDToError(ctx))
+	h := obm.GetHandler(obt)
+	ctx = session.ContextWithOutbound(ctx, &session.Outbound{dst, nil})
+	if h != nil {
+		ur, uw := pipe.New(pipe.OptionsFromContext(ctx)...)
+		dr, dw := pipe.New(pipe.OptionsFromContext(ctx)...)
+
+		go h.Dispatch(ctx, &transport.Link{ur, dw})
+		nc := cnc.NewConnection(
+			cnc.ConnectionInputMulti(uw),
+			cnc.ConnectionOutputMulti(dr),
+			cnc.ConnectionOnClose(common.ChainedClosable{uw, dw}),
+		)
+		return nc
+	}
+	return nil
+}
+
 // DialSystem calls system dialer to create a network connection.
 func DialSystem(ctx context.Context, dest net.Destination, sockopt *SocketConfig) (net.Conn, error) {
 	var src net.Address
 	if outbound := session.OutboundFromContext(ctx); outbound != nil {
 		src = outbound.Gateway
 	}
+	if sockopt == nil {
+		return effectiveSystemDialer.Dial(ctx, src, dest, sockopt)
+	}
+
+	if canLookupIP(ctx, dest, sockopt) {
+		ips, err := lookupIP(dest.Address.String(), sockopt.DomainStrategy, src)
+		if err == nil && len(ips) > 0 {
+			dest.Address = net.IPAddress(ips[dice.Roll(len(ips))])
+			newError("replace destination with " + dest.String()).AtInfo().WriteToLog()
+		} else if err != nil {
+			newError("failed to resolve ip").Base(err).AtWarning().WriteToLog()
+		}
+	}
+
+	if obm != nil && len(sockopt.DialerProxy) > 0 {
+		nc := redirect(ctx, dest, sockopt.DialerProxy)
+		if nc != nil {
+			return nc, nil
+		}
+	}
+
 	return effectiveSystemDialer.Dial(ctx, src, dest, sockopt)
 }
+
+func InitSystemDialer(dc dns.Client, om outbound.Manager) {
+	dnsClient = dc
+	obm = om
+}

transport/internet/system_dialer.go

@@ -5,29 +5,18 @@ import (
 	"syscall"
 	"time"
 
-	"github.com/xtls/xray-core/common"
-	"github.com/xtls/xray-core/common/dice"
 	"github.com/xtls/xray-core/common/net"
-	"github.com/xtls/xray-core/common/net/cnc"
 	"github.com/xtls/xray-core/common/session"
 	"github.com/xtls/xray-core/features/dns"
 	"github.com/xtls/xray-core/features/outbound"
-	"github.com/xtls/xray-core/transport"
-	"github.com/xtls/xray-core/transport/pipe"
 )
 
 var (
 	effectiveSystemDialer SystemDialer = &DefaultSystemDialer{}
 )
 
-// InitSystemDialer: It's private method and you are NOT supposed to use this function.
-func InitSystemDialer(dc dns.Client, om outbound.Manager) {
-	effectiveSystemDialer.Init(dc, om)
-}
-
 type SystemDialer interface {
 	Dial(ctx context.Context, source net.Address, destination net.Destination, sockopt *SocketConfig) (net.Conn, error)
-	Init(dc dns.Client, om outbound.Manager)
 }
 
 type DefaultSystemDialer struct {
@@ -58,85 +47,8 @@ func hasBindAddr(sockopt *SocketConfig) bool {
 	return sockopt != nil && len(sockopt.BindAddress) > 0 && sockopt.BindPort > 0
 }
 
-func (d *DefaultSystemDialer) lookupIP(domain string, strategy DomainStrategy, localAddr net.Address) ([]net.IP, error) {
-	if d.dns == nil {
-		return nil, nil
-	}
-
-	var option = dns.IPOption{
-		IPv4Enable: true,
-		IPv6Enable: true,
-		FakeEnable: false,
-	}
-
-	switch {
-	case strategy == DomainStrategy_USE_IP4 || (localAddr != nil && localAddr.Family().IsIPv4()):
-		option = dns.IPOption{
-			IPv4Enable: true,
-			IPv6Enable: false,
-			FakeEnable: false,
-		}
-	case strategy == DomainStrategy_USE_IP6 || (localAddr != nil && localAddr.Family().IsIPv6()):
-		option = dns.IPOption{
-			IPv4Enable: false,
-			IPv6Enable: true,
-			FakeEnable: false,
-		}
-	case strategy == DomainStrategy_AS_IS:
-		return nil, nil
-	}
-
-	return d.dns.LookupIP(domain, option)
-}
-
-func (d *DefaultSystemDialer) canLookupIP(ctx context.Context, dst net.Destination, sockopt *SocketConfig) bool {
-	if sockopt == nil || dst.Address.Family().IsIP() || d.dns == nil {
-		return false
-	}
-	if dst.Address.Domain() == LookupDomainFromContext(ctx) {
-		newError("infinite loop detected").AtError().WriteToLog(session.ExportIDToError(ctx))
-		return false
-	}
-	return sockopt.DomainStrategy != DomainStrategy_AS_IS
-}
-
-func (d *DefaultSystemDialer) redirect(ctx context.Context, dst net.Destination, obt string) net.Conn {
-	newError("redirecting request " + dst.String() + " to " + obt).WriteToLog(session.ExportIDToError(ctx))
-	h := d.obm.GetHandler(obt)
-	ctx = session.ContextWithOutbound(ctx, &session.Outbound{dst, nil})
-	if h != nil {
-		ur, uw := pipe.New(pipe.OptionsFromContext(ctx)...)
-		dr, dw := pipe.New(pipe.OptionsFromContext(ctx)...)
-
-		go h.Dispatch(ctx, &transport.Link{ur, dw})
-		nc := cnc.NewConnection(
-			cnc.ConnectionInputMulti(uw),
-			cnc.ConnectionOutputMulti(dr),
-			cnc.ConnectionOnClose(common.ChainedClosable{uw, dw}),
-		)
-		return nc
-	}
-	return nil
-}
-
 func (d *DefaultSystemDialer) Dial(ctx context.Context, src net.Address, dest net.Destination, sockopt *SocketConfig) (net.Conn, error) {
 	newError("dialing to " + dest.String()).AtDebug().WriteToLog()
-	if d.obm != nil && sockopt != nil && len(sockopt.DialerProxy) > 0 {
-		nc := d.redirect(ctx, dest, sockopt.DialerProxy)
-		if nc != nil {
-			return nc, nil
-		}
-	}
-
-	if d.canLookupIP(ctx, dest, sockopt) {
-		ips, err := d.lookupIP(dest.Address.String(), sockopt.DomainStrategy, src)
-		if err == nil && len(ips) > 0 {
-			dest.Address = net.IPAddress(ips[dice.Roll(len(ips))])
-			newError("replace destination with " + dest.String()).AtInfo().WriteToLog()
-		} else if err != nil {
-			newError("failed to resolve ip").Base(err).AtWarning().WriteToLog()
-		}
-	}
 
 	if dest.Network == net.Network_UDP && !hasBindAddr(sockopt) {
 		srcAddr := resolveSrcAddr(net.Network_UDP, src)
@@ -192,11 +104,6 @@ func (d *DefaultSystemDialer) Dial(ctx context.Context, src net.Address, dest ne
 	return dialer.DialContext(ctx, dest.Network.SystemString(), dest.NetAddr())
 }
 
-func (d *DefaultSystemDialer) Init(dc dns.Client, om outbound.Manager) {
-	d.dns = dc
-	d.obm = om
-}
-
 type PacketConnWrapper struct {
 	conn net.PacketConn
 	dest net.Addr
@@ -257,8 +164,6 @@ func WithAdapter(dialer SystemDialerAdapter) SystemDialer {
 	}
 }
 
-func (v *SimpleSystemDialer) Init(_ dns.Client, _ outbound.Manager) {}
-
 func (v *SimpleSystemDialer) Dial(ctx context.Context, src net.Address, dest net.Destination, sockopt *SocketConfig) (net.Conn, error) {
 	return v.adapter.Dial(dest.Network.SystemString(), dest.NetAddr())
 }

transport/internet/system_dialer_context.go

@@ -1,18 +0,0 @@
-package internet
-
-import "context"
-
-type systemDialer int
-
-const systemDialerKey systemDialer = 0
-
-func ContextWithLookupDomain(ctx context.Context, domain string) context.Context {
-	return context.WithValue(ctx, systemDialerKey, domain)
-}
-
-func LookupDomainFromContext(ctx context.Context) string {
-	if domain, ok := ctx.Value(systemDialerKey).(string); ok {
-		return domain
-	}
-	return ""
-}