update chain route

chain/chain.go

@@ -0,0 +1,107 @@
+package chain
+
+import (
+	"context"
+
+	"github.com/go-gost/core/chain"
+	"github.com/go-gost/core/metadata"
+	"github.com/go-gost/core/selector"
+)
+
+var (
+	_ chain.Chainer = (*chainGroup)(nil)
+)
+
+type chainNamer interface {
+	Name() string
+}
+
+type Chain struct {
+	name     string
+	hops     []chain.Hop
+	marker   selector.Marker
+	metadata metadata.Metadata
+}
+
+func NewChain(name string, hops ...chain.Hop) *Chain {
+	return &Chain{
+		name:   name,
+		hops:   hops,
+		marker: selector.NewFailMarker(),
+	}
+}
+
+func (c *Chain) AddHop(hop chain.Hop) {
+	c.hops = append(c.hops, hop)
+}
+
+func (c *Chain) WithMetadata(md metadata.Metadata) {
+	c.metadata = md
+}
+
+// Metadata implements metadata.Metadatable interface.
+func (c *Chain) Metadata() metadata.Metadata {
+	return c.metadata
+}
+
+// Marker implements selector.Markable interface.
+func (c *Chain) Marker() selector.Marker {
+	return c.marker
+}
+
+func (c *Chain) Name() string {
+	return c.name
+}
+
+func (c *Chain) Route(ctx context.Context, network, address string) chain.Route {
+	if c == nil || len(c.hops) == 0 {
+		return nil
+	}
+
+	rt := NewRoute(ChainRouteOption(c))
+	for _, hop := range c.hops {
+		node := hop.Select(ctx, chain.AddrSelectOption(address))
+		if node == nil {
+			return rt
+		}
+		if node.Options().Transport.Multiplex() {
+			tr := node.Options().Transport.Copy()
+			tr.Options().Route = rt
+			node = node.Copy()
+			node.Options().Transport = tr
+			rt = NewRoute()
+		}
+
+		rt.addNode(node)
+	}
+	return rt
+}
+
+type chainGroup struct {
+	chains   []chain.Chainer
+	selector selector.Selector[chain.Chainer]
+}
+
+func NewChainGroup(chains ...chain.Chainer) *chainGroup {
+	return &chainGroup{chains: chains}
+}
+
+func (p *chainGroup) WithSelector(s selector.Selector[chain.Chainer]) *chainGroup {
+	p.selector = s
+	return p
+}
+
+func (p *chainGroup) Route(ctx context.Context, network, address string) chain.Route {
+	if chain := p.next(ctx); chain != nil {
+		return chain.Route(ctx, network, address)
+	}
+	return nil
+}
+
+func (p *chainGroup) next(ctx context.Context) chain.Chainer {
+	if p == nil || len(p.chains) == 0 {
+		return nil
+	}
+
+	return p.selector.Select(ctx, p.chains...)
+}

chain/hop.go

@@ -0,0 +1,87 @@
+package chain
+
+import (
+	"context"
+
+	"github.com/go-gost/core/bypass"
+	"github.com/go-gost/core/chain"
+	"github.com/go-gost/core/selector"
+)
+
+type HopOptions struct {
+	bypass   bypass.Bypass
+	selector selector.Selector[*chain.Node]
+}
+
+type HopOption func(*HopOptions)
+
+func BypassHopOption(bp bypass.Bypass) HopOption {
+	return func(o *HopOptions) {
+		o.bypass = bp
+	}
+}
+
+func SelectorHopOption(s selector.Selector[*chain.Node]) HopOption {
+	return func(o *HopOptions) {
+		o.selector = s
+	}
+}
+
+type chainHop struct {
+	nodes   []*chain.Node
+	options HopOptions
+}
+
+func NewChainHop(nodes []*chain.Node, opts ...HopOption) chain.Hop {
+	var options HopOptions
+	for _, opt := range opts {
+		if opt != nil {
+			opt(&options)
+		}
+	}
+
+	return &chainHop{
+		nodes:   nodes,
+		options: options,
+	}
+}
+
+func (p *chainHop) Nodes() []*chain.Node {
+	return p.nodes
+}
+
+func (p *chainHop) Select(ctx context.Context, opts ...chain.SelectOption) *chain.Node {
+	var options chain.SelectOptions
+	for _, opt := range opts {
+		opt(&options)
+	}
+
+	if p == nil || len(p.nodes) == 0 {
+		return nil
+	}
+
+	// hop level bypass
+	if p.options.bypass != nil && p.options.bypass.Contains(options.Addr) {
+		return nil
+	}
+
+	var nodes []*chain.Node
+	for _, node := range p.nodes {
+		if node == nil {
+			continue
+		}
+		// node level bypass
+		if node.Options().Bypass != nil && node.Options().Bypass.Contains(options.Addr) {
+			continue
+		}
+		nodes = append(nodes, node)
+	}
+	if len(nodes) == 0 {
+		return nil
+	}
+
+	if s := p.options.selector; s != nil {
+		return s.Select(ctx, nodes...)
+	}
+	return nodes[0]
+}

chain/route.go

@@ -0,0 +1,231 @@
+package chain
+
+import (
+	"context"
+	"net"
+	"time"
+
+	"github.com/go-gost/core/chain"
+	"github.com/go-gost/core/connector"
+	"github.com/go-gost/core/logger"
+	"github.com/go-gost/core/metrics"
+	"github.com/go-gost/core/selector"
+)
+
+type RouteOptions struct {
+	Chain chain.Chainer
+}
+
+type RouteOption func(*RouteOptions)
+
+func ChainRouteOption(c chain.Chainer) RouteOption {
+	return func(o *RouteOptions) {
+		o.Chain = c
+	}
+}
+
+type route struct {
+	nodes   []*chain.Node
+	options RouteOptions
+}
+
+func NewRoute(opts ...RouteOption) *route {
+	var options RouteOptions
+	for _, opt := range opts {
+		if opt != nil {
+			opt(&options)
+		}
+	}
+
+	return &route{
+		options: options,
+	}
+}
+
+func (r *route) addNode(nodes ...*chain.Node) {
+	r.nodes = append(r.nodes, nodes...)
+}
+
+func (r *route) Dial(ctx context.Context, network, address string, opts ...chain.DialOption) (net.Conn, error) {
+	if len(r.Nodes()) == 0 {
+		return chain.DefaultRoute.Dial(ctx, network, address, opts...)
+	}
+
+	var options chain.DialOptions
+	for _, opt := range opts {
+		if opt != nil {
+			opt(&options)
+		}
+	}
+	conn, err := r.connect(ctx, options.Logger)
+	if err != nil {
+		return nil, err
+	}
+
+	cc, err := r.getNode(len(r.Nodes())-1).Options().Transport.Connect(ctx, conn, network, address)
+	if err != nil {
+		if conn != nil {
+			conn.Close()
+		}
+		return nil, err
+	}
+	return cc, nil
+}
+
+func (r *route) Bind(ctx context.Context, network, address string, opts ...chain.BindOption) (net.Listener, error) {
+	if len(r.Nodes()) == 0 {
+		return chain.DefaultRoute.Bind(ctx, network, address, opts...)
+	}
+
+	var options chain.BindOptions
+	for _, opt := range opts {
+		if opt != nil {
+			opt(&options)
+		}
+	}
+
+	conn, err := r.connect(ctx, options.Logger)
+	if err != nil {
+		return nil, err
+	}
+
+	ln, err := r.getNode(len(r.Nodes())-1).Options().Transport.Bind(ctx,
+		conn, network, address,
+		connector.BacklogBindOption(options.Backlog),
+		connector.MuxBindOption(options.Mux),
+		connector.UDPConnTTLBindOption(options.UDPConnTTL),
+		connector.UDPDataBufferSizeBindOption(options.UDPDataBufferSize),
+		connector.UDPDataQueueSizeBindOption(options.UDPDataQueueSize),
+	)
+	if err != nil {
+		conn.Close()
+		return nil, err
+	}
+
+	return ln, nil
+}
+
+func (r *route) connect(ctx context.Context, logger logger.Logger) (conn net.Conn, err error) {
+	network := "ip"
+	node := r.nodes[0]
+
+	defer func() {
+		if r.options.Chain != nil {
+			var marker selector.Marker
+			if m, ok := r.options.Chain.(selector.Markable); ok && m != nil {
+				marker = m.Marker()
+			}
+			var name string
+			if cn, _ := r.options.Chain.(chainNamer); cn != nil {
+				name = cn.Name()
+			}
+			// chain error
+			if err != nil {
+				if marker != nil {
+					marker.Mark()
+				}
+				if v := metrics.GetCounter(metrics.MetricChainErrorsCounter,
+					metrics.Labels{"chain": name, "node": node.Name}); v != nil {
+					v.Inc()
+				}
+			} else {
+				if marker != nil {
+					marker.Reset()
+				}
+			}
+		}
+	}()
+
+	addr, err := chain.Resolve(ctx, network, node.Addr, node.Options().Resolver, node.Options().HostMapper, logger)
+	marker := node.Marker()
+	if err != nil {
+		if marker != nil {
+			marker.Mark()
+		}
+		return
+	}
+
+	start := time.Now()
+	cc, err := node.Options().Transport.Dial(ctx, addr)
+	if err != nil {
+		if marker != nil {
+			marker.Mark()
+		}
+		return
+	}
+
+	cn, err := node.Options().Transport.Handshake(ctx, cc)
+	if err != nil {
+		cc.Close()
+		if marker != nil {
+			marker.Mark()
+		}
+		return
+	}
+	if marker != nil {
+		marker.Reset()
+	}
+
+	if r.options.Chain != nil {
+		var name string
+		if cn, _ := r.options.Chain.(chainNamer); cn != nil {
+			name = cn.Name()
+		}
+		if v := metrics.GetObserver(metrics.MetricNodeConnectDurationObserver,
+			metrics.Labels{"chain": name, "node": node.Name}); v != nil {
+			v.Observe(time.Since(start).Seconds())
+		}
+	}
+
+	preNode := node
+	for _, node := range r.nodes[1:] {
+		marker := node.Marker()
+		addr, err = chain.Resolve(ctx, network, node.Addr, node.Options().Resolver, node.Options().HostMapper, logger)
+		if err != nil {
+			cn.Close()
+			if marker != nil {
+				marker.Mark()
+			}
+			return
+		}
+		cc, err = preNode.Options().Transport.Connect(ctx, cn, "tcp", addr)
+		if err != nil {
+			cn.Close()
+			if marker != nil {
+				marker.Mark()
+			}
+			return
+		}
+		cc, err = node.Options().Transport.Handshake(ctx, cc)
+		if err != nil {
+			cn.Close()
+			if marker != nil {
+				marker.Mark()
+			}
+			return
+		}
+		if marker != nil {
+			marker.Reset()
+		}
+
+		cn = cc
+		preNode = node
+	}
+
+	conn = cn
+	return
+}
+
+func (r *route) getNode(index int) *chain.Node {
+	if r == nil || len(r.Nodes()) == 0 || index < 0 || index >= len(r.Nodes()) {
+		return nil
+	}
+	return r.nodes[index]
+}
+
+func (r *route) Nodes() []*chain.Node {
+	if r != nil {
+		return r.nodes
+	}
+	return nil
+}

config/config.go

@@ -217,9 +217,16 @@ type HandlerConfig struct {
 
 type ForwarderConfig struct {
 	// DEPRECATED by nodes since beta.4
-	Targets  []string        `yaml:",omitempty" json:"targets,omitempty"`
+	Targets  []string             `yaml:",omitempty" json:"targets,omitempty"`
-	Nodes    []*NodeConfig   `json:"nodes"`
+	Nodes    []*ForwardNodeConfig `json:"nodes"`
-	Selector *SelectorConfig `yaml:",omitempty" json:"selector,omitempty"`
+	Selector *SelectorConfig      `yaml:",omitempty" json:"selector,omitempty"`
+}
+
+type ForwardNodeConfig struct {
+	Name     string   `yaml:",omitempty" json:"name,omitempty"`
+	Addr     string   `yaml:",omitempty" json:"addr,omitempty"`
+	Bypass   string   `yaml:",omitempty" json:"bypass,omitempty"`
+	Bypasses []string `yaml:",omitempty" json:"bypasses,omitempty"`
 }
 
 type DialerConfig struct {

config/parsing/chain.go

@@ -11,6 +11,7 @@ import (
 	"github.com/go-gost/core/logger"
 	"github.com/go-gost/core/metadata"
 	mdutil "github.com/go-gost/core/metadata/util"
+	xchain "github.com/go-gost/x/chain"
 	"github.com/go-gost/x/config"
 	tls_util "github.com/go-gost/x/internal/util/tls"
 	mdx "github.com/go-gost/x/metadata"
@@ -27,14 +28,14 @@ func ParseChain(cfg *config.ChainConfig) (chain.Chainer, error) {
 		"chain": cfg.Name,
 	})
 
-	c := chain.NewChain(cfg.Name)
+	c := xchain.NewChain(cfg.Name)
 	if cfg.Metadata != nil {
 		c.WithMetadata(mdx.NewMetadata(cfg.Metadata))
 	}
 
-	selector := parseNodeSelector(cfg.Selector)
+	sel := parseNodeSelector(cfg.Selector)
 	for _, hop := range cfg.Hops {
-		group := &chain.NodeGroup{}
+		var nodes []*chain.Node
 		for _, v := range hop.Nodes {
 			nodeLogger := chainLogger.WithFields(map[string]any{
 				"kind":      "node",
@@ -144,35 +145,35 @@ func ParseChain(cfg *config.ChainConfig) (chain.Chainer, error) {
 				}
 			}
 
-			tr := (&chain.Transport{}).
+			tr := chain.NewTransport(d, cr,
-				WithConnector(cr).
+				chain.AddrTransportOption(v.Addr),
-				WithDialer(d).
+				chain.InterfaceTransportOption(v.Interface),
-				WithAddr(v.Addr).
+				chain.SockOptsTransportOption(sockOpts),
-				WithInterface(v.Interface).
+				chain.TimeoutTransportOption(10*time.Second),
-				WithSockOpts(sockOpts).
+			)
-				WithTimeout(10 * time.Second)
 
-			node := chain.NewNode(v.Name, v.Addr).
+			node := chain.NewNode(v.Name, v.Addr,
-				WithTransport(tr).
+				chain.TransportNodeOption(tr),
-				WithBypass(bypass.BypassGroup(bypassList(v.Bypass, v.Bypasses...)...)).
+				chain.BypassNodeOption(bypass.BypassGroup(bypassList(v.Bypass, v.Bypasses...)...)),
-				WithResolver(registry.ResolverRegistry().Get(v.Resolver)).
+				chain.ResoloverNodeOption(registry.ResolverRegistry().Get(v.Resolver)),
-				WithHostMapper(registry.HostsRegistry().Get(v.Hosts)).
+				chain.HostMapperNodeOption(registry.HostsRegistry().Get(v.Hosts)),
-				WithMetadata(nm)
+				chain.MetadataNodeOption(nm),
-
+			)
-			group.AddNode(node)
+			nodes = append(nodes, node)
 		}
 
-		sel := selector
+		sl := sel
 		if s := parseNodeSelector(hop.Selector); s != nil {
-			sel = s
+			sl = s
 		}
-		if sel == nil {
+		if sl == nil {
-			sel = defaultNodeSelector()
+			sl = defaultNodeSelector()
 		}
-		group.WithSelector(sel).
-			WithBypass(bypass.BypassGroup(bypassList(hop.Bypass, hop.Bypasses...)...))
 
-		c.AddNodeGroup(group)
+		c.AddHop(xchain.NewChainHop(nodes,
+			xchain.SelectorHopOption(sl),
+			xchain.BypassHopOption(bypass.BypassGroup(bypassList(hop.Bypass, hop.Bypasses...)...))),
+		)
 	}
 
 	return c, nil

config/parsing/service.go

@@ -15,6 +15,7 @@ import (
 	"github.com/go-gost/core/recorder"
 	"github.com/go-gost/core/selector"
 	"github.com/go-gost/core/service"
+	xchain "github.com/go-gost/x/chain"
 	"github.com/go-gost/x/config"
 	tls_util "github.com/go-gost/x/internal/util/tls"
 	"github.com/go-gost/x/metadata"
@@ -156,16 +157,17 @@ func ParseService(cfg *config.ServiceConfig) (service.Service, error) {
 			Record:   r.Record,
 		})
 	}
-	router := (&chain.Router{}).
+	router := chain.NewRouter(
-		WithRetries(cfg.Handler.Retries).
+		chain.RetriesRouterOption(cfg.Handler.Retries),
-		// WithTimeout(timeout time.Duration).
+		// chain.TimeoutRouterOption(10*time.Second),
-		WithInterface(ifce).
+		chain.InterfaceRouterOption(ifce),
-		WithSockOpts(sockOpts).
+		chain.SockOptsRouterOption(sockOpts),
-		WithChain(chainGroup(cfg.Handler.Chain, cfg.Handler.ChainGroup)).
+		chain.ChainRouterOption(chainGroup(cfg.Handler.Chain, cfg.Handler.ChainGroup)),
-		WithResolver(registry.ResolverRegistry().Get(cfg.Resolver)).
+		chain.ResolverRouterOption(registry.ResolverRegistry().Get(cfg.Resolver)),
-		WithHosts(registry.HostsRegistry().Get(cfg.Hosts)).
+		chain.HostMapperRouterOption(registry.HostsRegistry().Get(cfg.Hosts)),
-		WithRecorder(recorders...).
+		chain.RecordersRouterOption(recorders...),
-		WithLogger(handlerLogger)
+		chain.LoggerRouterOption(handlerLogger),
+	)
 
 	var h handler.Handler
 	if rf := registry.HandlerRegistry().Get(cfg.Handler.Type); rf != nil {
@@ -203,24 +205,27 @@ func ParseService(cfg *config.ServiceConfig) (service.Service, error) {
 	return s, nil
 }
 
-func parseForwarder(cfg *config.ForwarderConfig) *chain.NodeGroup {
+func parseForwarder(cfg *config.ForwarderConfig) chain.Hop {
 	if cfg == nil ||
 		(len(cfg.Targets) == 0 && len(cfg.Nodes) == 0) {
 		return nil
 	}
 
-	group := &chain.NodeGroup{}
+	var nodes []*chain.Node
 	if len(cfg.Nodes) > 0 {
 		for _, node := range cfg.Nodes {
 			if node != nil {
-				group.AddNode(chain.NewNode(node.Name, node.Addr).
+				nodes = append(nodes,
-					WithBypass(bypass.BypassGroup(bypassList(node.Bypass, node.Bypasses...)...)))
+					chain.NewNode(node.Name, node.Addr,
+						chain.BypassNodeOption(bypass.BypassGroup(bypassList(node.Bypass, node.Bypasses...)...)),
+					),
+				)
 			}
 		}
 	} else {
 		for _, target := range cfg.Targets {
 			if v := strings.TrimSpace(target); v != "" {
-				group.AddNode(chain.NewNode(target, target))
+				nodes = append(nodes, chain.NewNode(target, target))
 			}
 		}
 	}
@@ -229,7 +234,7 @@ func parseForwarder(cfg *config.ForwarderConfig) *chain.NodeGroup {
 	if sel == nil {
 		sel = defaultNodeSelector()
 	}
-	return group.WithSelector(sel)
+	return xchain.NewChainHop(nodes, xchain.SelectorHopOption(sel))
 }
 
 func bypassList(name string, names ...string) []bypass.Bypass {
@@ -292,6 +297,6 @@ func chainGroup(name string, group *config.ChainGroupConfig) chain.Chainer {
 		sel = defaultChainSelector()
 	}
 
-	return chain.NewChainGroup(chains...).
+	return xchain.NewChainGroup(chains...).
 		WithSelector(sel)
 }

handler/dns/handler.go

@@ -14,6 +14,7 @@ import (
 	"github.com/go-gost/core/hosts"
 	"github.com/go-gost/core/logger"
 	md "github.com/go-gost/core/metadata"
+	xchain "github.com/go-gost/x/chain"
 	resolver_util "github.com/go-gost/x/internal/util/resolver"
 	"github.com/go-gost/x/registry"
 	"github.com/go-gost/x/resolver/exchanger"
@@ -29,11 +30,11 @@ func init() {
 }
 
 type dnsHandler struct {
-	group      *chain.NodeGroup
+	hop        chain.Hop
 	exchangers map[string]exchanger.Exchanger
 	cache      *resolver_util.Cache
 	router     *chain.Router
-	hosts      hosts.HostMapper
+	hostMapper hosts.HostMapper
 	md         metadata
 	options    handler.Options
 }
@@ -60,21 +61,19 @@ func (h *dnsHandler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(log)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(log))
 	}
-	h.hosts = h.router.Hosts()
+	h.hostMapper = h.router.Options().HostMapper
 
-	if h.group == nil {
+	if h.hop == nil {
-		h.group = &chain.NodeGroup{}
+		var nodes []*chain.Node
 		for i, addr := range h.md.dns {
-			addr = strings.TrimSpace(addr)
+			nodes = append(nodes, chain.NewNode(fmt.Sprintf("target-%d", i), addr))
-			if addr == "" {
-				continue
-			}
-			h.group.AddNode(chain.NewNode(fmt.Sprintf("target-%d", i), addr))
 		}
+		h.hop = xchain.NewChainHop(nodes)
 	}
-	for _, node := range h.group.Nodes() {
+
+	for _, node := range h.hop.Nodes() {
 		addr := strings.TrimSpace(node.Addr)
 		if addr == "" {
 			continue
@@ -99,7 +98,7 @@ func (h *dnsHandler) Init(md md.Metadata) (err error) {
 			exchanger.TimeoutOption(h.md.timeout),
 			exchanger.LoggerOption(log),
 		)
-		log.Warnf("resolver not found, default to %s", defaultNameserver)
+		log.Warnf("resolver not found, use default %s", defaultNameserver)
 		if err != nil {
 			return err
 		}
@@ -110,8 +109,8 @@ func (h *dnsHandler) Init(md md.Metadata) (err error) {
 }
 
 // Forward implements handler.Forwarder.
-func (h *dnsHandler) Forward(group *chain.NodeGroup) {
+func (h *dnsHandler) Forward(hop chain.Hop) {
-	h.group = group
+	h.hop = hop
 }
 
 func (h *dnsHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.HandleOption) error {
@@ -261,7 +260,7 @@ func (h *dnsHandler) exchange(ctx context.Context, msg []byte, log logger.Logger
 
 // lookup host mapper
 func (h *dnsHandler) lookupHosts(r *dns.Msg, log logger.Logger) (m *dns.Msg) {
-	if h.hosts == nil ||
+	if h.hostMapper == nil ||
 		r.Question[0].Qclass != dns.ClassINET ||
 		(r.Question[0].Qtype != dns.TypeA && r.Question[0].Qtype != dns.TypeAAAA) {
 		return nil
@@ -274,7 +273,7 @@ func (h *dnsHandler) lookupHosts(r *dns.Msg, log logger.Logger) (m *dns.Msg) {
 
 	switch r.Question[0].Qtype {
 	case dns.TypeA:
-		ips, _ := h.hosts.Lookup("ip4", host)
+		ips, _ := h.hostMapper.Lookup("ip4", host)
 		if len(ips) == 0 {
 			return nil
 		}
@@ -290,7 +289,7 @@ func (h *dnsHandler) lookupHosts(r *dns.Msg, log logger.Logger) (m *dns.Msg) {
 		}
 
 	case dns.TypeAAAA:
-		ips, _ := h.hosts.Lookup("ip6", host)
+		ips, _ := h.hostMapper.Lookup("ip6", host)
 		if len(ips) == 0 {
 			return nil
 		}
@@ -310,10 +309,10 @@ func (h *dnsHandler) lookupHosts(r *dns.Msg, log logger.Logger) (m *dns.Msg) {
 }
 
 func (h *dnsHandler) selectExchanger(ctx context.Context, addr string) exchanger.Exchanger {
-	if h.group == nil {
+	if h.hop == nil {
 		return nil
 	}
-	node := h.group.FilterAddr(addr).Next(ctx)
+	node := h.hop.Select(ctx, chain.AddrSelectOption(addr))
 	if node == nil {
 		return nil
 	}

handler/forward/local/handler.go

@@ -10,6 +10,7 @@ import (
 	"github.com/go-gost/core/chain"
 	"github.com/go-gost/core/handler"
 	md "github.com/go-gost/core/metadata"
+	xchain "github.com/go-gost/x/chain"
 	netpkg "github.com/go-gost/x/internal/net"
 	"github.com/go-gost/x/registry"
 )
@@ -21,7 +22,7 @@ func init() {
 }
 
 type forwardHandler struct {
-	group   *chain.NodeGroup
+	hop     chain.Hop
 	router  *chain.Router
 	md      metadata
 	options handler.Options
@@ -43,22 +44,24 @@ func (h *forwardHandler) Init(md md.Metadata) (err error) {
 		return
 	}
 
-	if h.group == nil {
+	if h.hop == nil {
 		// dummy node used by relay connector.
-		h.group = chain.NewNodeGroup(&chain.Node{Name: "dummy", Addr: ":0"})
+		h.hop = xchain.NewChainHop([]*chain.Node{
+			{Name: "dummy", Addr: ":0"},
+		})
 	}
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return
 }
 
 // Forward implements handler.Forwarder.
-func (h *forwardHandler) Forward(group *chain.NodeGroup) {
+func (h *forwardHandler) Forward(hop chain.Hop) {
-	h.group = group
+	h.hop = hop
 }
 
 func (h *forwardHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.HandleOption) error {
@@ -81,7 +84,7 @@ func (h *forwardHandler) Handle(ctx context.Context, conn net.Conn, opts ...hand
 		return nil
 	}
 
-	target := h.group.Next(ctx)
+	target := h.hop.Select(ctx)
 	if target == nil {
 		err := errors.New("target not available")
 		log.Error(err)

handler/forward/remote/handler.go

@@ -20,7 +20,7 @@ func init() {
 }
 
 type forwardHandler struct {
-	group   *chain.NodeGroup
+	hop     chain.Hop
 	router  *chain.Router
 	md      metadata
 	options handler.Options
@@ -44,15 +44,15 @@ func (h *forwardHandler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return
 }
 
 // Forward implements handler.Forwarder.
-func (h *forwardHandler) Forward(group *chain.NodeGroup) {
+func (h *forwardHandler) Forward(hop chain.Hop) {
-	h.group = group
+	h.hop = hop
 }
 
 func (h *forwardHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.HandleOption) error {
@@ -75,7 +75,10 @@ func (h *forwardHandler) Handle(ctx context.Context, conn net.Conn, opts ...hand
 		return nil
 	}
 
-	target := h.group.Next(ctx)
+	var target *chain.Node
+	if h.hop != nil {
+		target = h.hop.Select(ctx)
+	}
 	if target == nil {
 		err := errors.New("target not available")
 		log.Error(err)

handler/http/handler.go

@@ -52,7 +52,7 @@ func (h *httpHandler) Init(md md.Metadata) error {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return nil

handler/http2/handler.go

@@ -54,7 +54,7 @@ func (h *http2Handler) Init(md md.Metadata) error {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return nil

handler/redirect/tcp/handler.go

@@ -52,7 +52,7 @@ func (h *redirectHandler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return

handler/redirect/udp/handler.go

@@ -41,7 +41,7 @@ func (h *redirectHandler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return

handler/relay/forward.go

@@ -17,7 +17,7 @@ func (h *relayHandler) handleForward(ctx context.Context, conn net.Conn, network
 		Version: relay.Version1,
 		Status:  relay.StatusOK,
 	}
-	target := h.group.Next(ctx)
+	target := h.hop.Select(ctx)
 	if target == nil {
 		resp.Status = relay.StatusServiceUnavailable
 		resp.WriteTo(conn)

handler/relay/handler.go

@@ -24,7 +24,7 @@ func init() {
 }
 
 type relayHandler struct {
-	group   *chain.NodeGroup
+	hop     chain.Hop
 	router  *chain.Router
 	md      metadata
 	options handler.Options
@@ -48,15 +48,15 @@ func (h *relayHandler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return nil
 }
 
 // Forward implements handler.Forwarder.
-func (h *relayHandler) Forward(group *chain.NodeGroup) {
+func (h *relayHandler) Forward(hop chain.Hop) {
-	h.group = group
+	h.hop = hop
 }
 
 func (h *relayHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.HandleOption) error {
@@ -130,7 +130,7 @@ func (h *relayHandler) Handle(ctx context.Context, conn net.Conn, opts ...handle
 		network = "udp"
 	}
 
-	if h.group != nil {
+	if h.hop != nil {
 		if address != "" {
 			resp.Status = relay.StatusForbidden
 			log.Error("forward mode, connect is forbidden")

handler/sni/handler.go

@@ -54,7 +54,7 @@ func (h *sniHandler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return nil

handler/socks/v4/handler.go

@@ -49,7 +49,7 @@ func (h *socks4Handler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return nil

handler/socks/v5/handler.go

@@ -48,7 +48,7 @@ func (h *socks5Handler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	h.selector = &serverSelector{

handler/ss/handler.go

@@ -54,7 +54,7 @@ func (h *ssHandler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return

handler/ss/udp/handler.go

@@ -55,7 +55,7 @@ func (h *ssuHandler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return

handler/sshd/handler.go

@@ -52,7 +52,7 @@ func (h *forwardHandler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return nil

handler/tap/handler.go

@@ -28,7 +28,7 @@ func init() {
 }
 
 type tapHandler struct {
-	group   *chain.NodeGroup
+	hop     chain.Hop
 	routes  sync.Map
 	exit    chan struct{}
 	cipher  core.Cipher
@@ -65,15 +65,15 @@ func (h *tapHandler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return
 }
 
 // Forward implements handler.Forwarder.
-func (h *tapHandler) Forward(group *chain.NodeGroup) {
+func (h *tapHandler) Forward(hop chain.Hop) {
-	h.group = group
+	h.hop = hop
 }
 
 func (h *tapHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.HandleOption) error {
@@ -105,7 +105,10 @@ func (h *tapHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.
 	var raddr net.Addr
 	var err error
 
-	target := h.group.Next(ctx)
+	var target *chain.Node
+	if h.hop != nil {
+		target = h.hop.Select(ctx)
+	}
 	if target != nil {
 		raddr, err = net.ResolveUDPAddr(network, target.Addr)
 		if err != nil {

handler/tun/handler.go

@@ -21,7 +21,7 @@ func init() {
 }
 
 type tunHandler struct {
-	group   *chain.NodeGroup
+	hop     chain.Hop
 	routes  sync.Map
 	router  *chain.Router
 	md      metadata
@@ -46,15 +46,15 @@ func (h *tunHandler) Init(md md.Metadata) (err error) {
 
 	h.router = h.options.Router
 	if h.router == nil {
-		h.router = (&chain.Router{}).WithLogger(h.options.Logger)
+		h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
 	}
 
 	return
 }
 
 // Forward implements handler.Forwarder.
-func (h *tunHandler) Forward(group *chain.NodeGroup) {
+func (h *tunHandler) Forward(hop chain.Hop) {
-	h.group = group
+	h.hop = hop
 }
 
 func (h *tunHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.HandleOption) error {
@@ -87,7 +87,10 @@ func (h *tunHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.
 	var raddr net.Addr
 	var err error
 
-	target := h.group.Next(ctx)
+	var target *chain.Node
+	if h.hop != nil {
+		target = h.hop.Select(ctx)
+	}
 	if target != nil {
 		raddr, err = net.ResolveUDPAddr(network, target.Addr)
 		if err != nil {

listener/rtcp/listener.go

@@ -56,9 +56,10 @@ func (l *rtcpListener) Init(md md.Metadata) (err error) {
 	}
 
 	l.laddr = laddr
-	l.router = (&chain.Router{}).
+	l.router = chain.NewRouter(
-		WithChain(l.options.Chain).
+		chain.ChainRouterOption(l.options.Chain),
-		WithLogger(l.logger)
+		chain.LoggerRouterOption(l.logger),
+	)
 
 	return
 }

listener/rudp/listener.go

@@ -56,9 +56,10 @@ func (l *rudpListener) Init(md md.Metadata) (err error) {
 	}
 
 	l.laddr = laddr
-	l.router = (&chain.Router{}).
+	l.router = chain.NewRouter(
-		WithChain(l.options.Chain).
+		chain.ChainRouterOption(l.options.Chain),
-		WithLogger(l.logger)
+		chain.LoggerRouterOption(l.logger),
+	)
 
 	return
 }

resolver/exchanger/exchanger.go

@@ -102,7 +102,7 @@ func NewExchanger(addr string, opts ...Option) (Exchanger, error) {
 		ex.addr = net.JoinHostPort(ex.addr, "53")
 	}
 	if ex.router == nil {
-		ex.router = (&chain.Router{}).WithLogger(options.logger)
+		ex.router = chain.NewRouter(chain.LoggerRouterOption(options.logger))
 	}
 
 	switch ex.network {

resolver/resolver.go

@@ -65,9 +65,10 @@ func NewResolver(nameservers []NameServer, opts ...ResolverOption) (resolverpkg.
 		ex, err := exchanger.NewExchanger(
 			addr,
 			exchanger.RouterOption(
-				(&chain.Router{}).
+				chain.NewRouter(
-					WithChain(server.Chain).
+					chain.ChainRouterOption(server.Chain),
-					WithLogger(options.logger),
+					chain.LoggerRouterOption(options.logger),
+				),
 			),
 			exchanger.TimeoutOption(server.Timeout),
 			exchanger.LoggerOption(options.logger),