Routing: Implement Route interface as the routing result of Router

app/dispatcher/default.go

@@ -266,7 +266,8 @@ func (d *DefaultDispatcher) routedDispatch(ctx context.Context, link *transport.
 	}
 
 	if d.router != nil && !skipRoutePick {
-		if tag, err := d.router.PickRoute(routing_session.AsRoutingContext(ctx)); err == nil {
+		if route, err := d.router.PickRoute(routing_session.AsRoutingContext(ctx)); err == nil {
+			tag := route.GetOutboundTag()
 			if h := d.ohm.GetHandler(tag); h != nil {
 				newError("taking detour [", tag, "] for [", destination, "]").WriteToLog(session.ExportIDToError(ctx))
 				handler = h

app/router/router.go

@@ -9,24 +9,12 @@ import (
 
 	"v2ray.com/core"
 	"v2ray.com/core/common"
-	"v2ray.com/core/common/net"
 	"v2ray.com/core/features/dns"
 	"v2ray.com/core/features/outbound"
 	"v2ray.com/core/features/routing"
+	routing_dns "v2ray.com/core/features/routing/dns"
 )
 
-func init() {
-	common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
-		r := new(Router)
-		if err := core.RequireFeatures(ctx, func(d dns.Client, ohm outbound.Manager) error {
-			return r.Init(config.(*Config), d, ohm)
-		}); err != nil {
-			return nil, err
-		}
-		return r, nil
-	}))
-}
-
 // Router is an implementation of routing.Router.
 type Router struct {
 	domainStrategy Config_DomainStrategy
@@ -35,6 +23,13 @@ type Router struct {
 	dns            dns.Client
 }
 
+// Route is an implementation of routing.Route.
+type Route struct {
+	routing.Context
+	outboundGroupTags []string
+	outboundTag       string
+}
+
 // Init initializes the Router.
 func (r *Router) Init(config *Config, d dns.Client, ohm outbound.Manager) error {
 	r.domainStrategy = config.DomainStrategy
@@ -74,39 +69,43 @@ func (r *Router) Init(config *Config, d dns.Client, ohm outbound.Manager) error
 }
 
 // PickRoute implements routing.Router.
-func (r *Router) PickRoute(ctx routing.Context) (string, error) {
-	rule, err := r.pickRouteInternal(ctx)
+func (r *Router) PickRoute(ctx routing.Context) (routing.Route, error) {
+	rule, ctx, err := r.pickRouteInternal(ctx)
+	if err != nil {
+		return nil, err
+	}
+	tag, err := rule.GetTag()
 	if err != nil {
-		return "", err
+		return nil, err
 	}
-	return rule.GetTag()
+	return &Route{Context: ctx, outboundTag: tag}, nil
 }
 
-func (r *Router) pickRouteInternal(ctx routing.Context) (*Rule, error) {
+func (r *Router) pickRouteInternal(ctx routing.Context) (*Rule, routing.Context, error) {
 	if r.domainStrategy == Config_IpOnDemand {
-		ctx = ContextWithDNSClient(ctx, r.dns)
+		ctx = routing_dns.ContextWithDNSClient(ctx, r.dns)
 	}
 
 	for _, rule := range r.rules {
 		if rule.Apply(ctx) {
-			return rule, nil
+			return rule, ctx, nil
 		}
 	}
 
 	if r.domainStrategy != Config_IpIfNonMatch || len(ctx.GetTargetDomain()) == 0 {
-		return nil, common.ErrNoClue
+		return nil, ctx, common.ErrNoClue
 	}
 
-	ctx = ContextWithDNSClient(ctx, r.dns)
+	ctx = routing_dns.ContextWithDNSClient(ctx, r.dns)
 
 	// Try applying rules again if we have IPs.
 	for _, rule := range r.rules {
 		if rule.Apply(ctx) {
-			return rule, nil
+			return rule, ctx, nil
 		}
 	}
 
-	return nil, common.ErrNoClue
+	return nil, ctx, common.ErrNoClue
 }
 
 // Start implements common.Runnable.
@@ -124,34 +123,24 @@ func (*Router) Type() interface{} {
 	return routing.RouterType()
 }
 
-// ContextWithDNSClient creates a new routing context with domain resolving capability. Resolved domain IPs can be retrieved by GetTargetIPs().
-func ContextWithDNSClient(ctx routing.Context, client dns.Client) routing.Context {
-	return &resolvableContext{Context: ctx, dnsClient: client}
+// GetOutboundGroupTags implements routing.Route.
+func (r *Route) GetOutboundGroupTags() []string {
+	return r.outboundGroupTags
 }
 
-type resolvableContext struct {
-	routing.Context
-	dnsClient   dns.Client
-	resolvedIPs []net.IP
+// GetOutboundTag implements routing.Route.
+func (r *Route) GetOutboundTag() string {
+	return r.outboundTag
 }
 
-func (ctx *resolvableContext) GetTargetIPs() []net.IP {
-	if ips := ctx.Context.GetTargetIPs(); len(ips) != 0 {
-		return ips
-	}
-
-	if len(ctx.resolvedIPs) > 0 {
-		return ctx.resolvedIPs
-	}
-
-	if domain := ctx.GetTargetDomain(); len(domain) != 0 {
-		ips, err := ctx.dnsClient.LookupIP(domain)
-		if err == nil {
-			ctx.resolvedIPs = ips
-			return ips
+func init() {
+	common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
+		r := new(Router)
+		if err := core.RequireFeatures(ctx, func(d dns.Client, ohm outbound.Manager) error {
+			return r.Init(config.(*Config), d, ohm)
+		}); err != nil {
+			return nil, err
 		}
-		newError("resolve ip for ", domain).Base(err).WriteToLog()
-	}
-
-	return nil
+		return r, nil
+	}))
 }

app/router/router_test.go

@@ -45,9 +45,9 @@ func TestSimpleRouter(t *testing.T) {
 	}))
 
 	ctx := session.ContextWithOutbound(context.Background(), &session.Outbound{Target: net.TCPDestination(net.DomainAddress("v2ray.com"), 80)})
-	tag, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
+	route, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
 	common.Must(err)
-	if tag != "test" {
+	if tag := route.GetOutboundTag(); tag != "test" {
 		t.Error("expect tag 'test', bug actually ", tag)
 	}
 }
@@ -86,9 +86,9 @@ func TestSimpleBalancer(t *testing.T) {
 	}))
 
 	ctx := session.ContextWithOutbound(context.Background(), &session.Outbound{Target: net.TCPDestination(net.DomainAddress("v2ray.com"), 80)})
-	tag, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
+	route, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
 	common.Must(err)
-	if tag != "test" {
+	if tag := route.GetOutboundTag(); tag != "test" {
 		t.Error("expect tag 'test', bug actually ", tag)
 	}
 }
@@ -121,9 +121,9 @@ func TestIPOnDemand(t *testing.T) {
 	common.Must(r.Init(config, mockDns, nil))
 
 	ctx := session.ContextWithOutbound(context.Background(), &session.Outbound{Target: net.TCPDestination(net.DomainAddress("v2ray.com"), 80)})
-	tag, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
+	route, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
 	common.Must(err)
-	if tag != "test" {
+	if tag := route.GetOutboundTag(); tag != "test" {
 		t.Error("expect tag 'test', bug actually ", tag)
 	}
 }
@@ -156,9 +156,9 @@ func TestIPIfNonMatchDomain(t *testing.T) {
 	common.Must(r.Init(config, mockDns, nil))
 
 	ctx := session.ContextWithOutbound(context.Background(), &session.Outbound{Target: net.TCPDestination(net.DomainAddress("v2ray.com"), 80)})
-	tag, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
+	route, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
 	common.Must(err)
-	if tag != "test" {
+	if tag := route.GetOutboundTag(); tag != "test" {
 		t.Error("expect tag 'test', bug actually ", tag)
 	}
 }
@@ -190,9 +190,9 @@ func TestIPIfNonMatchIP(t *testing.T) {
 	common.Must(r.Init(config, mockDns, nil))
 
 	ctx := session.ContextWithOutbound(context.Background(), &session.Outbound{Target: net.TCPDestination(net.LocalHostIP, 80)})
-	tag, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
+	route, err := r.PickRoute(routing_session.AsRoutingContext(ctx))
 	common.Must(err)
-	if tag != "test" {
+	if tag := route.GetOutboundTag(); tag != "test" {
 		t.Error("expect tag 'test', bug actually ", tag)
 	}
 }

features/routing/dns/context.go

@@ -0,0 +1,44 @@
+package dns
+
+//go:generate errorgen
+
+import (
+	"v2ray.com/core/common/net"
+	"v2ray.com/core/features/dns"
+	"v2ray.com/core/features/routing"
+)
+
+// ResolvableContext is an implementation of routing.Context, with domain resolving capability.
+type ResolvableContext struct {
+	routing.Context
+	dnsClient   dns.Client
+	resolvedIPs []net.IP
+}
+
+// GetTargetIPs overrides original routing.Context's implementation.
+func (ctx *ResolvableContext) GetTargetIPs() []net.IP {
+	if ips := ctx.Context.GetTargetIPs(); len(ips) != 0 {
+		return ips
+	}
+
+	if len(ctx.resolvedIPs) > 0 {
+		return ctx.resolvedIPs
+	}
+
+	if domain := ctx.GetTargetDomain(); len(domain) != 0 {
+		ips, err := ctx.dnsClient.LookupIP(domain)
+		if err == nil {
+			ctx.resolvedIPs = ips
+			return ips
+		}
+		newError("resolve ip for ", domain).Base(err).WriteToLog()
+	}
+
+	return nil
+}
+
+// ContextWithDNSClient creates a new routing context with domain resolving capability.
+// Resolved domain IPs can be retrieved by GetTargetIPs().
+func ContextWithDNSClient(ctx routing.Context, client dns.Client) routing.Context {
+	return &ResolvableContext{Context: ctx, dnsClient: client}
+}

features/routing/dns/errors.generated.go

@@ -0,0 +1,9 @@
+package dns
+
+import "v2ray.com/core/common/errors"
+
+type errPathObjHolder struct{}
+
+func newError(values ...interface{}) *errors.Error {
+	return errors.New(values...).WithPathObj(errPathObjHolder{})
+}

features/routing/router.go

@@ -7,12 +7,26 @@ import (
 
 // Router is a feature to choose an outbound tag for the given request.
 //
-// v2ray:api:beta
+// v2ray:api:stable
 type Router interface {
 	features.Feature
 
-	// PickRoute returns a tag of an OutboundHandler based on the given context.
-	PickRoute(ctx Context) (string, error)
+	// PickRoute returns a route decision based on the given routing context.
+	PickRoute(ctx Context) (Route, error)
+}
+
+// Route is the routing result of Router feature.
+//
+// v2ray:api:stable
+type Route interface {
+	// A Route is also a routing context.
+	Context
+
+	// GetOutboundGroupTags returns the detoured outbound group tags in sequence before a final outbound is chosen.
+	GetOutboundGroupTags() []string
+
+	// GetOutboundTag returns the tag of the outbound the connection was dispatched to.
+	GetOutboundTag() string
 }
 
 // RouterType return the type of Router interface. Can be used to implement common.HasType.
@@ -31,8 +45,8 @@ func (DefaultRouter) Type() interface{} {
 }
 
 // PickRoute implements Router.
-func (DefaultRouter) PickRoute(ctx Context) (string, error) {
-	return "", common.ErrNoClue
+func (DefaultRouter) PickRoute(ctx Context) (Route, error) {
+	return nil, common.ErrNoClue
 }
 
 // Start implements common.Runnable.