Routing: Implement Route interface as the routing result of Router

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.