prototype for balancing rules

app/proxyman/outbound/outbound.go

@@ -4,6 +4,7 @@ package outbound
 
 import (
 	"context"
+	"strings"
 	"sync"
 
 	"v2ray.com/core"
@@ -134,6 +135,28 @@ func (m *Manager) RemoveHandler(ctx context.Context, tag string) error {
 	return nil
 }
 
+func (m *Manager) Select(selectors []string) []string {
+	m.access.RLock()
+	defer m.access.RUnlock()
+
+	tags := make([]string, 0, len(selectors))
+
+	for tag := range m.taggedHandler {
+		match := false
+		for _, selector := range selectors {
+			if strings.HasPrefix(tag, selector) {
+				match = true
+				break
+			}
+		}
+		if match {
+			tags = append(tags, tag)
+		}
+	}
+
+	return tags
+}
+
 func init() {
 	common.Must(common.RegisterConfig((*proxyman.OutboundConfig)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
 		return New(ctx, config.(*proxyman.OutboundConfig))

app/router/balancing.go

@@ -0,0 +1,44 @@
+package router
+
+import (
+	"v2ray.com/core/common/dice"
+	"v2ray.com/core/features/outbound"
+)
+
+type BalancingStrategy interface {
+	PickOutbound([]string) string
+}
+
+type RandomStrategy struct {
+}
+
+func (s *RandomStrategy) PickOutbound(tags []string) string {
+	n := len(tags)
+	if n == 0 {
+		panic("0 tags")
+	}
+
+	return tags[dice.Roll(n)]
+}
+
+type Balancer struct {
+	selectors []string
+	strategy  BalancingStrategy
+	ohm       outbound.Manager
+}
+
+func (b *Balancer) PickOutbound() (string, error) {
+	hs, ok := b.ohm.(outbound.HandlerSelector)
+	if !ok {
+		return "", newError("outbound.Manager is not a HandlerSelector")
+	}
+	tags := hs.Select(b.selectors)
+	if len(tags) == 0 {
+		return "", newError("no available outbounds selected")
+	}
+	tag := b.strategy.PickOutbound(tags)
+	if len(tag) == 0 {
+		return "", newError("balancing strategy returns empty tag")
+	}
+	return tag, nil
+}

app/router/config.go

@@ -2,6 +2,8 @@ package router
 
 import (
 	"context"
+
+	"v2ray.com/core/features/outbound"
 )
 
 // CIDRList is an alias of []*CIDR to provide sort.Interface.
@@ -45,9 +47,17 @@ func (l *CIDRList) Swap(i int, j int) {
 
 type Rule struct {
 	Tag       string
+	Balancer  *Balancer
 	Condition Condition
 }
 
+func (r *Rule) GetTag() (string, error) {
+	if r.Balancer != nil {
+		return r.Balancer.PickOutbound()
+	}
+	return r.Tag, nil
+}
+
 func (r *Rule) Apply(ctx context.Context) bool {
 	return r.Condition.Apply(ctx)
 }
@@ -117,3 +127,10 @@ func (rr *RoutingRule) BuildCondition() (Condition, error) {
 
 	return conds, nil
 }
+
+func (br *BalancingRule) Build(ohm outbound.Manager) (*Balancer, error) {
+	return &Balancer{
+		selectors: br.OutboundSelector,
+		strategy:  &RandomStrategy{},
+	}, nil
+}

app/router/config.pb.go

@@ -86,7 +86,7 @@ func (x Config_DomainStrategy) String() string {
 }
 
 func (Config_DomainStrategy) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_6b1608360690c5fc, []int{7, 0}
+	return fileDescriptor_6b1608360690c5fc, []int{8, 0}
 }
 
 // Domain for routing decision.
@@ -362,8 +362,10 @@ func (m *GeoSiteList) GetEntry() []*GeoSite {
 }
 
 type RoutingRule struct {
-	// Tag of outbound that this rule is pointing to.
+	// Types that are valid to be assigned to TargetTag:
-	Tag string `protobuf:"bytes,1,opt,name=tag,proto3" json:"tag,omitempty"`
+	//	*RoutingRule_Tag
+	//	*RoutingRule_BalancingTag
+	TargetTag isRoutingRule_TargetTag `protobuf_oneof:"target_tag"`
 	// List of domains for target domain matching.
 	Domain []*Domain `protobuf:"bytes,2,rep,name=domain,proto3" json:"domain,omitempty"`
 	// List of CIDRs for target IP address matching.
@@ -412,9 +414,39 @@ func (m *RoutingRule) XXX_DiscardUnknown() {
 
 var xxx_messageInfo_RoutingRule proto.InternalMessageInfo
 
-func (m *RoutingRule) GetTag() string {
+type isRoutingRule_TargetTag interface {
+	isRoutingRule_TargetTag()
+}
+
+type RoutingRule_Tag struct {
+	Tag string `protobuf:"bytes,1,opt,name=tag,proto3,oneof"`
+}
+
+type RoutingRule_BalancingTag struct {
+	BalancingTag string `protobuf:"bytes,12,opt,name=balancing_tag,json=balancingTag,proto3,oneof"`
+}
+
+func (*RoutingRule_Tag) isRoutingRule_TargetTag() {}
+
+func (*RoutingRule_BalancingTag) isRoutingRule_TargetTag() {}
+
+func (m *RoutingRule) GetTargetTag() isRoutingRule_TargetTag {
 	if m != nil {
-		return m.Tag
+		return m.TargetTag
+	}
+	return nil
+}
+
+func (m *RoutingRule) GetTag() string {
+	if x, ok := m.GetTargetTag().(*RoutingRule_Tag); ok {
+		return x.Tag
+	}
+	return ""
+}
+
+func (m *RoutingRule) GetBalancingTag() string {
+	if x, ok := m.GetTargetTag().(*RoutingRule_BalancingTag); ok {
+		return x.BalancingTag
 	}
 	return ""
 }
@@ -491,9 +523,123 @@ func (m *RoutingRule) GetProtocol() []string {
 	return nil
 }
 
+// XXX_OneofFuncs is for the internal use of the proto package.
+func (*RoutingRule) XXX_OneofFuncs() (func(msg proto.Message, b *proto.Buffer) error, func(msg proto.Message, tag, wire int, b *proto.Buffer) (bool, error), func(msg proto.Message) (n int), []interface{}) {
+	return _RoutingRule_OneofMarshaler, _RoutingRule_OneofUnmarshaler, _RoutingRule_OneofSizer, []interface{}{
+		(*RoutingRule_Tag)(nil),
+		(*RoutingRule_BalancingTag)(nil),
+	}
+}
+
+func _RoutingRule_OneofMarshaler(msg proto.Message, b *proto.Buffer) error {
+	m := msg.(*RoutingRule)
+	// target_tag
+	switch x := m.TargetTag.(type) {
+	case *RoutingRule_Tag:
+		b.EncodeVarint(1<<3 | proto.WireBytes)
+		b.EncodeStringBytes(x.Tag)
+	case *RoutingRule_BalancingTag:
+		b.EncodeVarint(12<<3 | proto.WireBytes)
+		b.EncodeStringBytes(x.BalancingTag)
+	case nil:
+	default:
+		return fmt.Errorf("RoutingRule.TargetTag has unexpected type %T", x)
+	}
+	return nil
+}
+
+func _RoutingRule_OneofUnmarshaler(msg proto.Message, tag, wire int, b *proto.Buffer) (bool, error) {
+	m := msg.(*RoutingRule)
+	switch tag {
+	case 1: // target_tag.tag
+		if wire != proto.WireBytes {
+			return true, proto.ErrInternalBadWireType
+		}
+		x, err := b.DecodeStringBytes()
+		m.TargetTag = &RoutingRule_Tag{x}
+		return true, err
+	case 12: // target_tag.balancing_tag
+		if wire != proto.WireBytes {
+			return true, proto.ErrInternalBadWireType
+		}
+		x, err := b.DecodeStringBytes()
+		m.TargetTag = &RoutingRule_BalancingTag{x}
+		return true, err
+	default:
+		return false, nil
+	}
+}
+
+func _RoutingRule_OneofSizer(msg proto.Message) (n int) {
+	m := msg.(*RoutingRule)
+	// target_tag
+	switch x := m.TargetTag.(type) {
+	case *RoutingRule_Tag:
+		n += 1 // tag and wire
+		n += proto.SizeVarint(uint64(len(x.Tag)))
+		n += len(x.Tag)
+	case *RoutingRule_BalancingTag:
+		n += 1 // tag and wire
+		n += proto.SizeVarint(uint64(len(x.BalancingTag)))
+		n += len(x.BalancingTag)
+	case nil:
+	default:
+		panic(fmt.Sprintf("proto: unexpected type %T in oneof", x))
+	}
+	return n
+}
+
+type BalancingRule struct {
+	Tag                  string   `protobuf:"bytes,1,opt,name=tag,proto3" json:"tag,omitempty"`
+	OutboundSelector     []string `protobuf:"bytes,2,rep,name=outbound_selector,json=outboundSelector,proto3" json:"outbound_selector,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *BalancingRule) Reset()         { *m = BalancingRule{} }
+func (m *BalancingRule) String() string { return proto.CompactTextString(m) }
+func (*BalancingRule) ProtoMessage()    {}
+func (*BalancingRule) Descriptor() ([]byte, []int) {
+	return fileDescriptor_6b1608360690c5fc, []int{7}
+}
+
+func (m *BalancingRule) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_BalancingRule.Unmarshal(m, b)
+}
+func (m *BalancingRule) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_BalancingRule.Marshal(b, m, deterministic)
+}
+func (m *BalancingRule) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_BalancingRule.Merge(m, src)
+}
+func (m *BalancingRule) XXX_Size() int {
+	return xxx_messageInfo_BalancingRule.Size(m)
+}
+func (m *BalancingRule) XXX_DiscardUnknown() {
+	xxx_messageInfo_BalancingRule.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_BalancingRule proto.InternalMessageInfo
+
+func (m *BalancingRule) GetTag() string {
+	if m != nil {
+		return m.Tag
+	}
+	return ""
+}
+
+func (m *BalancingRule) GetOutboundSelector() []string {
+	if m != nil {
+		return m.OutboundSelector
+	}
+	return nil
+}
+
 type Config struct {
 	DomainStrategy       Config_DomainStrategy `protobuf:"varint,1,opt,name=domain_strategy,json=domainStrategy,proto3,enum=v2ray.core.app.router.Config_DomainStrategy" json:"domain_strategy,omitempty"`
 	Rule                 []*RoutingRule        `protobuf:"bytes,2,rep,name=rule,proto3" json:"rule,omitempty"`
+	BalancingRule        []*BalancingRule      `protobuf:"bytes,3,rep,name=balancing_rule,json=balancingRule,proto3" json:"balancing_rule,omitempty"`
 	XXX_NoUnkeyedLiteral struct{}              `json:"-"`
 	XXX_unrecognized     []byte                `json:"-"`
 	XXX_sizecache        int32                 `json:"-"`
@@ -503,7 +649,7 @@ func (m *Config) Reset()         { *m = Config{} }
 func (m *Config) String() string { return proto.CompactTextString(m) }
 func (*Config) ProtoMessage()    {}
 func (*Config) Descriptor() ([]byte, []int) {
-	return fileDescriptor_6b1608360690c5fc, []int{7}
+	return fileDescriptor_6b1608360690c5fc, []int{8}
 }
 
 func (m *Config) XXX_Unmarshal(b []byte) error {
@@ -538,6 +684,13 @@ func (m *Config) GetRule() []*RoutingRule {
 	return nil
 }
 
+func (m *Config) GetBalancingRule() []*BalancingRule {
+	if m != nil {
+		return m.BalancingRule
+	}
+	return nil
+}
+
 func init() {
 	proto.RegisterEnum("v2ray.core.app.router.Domain_Type", Domain_Type_name, Domain_Type_value)
 	proto.RegisterEnum("v2ray.core.app.router.Config_DomainStrategy", Config_DomainStrategy_name, Config_DomainStrategy_value)
@@ -548,6 +701,7 @@ func init() {
 	proto.RegisterType((*GeoSite)(nil), "v2ray.core.app.router.GeoSite")
 	proto.RegisterType((*GeoSiteList)(nil), "v2ray.core.app.router.GeoSiteList")
 	proto.RegisterType((*RoutingRule)(nil), "v2ray.core.app.router.RoutingRule")
+	proto.RegisterType((*BalancingRule)(nil), "v2ray.core.app.router.BalancingRule")
 	proto.RegisterType((*Config)(nil), "v2ray.core.app.router.Config")
 }
 
@@ -556,49 +710,54 @@ func init() {
 }
 
 var fileDescriptor_6b1608360690c5fc = []byte{
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+	// 776 bytes of a gzipped FileDescriptorProto
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+	0x0c, 0x14, 0x9d, 0x00, 0xe8, 0x35, 0x59, 0x48, 0xc2, 0x32, 0x1a, 0xb5, 0xfb, 0xce, 0xc0, 0x1f,
-	0x2f, 0x65, 0xd8, 0xd0, 0x29, 0xa2, 0x25, 0x29, 0x0e, 0x0d, 0x54, 0x59, 0x8e, 0x7d, 0xfa, 0x2b,
+	0xf5, 0x9f, 0x1a, 0xda, 0x4d, 0x49, 0x18, 0x55, 0xc9, 0x9c, 0x4b, 0x85, 0x35, 0x0e, 0x7b, 0x62,
-	0x40, 0x2f, 0xc1, 0x2f, 0x59, 0x25, 0x52, 0x32, 0xd1, 0x7d, 0x37, 0x57, 0xeb, 0x1b, 0x0c, 0x67,
+	0xf3, 0x44, 0xe7, 0x10, 0xd4, 0x1b, 0xb4, 0x28, 0xf2, 0x52, 0x45, 0x1d, 0xe3, 0x22, 0x6e, 0x70,
-	0xa0, 0xba, 0xdf, 0x81, 0x96, 0xcd, 0x60, 0x4c, 0xf0, 0x57, 0x30, 0xc1, 0xd6, 0x1c, 0x6a, 0x2b,
+	0x71, 0x61, 0xa1, 0xba, 0x37, 0xd8, 0x67, 0x8f, 0x02, 0xfa, 0x1a, 0xfc, 0x92, 0x57, 0x32, 0xa5,
-	0xb6, 0x00, 0xaa, 0x92, 0x88, 0x09, 0x99, 0x25, 0x79, 0x11, 0xae, 0x75, 0x6a, 0x5d, 0x0f, 0x7b,
+	0x0b, 0x93, 0x77, 0x77, 0xb7, 0xbc, 0xc1, 0xda, 0x4c, 0x74, 0xf6, 0x27, 0x10, 0xd4, 0x1e, 0x6c,
-	0xea, 0xe6, 0x40, 0x5d, 0xa0, 0xfb, 0xe0, 0xe7, 0xf4, 0x94, 0x55, 0x74, 0x3a, 0x51, 0xff, 0x78,
+	0x11, 0xfc, 0x1d, 0x8a, 0x50, 0xc7, 0x9c, 0x9a, 0x52, 0x1c, 0x02, 0x54, 0x25, 0x95, 0x0b, 0xba,
-	0x5d, 0x7f, 0x07, 0x7b, 0x75, 0x9c, 0x64, 0x68, 0x13, 0xd6, 0xf5, 0x6a, 0x48, 0x59, 0x11, 0x7a,
+	0x22, 0x79, 0x11, 0xbd, 0xec, 0xb7, 0x06, 0x1e, 0xf6, 0xb4, 0xe6, 0x5c, 0x2b, 0xd0, 0x07, 0xe0,
-	0xfa, 0xeb, 0xcf, 0x38, 0xfa, 0xee, 0x40, 0x73, 0xa0, 0x97, 0x14, 0x3a, 0x81, 0x1b, 0xe6, 0x27,
+	0xe7, 0xec, 0x86, 0x57, 0x6c, 0x69, 0xda, 0xbd, 0x67, 0xfe, 0xa1, 0x56, 0xe9, 0x56, 0x1f, 0xc0,
-	0x4f, 0x4a, 0x29, 0x12, 0x49, 0xb2, 0xb9, 0x5d, 0x1c, 0x4f, 0x96, 0x75, 0x6b, 0x96, 0x9b, 0x99,
+	0x9e, 0xb9, 0x21, 0x29, 0x2f, 0x22, 0xcf, 0xfc, 0x3e, 0xc8, 0xe3, 0x00, 0x40, 0x11, 0x99, 0x51,
-	0x90, 0x23, 0xcb, 0xc1, 0xed, 0xe9, 0x95, 0x58, 0x2d, 0x21, 0x51, 0x15, 0xc4, 0x8e, 0xd9, 0xb2,
+	0xa5, 0x6d, 0xe3, 0x0b, 0xd8, 0x1f, 0x6f, 0x86, 0xc4, 0x0c, 0x58, 0xf8, 0x64, 0xc0, 0xec, 0x78,
-	0x25, 0x74, 0x69, 0x58, 0xb1, 0xc6, 0x47, 0x43, 0x68, 0x5f, 0xcd, 0xac, 0xd6, 0xca, 0x6e, 0x39,
+	0x7d, 0x0a, 0x6f, 0xf2, 0x4a, 0xd9, 0x70, 0x25, 0x2d, 0x68, 0xaa, 0xb8, 0xdd, 0x55, 0x0f, 0x87,
-	0x2a, 0xcd, 0xde, 0x39, 0x29, 0xc9, 0x88, 0x07, 0x0e, 0x0a, 0xa0, 0x35, 0xe2, 0xa3, 0xb3, 0x43,
+	0x9b, 0x8f, 0xcb, 0x5a, 0x1f, 0xff, 0xe5, 0x42, 0x77, 0x62, 0x6e, 0x25, 0xba, 0x86, 0x37, 0xec,
-	0x46, 0xdf, 0x24, 0x32, 0xfd, 0x18, 0xb8, 0xa8, 0x0d, 0x30, 0xe2, 0x6f, 0xe9, 0x3e, 0x99, 0x25,
+	0x08, 0x2d, 0x4a, 0x25, 0x89, 0xa2, 0xd9, 0xba, 0xbe, 0x5f, 0x9f, 0x35, 0xd5, 0xd2, 0xde, 0x58,
-	0x74, 0x1a, 0xd4, 0xf6, 0x5e, 0xc0, 0xed, 0x94, 0xcd, 0xae, 0xaf, 0x3b, 0x76, 0xde, 0x37, 0xcd,
+	0x3b, 0x7f, 0x97, 0xb5, 0x0d, 0xee, 0x2d, 0xb7, 0x64, 0x7d, 0x0b, 0x65, 0x55, 0xd0, 0x7a, 0x88,
-	0xe9, 0x9b, 0xbb, 0xf1, 0xae, 0x8f, 0x93, 0x79, 0x3c, 0x50, 0x88, 0x5d, 0xce, 0xb5, 0x24, 0x22,
+	0x9b, 0x6e, 0xe1, 0x93, 0x9d, 0xc1, 0x06, 0x8f, 0xbe, 0x83, 0xde, 0xe3, 0x96, 0x18, 0x0f, 0x76,
-	0x4e, 0x9b, 0xda, 0xab, 0xed, 0x1f, 0x01, 0x00, 0x00, 0xff, 0xff, 0x42, 0x5b, 0xf4, 0x78, 0xe6,
+	0xa2, 0x8f, 0x1a, 0x3c, 0x6c, 0x95, 0x05, 0x3f, 0x6e, 0x98, 0x16, 0xe3, 0x29, 0xf4, 0xb6, 0x69,
-	0x05, 0x00, 0x00,
+	0xea, 0x53, 0x79, 0x5a, 0xce, 0x4a, 0x7b, 0x4b, 0xaf, 0x4b, 0x3a, 0x13, 0xa1, 0x83, 0x42, 0x08,
+	0x66, 0x62, 0x76, 0x7b, 0xc1, 0xd9, 0x0f, 0x44, 0xa5, 0xbf, 0x86, 0x2e, 0xea, 0x01, 0xcc, 0xc4,
+	0x8f, 0xec, 0x8c, 0xae, 0x08, 0x5b, 0x86, 0xad, 0xf1, 0x57, 0xf0, 0x4e, 0xca, 0x57, 0xcf, 0x53,
+	0x98, 0x3b, 0x3f, 0x77, 0xed, 0xeb, 0x4f, 0xf7, 0xd5, 0x4f, 0x23, 0x4c, 0xd6, 0xc9, 0x44, 0x23,
+	0x4e, 0x85, 0x30, 0xf9, 0x51, 0x79, 0xd3, 0x35, 0x6d, 0x3d, 0xfe, 0x27, 0x00, 0x00, 0xff, 0xff,
+	0x7c, 0x01, 0x52, 0xfa, 0xba, 0x06, 0x00, 0x00,
 }

app/router/config.proto

@@ -58,8 +58,14 @@ message GeoSiteList{
 }
 
 message RoutingRule {
-  // Tag of outbound that this rule is pointing to.
+  oneof target_tag {
-  string tag = 1;
+    // Tag of outbound that this rule is pointing to.
+    string tag = 1;
+
+    // Tag of routing balancer.
+    string balancing_tag = 12;
+  }
+  
 
   // List of domains for target domain matching.
   repeated Domain domain = 2;
@@ -87,6 +93,11 @@ message RoutingRule {
   repeated string protocol = 9;
 }
 
+message BalancingRule {
+  string tag = 1;
+  repeated string outbound_selector = 2;
+}
+
 message Config {
   enum DomainStrategy {
     // Use domain as is.
@@ -103,4 +114,5 @@ message Config {
   }
   DomainStrategy domain_strategy = 1;
   repeated RoutingRule rule = 2;
+  repeated BalancingRule balancing_rule = 3;
 }

app/router/router.go

@@ -10,6 +10,7 @@ import (
 	"v2ray.com/core/common/net"
 	"v2ray.com/core/common/session"
 	"v2ray.com/core/features/dns"
+	"v2ray.com/core/features/outbound"
 	"v2ray.com/core/features/routing"
 )
 
@@ -35,8 +36,8 @@ func ResolvedIPsFromContext(ctx context.Context) (IPResolver, bool) {
 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) error {
+		if err := core.RequireFeatures(ctx, func(d dns.Client, ohm outbound.Manager) error {
-			return r.Init(config.(*Config), d)
+			return r.Init(config.(*Config), d, ohm)
 		}); err != nil {
 			return nil, err
 		}
@@ -47,23 +48,44 @@ func init() {
 // Router is an implementation of routing.Router.
 type Router struct {
 	domainStrategy Config_DomainStrategy
-	rules          []Rule
+	rules          []*Rule
+	balancers      map[string]*Balancer
 	dns            dns.Client
 }
 
 // Init initializes the Router.
-func (r *Router) Init(config *Config, d dns.Client) error {
+func (r *Router) Init(config *Config, d dns.Client, ohm outbound.Manager) error {
 	r.domainStrategy = config.DomainStrategy
-	r.rules = make([]Rule, len(config.Rule))
 	r.dns = d
 
-	for idx, rule := range config.Rule {
+	r.balancers = make(map[string]*Balancer, len(config.BalancingRule))
-		r.rules[idx].Tag = rule.Tag
+	for _, rule := range config.BalancingRule {
+		balancer, err := rule.Build(ohm)
+		if err != nil {
+			return err
+		}
+		r.balancers[rule.Tag] = balancer
+	}
+
+	r.rules = make([]*Rule, 0, len(config.Rule))
+	for _, rule := range config.Rule {
 		cond, err := rule.BuildCondition()
 		if err != nil {
 			return err
 		}
-		r.rules[idx].Condition = cond
+		rr := &Rule{
+			Condition: cond,
+			Tag:       rule.GetTag(),
+		}
+		btag := rule.GetBalancingTag()
+		if len(btag) > 0 {
+			brule, found := r.balancers[btag]
+			if !found {
+				return newError("balancer ", btag, " not found")
+			}
+			rr.Balancer = brule
+		}
+		r.rules = append(r.rules, rr)
 	}
 
 	return nil
@@ -97,8 +119,16 @@ func (r *ipResolver) Resolve() []net.Address {
 	return r.ip
 }
 
-// PickRoute implements routing.Router.
 func (r *Router) PickRoute(ctx context.Context) (string, error) {
+	rule, err := r.pickRouteInternal(ctx)
+	if err != nil {
+		return "", err
+	}
+	return rule.GetTag()
+}
+
+// PickRoute implements routing.Router.
+func (r *Router) pickRouteInternal(ctx context.Context) (*Rule, error) {
 	resolver := &ipResolver{
 		dns: r.dns,
 	}
@@ -113,12 +143,12 @@ func (r *Router) PickRoute(ctx context.Context) (string, error) {
 
 	for _, rule := range r.rules {
 		if rule.Apply(ctx) {
-			return rule.Tag, nil
+			return rule, nil
 		}
 	}
 
 	if outbound == nil || !outbound.Target.IsValid() {
-		return "", common.ErrNoClue
+		return nil, common.ErrNoClue
 	}
 
 	dest := outbound.Target
@@ -129,13 +159,13 @@ func (r *Router) PickRoute(ctx context.Context) (string, error) {
 			ctx = ContextWithResolveIPs(ctx, resolver)
 			for _, rule := range r.rules {
 				if rule.Apply(ctx) {
-					return rule.Tag, nil
+					return rule, nil
 				}
 			}
 		}
 	}
 
-	return "", common.ErrNoClue
+	return nil, common.ErrNoClue
 }
 
 // Start implements common.Runnable.

app/router/router_test.go

@@ -15,7 +15,9 @@ func TestSimpleRouter(t *testing.T) {
 	config := &Config{
 		Rule: []*RoutingRule{
 			{
-				Tag: "test",
+				TargetTag: &RoutingRule_Tag{
+					Tag: "test",
+				},
 				NetworkList: &net.NetworkList{
 					Network: []net.Network{net.Network_TCP},
 				},
@@ -29,7 +31,7 @@ func TestSimpleRouter(t *testing.T) {
 	mockDns := mocks.NewDNSClient(mockCtl)
 
 	r := new(Router)
-	common.Must(r.Init(config, mockDns))
+	common.Must(r.Init(config, mockDns, nil))
 
 	ctx := withOutbound(&session.Outbound{Target: net.TCPDestination(net.DomainAddress("v2ray.com"), 80)})
 	tag, err := r.PickRoute(ctx)
@@ -44,7 +46,9 @@ func TestIPOnDemand(t *testing.T) {
 		DomainStrategy: Config_IpOnDemand,
 		Rule: []*RoutingRule{
 			{
-				Tag: "test",
+				TargetTag: &RoutingRule_Tag{
+					Tag: "test",
+				},
 				Cidr: []*CIDR{
 					{
 						Ip:     []byte{192, 168, 0, 0},
@@ -62,7 +66,7 @@ func TestIPOnDemand(t *testing.T) {
 	mockDns.EXPECT().LookupIP(gomock.Eq("v2ray.com")).Return([]net.IP{{192, 168, 0, 1}}, nil).AnyTimes()
 
 	r := new(Router)
-	common.Must(r.Init(config, mockDns))
+	common.Must(r.Init(config, mockDns, nil))
 
 	ctx := withOutbound(&session.Outbound{Target: net.TCPDestination(net.DomainAddress("v2ray.com"), 80)})
 	tag, err := r.PickRoute(ctx)

features/outbound/outbound.go

@@ -15,6 +15,10 @@ type Handler interface {
 	Dispatch(ctx context.Context, link *transport.Link)
 }
 
+type HandlerSelector interface {
+	Select([]string) []string
+}
+
 // Manager is a feature that manages outbound.Handlers.
 type Manager interface {
 	features.Feature