Add L3 routing support

adapter/inbound.go

@@ -27,7 +27,7 @@ type InjectableInbound interface {
 type InboundContext struct {
 	Inbound     string
 	InboundType string
-	IPVersion   int
+	IPVersion   uint8
 	Network     string
 	Source      M.Socksaddr
 	Destination M.Socksaddr

adapter/outbound.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"net"
 
+	"github.com/sagernet/sing-tun"
 	N "github.com/sagernet/sing/common/network"
 )
 
@@ -17,3 +18,8 @@ type Outbound interface {
 	NewConnection(ctx context.Context, conn net.Conn, metadata InboundContext) error
 	NewPacketConnection(ctx context.Context, conn N.PacketConn, metadata InboundContext) error
 }
+
+type IPOutbound interface {
+	Outbound
+	NewIPConnection(ctx context.Context, conn tun.RouteContext, metadata InboundContext) (tun.DirectDestination, error)
+}

adapter/router.go

@@ -23,6 +23,9 @@ type Router interface {
 
 	RouteConnection(ctx context.Context, conn net.Conn, metadata InboundContext) error
 	RoutePacketConnection(ctx context.Context, conn N.PacketConn, metadata InboundContext) error
+	RouteIPConnection(ctx context.Context, conn tun.RouteContext, metadata InboundContext) tun.RouteAction
+
+	NatRequired(outbound string) bool
 
 	GeoIPReader() *geoip.Reader
 	LoadGeosite(code string) (Rule, error)
@@ -39,7 +42,9 @@ type Router interface {
 	NetworkMonitor() tun.NetworkUpdateMonitor
 	InterfaceMonitor() tun.DefaultInterfaceMonitor
 	PackageManager() tun.PackageManager
+
 	Rules() []Rule
+	IPRules() []IPRule
 
 	TimeService
 
@@ -76,6 +81,12 @@ type Rule interface {
 type DNSRule interface {
 	Rule
 	DisableCache() bool
+	RewriteTTL() *uint32
+}
+
+type IPRule interface {
+	Rule
+	Action() tun.ActionType
 }
 
 type InterfaceUpdateListener interface {