Add fakeip support

transport/fakeip/memory.go

@@ -0,0 +1,44 @@
+package fakeip
+
+import (
+	"net/netip"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing/common/cache"
+)
+
+var _ adapter.FakeIPStorage = (*MemoryStorage)(nil)
+
+type MemoryStorage struct {
+	metadata    *adapter.FakeIPMetadata
+	domainCache *cache.LruCache[netip.Addr, string]
+}
+
+func NewMemoryStorage() *MemoryStorage {
+	return &MemoryStorage{
+		domainCache: cache.New[netip.Addr, string](),
+	}
+}
+
+func (s *MemoryStorage) FakeIPMetadata() *adapter.FakeIPMetadata {
+	return s.metadata
+}
+
+func (s *MemoryStorage) FakeIPSaveMetadata(metadata *adapter.FakeIPMetadata) error {
+	s.metadata = metadata
+	return nil
+}
+
+func (s *MemoryStorage) FakeIPStore(address netip.Addr, domain string) error {
+	s.domainCache.Store(address, domain)
+	return nil
+}
+
+func (s *MemoryStorage) FakeIPLoad(address netip.Addr) (string, bool) {
+	return s.domainCache.Load(address)
+}
+
+func (s *MemoryStorage) FakeIPReset() error {
+	s.domainCache = cache.New[netip.Addr, string]()
+	return nil
+}

transport/fakeip/packet.go

@@ -0,0 +1,55 @@
+package fakeip
+
+import (
+	"github.com/sagernet/sing/common/buf"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+)
+
+var _ N.PacketConn = (*NATPacketConn)(nil)
+
+type NATPacketConn struct {
+	N.PacketConn
+	origin      M.Socksaddr
+	destination M.Socksaddr
+}
+
+func NewNATPacketConn(conn N.PacketConn, origin M.Socksaddr, destination M.Socksaddr) *NATPacketConn {
+	return &NATPacketConn{
+		PacketConn:  conn,
+		origin:      socksaddrWithoutPort(origin),
+		destination: socksaddrWithoutPort(destination),
+	}
+}
+
+func (c *NATPacketConn) ReadPacket(buffer *buf.Buffer) (destination M.Socksaddr, err error) {
+	destination, err = c.PacketConn.ReadPacket(buffer)
+	if socksaddrWithoutPort(destination) == c.origin {
+		destination = M.Socksaddr{
+			Addr: c.destination.Addr,
+			Fqdn: c.destination.Fqdn,
+			Port: destination.Port,
+		}
+	}
+	return
+}
+
+func (c *NATPacketConn) WritePacket(buffer *buf.Buffer, destination M.Socksaddr) error {
+	if socksaddrWithoutPort(destination) == c.destination {
+		destination = M.Socksaddr{
+			Addr: c.origin.Addr,
+			Fqdn: c.origin.Fqdn,
+			Port: destination.Port,
+		}
+	}
+	return c.PacketConn.WritePacket(buffer, destination)
+}
+
+func (c *NATPacketConn) Upstream() any {
+	return c.PacketConn
+}
+
+func socksaddrWithoutPort(destination M.Socksaddr) M.Socksaddr {
+	destination.Port = 0
+	return destination
+}

transport/fakeip/server.go

@@ -0,0 +1,83 @@
+package fakeip
+
+import (
+	"context"
+	"net/netip"
+	"os"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-dns"
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/logger"
+	N "github.com/sagernet/sing/common/network"
+
+	mDNS "github.com/miekg/dns"
+)
+
+var _ dns.Transport = (*Server)(nil)
+
+func init() {
+	dns.RegisterTransport([]string{"fakeip"}, NewTransport)
+}
+
+type Server struct {
+	name   string
+	router adapter.Router
+	store  adapter.FakeIPStore
+	logger logger.ContextLogger
+}
+
+func NewTransport(name string, ctx context.Context, logger logger.ContextLogger, dialer N.Dialer, link string) (dns.Transport, error) {
+	router := adapter.RouterFromContext(ctx)
+	if router == nil {
+		return nil, E.New("missing router in context")
+	}
+	return &Server{
+		name:   name,
+		router: router,
+		logger: logger,
+	}, nil
+}
+
+func (s *Server) Name() string {
+	return s.name
+}
+
+func (s *Server) Start() error {
+	s.store = s.router.FakeIPStore()
+	if s.store == nil {
+		return E.New("fakeip not enabled")
+	}
+	return nil
+}
+
+func (s *Server) Close() error {
+	return nil
+}
+
+func (s *Server) Raw() bool {
+	return false
+}
+
+func (s *Server) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) {
+	return nil, os.ErrInvalid
+}
+
+func (s *Server) Lookup(ctx context.Context, domain string, strategy dns.DomainStrategy) ([]netip.Addr, error) {
+	var addresses []netip.Addr
+	if strategy != dns.DomainStrategyUseIPv6 {
+		inet4Address, err := s.store.Create(domain, dns.DomainStrategyUseIPv4)
+		if err != nil {
+			return nil, err
+		}
+		addresses = append(addresses, inet4Address)
+	}
+	if strategy != dns.DomainStrategyUseIPv4 {
+		inet6Address, err := s.store.Create(domain, dns.DomainStrategyUseIPv6)
+		if err != nil {
+			return nil, err
+		}
+		addresses = append(addresses, inet6Address)
+	}
+	return addresses, nil
+}

transport/fakeip/store.go

@@ -0,0 +1,108 @@
+package fakeip
+
+import (
+	"net/netip"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-dns"
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+var _ adapter.FakeIPStore = (*Store)(nil)
+
+type Store struct {
+	router       adapter.Router
+	inet4Range   netip.Prefix
+	inet6Range   netip.Prefix
+	storage      adapter.FakeIPStorage
+	inet4Current netip.Addr
+	inet6Current netip.Addr
+}
+
+func NewStore(router adapter.Router, inet4Range netip.Prefix, inet6Range netip.Prefix) *Store {
+	return &Store{
+		router:     router,
+		inet4Range: inet4Range,
+		inet6Range: inet6Range,
+	}
+}
+
+func (s *Store) Start() error {
+	var storage adapter.FakeIPStorage
+	if clashServer := s.router.ClashServer(); clashServer != nil && clashServer.StoreFakeIP() {
+		if cacheFile := clashServer.CacheFile(); cacheFile != nil {
+			storage = cacheFile
+		}
+	}
+	if storage == nil {
+		storage = NewMemoryStorage()
+	}
+	metadata := storage.FakeIPMetadata()
+	if metadata != nil && metadata.Inet4Range == s.inet4Range && metadata.Inet6Range == s.inet6Range {
+		s.inet4Current = metadata.Inet4Current
+		s.inet6Current = metadata.Inet6Current
+	} else {
+		if s.inet4Range.IsValid() {
+			s.inet4Current = s.inet4Range.Addr().Next().Next()
+		}
+		if s.inet6Range.IsValid() {
+			s.inet6Current = s.inet6Range.Addr().Next().Next()
+		}
+	}
+	s.storage = storage
+	return nil
+}
+
+func (s *Store) Contains(address netip.Addr) bool {
+	return s.inet4Range.Contains(address) || s.inet6Range.Contains(address)
+}
+
+func (s *Store) Close() error {
+	if s.storage == nil {
+		return nil
+	}
+	return s.storage.FakeIPSaveMetadata(&adapter.FakeIPMetadata{
+		Inet4Range:   s.inet4Range,
+		Inet6Range:   s.inet6Range,
+		Inet4Current: s.inet4Current,
+		Inet6Current: s.inet6Current,
+	})
+}
+
+func (s *Store) Create(domain string, strategy dns.DomainStrategy) (netip.Addr, error) {
+	var address netip.Addr
+	if strategy == dns.DomainStrategyUseIPv4 {
+		if !s.inet4Current.IsValid() {
+			return netip.Addr{}, E.New("missing IPv4 fakeip address range")
+		}
+		nextAddress := s.inet4Current.Next()
+		if !s.inet4Range.Contains(nextAddress) {
+			nextAddress = s.inet4Range.Addr().Next().Next()
+		}
+		s.inet4Current = nextAddress
+		address = nextAddress
+	} else {
+		if !s.inet6Current.IsValid() {
+			return netip.Addr{}, E.New("missing IPv6 fakeip address range")
+		}
+		nextAddress := s.inet6Current.Next()
+		if !s.inet6Range.Contains(nextAddress) {
+			nextAddress = s.inet6Range.Addr().Next().Next()
+		}
+		s.inet6Current = nextAddress
+		address = nextAddress
+	}
+	err := s.storage.FakeIPStore(address, domain)
+	if err != nil {
+		return netip.Addr{}, err
+	}
+	return address, nil
+}
+
+func (s *Store) Lookup(address netip.Addr) (string, bool) {
+	return s.storage.FakeIPLoad(address)
+}
+
+func (s *Store) Reset() error {
+	return s.storage.FakeIPReset()
+}