Add support for client-subnet DNS options

adapter/router.go

@@ -84,6 +84,7 @@ type DNSRule interface {
 	Rule
 	DisableCache() bool
 	RewriteTTL() *uint32
+	ClientSubnet() *netip.Addr
 	WithAddressLimit() bool
 	MatchAddressLimit(metadata *InboundContext) bool
 }

experimental/libbox/dns.go

@@ -9,9 +9,7 @@ import (
 	"github.com/sagernet/sing-dns"
 	"github.com/sagernet/sing/common"
 	E "github.com/sagernet/sing/common/exceptions"
-	"github.com/sagernet/sing/common/logger"
 	M "github.com/sagernet/sing/common/metadata"
-	N "github.com/sagernet/sing/common/network"
 	"github.com/sagernet/sing/common/task"
 
 	mDNS "github.com/miekg/dns"
@@ -25,9 +23,11 @@ type LocalDNSTransport interface {
 
 func RegisterLocalDNSTransport(transport LocalDNSTransport) {
 	if transport == nil {
-		dns.RegisterTransport([]string{"local"}, dns.CreateLocalTransport)
+		dns.RegisterTransport([]string{"local"}, func(options dns.TransportOptions) (dns.Transport, error) {
+			return dns.NewLocalTransport(options), nil
+		})
 	} else {
-		dns.RegisterTransport([]string{"local"}, func(name string, ctx context.Context, logger logger.ContextLogger, dialer N.Dialer, link string) (dns.Transport, error) {
+		dns.RegisterTransport([]string{"local"}, func(options dns.TransportOptions) (dns.Transport, error) {
 			return &platformLocalDNSTransport{
 				iif: transport,
 			}, nil

include/dhcp_stub.go

@@ -3,16 +3,12 @@
 package include
 
 import (
-	"context"
-
 	"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"
 )
 
 func init() {
-	dns.RegisterTransport([]string{"dhcp"}, func(name string, ctx context.Context, logger logger.ContextLogger, dialer N.Dialer, link string) (dns.Transport, error) {
+	dns.RegisterTransport([]string{"dhcp"}, func(options dns.TransportOptions) (dns.Transport, error) {
 		return nil, E.New(`DHCP is not included in this build, rebuild with -tags with_dhcp`)
 	})
 }

option/dns.go

@@ -19,6 +19,7 @@ type DNSServerOptions struct {
 	AddressFallbackDelay Duration       `json:"address_fallback_delay,omitempty"`
 	Strategy             DomainStrategy `json:"strategy,omitempty"`
 	Detour               string         `json:"detour,omitempty"`
+	ClientSubnet         *ListenAddress `json:"client_subnet,omitempty"`
 }
 
 type DNSClientOptions struct {
@@ -26,6 +27,7 @@ type DNSClientOptions struct {
 	DisableCache     bool           `json:"disable_cache,omitempty"`
 	DisableExpire    bool           `json:"disable_expire,omitempty"`
 	IndependentCache bool           `json:"independent_cache,omitempty"`
+	ClientSubnet     *ListenAddress `json:"client_subnet,omitempty"`
 }
 
 type DNSFakeIPOptions struct {

option/rule_dns.go

@@ -100,6 +100,7 @@ type DefaultDNSRule struct {
 	Server            string                 `json:"server,omitempty"`
 	DisableCache      bool                   `json:"disable_cache,omitempty"`
 	RewriteTTL        *uint32                `json:"rewrite_ttl,omitempty"`
+	ClientSubnet      *ListenAddress         `json:"client_subnet,omitempty"`
 }
 
 func (r DefaultDNSRule) IsValid() bool {
@@ -108,16 +109,18 @@ func (r DefaultDNSRule) IsValid() bool {
 	defaultValue.Server = r.Server
 	defaultValue.DisableCache = r.DisableCache
 	defaultValue.RewriteTTL = r.RewriteTTL
+	defaultValue.ClientSubnet = r.ClientSubnet
 	return !reflect.DeepEqual(r, defaultValue)
 }
 
 type LogicalDNSRule struct {
-	Mode         string    `json:"mode"`
+	Mode         string         `json:"mode"`
-	Rules        []DNSRule `json:"rules,omitempty"`
+	Rules        []DNSRule      `json:"rules,omitempty"`
-	Invert       bool      `json:"invert,omitempty"`
+	Invert       bool           `json:"invert,omitempty"`
-	Server       string    `json:"server,omitempty"`
+	Server       string         `json:"server,omitempty"`
-	DisableCache bool      `json:"disable_cache,omitempty"`
+	DisableCache bool           `json:"disable_cache,omitempty"`
-	RewriteTTL   *uint32   `json:"rewrite_ttl,omitempty"`
+	RewriteTTL   *uint32        `json:"rewrite_ttl,omitempty"`
+	ClientSubnet *ListenAddress `json:"client_subnet,omitempty"`
 }
 
 func (r LogicalDNSRule) IsValid() bool {

route/router.go

@@ -222,7 +222,20 @@ func NewRouter(
 					return nil, E.New("parse dns server[", tag, "]: missing address_resolver")
 				}
 			}
-			transport, err := dns.CreateTransport(tag, ctx, logFactory.NewLogger(F.ToString("dns/transport[", tag, "]")), detour, server.Address)
+			var clientSubnet netip.Addr
+			if server.ClientSubnet != nil {
+				clientSubnet = server.ClientSubnet.Build()
+			} else if dnsOptions.ClientSubnet != nil {
+				clientSubnet = dnsOptions.ClientSubnet.Build()
+			}
+			transport, err := dns.CreateTransport(dns.TransportOptions{
+				Context:      ctx,
+				Logger:       logFactory.NewLogger(F.ToString("dns/transport[", tag, "]")),
+				Name:         tag,
+				Dialer:       detour,
+				Address:      server.Address,
+				ClientSubnet: clientSubnet,
+			})
 			if err != nil {
 				return nil, E.Cause(err, "parse dns server[", tag, "]")
 			}
@@ -262,7 +275,11 @@ func NewRouter(
 	}
 	if defaultTransport == nil {
 		if len(transports) == 0 {
-			transports = append(transports, dns.NewLocalTransport("local", N.SystemDialer))
+			transports = append(transports, common.Must1(dns.CreateTransport(dns.TransportOptions{
+				Context: ctx,
+				Name:    "local",
+				Dialer:  common.Must1(dialer.NewDefault(router, option.DialerOptions{})),
+			})))
 		}
 		defaultTransport = transports[0]
 	}

route/router_dns.go

@@ -70,6 +70,9 @@ func (r *Router) matchDNS(ctx context.Context, allowFakeIP bool, index int) (con
 				if rewriteTTL := rule.RewriteTTL(); rewriteTTL != nil {
 					ctx = dns.ContextWithRewriteTTL(ctx, *rewriteTTL)
 				}
+				if clientSubnet := rule.ClientSubnet(); clientSubnet != nil {
+					ctx = dns.ContextWithClientSubnet(ctx, *clientSubnet)
+				}
 				if domainStrategy, dsLoaded := r.transportDomainStrategy[transport]; dsLoaded {
 					return ctx, transport, domainStrategy, rule, ruleIndex
 				} else {

route/rule_dns.go

@@ -1,6 +1,8 @@
 package route
 
 import (
+	"net/netip"
+
 	"github.com/sagernet/sing-box/adapter"
 	C "github.com/sagernet/sing-box/constant"
 	"github.com/sagernet/sing-box/log"
@@ -38,6 +40,7 @@ type DefaultDNSRule struct {
 	abstractDefaultRule
 	disableCache bool
 	rewriteTTL   *uint32
+	clientSubnet *netip.Addr
 }
 
 func NewDefaultDNSRule(router adapter.Router, logger log.ContextLogger, options option.DefaultDNSRule) (*DefaultDNSRule, error) {
@@ -48,6 +51,7 @@ func NewDefaultDNSRule(router adapter.Router, logger log.ContextLogger, options
 		},
 		disableCache: options.DisableCache,
 		rewriteTTL:   options.RewriteTTL,
+		clientSubnet: (*netip.Addr)(options.ClientSubnet),
 	}
 	if len(options.Inbound) > 0 {
 		item := NewInboundRule(options.Inbound)
@@ -230,6 +234,10 @@ func (r *DefaultDNSRule) RewriteTTL() *uint32 {
 	return r.rewriteTTL
 }
 
+func (r *DefaultDNSRule) ClientSubnet() *netip.Addr {
+	return r.clientSubnet
+}
+
 func (r *DefaultDNSRule) WithAddressLimit() bool {
 	if len(r.destinationIPCIDRItems) > 0 {
 		return true
@@ -264,6 +272,7 @@ type LogicalDNSRule struct {
 	abstractLogicalRule
 	disableCache bool
 	rewriteTTL   *uint32
+	clientSubnet *netip.Addr
 }
 
 func NewLogicalDNSRule(router adapter.Router, logger log.ContextLogger, options option.LogicalDNSRule) (*LogicalDNSRule, error) {
@@ -302,6 +311,10 @@ func (r *LogicalDNSRule) RewriteTTL() *uint32 {
 	return r.rewriteTTL
 }
 
+func (r *LogicalDNSRule) ClientSubnet() *netip.Addr {
+	return r.clientSubnet
+}
+
 func (r *LogicalDNSRule) WithAddressLimit() bool {
 	for _, rawRule := range r.rules {
 		switch rule := rawRule.(type) {

transport/dhcp/server.go

@@ -21,9 +21,6 @@ import (
 	"github.com/sagernet/sing/common/buf"
 	"github.com/sagernet/sing/common/control"
 	E "github.com/sagernet/sing/common/exceptions"
-	"github.com/sagernet/sing/common/logger"
-	M "github.com/sagernet/sing/common/metadata"
-	N "github.com/sagernet/sing/common/network"
 	"github.com/sagernet/sing/common/task"
 	"github.com/sagernet/sing/common/x/list"
 
@@ -32,14 +29,14 @@ import (
 )
 
 func init() {
-	dns.RegisterTransport([]string{"dhcp"}, NewTransport)
+	dns.RegisterTransport([]string{"dhcp"}, func(options dns.TransportOptions) (dns.Transport, error) {
+		return NewTransport(options)
+	})
 }
 
 type Transport struct {
-	name              string
+	options           dns.TransportOptions
-	ctx               context.Context
 	router            adapter.Router
-	logger            logger.Logger
 	interfaceName     string
 	autoInterface     bool
 	interfaceCallback *list.Element[tun.DefaultInterfaceUpdateCallback]
@@ -48,23 +45,20 @@ type Transport struct {
 	updatedAt         time.Time
 }
 
-func NewTransport(name string, ctx context.Context, logger logger.ContextLogger, dialer N.Dialer, link string) (dns.Transport, error) {
+func NewTransport(options dns.TransportOptions) (*Transport, error) {
-	linkURL, err := url.Parse(link)
+	linkURL, err := url.Parse(options.Address)
 	if err != nil {
 		return nil, err
 	}
 	if linkURL.Host == "" {
 		return nil, E.New("missing interface name for DHCP")
 	}
-	router := adapter.RouterFromContext(ctx)
+	router := adapter.RouterFromContext(options.Context)
 	if router == nil {
 		return nil, E.New("missing router in context")
 	}
 	transport := &Transport{
-		name:          name,
-		ctx:           ctx,
 		router:        router,
-		logger:        logger,
 		interfaceName: linkURL.Host,
 		autoInterface: linkURL.Host == "auto",
 	}
@@ -72,7 +66,7 @@ func NewTransport(name string, ctx context.Context, logger logger.ContextLogger,
 }
 
 func (t *Transport) Name() string {
-	return t.name
+	return t.options.Name
 }
 
 func (t *Transport) Start() error {
@@ -158,8 +152,8 @@ func (t *Transport) updateServers() error {
 		return E.Cause(err, "dhcp: prepare interface")
 	}
 
-	t.logger.Info("dhcp: query DNS servers on ", iface.Name)
+	t.options.Logger.Info("dhcp: query DNS servers on ", iface.Name)
-	fetchCtx, cancel := context.WithTimeout(t.ctx, C.DHCPTimeout)
+	fetchCtx, cancel := context.WithTimeout(t.options.Context, C.DHCPTimeout)
 	err = t.fetchServers0(fetchCtx, iface)
 	cancel()
 	if err != nil {
@@ -175,7 +169,7 @@ func (t *Transport) updateServers() error {
 func (t *Transport) interfaceUpdated(int) {
 	err := t.updateServers()
 	if err != nil {
-		t.logger.Error("update servers: ", err)
+		t.options.Logger.Error("update servers: ", err)
 	}
 }
 
@@ -187,7 +181,7 @@ func (t *Transport) fetchServers0(ctx context.Context, iface *net.Interface) err
 	if runtime.GOOS == "linux" || runtime.GOOS == "android" {
 		listenAddr = "255.255.255.255:68"
 	}
-	packetConn, err := listener.ListenPacket(t.ctx, "udp4", listenAddr)
+	packetConn, err := listener.ListenPacket(t.options.Context, "udp4", listenAddr)
 	if err != nil {
 		return err
 	}
@@ -225,17 +219,17 @@ func (t *Transport) fetchServersResponse(iface *net.Interface, packetConn net.Pa
 
 		dhcpPacket, err := dhcpv4.FromBytes(buffer.Bytes())
 		if err != nil {
-			t.logger.Trace("dhcp: parse DHCP response: ", err)
+			t.options.Logger.Trace("dhcp: parse DHCP response: ", err)
 			return err
 		}
 
 		if dhcpPacket.MessageType() != dhcpv4.MessageTypeOffer {
-			t.logger.Trace("dhcp: expected OFFER response, but got ", dhcpPacket.MessageType())
+			t.options.Logger.Trace("dhcp: expected OFFER response, but got ", dhcpPacket.MessageType())
 			continue
 		}
 
 		if dhcpPacket.TransactionID != transactionID {
-			t.logger.Trace("dhcp: expected transaction ID ", transactionID, ", but got ", dhcpPacket.TransactionID)
+			t.options.Logger.Trace("dhcp: expected transaction ID ", transactionID, ", but got ", dhcpPacket.TransactionID)
 			continue
 		}
 
@@ -255,20 +249,22 @@ func (t *Transport) fetchServersResponse(iface *net.Interface, packetConn net.Pa
 
 func (t *Transport) recreateServers(iface *net.Interface, serverAddrs []netip.Addr) error {
 	if len(serverAddrs) > 0 {
-		t.logger.Info("dhcp: updated DNS servers from ", iface.Name, ": [", strings.Join(common.Map(serverAddrs, func(it netip.Addr) string {
+		t.options.Logger.Info("dhcp: updated DNS servers from ", iface.Name, ": [", strings.Join(common.Map(serverAddrs, func(it netip.Addr) string {
 			return it.String()
 		}), ","), "]")
 	}
-
 	serverDialer := common.Must1(dialer.NewDefault(t.router, option.DialerOptions{
 		BindInterface:      iface.Name,
 		UDPFragmentDefault: true,
 	}))
 	var transports []dns.Transport
 	for _, serverAddr := range serverAddrs {
-		serverTransport, err := dns.NewUDPTransport(t.name, t.ctx, serverDialer, M.Socksaddr{Addr: serverAddr, Port: 53})
+		newOptions := t.options
+		newOptions.Address = serverAddr.String()
+		newOptions.Dialer = serverDialer
+		serverTransport, err := dns.NewUDPTransport(newOptions)
 		if err != nil {
-			return err
+			return E.Cause(err, "create UDP transport from DHCP result: ", serverAddr)
 		}
 		transports = append(transports, serverTransport)
 	}

transport/fakeip/server.go

@@ -9,7 +9,6 @@ import (
 	"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"
 )
@@ -20,7 +19,9 @@ var (
 )
 
 func init() {
-	dns.RegisterTransport([]string{"fakeip"}, NewTransport)
+	dns.RegisterTransport([]string{"fakeip"}, func(options dns.TransportOptions) (dns.Transport, error) {
+		return NewTransport(options)
+	})
 }
 
 type Transport struct {
@@ -30,15 +31,15 @@ type Transport struct {
 	logger logger.ContextLogger
 }
 
-func NewTransport(name string, ctx context.Context, logger logger.ContextLogger, dialer N.Dialer, link string) (dns.Transport, error) {
+func NewTransport(options dns.TransportOptions) (*Transport, error) {
-	router := adapter.RouterFromContext(ctx)
+	router := adapter.RouterFromContext(options.Context)
 	if router == nil {
 		return nil, E.New("missing router in context")
 	}
 	return &Transport{
-		name:   name,
+		name:   options.Name,
 		router: router,
-		logger: logger,
+		logger: options.Logger,
 	}, nil
 }