WireGuard outbound: Add remoteDNS & honor TTL

infra/conf/wireguard.go

@@ -66,6 +66,7 @@ type WireGuardConfig struct {
 	MTU            int32                  `json:"mtu"`
 	Reserved       []byte                 `json:"reserved"`
 	DomainStrategy string                 `json:"domainStrategy"`
+	DNS            []string               `json:"remoteDNS"`
 }
 
 func (c *WireGuardConfig) Build() (proto.Message, error) {
@@ -141,6 +142,7 @@ func (c *WireGuardConfig) Build() (proto.Message, error) {
 
 	config.IsClient = c.IsClient
 	config.NoKernelTun = c.NoKernelTun
+	config.DNS = c.DNS
 
 	return config, nil
 }

proxy/wireguard/client.go

@@ -5,9 +5,10 @@ import (
 	"fmt"
 	gonet "net"
 	"net/netip"
-	reflect "reflect"
+	"reflect"
 	"strings"
 	"sync"
+	"time"
 
 	"golang.zx2c4.com/wireguard/tun"
 
@@ -30,6 +31,11 @@ import (
 	"golang.zx2c4.com/wireguard/device"
 )
 
+type entry struct {
+	got  []net.IP
+	time time.Time
+}
+
 type Handler struct {
 	conf          *DeviceConfig
 	policyManager policy.Manager
@@ -43,6 +49,11 @@ type Handler struct {
 	tnet *Net
 	dev  *device.Device
 	mu   sync.Mutex
+
+	// TODO: cache cleanup loop
+	local   bool
+	cache   map[string]entry
+	cacheMu sync.Mutex
 }
 
 func NewClient(ctx context.Context, conf *DeviceConfig) (*Handler, error) {
@@ -98,6 +109,20 @@ func NewClient(ctx context.Context, conf *DeviceConfig) (*Handler, error) {
 		return nil, err
 	}
 
+	local := false
+	dns := conf.DNS
+	if len(dns) == 0 {
+		dns = []string{"1.1.1.1", "1.0.0.1", "2606:4700:4700::1111", "2606:4700:4700::1001"}
+	}
+	if len(dns) == 1 && dns[0] == "local" {
+		local = true
+		dns = nil
+	}
+	dnses := make([]netip.Addr, 0, len(dns))
+	for _, dns := range dns {
+		dnses = append(dnses, netip.MustParseAddr(dns))
+	}
+
 	kernelTunSupported, err := KernelTunSupported()
 	if err != nil {
 		errors.LogWarningInner(context.Background(), err, "Failed to check kernel TUN support")
@@ -106,10 +131,10 @@ func NewClient(ctx context.Context, conf *DeviceConfig) (*Handler, error) {
 	var tnet *Net
 	if !conf.NoKernelTun && kernelTunSupported {
 		errors.LogWarning(context.Background(), "Using kernel TUN")
-		tun, tnet, err = createKernelTun(localAddresses, []netip.Addr{netip.MustParseAddr("1.1.1.1"), netip.MustParseAddr("1.0.0.1"), netip.MustParseAddr("2606:4700:4700::1111"), netip.MustParseAddr("2606:4700:4700::1001")}, int(conf.Mtu))
+		tun, tnet, err = createKernelTun(localAddresses, dnses, int(conf.Mtu))
 	} else {
 		errors.LogWarning(context.Background(), "Using gVisor TUN")
-		tun, tnet, _, err = CreateNetTUN(localAddresses, []netip.Addr{netip.MustParseAddr("1.1.1.1"), netip.MustParseAddr("1.0.0.1"), netip.MustParseAddr("2606:4700:4700::1111"), netip.MustParseAddr("2606:4700:4700::1001")}, int(conf.Mtu), true)
+		tun, tnet, _, err = CreateNetTUN(localAddresses, dnses, int(conf.Mtu), true)
 	}
 	if err != nil {
 		return nil, err
@@ -126,6 +151,9 @@ func NewClient(ctx context.Context, conf *DeviceConfig) (*Handler, error) {
 
 		tun:  tun,
 		tnet: tnet,
+
+		local: local,
+		cache: make(map[string]entry),
 	}, nil
 }
 
@@ -343,31 +371,34 @@ func (h *Handler) init(ctx context.Context) error {
 }
 
 func (h *Handler) resolveLocal(host string) (net.IP, error) {
-	return resolveDomain(host, h.conf.DomainStrategy, func(host string) ([]net.IP, error) {
-		ips, _, err := h.dns.LookupIP(host, dns.IPOption{IPv4Enable: true, IPv6Enable: true})
-		return ips, err
+	return h.resolveDomain(host, h.conf.DomainStrategy, func(host string) ([]net.IP, uint32, error) {
+		return h.dns.LookupIP(host, dns.IPOption{IPv4Enable: true, IPv6Enable: true})
 	})
 }
 
 func (h *Handler) resolveRemote(host string) (net.IP, error) {
-	return resolveDomain(host, h.conf.DomainStrategy, func(host string) ([]net.IP, error) {
-		addrs, err := h.tnet.LookupHost(host)
-		if err != nil {
-			return nil, err
-		}
-		ips := make([]net.IP, 0, len(addrs))
-		for _, addr := range addrs {
-			ips = append(ips, net.ParseIP(addr))
+	return h.resolveDomain(host, h.conf.DomainStrategy, func(host string) ([]net.IP, uint32, error) {
+		if h.local {
+			return h.dns.LookupIP(host, dns.IPOption{IPv4Enable: true, IPv6Enable: true})
 		}
-		return ips, nil
+		return h.tnet.LookupHost(host)
 	})
 }
 
-func resolveDomain(host string, strategy DeviceConfig_DomainStrategy, lookupIP func(host string) ([]net.IP, error)) (net.IP, error) {
+func (h *Handler) resolveDomain(host string, strategy DeviceConfig_DomainStrategy, lookupIP func(host string) ([]net.IP, uint32, error)) (net.IP, error) {
 	if ip := net.ParseIP(host); ip != nil {
 		return ip, nil
 	}
-	ips, err := lookupIP(host)
+	h.cacheMu.Lock()
+	if entry, ok := h.cache[host]; ok {
+		if time.Now().Before(entry.time) {
+			h.cacheMu.Unlock()
+			return entry.got[dice.Roll(len(entry.got))], nil
+		}
+		delete(h.cache, host)
+	}
+	h.cacheMu.Unlock()
+	ips, ttl, err := lookupIP(host)
 	if err != nil {
 		return nil, err
 	}
@@ -407,6 +438,13 @@ func resolveDomain(host string, strategy DeviceConfig_DomainStrategy, lookupIP f
 	if len(got) == 0 {
 		return nil, dns.ErrEmptyResponse
 	}
+	entry := entry{
+		got:  got,
+		time: time.Now().Add(time.Duration(ttl) * time.Second),
+	}
+	h.cacheMu.Lock()
+	h.cache[host] = entry
+	h.cacheMu.Unlock()
 	return got[dice.Roll(len(got))], nil
 }
 

proxy/wireguard/config.proto

@@ -34,4 +34,5 @@ message DeviceConfig {
   DomainStrategy domain_strategy = 7;
   bool is_client = 8;
   bool no_kernel_tun = 9;
+  repeated string DNS = 10;
 }

proxy/wireguard/netstack.go

@@ -248,7 +248,7 @@ var (
 	errTimeout                      = errors.New("i/o timeout")
 )
 
-func (net *Net) LookupHost(host string) (addrs []string, err error) {
+func (net *Net) LookupHost(host string) (addrs []net.IP, ttl uint32, err error) {
 	return net.LookupContextHost(context.Background(), host)
 }
 
@@ -567,9 +567,9 @@ func (tnet *Net) tryOneName(ctx context.Context, name string, qtype dnsmessage.T
 	return dnsmessage.Parser{}, "", lastErr
 }
 
-func (tnet *Net) LookupContextHost(ctx context.Context, host string) ([]string, error) {
+func (tnet *Net) LookupContextHost(ctx context.Context, host string) ([]net.IP, uint32, error) {
 	if host == "" || (!tnet.hasV6 && !tnet.hasV4) {
-		return nil, &net.DNSError{Err: errNoSuchHost.Error(), Name: host, IsNotFound: true}
+		return nil, 0, &net.DNSError{Err: errNoSuchHost.Error(), Name: host, IsNotFound: true}
 	}
 	zlen := len(host)
 	if strings.IndexByte(host, ':') != -1 {
@@ -578,11 +578,11 @@ func (tnet *Net) LookupContextHost(ctx context.Context, host string) ([]string,
 		}
 	}
 	if ip, err := netip.ParseAddr(host[:zlen]); err == nil {
-		return []string{ip.String()}, nil
+		return []net.IP{ip.AsSlice()}, 0, nil
 	}
 
 	if !isDomainName(host) {
-		return nil, &net.DNSError{Err: errNoSuchHost.Error(), Name: host, IsNotFound: true}
+		return nil, 0, &net.DNSError{Err: errNoSuchHost.Error(), Name: host, IsNotFound: true}
 	}
 	type result struct {
 		p      dnsmessage.Parser
@@ -611,6 +611,7 @@ func (tnet *Net) LookupContextHost(ctx context.Context, host string) ([]string,
 			lane <- result{p, server, err}
 		}()
 	}
+	ttl := uint32(300)
 	for l := 0; l < lanes; l++ {
 		result := <-lane
 		if result.error != nil {
@@ -644,6 +645,7 @@ func (tnet *Net) LookupContextHost(ctx context.Context, host string) ([]string,
 					}
 					break loop
 				}
+				ttl = min(ttl, h.TTL)
 				addrsV4 = append(addrsV4, netip.AddrFrom4(a.A))
 
 			case dnsmessage.TypeAAAA:
@@ -656,6 +658,7 @@ func (tnet *Net) LookupContextHost(ctx context.Context, host string) ([]string,
 					}
 					break loop
 				}
+				ttl = min(ttl, h.TTL)
 				addrsV6 = append(addrsV6, netip.AddrFrom16(aaaa.AAAA))
 
 			default:
@@ -680,11 +683,11 @@ func (tnet *Net) LookupContextHost(ctx context.Context, host string) ([]string,
 	}
 
 	if len(addrs) == 0 && lastErr != nil {
-		return nil, lastErr
+		return nil, 0, lastErr
 	}
-	saddrs := make([]string, 0, len(addrs))
+	ips := make([]net.IP, 0, len(addrs))
 	for _, ip := range addrs {
-		saddrs = append(saddrs, ip.String())
+		ips = append(ips, ip.AsSlice())
 	}
-	return saddrs, nil
+	return ips, ttl, nil
 }