Feature(dns): support custom hosts

README.md

@@ -120,6 +120,12 @@ experimental:
   # listen: 0.0.0.0:53
   # enhanced-mode: redir-host # or fake-ip
   # # fake-ip-range: 198.18.0.1/16 # if you don't know what it is, don't change it
+  # # experimental hosts, support wildcard (e.g. *.clash.dev Even *.foo.*.example.com)
+  # # static domain has a higher priority than wildcard domain (foo.example.com > *.example.com)
+  # # NOTE: hosts don't work with `fake-ip`
+  # hosts:
+  #   '*.clash.dev': 127.0.0.1
+  #   'alpha.clash.dev': '::1'
   # nameserver:
   #   - 114.114.114.114
   #   - tls://dns.rubyfish.cn:853 # dns over tls

component/domain-trie/node.go

@@ -0,0 +1,26 @@
+package trie
+
+// Node is the trie's node
+type Node struct {
+	Data     interface{}
+	children map[string]*Node
+}
+
+func (n *Node) getChild(s string) *Node {
+	return n.children[s]
+}
+
+func (n *Node) hasChild(s string) bool {
+	return n.getChild(s) != nil
+}
+
+func (n *Node) addChild(s string, child *Node) {
+	n.children[s] = child
+}
+
+func newNode(data interface{}) *Node {
+	return &Node{
+		Data:     data,
+		children: map[string]*Node{},
+	}
+}

component/domain-trie/tire.go

@@ -0,0 +1,84 @@
+package trie
+
+import (
+	"errors"
+	"strings"
+)
+
+const (
+	wildcard   = "*"
+	domainStep = "."
+)
+
+var (
+	// ErrInvalidDomain means insert domain is invalid
+	ErrInvalidDomain = errors.New("invalid domain")
+)
+
+// Trie contains the main logic for adding and searching nodes for domain segments.
+// support wildcard domain (e.g *.google.com)
+type Trie struct {
+	root *Node
+}
+
+// Insert adds a node to the trie.
+// Support
+// 1. www.example.com
+// 2. *.example.com
+// 3. subdomain.*.example.com
+func (t *Trie) Insert(domain string, data interface{}) error {
+	parts := strings.Split(domain, domainStep)
+	if len(parts) < 2 {
+		return ErrInvalidDomain
+	}
+
+	node := t.root
+	// reverse storage domain part to save space
+	for i := len(parts) - 1; i >= 0; i-- {
+		part := parts[i]
+		if !node.hasChild(part) {
+			node.addChild(part, newNode(nil))
+		}
+
+		node = node.getChild(part)
+	}
+
+	node.Data = data
+	return nil
+}
+
+// Search is the most important part of the Trie.
+// Priority as:
+// 1. static part
+// 2. wildcard domain
+func (t *Trie) Search(domain string) *Node {
+	parts := strings.Split(domain, domainStep)
+	if len(parts) < 2 {
+		return nil
+	}
+
+	n := t.root
+	for i := len(parts) - 1; i >= 0; i-- {
+		part := parts[i]
+
+		var child *Node
+		if !n.hasChild(part) {
+			if !n.hasChild(wildcard) {
+				return nil
+			}
+
+			child = n.getChild(wildcard)
+		} else {
+			child = n.getChild(part)
+		}
+
+		n = child
+	}
+
+	return n
+}
+
+// New returns a new, empty Trie.
+func New() *Trie {
+	return &Trie{root: newNode(nil)}
+}

component/domain-trie/trie_test.go

@@ -0,0 +1,69 @@
+package trie
+
+import (
+	"net"
+	"testing"
+)
+
+func TestTrie_Basic(t *testing.T) {
+	tree := New()
+	domains := []string{
+		"example.com",
+		"google.com",
+	}
+
+	for _, domain := range domains {
+		tree.Insert(domain, net.ParseIP("127.0.0.1"))
+	}
+
+	node := tree.Search("example.com")
+	if node == nil {
+		t.Error("should not recv nil")
+	}
+
+	if !node.Data.(net.IP).Equal(net.IP{127, 0, 0, 1}) {
+		t.Error("should equal 127.0.0.1")
+	}
+}
+
+func TestTrie_Wildcard(t *testing.T) {
+	tree := New()
+	domains := []string{
+		"*.example.com",
+		"sub.*.example.com",
+		"*.dev",
+	}
+
+	for _, domain := range domains {
+		tree.Insert(domain, nil)
+	}
+
+	if tree.Search("sub.example.com") == nil {
+		t.Error("should not recv nil")
+	}
+
+	if tree.Search("sub.foo.example.com") == nil {
+		t.Error("should not recv nil")
+	}
+
+	if tree.Search("foo.sub.example.com") != nil {
+		t.Error("should recv nil")
+	}
+
+	if tree.Search("foo.example.dev") != nil {
+		t.Error("should recv nil")
+	}
+}
+
+func TestTrie_Boundary(t *testing.T) {
+	tree := New()
+	tree.Insert("*.dev", nil)
+
+	if err := tree.Insert("com", nil); err == nil {
+		t.Error("should recv err")
+	}
+
+	if tree.Search("dev") != nil {
+		t.Error("should recv nil")
+	}
+}

config/config.go

@@ -12,6 +12,7 @@ import (
 	adapters "github.com/Dreamacro/clash/adapters/outbound"
 	"github.com/Dreamacro/clash/common/structure"
 	"github.com/Dreamacro/clash/component/auth"
+	trie "github.com/Dreamacro/clash/component/domain-trie"
 	"github.com/Dreamacro/clash/component/fakeip"
 	C "github.com/Dreamacro/clash/constant"
 	"github.com/Dreamacro/clash/dns"
@@ -42,6 +43,7 @@ type DNS struct {
 	IPv6         bool             `yaml:"ipv6"`
 	NameServer   []dns.NameServer `yaml:"nameserver"`
 	Fallback     []dns.NameServer `yaml:"fallback"`
+	Hosts        *trie.Trie       `yaml:"-"`
 	Listen       string           `yaml:"listen"`
 	EnhancedMode dns.EnhancedMode `yaml:"enhanced-mode"`
 	FakeIPRange  *fakeip.Pool
@@ -66,6 +68,7 @@ type rawDNS struct {
 	Enable       bool              `yaml:"enable"`
 	IPv6         bool              `yaml:"ipv6"`
 	NameServer   []string          `yaml:"nameserver"`
+	Hosts        map[string]string `yaml:"hosts"`
 	Fallback     []string          `yaml:"fallback"`
 	Listen       string            `yaml:"listen"`
 	EnhancedMode dns.EnhancedMode  `yaml:"enhanced-mode"`
@@ -134,6 +137,7 @@ func readConfig(path string) (*rawConfig, error) {
 		DNS: rawDNS{
 			Enable:      false,
 			FakeIPRange: "198.18.0.1/16",
+			Hosts:       map[string]string{},
 		},
 	}
 	err = yaml.Unmarshal([]byte(data), &rawConfig)
@@ -518,6 +522,18 @@ func parseDNS(cfg rawDNS) (*DNS, error) {
 		return nil, err
 	}
 
+	if len(cfg.Hosts) != 0 {
+		tree := trie.New()
+		for domain, ipStr := range cfg.Hosts {
+			ip := net.ParseIP(ipStr)
+			if ip == nil {
+				return nil, fmt.Errorf("%s is not a valid IP", ipStr)
+			}
+			tree.Insert(domain, ip)
+		}
+		dnsCfg.Hosts = tree
+	}
+
 	if cfg.EnhancedMode == dns.FAKEIP {
 		_, ipnet, err := net.ParseCIDR(cfg.FakeIPRange)
 		if err != nil {

dns/middleware.go

@@ -0,0 +1,121 @@
+package dns
+
+import (
+	"fmt"
+	"net"
+	"strings"
+
+	"github.com/Dreamacro/clash/common/cache"
+	"github.com/Dreamacro/clash/component/fakeip"
+	"github.com/Dreamacro/clash/log"
+
+	D "github.com/miekg/dns"
+)
+
+type handler func(w D.ResponseWriter, r *D.Msg)
+
+func withFakeIP(cache *cache.Cache, pool *fakeip.Pool) handler {
+	return func(w D.ResponseWriter, r *D.Msg) {
+		q := r.Question[0]
+
+		cacheItem := cache.Get("fakeip:" + q.String())
+		if cache != nil {
+			msg := cacheItem.(*D.Msg).Copy()
+			setMsgTTL(msg, 1)
+			msg.SetReply(r)
+			w.WriteMsg(msg)
+			return
+		}
+
+		rr := &D.A{}
+		rr.Hdr = D.RR_Header{Name: q.Name, Rrtype: D.TypeA, Class: D.ClassINET, Ttl: dnsDefaultTTL}
+		ip := pool.Get()
+		rr.A = ip
+		msg := r.Copy()
+		msg.Answer = []D.RR{rr}
+		putMsgToCache(cache, "fakeip:"+q.String(), msg)
+		putMsgToCache(cache, ip.String(), msg)
+
+		setMsgTTL(msg, 1)
+		return
+	}
+}
+
+func withResolver(resolver *Resolver) handler {
+	return func(w D.ResponseWriter, r *D.Msg) {
+		msg, err := resolver.Exchange(r)
+
+		if err != nil {
+			q := r.Question[0]
+			qString := fmt.Sprintf("%s %s %s", q.Name, D.Class(q.Qclass).String(), D.Type(q.Qtype).String())
+			log.Debugln("[DNS Server] Exchange %s failed: %v", qString, err)
+			D.HandleFailed(w, r)
+			return
+		}
+		msg.SetReply(r)
+		w.WriteMsg(msg)
+		return
+	}
+}
+
+func withHost(resolver *Resolver, next handler) handler {
+	hosts := resolver.hosts
+	if hosts == nil {
+		panic("dns/withHost: hosts should not be nil")
+	}
+
+	return func(w D.ResponseWriter, r *D.Msg) {
+		q := r.Question[0]
+		if q.Qtype != D.TypeA && q.Qtype != D.TypeAAAA {
+			next(w, r)
+			return
+		}
+
+		domain := strings.TrimRight(q.Name, ".")
+		host := hosts.Search(domain)
+		if host == nil {
+			next(w, r)
+			return
+		}
+
+		ip := host.Data.(net.IP)
+		if q.Qtype == D.TypeAAAA && ip.To16() == nil {
+			next(w, r)
+			return
+		} else if q.Qtype == D.TypeA && ip.To4() == nil {
+			next(w, r)
+			return
+		}
+
+		var rr D.RR
+		if q.Qtype == D.TypeAAAA {
+			record := &D.AAAA{}
+			record.Hdr = D.RR_Header{Name: q.Name, Rrtype: D.TypeAAAA, Class: D.ClassINET, Ttl: dnsDefaultTTL}
+			record.AAAA = ip
+			rr = record
+		} else {
+			record := &D.A{}
+			record.Hdr = D.RR_Header{Name: q.Name, Rrtype: D.TypeA, Class: D.ClassINET, Ttl: dnsDefaultTTL}
+			record.A = ip
+			rr = record
+		}
+
+		msg := r.Copy()
+		msg.Answer = []D.RR{rr}
+		msg.SetReply(r)
+		w.WriteMsg(msg)
+		return
+	}
+}
+
+func newHandler(resolver *Resolver) handler {
+	if resolver.IsFakeIP() {
+		return withFakeIP(resolver.cache, resolver.pool)
+	}
+
+	if resolver.hosts != nil {
+		return withHost(resolver, withResolver(resolver))
+	}
+
+	return withResolver(resolver)
+}

dns/resolver.go

@@ -11,11 +11,13 @@ import (
 
 	"github.com/Dreamacro/clash/common/cache"
 	"github.com/Dreamacro/clash/common/picker"
+	trie "github.com/Dreamacro/clash/component/domain-trie"
 	"github.com/Dreamacro/clash/component/fakeip"
 	C "github.com/Dreamacro/clash/constant"
 
 	D "github.com/miekg/dns"
 	geoip2 "github.com/oschwald/geoip2-golang"
+	"golang.org/x/sync/singleflight"
 )
 
 var (
@@ -44,9 +46,11 @@ type Resolver struct {
 	ipv6     bool
 	mapping  bool
 	fakeip   bool
+	hosts    *trie.Trie
 	pool     *fakeip.Pool
 	fallback []resolver
 	main     []resolver
+	group    singleflight.Group
 	cache    *cache.Cache
 }
 
@@ -134,13 +138,20 @@ func (r *Resolver) Exchange(m *D.Msg) (msg *D.Msg, err error) {
 		}
 	}()
 
+	ret, err, _ := r.group.Do(q.String(), func() (interface{}, error) {
 		isIPReq := isIPRequest(q)
 		if isIPReq {
-		msg, err = r.fallbackExchange(m)
-		return
+			msg, err := r.fallbackExchange(m)
+			return msg, err
+		}
+
+		return r.batchExchange(r.main, m)
+	})
+
+	if err == nil {
+		msg = ret.(*D.Msg)
 	}
 
-	msg, err = r.batchExchange(r.main, m)
 	return
 }
 
@@ -266,6 +277,7 @@ type Config struct {
 	Main, Fallback []NameServer
 	IPv6           bool
 	EnhancedMode   EnhancedMode
+	Hosts          *trie.Trie
 	Pool           *fakeip.Pool
 }
 
@@ -280,6 +292,7 @@ func New(config Config) *Resolver {
 		cache:   cache.New(time.Second * 60),
 		mapping: config.EnhancedMode == MAPPING,
 		fakeip:  config.EnhancedMode == FAKEIP,
+		hosts:   config.Hosts,
 		pool:    config.Pool,
 	}
 	if len(config.Fallback) != 0 {

dns/server.go

@@ -1,12 +1,8 @@
 package dns
 
 import (
-	"errors"
-	"fmt"
 	"net"
 
-	"github.com/Dreamacro/clash/log"
-	"github.com/miekg/dns"
 	D "github.com/miekg/dns"
 )
 
@@ -19,79 +15,26 @@ var (
 
 type Server struct {
 	*D.Server
-	r *Resolver
+	handler handler
 }
 
 func (s *Server) ServeDNS(w D.ResponseWriter, r *D.Msg) {
-	if s.r.IsFakeIP() {
-		msg, err := s.handleFakeIP(r)
-		if err != nil {
-			D.HandleFailed(w, r)
-			return
-		}
-		msg.SetReply(r)
-		w.WriteMsg(msg)
-		return
-	}
-
-	msg, err := s.r.Exchange(r)
-
-	if err != nil {
-		if len(r.Question) > 0 {
-			q := r.Question[0]
-			qString := fmt.Sprintf("%s %s %s", q.Name, D.Class(q.Qclass).String(), D.Type(q.Qtype).String())
-			log.Debugln("[DNS Server] Exchange %s failed: %v", qString, err)
-		}
-		D.HandleFailed(w, r)
-		return
-	}
-	msg.SetReply(r)
-	w.WriteMsg(msg)
-}
-
-func (s *Server) handleFakeIP(r *D.Msg) (msg *D.Msg, err error) {
 	if len(r.Question) == 0 {
-		err = errors.New("should have one question at least")
+		D.HandleFailed(w, r)
 		return
 	}
 
-	q := r.Question[0]
-
-	cache := s.r.cache.Get("fakeip:" + q.String())
-	if cache != nil {
-		msg = cache.(*D.Msg).Copy()
-		setMsgTTL(msg, 1)
-		return
-	}
-
-	var ip net.IP
-	defer func() {
-		if msg == nil {
-			return
-		}
-
-		putMsgToCache(s.r.cache, "fakeip:"+q.String(), msg)
-		putMsgToCache(s.r.cache, ip.String(), msg)
-
-		setMsgTTL(msg, 1)
-	}()
-
-	rr := &D.A{}
-	rr.Hdr = dns.RR_Header{Name: r.Question[0].Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: dnsDefaultTTL}
-	ip = s.r.pool.Get()
-	rr.A = ip
-	msg = r.Copy()
-	msg.Answer = []D.RR{rr}
-	return
+	s.handler(w, r)
 }
 
-func (s *Server) setReslover(r *Resolver) {
-	s.r = r
+func (s *Server) setHandler(handler handler) {
+	s.handler = handler
 }
 
 func ReCreateServer(addr string, resolver *Resolver) error {
 	if addr == address {
-		server.setReslover(resolver)
+		handler := newHandler(resolver)
+		server.setHandler(handler)
 		return nil
 	}
 
@@ -116,7 +59,8 @@ func ReCreateServer(addr string, resolver *Resolver) error {
 	}
 
 	address = addr
-	server = &Server{r: resolver}
+	handler := newHandler(resolver)
+	server = &Server{handler: handler}
 	server.Server = &D.Server{Addr: addr, PacketConn: p, Handler: server}
 
 	go func() {

go.mod

@@ -14,7 +14,7 @@ require (
 	github.com/sirupsen/logrus v1.4.2
 	golang.org/x/crypto v0.0.0-20190426145343-a29dc8fdc734
 	golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3
-	golang.org/x/sync v0.0.0-20190423024810-112230192c58 // indirect
+	golang.org/x/sync v0.0.0-20190423024810-112230192c58
 	gopkg.in/eapache/channels.v1 v1.1.0
 	gopkg.in/yaml.v2 v2.2.2
 )

hub/executor/executor.go

@@ -67,6 +67,7 @@ func updateDNS(c *config.DNS) {
 		Main:         c.NameServer,
 		Fallback:     c.Fallback,
 		IPv6:         c.IPv6,
+		Hosts:        c.Hosts,
 		EnhancedMode: c.EnhancedMode,
 		Pool:         c.FakeIPRange,
 	})