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
@@ -63,13 +65,14 @@ type Config struct {
 }
 
 type rawDNS struct {
-	Enable       bool             `yaml:"enable"`
-	IPv6         bool             `yaml:"ipv6"`
-	NameServer   []string         `yaml:"nameserver"`
-	Fallback     []string         `yaml:"fallback"`
-	Listen       string           `yaml:"listen"`
-	EnhancedMode dns.EnhancedMode `yaml:"enhanced-mode"`
-	FakeIPRange  string           `yaml:"fake-ip-range"`
+	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"`
+	FakeIPRange  string            `yaml:"fake-ip-range"`
 }
 
 type rawConfig struct {
@@ -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)
+}