feta: add hosts support domain and mulitple ip (#439)

* feat: host support domain and multiple ips

* chore: append local address via `clash`

* chore: update hosts demo

* chore: unified parse mixed string and array

* fix: flatten cname

* chore: adjust logic

* chore: reuse code

* chore: use cname in tunnel

* chore: try use domain mapping when normal dns

* chore: format code

component/resolver/host.go

@@ -0,0 +1,112 @@
+package resolver
+
+import (
+	"errors"
+	"math/rand"
+	"net/netip"
+	"strings"
+
+	"github.com/Dreamacro/clash/common/utils"
+	"github.com/Dreamacro/clash/component/trie"
+)
+
+type Hosts struct {
+	*trie.DomainTrie[HostValue]
+}
+
+func NewHosts(hosts *trie.DomainTrie[HostValue]) Hosts {
+	return Hosts{
+		hosts,
+	}
+}
+
+func (h *Hosts) Search(domain string, isDomain bool) (*HostValue, bool) {
+	value := h.DomainTrie.Search(domain)
+	if value == nil {
+		return nil, false
+	}
+	hostValue := value.Data()
+	for {
+		if isDomain && hostValue.IsDomain {
+			return &hostValue, true
+		} else {
+			if node := h.DomainTrie.Search(hostValue.Domain); node != nil {
+				hostValue = node.Data()
+			} else {
+				break
+			}
+		}
+	}
+	if isDomain == hostValue.IsDomain {
+		return &hostValue, true
+	}
+	return &hostValue, false
+}
+
+type HostValue struct {
+	IsDomain bool
+	IPs      []netip.Addr
+	Domain   string
+}
+
+func NewHostValue(value any) (HostValue, error) {
+	isDomain := true
+	ips := make([]netip.Addr, 0)
+	domain := ""
+	if valueArr, err := utils.ToStringSlice(value); err != nil {
+		return HostValue{}, err
+	} else {
+		if len(valueArr) > 1 {
+			isDomain = false
+			for _, str := range valueArr {
+				if ip, err := netip.ParseAddr(str); err == nil {
+					ips = append(ips, ip)
+				} else {
+					return HostValue{}, err
+				}
+			}
+		} else if len(valueArr) == 1 {
+			host := valueArr[0]
+			if ip, err := netip.ParseAddr(host); err == nil {
+				ips = append(ips, ip)
+				isDomain = false
+			} else {
+				domain = host
+			}
+		}
+	}
+	if isDomain {
+		return NewHostValueByDomain(domain)
+	} else {
+		return NewHostValueByIPs(ips)
+	}
+}
+
+func NewHostValueByIPs(ips []netip.Addr) (HostValue, error) {
+	if len(ips) == 0 {
+		return HostValue{}, errors.New("ip list is empty")
+	}
+	return HostValue{
+		IsDomain: false,
+		IPs:      ips,
+	}, nil
+}
+
+func NewHostValueByDomain(domain string) (HostValue, error) {
+	domain = strings.Trim(domain, ".")
+	item := strings.Split(domain, ".")
+	if len(item) < 2 {
+		return HostValue{}, errors.New("invaild domain")
+	}
+	return HostValue{
+		IsDomain: true,
+		Domain:   domain,
+	}, nil
+}
+
+func (hv HostValue) RandIP() (netip.Addr, error) {
+	if hv.IsDomain {
+		return netip.Addr{}, errors.New("value type is error")
+	}
+	return hv.IPs[rand.Intn(len(hv.IPs)-1)], nil
+}

component/resolver/resolver.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/Dreamacro/clash/common/utils"
 	"github.com/Dreamacro/clash/component/trie"
 
 	"github.com/miekg/dns"
@@ -27,7 +28,7 @@ var (
 	DisableIPv6 = true
 
 	// DefaultHosts aim to resolve hosts
-	DefaultHosts = trie.New[netip.Addr]()
+	DefaultHosts = NewHosts(trie.New[HostValue]())
 
 	// DefaultDNSTimeout defined the default dns request timeout
 	DefaultDNSTimeout = time.Second * 5
@@ -51,9 +52,11 @@ type Resolver interface {
 
 // LookupIPv4WithResolver same as LookupIPv4, but with a resolver
 func LookupIPv4WithResolver(ctx context.Context, host string, r Resolver) ([]netip.Addr, error) {
-	if node := DefaultHosts.Search(host); node != nil {
-		if ip := node.Data(); ip.Is4() {
-			return []netip.Addr{node.Data()}, nil
+	if node, ok := DefaultHosts.Search(host, false); ok {
+		if addrs := utils.Filter(node.IPs, func(ip netip.Addr) bool {
+			return ip.Is4()
+		}); len(addrs) > 0 {
+			return addrs, nil
 		}
 	}
 
@@ -106,9 +109,11 @@ func LookupIPv6WithResolver(ctx context.Context, host string, r Resolver) ([]net
 		return nil, ErrIPv6Disabled
 	}
 
-	if node := DefaultHosts.Search(host); node != nil {
-		if ip := node.Data(); ip.Is6() {
-			return []netip.Addr{ip}, nil
+	if node, ok := DefaultHosts.Search(host, false); ok {
+		if addrs := utils.Filter(node.IPs, func(ip netip.Addr) bool {
+			return ip.Is6()
+		}); len(addrs) > 0 {
+			return addrs, nil
 		}
 	}
 
@@ -155,8 +160,8 @@ func ResolveIPv6(ctx context.Context, host string) (netip.Addr, error) {
 
 // LookupIPWithResolver same as LookupIP, but with a resolver
 func LookupIPWithResolver(ctx context.Context, host string, r Resolver) ([]netip.Addr, error) {
-	if node := DefaultHosts.Search(host); node != nil {
-		return []netip.Addr{node.Data()}, nil
+	if node, ok := DefaultHosts.Search(host, false); ok {
+		return node.IPs, nil
 	}
 
 	if r != nil {