feat: host support domain and multiple ips

component/resolver/host.go

@@ -0,0 +1,78 @@
+package resolver
+
+import (
+	"errors"
+	"fmt"
+	"math/rand"
+	"net/netip"
+	"reflect"
+	"strings"
+)
+
+type HostValue struct {
+	IsDomain bool
+	IPs      []netip.Addr
+	Domain   string
+}
+
+func NewHostValue(value any) (HostValue, error) {
+	isDomain := true
+	ips := make([]netip.Addr, 0)
+	domain := ""
+	switch reflect.TypeOf(value).Kind() {
+	case reflect.Slice, reflect.Array:
+		isDomain = false
+		origin := reflect.ValueOf(value)
+		for i := 0; i < origin.Len(); i++ {
+			if ip, err := netip.ParseAddr(fmt.Sprintf("%v", origin.Index(i))); err == nil {
+				ips = append(ips, ip)
+			} else {
+				return HostValue{}, err
+			}
+		}
+	case reflect.String:
+		host := fmt.Sprintf("%v", value)
+		if ip, err := netip.ParseAddr(host); err == nil {
+			ips = append(ips, ip)
+			isDomain = false
+		} else {
+			domain = host
+		}
+	default:
+		return HostValue{}, errors.New("value format error, must be string or array")
+	}
+	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
+}