Feature: sync missing resolver logic from premium, but still net.IP on opensource

component/resolver/resolver.go

@@ -3,6 +3,7 @@ package resolver
 import (
 	"context"
 	"errors"
+	"fmt"
 	"math/rand"
 	"net"
 	"strings"
@@ -33,29 +34,32 @@ var (
 )
 
 type Resolver interface {
+	LookupIP(ctx context.Context, host string) ([]net.IP, error)
+	LookupIPv4(ctx context.Context, host string) ([]net.IP, error)
+	LookupIPv6(ctx context.Context, host string) ([]net.IP, error)
 	ResolveIP(host string) (ip net.IP, err error)
 	ResolveIPv4(host string) (ip net.IP, err error)
 	ResolveIPv6(host string) (ip net.IP, err error)
 }
 
-// ResolveIPv4 with a host, return ipv4
-func ResolveIPv4(host string) (net.IP, error) {
+// LookupIPv4 with a host, return ipv4 list
+func LookupIPv4(ctx context.Context, host string) ([]net.IP, error) {
 	if node := DefaultHosts.Search(host); node != nil {
 		if ip := node.Data.(net.IP).To4(); ip != nil {
-			return ip, nil
+			return []net.IP{ip}, nil
 		}
 	}
 
 	ip := net.ParseIP(host)
 	if ip != nil {
 		if !strings.Contains(host, ":") {
-			return ip, nil
+			return []net.IP{ip}, nil
 		}
 		return nil, ErrIPVersion
 	}
 
 	if DefaultResolver != nil {
-		return DefaultResolver.ResolveIPv4(host)
+		return DefaultResolver.LookupIPv4(ctx, host)
 	}
 
 	ctx, cancel := context.WithTimeout(context.Background(), DefaultDNSTimeout)
@@ -67,31 +71,42 @@ func ResolveIPv4(host string) (net.IP, error) {
 		return nil, ErrIPNotFound
 	}
 
-	return ipAddrs[rand.Intn(len(ipAddrs))], nil
+	return ipAddrs, nil
 }
 
-// ResolveIPv6 with a host, return ipv6
-func ResolveIPv6(host string) (net.IP, error) {
+// ResolveIPv4 with a host, return ipv4
+func ResolveIPv4(host string) (net.IP, error) {
+	ips, err := LookupIPv4(context.Background(), host)
+	if err != nil {
+		return nil, err
+	} else if len(ips) == 0 {
+		return nil, fmt.Errorf("%w: %s", ErrIPNotFound, host)
+	}
+	return ips[rand.Intn(len(ips))], nil
+}
+
+// LookupIPv6 with a host, return ipv6 list
+func LookupIPv6(ctx context.Context, host string) ([]net.IP, error) {
 	if DisableIPv6 {
 		return nil, ErrIPv6Disabled
 	}
 
 	if node := DefaultHosts.Search(host); node != nil {
 		if ip := node.Data.(net.IP).To16(); ip != nil {
-			return ip, nil
+			return []net.IP{ip}, nil
 		}
 	}
 
 	ip := net.ParseIP(host)
 	if ip != nil {
 		if strings.Contains(host, ":") {
-			return ip, nil
+			return []net.IP{ip}, nil
 		}
 		return nil, ErrIPVersion
 	}
 
 	if DefaultResolver != nil {
-		return DefaultResolver.ResolveIPv6(host)
+		return DefaultResolver.LookupIPv6(ctx, host)
 	}
 
 	ctx, cancel := context.WithTimeout(context.Background(), DefaultDNSTimeout)
@@ -103,38 +118,62 @@ func ResolveIPv6(host string) (net.IP, error) {
 		return nil, ErrIPNotFound
 	}
 
-	return ipAddrs[rand.Intn(len(ipAddrs))], nil
+	return ipAddrs, nil
 }
 
-// ResolveIPWithResolver same as ResolveIP, but with a resolver
-func ResolveIPWithResolver(host string, r Resolver) (net.IP, error) {
+// ResolveIPv6 with a host, return ipv6
+func ResolveIPv6(host string) (net.IP, error) {
+	ips, err := LookupIPv6(context.Background(), host)
+	if err != nil {
+		return nil, err
+	} else if len(ips) == 0 {
+		return nil, fmt.Errorf("%w: %s", ErrIPNotFound, host)
+	}
+	return ips[rand.Intn(len(ips))], nil
+}
+
+// LookupIPWithResolver same as ResolveIP, but with a resolver
+func LookupIPWithResolver(ctx context.Context, host string, r Resolver) ([]net.IP, error) {
 	if node := DefaultHosts.Search(host); node != nil {
-		return node.Data.(net.IP), nil
+		return []net.IP{node.Data.(net.IP)}, nil
 	}
 
 	if r != nil {
 		if DisableIPv6 {
-			return r.ResolveIPv4(host)
+			return r.LookupIPv4(ctx, host)
 		}
-		return r.ResolveIP(host)
+		return r.LookupIP(ctx, host)
 	} else if DisableIPv6 {
-		return ResolveIPv4(host)
+		return LookupIPv4(ctx, host)
 	}
 
 	ip := net.ParseIP(host)
 	if ip != nil {
-		return ip, nil
+		return []net.IP{ip}, nil
 	}
 
-	ipAddr, err := net.ResolveIPAddr("ip", host)
+	ips, err := net.DefaultResolver.LookupIP(ctx, "ip", host)
 	if err != nil {
 		return nil, err
+	} else if len(ips) == 0 {
+		return nil, ErrIPNotFound
 	}
 
-	return ipAddr.IP, nil
+	return ips, nil
+}
+
+// ResolveIP with a host, return ip
+func LookupIP(ctx context.Context, host string) ([]net.IP, error) {
+	return LookupIPWithResolver(ctx, host, DefaultResolver)
 }
 
 // ResolveIP with a host, return ip
 func ResolveIP(host string) (net.IP, error) {
-	return ResolveIPWithResolver(host, DefaultResolver)
+	ips, err := LookupIP(context.Background(), host)
+	if err != nil {
+		return nil, err
+	} else if len(ips) == 0 {
+		return nil, fmt.Errorf("%w: %s", ErrIPNotFound, host)
+	}
+	return ips[rand.Intn(len(ips))], nil
 }