Release 2.6.1: resolve AWG endpoint hostnames to IP before connect.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/protocols/awg/conf.go

@@ -1,6 +1,7 @@
 package awg
 
 import (
+	"context"
 	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
@@ -9,6 +10,7 @@ import (
 	"net/netip"
 	"strconv"
 	"strings"
+	"time"
 )
 
 // Conf is a parsed AmneziaWG / WireGuard client configuration (AWG 2.0 fields included).
@@ -444,7 +446,117 @@ func HostPort(raw string) (host, port string, err error) {
 	return h, p, nil
 }
 
+// lookupIP is overridable in tests.
+var lookupIP = defaultLookupIP
+
+func defaultLookupIP(host string) ([]net.IP, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 8*time.Second)
+	defer cancel()
+
+	try := func(r *net.Resolver) ([]net.IP, error) {
+		addrs, err := r.LookupIPAddr(ctx, host)
+		if err != nil {
+			return nil, err
+		}
+		out := make([]net.IP, 0, len(addrs))
+		for _, a := range addrs {
+			if a.IP != nil {
+				out = append(out, a.IP)
+			}
+		}
+		if len(out) == 0 {
+			return nil, fmt.Errorf("нет IP-адресов")
+		}
+		return out, nil
+	}
+
+	// PreferGo avoids flaky Windows WinDNS "No such host" for some A/AAAA shapes.
+	if ips, err := try(&net.Resolver{PreferGo: true, Dial: resolverDial}); err == nil {
+		return ips, nil
+	}
+	if ips, err := try(net.DefaultResolver); err == nil {
+		return ips, nil
+	}
+	// Last resort: classic LookupIP (system).
+	return net.LookupIP(host)
+}
+
+func resolverDial(ctx context.Context, network, _ string) (net.Conn, error) {
+	d := net.Dialer{Timeout: 3 * time.Second}
+	var last error
+	for _, dns := range []string{"1.1.1.1:53", "8.8.8.8:53", "9.9.9.9:53"} {
+		c, err := d.DialContext(ctx, network, dns)
+		if err == nil {
+			return c, nil
+		}
+		last = err
+	}
+	return nil, last
+}
+
+// ResolveEndpoint turns "hostname:port" into "ip:port" for amneziawg-go IpcSet
+// (which fails on bare hostnames with "No such host is known"). Prefers IPv4.
+func ResolveEndpoint(endpoint string) (string, error) {
+	return resolveEndpointWith(endpoint, lookupIP)
+}
+
+// ResolveEndpoint rewrites c.Endpoint to a resolved IP:port (IPv4 preferred).
+func (c *Conf) ResolveEndpoint() error {
+	resolved, err := ResolveEndpoint(c.Endpoint)
+	if err != nil {
+		return err
+	}
+	c.Endpoint = resolved
+	return nil
+}
+
+func resolveEndpointWith(endpoint string, lookup func(string) ([]net.IP, error)) (string, error) {
+	endpoint = strings.TrimSpace(endpoint)
+	if endpoint == "" {
+		return "", fmt.Errorf("awg: нет Endpoint")
+	}
+	host, port, err := net.SplitHostPort(endpoint)
+	if err != nil {
+		host = trimBrackets(endpoint)
+		port = "51820"
+	} else {
+		host = trimBrackets(host)
+	}
+	if host == "" {
+		return "", fmt.Errorf("awg: нет Endpoint")
+	}
+	if ip := net.ParseIP(host); ip != nil {
+		return net.JoinHostPort(ip.String(), port), nil
+	}
+	ips, err := lookup(host)
+	if err != nil {
+		return "", fmt.Errorf("awg: не удалось разрешить DNS для Endpoint %q: %v", host, err)
+	}
+	var v4, v6 net.IP
+	for _, ip := range ips {
+		if ip == nil {
+			continue
+		}
+		if ip4 := ip.To4(); ip4 != nil {
+			v4 = ip4
+			break
+		}
+		if v6 == nil {
+			v6 = ip
+		}
+	}
+	chosen := v4
+	if chosen == nil {
+		chosen = v6
+	}
+	if chosen == nil {
+		return "", fmt.Errorf("awg: не удалось разрешить DNS для Endpoint %q: нет IP-адресов", host)
+	}
+	return net.JoinHostPort(chosen.String(), port), nil
+}
+
 // ToIPC builds the amneziawg-go UAPI configuration string.
+// Endpoint hostnames are resolved to IP first (IPv4 preferred).
 func (c Conf) ToIPC() (string, error) {
 	priv, err := decodeKey(c.PrivateKey)
 	if err != nil {
@@ -454,6 +566,10 @@ func (c Conf) ToIPC() (string, error) {
 	if err != nil {
 		return "", fmt.Errorf("public key: %w", err)
 	}
+	endpoint, err := ResolveEndpoint(c.Endpoint)
+	if err != nil {
+		return "", err
+	}
 	var b strings.Builder
 	b.WriteString("private_key=")
 	b.WriteString(hex.EncodeToString(priv))
@@ -477,7 +593,7 @@ func (c Conf) ToIPC() (string, error) {
 	b.WriteString("\npublic_key=")
 	b.WriteString(hex.EncodeToString(pub))
 	b.WriteString("\nendpoint=")
-	b.WriteString(c.Endpoint)
+	b.WriteString(endpoint)
 	for _, ip := range c.AllowedIPs {
 		b.WriteString("\nallowed_ip=")
 		b.WriteString(strings.TrimSpace(ip))