Switch to lightweight secure DNS client

resolver/plain.go

@@ -0,0 +1,35 @@
+package resolver
+
+import (
+	"context"
+	"net"
+)
+
+func NewPlainResolver(addr string) *net.Resolver {
+	return &net.Resolver{
+		PreferGo: true,
+		Dial: func(ctx context.Context, network, _ string) (net.Conn, error) {
+			return (&net.Dialer{
+				Resolver: &net.Resolver{},
+			}).DialContext(ctx, network, addr)
+		},
+	}
+}
+
+func NewTCPResolver(addr string) *net.Resolver {
+	return &net.Resolver{
+		PreferGo: true,
+		Dial: func(ctx context.Context, network, _ string) (net.Conn, error) {
+			dnet := "tcp"
+			switch (network) {
+			case "udp4":
+				dnet = "tcp4"
+			case "udp6":
+				dnet = "tcp6"
+			}
+			return (&net.Dialer{
+				Resolver: &net.Resolver{},
+			}).DialContext(ctx, dnet, addr)
+		},
+	}
+}