Fix #706 -- rDNS for DOH/DOT clients

dnsforward/helpers.go

@@ -0,0 +1,14 @@
+package dnsforward
+
+import "net"
+
+// GetIPString is a helper function that extracts IP address from net.Addr
+func GetIPString(addr net.Addr) string {
+	switch addr := addr.(type) {
+	case *net.UDPAddr:
+		return addr.IP.String()
+	case *net.TCPAddr:
+		return addr.IP.String()
+	}
+	return ""
+}