From 72d223fed7f8e4ef364ca385836f68bebe2da9ac Mon Sep 17 00:00:00 2001
From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Wed, 12 Jul 2023 10:49:31 +0200
Subject: [PATCH] calidns: Fix setting an ECS source of 0

(cherry picked from commit ba770e4f65aefdadc489a169ae66fd20c897162c)
---
 pdns/calidns.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pdns/calidns.cc b/pdns/calidns.cc
index 89886e3a70..6a3cf25c59 100644
--- a/pdns/calidns.cc
+++ b/pdns/calidns.cc
@@ -121,7 +121,7 @@ static ComboAddress getRandomAddressFromRange(const Netmask& ecsRange)
 {
   ComboAddress result = ecsRange.getMaskedNetwork();
   uint8_t bits = ecsRange.getBits();
-  uint32_t mod = 1 << (32 - bits);
+  uint32_t mod = (bits > 0) ? (1 << (32 - bits)) : std::numeric_limits<uint32_t>::max();
   result.sin4.sin_addr.s_addr = result.sin4.sin_addr.s_addr + ntohl(dns_random(mod));
   return result;
 }
-- 
2.47.2