From 2eed62f1e2a985f5d522899f27aafd9f227f1a2b Mon Sep 17 00:00:00 2001
From: Frank Denis <github@pureftpd.org>
Date: Sun, 4 Feb 2018 12:39:33 +0100
Subject: [PATCH] Add a setMaxTTL() function

Will be useful to interprete HTTP cache headers in DoH
---
 dnscrypt-proxy/dnsutils.go | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/dnscrypt-proxy/dnsutils.go b/dnscrypt-proxy/dnsutils.go
index 6ee90b7c..0fc217d1 100644
--- a/dnscrypt-proxy/dnsutils.go
+++ b/dnscrypt-proxy/dnsutils.go
@@ -73,3 +73,21 @@ func getMinTTL(msg *dns.Msg, minTTL uint32, maxTTL uint32, negCacheMinTTL uint32
 	}
 	return time.Duration(ttl) * time.Second
 }
+
+func setMaxTTL(msg *dns.Msg, ttl uint32) {
+	for _, rr := range msg.Answer {
+		if ttl < rr.Header().Ttl {
+			rr.Header().Ttl = ttl
+		}
+	}
+	for _, rr := range msg.Ns {
+		if ttl < rr.Header().Ttl {
+			rr.Header().Ttl = ttl
+		}
+	}
+	for _, rr := range msg.Extra {
+		if ttl < rr.Header().Ttl {
+			rr.Header().Ttl = ttl
+		}
+	}
+}