From e0c37f92fc92d466b48c1985046bf9f5e2d7e648 Mon Sep 17 00:00:00 2001
From: Frank Denis <github@pureftpd.org>
Date: Sun, 3 Nov 2019 00:33:17 +0100
Subject: [PATCH] Add a comment about why DoH addresses from stamps don't
 expire

---
 dnscrypt-proxy/serversInfo.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/dnscrypt-proxy/serversInfo.go b/dnscrypt-proxy/serversInfo.go
index 08a3c18b..d5fae958 100644
--- a/dnscrypt-proxy/serversInfo.go
+++ b/dnscrypt-proxy/serversInfo.go
@@ -325,6 +325,10 @@ func fetchDNSCryptServerInfo(proxy *Proxy, name string, stamp stamps.ServerStamp
 }
 
 func fetchDoHServerInfo(proxy *Proxy, name string, stamp stamps.ServerStamp, isNew bool) (ServerInfo, error) {
+	// If an IP has been provided, use it forever.
+	// Or else, if the fallback server and the DoH server are operated
+	// by the same entity, it could provide a unique IPv6 for each client
+	// in order to fingerprint clients across multiple IP addresses.
 	if len(stamp.ServerAddrStr) > 0 {
 		ipOnly, _ := ExtractHostAndPort(stamp.ServerAddrStr, -1)
 		if ip := ParseIP(ipOnly); ip != nil {