all: log changes, imp docs

CHANGELOG.md

@@ -22,6 +22,8 @@ and this project adheres to
 
 ### Added
 
+- Domain-specific upstream servers test.  Such test fails with an appropriate
+  warning message ([#4517]).
 - Support for Discovery of Designated Resolvers (DDR) according to the [RFC
   draft][ddr-draft] ([#4463]).
 - `windows/arm64` support ([#3057]).
@@ -32,6 +34,7 @@ and this project adheres to
 
 [#2993]: https://github.com/AdguardTeam/AdGuardHome/issues/2993
 [#3057]: https://github.com/AdguardTeam/AdGuardHome/issues/3057
+[#4517]: https://github.com/AdguardTeam/AdGuardHome/issues/4517
 
 [ddr-draft]: https://datatracker.ietf.org/doc/html/draft-ietf-add-ddr-08
 

internal/dnsforward/http.go

@@ -461,7 +461,7 @@ var protocols = []string{"udp://", "tcp://", "tls://", "https://", "sdns://", "q
 // upstream configuration.  useDefault is true if the upstream is
 // domain-specific and is configured to point at the default upstream server
 // which is validated separately.  The upstream is considered domain-specific
-// only if domains is nil.
+// only if domains is at least not nil.
 func validateUpstream(u string, domains []string) (useDefault bool, err error) {
 	// The special server address '#' means that default server must be used.
 	if useDefault = u == "#" && domains != nil; useDefault {