Pull request 2139: fix-invalid-addr

Squashed commit of the following:

commit 12e9e53ec20685989425411801bd836cbdefe9aa
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Wed Jan 31 19:34:40 2024 +0300

    all: fix chlog

commit 6a8d872dcf49ff685454297e36b888309e058fcf
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Wed Jan 31 19:33:18 2024 +0300

    all: doc

commit 12cd89634f9ae97876d8dd79e30de704b57ef47d
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Wed Jan 31 19:20:27 2024 +0300

    dnsforward: fix http private ptrs

CHANGELOG.md

@@ -71,6 +71,8 @@ In this release, the schema version has changed from 27 to 28.
 
 ### Fixed
 
+- “Invalid AddrPort” in the *Private reverse DNS servers* section on the
+  *Settings → DNS settings* page.
 - Panic on using `--no-etc-hosts` flag ([#6644]).
 - Schedule display in the client settings after creating or updating.
 - Zero value in `querylog.size_memory` disables logging ([#6570]).

internal/dnsforward/dnsforward.go

@@ -83,7 +83,9 @@ type DHCP interface {
 
 // SystemResolvers is an interface for accessing the OS-provided resolvers.
 type SystemResolvers interface {
-	// Addrs returns the list of system resolvers' addresses.
+	// Addrs returns the list of system resolvers' addresses.  Callers must
+	// clone the returned slice before modifying it.  Implementations of Addrs
+	// must be safe for concurrent use.
 	Addrs() (addrs []netip.AddrPort)
 }
 

internal/dnsforward/http.go

@@ -218,7 +218,7 @@ func (s *Server) defaultLocalPTRUpstreams() (ups []string, err error) {
 		return nil, err
 	}
 
-	sysResolvers := slices.DeleteFunc(s.sysResolvers.Addrs(), matcher.Has)
+	sysResolvers := slices.DeleteFunc(slices.Clone(s.sysResolvers.Addrs()), matcher.Has)
 	ups = make([]string, 0, len(sysResolvers))
 	for _, r := range sysResolvers {
 		ups = append(ups, r.String())