Pull request: 3115 domain case

Merge in DNS/adguard-home from 3115-domain-case to master

Updates #3115.

Squashed commit of the following:

commit 02b6d27d862b3e3dc2a17220cec35f0f18e31fb3
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue May 11 19:56:06 2021 +0300

    all: fix typos

commit cdd1de64d5f79605b5fdcad5879204194856b083
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Tue May 11 19:37:37 2021 +0300

    dnsforward: fix disallowed domains case matching

CHANGELOG.md

@@ -17,6 +17,12 @@ and this project adheres to
 ## [v0.106.3] - 2021-05-17 (APPROX.)
 -->
 
+### Fixed
+
+- Disallowed domains are now case-insensitive ([#3115]).
+
+[#3115]: https://github.com/AdguardTeam/AdGuardHome/issues/3115
+
 
 
 ## [v0.106.2] - 2021-05-06

internal/dnsforward/access.go

@@ -47,7 +47,7 @@ func newAccessCtx(allowedClients, disallowedClients, blockedHosts []string) (a *
 
 	b := &strings.Builder{}
 	for _, s := range blockedHosts {
-		aghstrings.WriteToBuilder(b, s, "\n")
+		aghstrings.WriteToBuilder(b, strings.ToLower(s), "\n")
 	}
 
 	listArray := []filterlist.RuleList{}

internal/dnsforward/filter.go

@@ -20,7 +20,11 @@ func (s *Server) beforeRequestHandler(_ *proxy.Proxy, d *proxy.DNSContext) (bool
 	}
 
 	if len(d.Req.Question) == 1 {
-		host := strings.TrimSuffix(d.Req.Question[0].Name, ".")
+		// It's lowercased here since this handler is called before any
+		// other one.
+		name := strings.ToLower(d.Req.Question[0].Name)
+		d.Req.Question[0].Name = name
+		host := strings.TrimSuffix(name, ".")
 		if s.access.IsBlockedDomain(host) {
 			log.Tracef("Domain %s is blocked by settings", host)
 			return false, nil