feat(dns): replace unbound with qdm12/dns@v2.0.0-beta-rc6 (#1742)

- Faster start up
- Clearer error messages
- Allow for more Gluetun-specific customization
- DNSSEC validation is dropped for now (it's sort of unneeded)
- Fix #137

internal/dns/settings.go

@@ -2,7 +2,14 @@ package dns
 
 import (
 	"context"
+	"fmt"
 
+	"github.com/qdm12/dns/v2/pkg/dot"
+	cachemiddleware "github.com/qdm12/dns/v2/pkg/middlewares/cache"
+	"github.com/qdm12/dns/v2/pkg/middlewares/cache/lru"
+	filtermiddleware "github.com/qdm12/dns/v2/pkg/middlewares/filter"
+	"github.com/qdm12/dns/v2/pkg/middlewares/filter/mapfilter"
+	"github.com/qdm12/dns/v2/pkg/provider"
 	"github.com/qdm12/gluetun/internal/configuration/settings"
 )
 
@@ -12,3 +19,55 @@ func (l *Loop) SetSettings(ctx context.Context, settings settings.DNS) (
 	outcome string) {
 	return l.state.SetSettings(ctx, settings)
 }
+
+func buildDoTSettings(settings settings.DNS,
+	filter *mapfilter.Filter, logger Logger) (
+	dotSettings dot.ServerSettings, err error) {
+	var middlewares []dot.Middleware
+
+	if *settings.DoT.Caching {
+		lruCache, err := lru.New(lru.Settings{})
+		if err != nil {
+			return dot.ServerSettings{}, fmt.Errorf("creating LRU cache: %w", err)
+		}
+		cacheMiddleware, err := cachemiddleware.New(cachemiddleware.Settings{
+			Cache: lruCache,
+		})
+		if err != nil {
+			return dot.ServerSettings{}, fmt.Errorf("creating cache middleware: %w", err)
+		}
+		middlewares = append(middlewares, cacheMiddleware)
+	}
+
+	filterMiddleware, err := filtermiddleware.New(filtermiddleware.Settings{
+		Filter: filter,
+	})
+	if err != nil {
+		return dot.ServerSettings{}, fmt.Errorf("creating filter middleware: %w", err)
+	}
+	middlewares = append(middlewares, filterMiddleware)
+
+	providersData := provider.NewProviders()
+	providers := make([]provider.Provider, len(settings.DoT.Providers))
+	for i := range settings.DoT.Providers {
+		var err error
+		providers[i], err = providersData.Get(settings.DoT.Providers[i])
+		if err != nil {
+			panic(err) // this should already had been checked
+		}
+	}
+
+	ipVersion := "ipv4"
+	if *settings.DoT.IPv6 {
+		ipVersion = "ipv6"
+	}
+	return dot.ServerSettings{
+		Resolver: dot.ResolverSettings{
+			UpstreamResolvers: providers,
+			IPVersion:         ipVersion,
+			Warner:            logger,
+		},
+		Middlewares: middlewares,
+		Logger:      logger,
+	}, nil
+}