MPH domian matcher: Support building & using cache directly (instead of building from geosite.dat when Xray starts) (#5505)

Like https://github.com/XTLS/Xray-core/pull/5488#issuecomment-3710995080

app/dns/dns.go

@@ -12,9 +12,11 @@ import (
 	"sync"
 	"time"
 
+	"github.com/xtls/xray-core/app/router"
 	"github.com/xtls/xray-core/common"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
+	"github.com/xtls/xray-core/common/platform"
 	"github.com/xtls/xray-core/common/session"
 	"github.com/xtls/xray-core/common/strmatcher"
 	"github.com/xtls/xray-core/features/dns"
@@ -83,9 +85,31 @@ func New(ctx context.Context, config *Config) (*DNS, error) {
 		return nil, errors.New("unexpected query strategy ", config.QueryStrategy)
 	}
 
-	hosts, err := NewStaticHosts(config.StaticHosts)
-	if err != nil {
-		return nil, errors.New("failed to create hosts").Base(err)
+	var hosts *StaticHosts
+	mphLoaded := false
+	domainMatcherPath := platform.NewEnvFlag(platform.MphCachePath).GetValue(func() string { return "" })
+	if domainMatcherPath != "" {
+		if f, err := os.Open(domainMatcherPath); err == nil {
+			defer f.Close()
+			if m, err := router.LoadGeoSiteMatcher(f, "HOSTS"); err == nil {
+				f.Seek(0, 0)
+				if hostIPs, err := router.LoadGeoSiteHosts(f); err == nil {
+					if sh, err := NewStaticHostsFromCache(m, hostIPs); err == nil {
+						hosts = sh
+						mphLoaded = true
+						errors.LogDebug(ctx, "MphDomainMatcher loaded from cache for DNS hosts, size: ", sh.matchers.Size())
+					}
+				}
+			}
+		}
+	}
+
+	if !mphLoaded {
+		sh, err := NewStaticHosts(config.StaticHosts)
+		if err != nil {
+			return nil, errors.New("failed to create hosts").Base(err)
+		}
+		hosts = sh
 	}
 
 	var clients []*Client