DNS: Fix some bugs; Refactors; Optimizations (#4659)

app/dns/cache_controller.go

@@ -0,0 +1,188 @@
+package dns
+
+import (
+	"context"
+	go_errors "errors"
+	"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/signal/pubsub"
+	"github.com/xtls/xray-core/common/task"
+	dns_feature "github.com/xtls/xray-core/features/dns"
+	"golang.org/x/net/dns/dnsmessage"
+	"sync"
+	"time"
+)
+
+type CacheController struct {
+	sync.RWMutex
+	ips          map[string]*record
+	pub          *pubsub.Service
+	cacheCleanup *task.Periodic
+	name         string
+	disableCache bool
+}
+
+func NewCacheController(name string, disableCache bool) *CacheController {
+	c := &CacheController{
+		name:         name,
+		disableCache: disableCache,
+		ips:          make(map[string]*record),
+		pub:          pubsub.NewService(),
+	}
+
+	c.cacheCleanup = &task.Periodic{
+		Interval: time.Minute,
+		Execute:  c.CacheCleanup,
+	}
+	return c
+}
+
+// CacheCleanup clears expired items from cache
+func (c *CacheController) CacheCleanup() error {
+	now := time.Now()
+	c.Lock()
+	defer c.Unlock()
+
+	if len(c.ips) == 0 {
+		return errors.New("nothing to do. stopping...")
+	}
+
+	for domain, record := range c.ips {
+		if record.A != nil && record.A.Expire.Before(now) {
+			record.A = nil
+		}
+		if record.AAAA != nil && record.AAAA.Expire.Before(now) {
+			record.AAAA = nil
+		}
+
+		if record.A == nil && record.AAAA == nil {
+			errors.LogDebug(context.Background(), c.name, "cache cleanup ", domain)
+			delete(c.ips, domain)
+		} else {
+			c.ips[domain] = record
+		}
+	}
+
+	if len(c.ips) == 0 {
+		c.ips = make(map[string]*record)
+	}
+
+	return nil
+}
+
+func (c *CacheController) updateIP(req *dnsRequest, ipRec *IPRecord) {
+	elapsed := time.Since(req.start)
+
+	c.Lock()
+	rec, found := c.ips[req.domain]
+	if !found {
+		rec = &record{}
+	}
+
+	switch req.reqType {
+	case dnsmessage.TypeA:
+		rec.A = ipRec
+	case dnsmessage.TypeAAAA:
+		rec.AAAA = ipRec
+	}
+
+	errors.LogInfo(context.Background(), c.name, " got answer: ", req.domain, " ", req.reqType, " -> ", ipRec.IP, " ", elapsed)
+	c.ips[req.domain] = rec
+
+	switch req.reqType {
+	case dnsmessage.TypeA:
+		c.pub.Publish(req.domain+"4", nil)
+		if !c.disableCache {
+			_, _, err := rec.AAAA.getIPs()
+			if !go_errors.Is(err, errRecordNotFound) {
+				c.pub.Publish(req.domain+"6", nil)
+			}
+		}
+	case dnsmessage.TypeAAAA:
+		c.pub.Publish(req.domain+"6", nil)
+		if !c.disableCache {
+			_, _, err := rec.A.getIPs()
+			if !go_errors.Is(err, errRecordNotFound) {
+				c.pub.Publish(req.domain+"4", nil)
+			}
+		}
+	}
+
+	c.Unlock()
+	common.Must(c.cacheCleanup.Start())
+}
+
+func (c *CacheController) findIPsForDomain(domain string, option dns_feature.IPOption) ([]net.IP, uint32, error) {
+	c.RLock()
+	record, found := c.ips[domain]
+	c.RUnlock()
+
+	if !found {
+		return nil, 0, errRecordNotFound
+	}
+
+	var errs []error
+	var allIPs []net.IP
+	var rTTL uint32 = dns_feature.DefaultTTL
+
+	mergeReq := option.IPv4Enable && option.IPv6Enable
+
+	if option.IPv4Enable {
+		ips, ttl, err := record.A.getIPs()
+		if !mergeReq || go_errors.Is(err, errRecordNotFound) {
+			return ips, ttl, err
+		}
+		if ttl < rTTL {
+			rTTL = ttl
+		}
+		if len(ips) > 0 {
+			allIPs = append(allIPs, ips...)
+		} else {
+			errs = append(errs, err)
+		}
+	}
+
+	if option.IPv6Enable {
+		ips, ttl, err := record.AAAA.getIPs()
+		if !mergeReq || go_errors.Is(err, errRecordNotFound) {
+			return ips, ttl, err
+		}
+		if ttl < rTTL {
+			rTTL = ttl
+		}
+		if len(ips) > 0 {
+			allIPs = append(allIPs, ips...)
+		} else {
+			errs = append(errs, err)
+		}
+	}
+
+	if len(allIPs) > 0 {
+		return allIPs, rTTL, nil
+	}
+	if go_errors.Is(errs[0], errs[1]) {
+		return nil, rTTL, errs[0]
+	}
+	return nil, rTTL, errors.Combine(errs...)
+}
+
+func (c *CacheController) registerSubscribers(domain string, option dns_feature.IPOption) (sub4 *pubsub.Subscriber, sub6 *pubsub.Subscriber) {
+	// ipv4 and ipv6 belong to different subscription groups
+	if option.IPv4Enable {
+		sub4 = c.pub.Subscribe(domain + "4")
+	}
+	if option.IPv6Enable {
+		sub6 = c.pub.Subscribe(domain + "6")
+	}
+	return
+}
+
+func closeSubscribers(sub4 *pubsub.Subscriber, sub6 *pubsub.Subscriber) {
+	if sub4 != nil {
+		sub4.Close()
+	}
+	if sub6 != nil {
+		sub6.Close()
+	}
+}