Add dns cache clearing mechanisms

resolver/namerecord.go

@@ -1,12 +1,15 @@
 package resolver
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"sync"
 
 	"github.com/safing/portbase/database"
+	"github.com/safing/portbase/database/query"
 	"github.com/safing/portbase/database/record"
+	"github.com/safing/portbase/log"
 )
 
 var (
@@ -14,6 +17,8 @@ var (
 		AlwaysSetRelativateExpiry: 2592000, // 30 days
 		CacheSize:                 256,
 	})
+
+	nameRecordsKeyPrefix = "cache:intel/nameRecord/"
 )
 
 // NameRecord is helper struct to RRCache to better save data to the database.
@@ -33,11 +38,11 @@ type NameRecord struct {
 }
 
 func makeNameRecordKey(domain string, question string) string {
-	return fmt.Sprintf("cache:intel/nameRecord/%s%s", domain, question)
+	return nameRecordsKeyPrefix + domain + question
 }
 
 // GetNameRecord gets a NameRecord from the database.
-func GetNameRecord(domain string, question string) (*NameRecord, error) {
+func GetNameRecord(domain, question string) (*NameRecord, error) {
 	key := makeNameRecordKey(domain, question)
 
 	r, err := recordDatabase.Get(key)
@@ -64,6 +69,12 @@ func GetNameRecord(domain string, question string) (*NameRecord, error) {
 	return new, nil
 }
 
+// DeleteNameRecord deletes a NameRecord from the database.
+func DeleteNameRecord(domain, question string) error {
+	key := makeNameRecordKey(domain, question)
+	return recordDatabase.Delete(key)
+}
+
 // Save saves the NameRecord to the database.
 func (rec *NameRecord) Save() error {
 	if rec.Domain == "" || rec.Question == "" {
@@ -73,3 +84,49 @@ func (rec *NameRecord) Save() error {
 	rec.SetKey(makeNameRecordKey(rec.Domain, rec.Question))
 	return recordDatabase.PutNew(rec)
 }
+
+func clearNameCache(_ context.Context, _ interface{}) error {
+	log.Debugf("resolver: name cache clearing started...")
+	for {
+		done, err := removeNameEntries(10000)
+		if err != nil {
+			return err
+		}
+
+		if done {
+			return nil
+		}
+	}
+}
+
+func removeNameEntries(batchSize int) (bool, error) {
+	iter, err := recordDatabase.Query(query.New(nameRecordsKeyPrefix))
+	if err != nil {
+		return false, err
+	}
+
+	keys := make([]string, 0, batchSize)
+
+	var cnt int
+	for r := range iter.Next {
+		cnt++
+		keys = append(keys, r.Key())
+
+		if cnt == batchSize {
+			break
+		}
+	}
+	iter.Cancel()
+
+	for _, key := range keys {
+		if err := recordDatabase.Delete(key); err != nil {
+			log.Warningf("resolver: failed to remove name cache entry %q: %s", key, err)
+		}
+	}
+
+	log.Debugf("resolver: successfully removed %d name cache entries", cnt)
+
+	// if we removed less entries that the batch size we
+	// are done and no more entries exist
+	return cnt < batchSize, nil
+}