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bloom.go
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bloom.go
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package filterlists
import (
"encoding/hex"
"fmt"
"strings"
"sync"
"github.com/tannerryan/ring"
"github.com/safing/portbase/database/record"
"github.com/safing/portbase/log"
)
var defaultFilter = newScopedBloom()
// scopedBloom is a wrapper around a bloomfilter implementation
// providing scoped filters for different entity types.
type scopedBloom struct {
rw sync.RWMutex
domain *ring.Ring
asn *ring.Ring
country *ring.Ring
ipv4 *ring.Ring
ipv6 *ring.Ring
}
func newScopedBloom() *scopedBloom {
mustInit := func(size int) *ring.Ring {
f, err := ring.Init(size, bfFalsePositiveRate)
if err != nil {
// we panic here as those values cannot be controlled
// by the user and invalid values shouldn't be
// in a release anyway.
panic("Invalid bloom filter parameters!")
}
return f
}
return &scopedBloom{
domain: mustInit(domainBfSize),
asn: mustInit(asnBfSize),
country: mustInit(countryBfSize),
ipv4: mustInit(ipv4BfSize),
ipv6: mustInit(ipv6BfSize),
}
}
func (bf *scopedBloom) getBloomForType(entityType string) (*ring.Ring, error) {
var r *ring.Ring
switch strings.ToLower(entityType) {
case "domain":
r = bf.domain
case "asn":
r = bf.asn
case "ipv4":
r = bf.ipv4
case "ipv6":
r = bf.ipv6
case "country":
r = bf.country
default:
return nil, fmt.Errorf("unsupported filterlists entity type %q", entityType)
}
return r, nil
}
func (bf *scopedBloom) add(scope, value string) {
bf.rw.Lock()
defer bf.rw.Unlock()
r, err := bf.getBloomForType(scope)
if err != nil {
// If we don't have a bloom filter for that scope
// we are probably running an older version that does
// not have support for it. We just drop the value
// as a call to Test() for that scope will always
// return "true"
log.Warningf("failed to add unknown entity type %q with value %q", scope, value)
return
}
r.Add([]byte(value))
}
func (bf *scopedBloom) test(scope, value string) bool {
bf.rw.RLock()
defer bf.rw.RUnlock()
r, err := bf.getBloomForType(scope)
if err != nil {
log.Warningf("testing for unknown entity type %q", scope)
return true // simulate a match to the caller
}
return r.Test([]byte(value))
}
func (bf *scopedBloom) loadFromCache() error {
bf.rw.Lock()
defer bf.rw.Unlock()
if err := loadBloomFromCache(bf.domain, "domain"); err != nil {
return err
}
if err := loadBloomFromCache(bf.asn, "asn"); err != nil {
return err
}
if err := loadBloomFromCache(bf.country, "country"); err != nil {
return err
}
if err := loadBloomFromCache(bf.ipv4, "ipv4"); err != nil {
return err
}
if err := loadBloomFromCache(bf.ipv6, "ipv6"); err != nil {
return err
}
return nil
}
func (bf *scopedBloom) saveToCache() error {
bf.rw.RLock()
defer bf.rw.RUnlock()
if err := saveBloomToCache(bf.domain, "domain"); err != nil {
return err
}
if err := saveBloomToCache(bf.asn, "asn"); err != nil {
return err
}
if err := saveBloomToCache(bf.country, "country"); err != nil {
return err
}
if err := saveBloomToCache(bf.ipv4, "ipv4"); err != nil {
return err
}
if err := saveBloomToCache(bf.ipv6, "ipv6"); err != nil {
return err
}
return nil
}
func (bf *scopedBloom) replaceWith(other *scopedBloom) {
bf.rw.Lock()
defer bf.rw.Unlock()
other.rw.RLock()
defer other.rw.RUnlock()
bf.domain = other.domain
bf.asn = other.asn
bf.country = other.country
bf.ipv4 = other.ipv4
bf.ipv6 = other.ipv6
}
type bloomFilterRecord struct {
record.Base
sync.Mutex
Filter string
}
// loadBloomFromCache loads the bloom filter stored under scope
// into bf.
func loadBloomFromCache(bf *ring.Ring, scope string) error {
r, err := cache.Get(makeBloomCacheKey(scope))
if err != nil {
return err
}
var filterRecord *bloomFilterRecord
if r.IsWrapped() {
filterRecord = new(bloomFilterRecord)
if err := record.Unwrap(r, filterRecord); err != nil {
return err
}
} else {
var ok bool
filterRecord, ok = r.(*bloomFilterRecord)
if !ok {
return fmt.Errorf("invalid type, expected bloomFilterRecord but got %T", r)
}
}
blob, err := hex.DecodeString(filterRecord.Filter)
if err != nil {
return err
}
if err := bf.UnmarshalBinary(blob); err != nil {
return err
}
return nil
}
// saveBloomToCache saves the bitset of the bloomfilter bf
// in the cache db.
func saveBloomToCache(bf *ring.Ring, scope string) error {
blob, err := bf.MarshalBinary()
if err != nil {
return err
}
filter := hex.EncodeToString(blob)
r := &bloomFilterRecord{
Filter: filter,
}
r.SetKey(makeBloomCacheKey(scope))
return cache.Put(r)
}