package home import ( "bufio" "fmt" "hash/crc32" "io" "io/ioutil" "os" "path/filepath" "regexp" "strconv" "strings" "sync" "sync/atomic" "time" "github.com/AdguardTeam/AdGuardHome/dnsfilter" "github.com/AdguardTeam/AdGuardHome/util" "github.com/AdguardTeam/golibs/log" ) var ( nextFilterID = time.Now().Unix() // semi-stable way to generate an unique ID ) // Filtering - module object type Filtering struct { // conf FilteringConf refreshStatus uint32 // 0:none; 1:in progress refreshLock sync.Mutex filterTitleRegexp *regexp.Regexp } // Init - initialize the module func (f *Filtering) Init() { f.filterTitleRegexp = regexp.MustCompile(`^! Title: +(.*)$`) _ = os.MkdirAll(filepath.Join(Context.getDataDir(), filterDir), 0755) f.loadFilters(config.Filters) f.loadFilters(config.WhitelistFilters) deduplicateFilters() updateUniqueFilterID(config.Filters) updateUniqueFilterID(config.WhitelistFilters) } // Start - start the module func (f *Filtering) Start() { f.RegisterFilteringHandlers() // Here we should start updating filters, // but currently we can't wake up the periodic task to do so. // So for now we just start this periodic task from here. go f.periodicallyRefreshFilters() } // Close - close the module func (f *Filtering) Close() { } func defaultFilters() []filter { return []filter{ {Filter: dnsfilter.Filter{ID: 1}, Enabled: true, URL: "https://adguardteam.github.io/AdGuardSDNSFilter/Filters/filter.txt", Name: "AdGuard Simplified Domain Names filter"}, {Filter: dnsfilter.Filter{ID: 2}, Enabled: false, URL: "https://adaway.org/hosts.txt", Name: "AdAway"}, {Filter: dnsfilter.Filter{ID: 3}, Enabled: false, URL: "https://hosts-file.net/ad_servers.txt", Name: "hpHosts - Ad and Tracking servers only"}, {Filter: dnsfilter.Filter{ID: 4}, Enabled: false, URL: "https://www.malwaredomainlist.com/hostslist/hosts.txt", Name: "MalwareDomainList.com Hosts List"}, } } // field ordering is important -- yaml fields will mirror ordering from here type filter struct { Enabled bool URL string Name string `yaml:"name"` RulesCount int `yaml:"-"` LastUpdated time.Time `yaml:"-"` checksum uint32 // checksum of the file data white bool dnsfilter.Filter `yaml:",inline"` } // Creates a helper object for working with the user rules func userFilter() filter { f := filter{ // User filter always has constant ID=0 Enabled: true, } f.Filter.Data = []byte(strings.Join(config.UserRules, "\n")) return f } const ( statusFound = 1 statusEnabledChanged = 2 statusURLChanged = 4 statusURLExists = 8 statusUpdateRequired = 0x10 ) // Update properties for a filter specified by its URL // Return status* flags. func (f *Filtering) filterSetProperties(url string, newf filter, whitelist bool) int { r := 0 config.Lock() defer config.Unlock() filters := &config.Filters if whitelist { filters = &config.WhitelistFilters } for i := range *filters { filt := &(*filters)[i] if filt.URL != url { continue } log.Debug("filter: set properties: %s: {%s %s %v}", filt.URL, newf.Name, newf.URL, newf.Enabled) filt.Name = newf.Name if filt.URL != newf.URL { r |= statusURLChanged | statusUpdateRequired if filterExistsNoLock(newf.URL) { return statusURLExists } filt.URL = newf.URL filt.unload() filt.LastUpdated = time.Time{} filt.checksum = 0 filt.RulesCount = 0 } if filt.Enabled != newf.Enabled { r |= statusEnabledChanged filt.Enabled = newf.Enabled if filt.Enabled { if (r & statusURLChanged) == 0 { e := f.load(filt) if e != nil { // This isn't a fatal error, // because it may occur when someone removes the file from disk. filt.LastUpdated = time.Time{} filt.checksum = 0 filt.RulesCount = 0 r |= statusUpdateRequired } } } else { filt.unload() } } return r | statusFound } return 0 } // Return TRUE if a filter with this URL exists func filterExists(url string) bool { config.RLock() r := filterExistsNoLock(url) config.RUnlock() return r } func filterExistsNoLock(url string) bool { for _, f := range config.Filters { if f.URL == url { return true } } for _, f := range config.WhitelistFilters { if f.URL == url { return true } } return false } // Add a filter // Return FALSE if a filter with this URL exists func filterAdd(f filter) bool { config.Lock() defer config.Unlock() // Check for duplicates if filterExistsNoLock(f.URL) { return false } if f.white { config.WhitelistFilters = append(config.WhitelistFilters, f) } else { config.Filters = append(config.Filters, f) } return true } // Load filters from the disk // And if any filter has zero ID, assign a new one func (f *Filtering) loadFilters(array []filter) { for i := range array { filter := &array[i] // otherwise we're operating on a copy if filter.ID == 0 { filter.ID = assignUniqueFilterID() } if !filter.Enabled { // No need to load a filter that is not enabled continue } err := f.load(filter) if err != nil { log.Error("Couldn't load filter %d contents due to %s", filter.ID, err) } } } func deduplicateFilters() { // Deduplicate filters i := 0 // output index, used for deletion later urls := map[string]bool{} for _, filter := range config.Filters { if _, ok := urls[filter.URL]; !ok { // we didn't see it before, keep it urls[filter.URL] = true // remember the URL config.Filters[i] = filter i++ } } // all entries we want to keep are at front, delete the rest config.Filters = config.Filters[:i] } // Set the next filter ID to max(filter.ID) + 1 func updateUniqueFilterID(filters []filter) { for _, filter := range filters { if nextFilterID < filter.ID { nextFilterID = filter.ID + 1 } } } func assignUniqueFilterID() int64 { value := nextFilterID nextFilterID++ return value } // Sets up a timer that will be checking for filters updates periodically func (f *Filtering) periodicallyRefreshFilters() { const maxInterval = 1 * 60 * 60 intval := 5 // use a dynamically increasing time interval for { isNetworkErr := false if config.DNS.FiltersUpdateIntervalHours != 0 && atomic.CompareAndSwapUint32(&f.refreshStatus, 0, 1) { f.refreshLock.Lock() _, isNetworkErr = f.refreshFiltersIfNecessary(FilterRefreshBlocklists | FilterRefreshAllowlists) f.refreshLock.Unlock() f.refreshStatus = 0 if !isNetworkErr { intval = maxInterval } } if isNetworkErr { intval *= 2 if intval > maxInterval { intval = maxInterval } } time.Sleep(time.Duration(intval) * time.Second) } } // Refresh filters // flags: FilterRefresh* // important: // TRUE: ignore the fact that we're currently updating the filters func (f *Filtering) refreshFilters(flags int, important bool) (int, error) { set := atomic.CompareAndSwapUint32(&f.refreshStatus, 0, 1) if !important && !set { return 0, fmt.Errorf("filters update procedure is already running") } f.refreshLock.Lock() nUpdated, _ := f.refreshFiltersIfNecessary(flags) f.refreshLock.Unlock() f.refreshStatus = 0 return nUpdated, nil } func (f *Filtering) refreshFiltersArray(filters *[]filter, force bool) (int, []filter, []bool, bool) { var updateFilters []filter var updateFlags []bool // 'true' if filter data has changed now := time.Now() config.RLock() for i := range *filters { f := &(*filters)[i] // otherwise we will be operating on a copy if !f.Enabled { continue } expireTime := f.LastUpdated.Unix() + int64(config.DNS.FiltersUpdateIntervalHours)*60*60 if !force && expireTime > now.Unix() { continue } var uf filter uf.ID = f.ID uf.URL = f.URL uf.Name = f.Name uf.checksum = f.checksum updateFilters = append(updateFilters, uf) } config.RUnlock() if len(updateFilters) == 0 { return 0, nil, nil, false } nfail := 0 for i := range updateFilters { uf := &updateFilters[i] updated, err := f.update(uf) updateFlags = append(updateFlags, updated) if err != nil { nfail++ log.Printf("Failed to update filter %s: %s\n", uf.URL, err) continue } } if nfail == len(updateFilters) { return 0, nil, nil, true } updateCount := 0 for i := range updateFilters { uf := &updateFilters[i] updated := updateFlags[i] config.Lock() for k := range *filters { f := &(*filters)[k] if f.ID != uf.ID || f.URL != uf.URL { continue } f.LastUpdated = uf.LastUpdated if !updated { continue } log.Info("Updated filter #%d. Rules: %d -> %d", f.ID, f.RulesCount, uf.RulesCount) f.Name = uf.Name f.RulesCount = uf.RulesCount f.checksum = uf.checksum updateCount++ } config.Unlock() } return updateCount, updateFilters, updateFlags, false } const ( FilterRefreshForce = 1 // ignore last file modification date FilterRefreshAllowlists = 2 // update allow-lists FilterRefreshBlocklists = 4 // update block-lists ) // Checks filters updates if necessary // If force is true, it ignores the filter.LastUpdated field value // flags: FilterRefresh* // // Algorithm: // . Get the list of filters to be updated // . For each filter run the download and checksum check operation // . Store downloaded data in a temporary file inside data/filters directory // . For each filter: // . If filter data hasn't changed, just set new update time on file // . If filter data has changed: // . rename the temporary file ( -> 1.txt) // Note that this method works only on UNIX. // On Windows we don't pass files to dnsfilter - we pass the whole data. // . Pass new filters to dnsfilter object - it analyzes new data while the old filters are still active // . dnsfilter activates new filters // // Return the number of updated filters // Return TRUE - there was a network error and nothing could be updated func (f *Filtering) refreshFiltersIfNecessary(flags int) (int, bool) { log.Debug("Filters: updating...") updateCount := 0 var updateFilters []filter var updateFlags []bool netError := false netErrorW := false force := false if (flags & FilterRefreshForce) != 0 { force = true } if (flags & FilterRefreshBlocklists) != 0 { updateCount, updateFilters, updateFlags, netError = f.refreshFiltersArray(&config.Filters, force) } if (flags & FilterRefreshAllowlists) != 0 { updateCountW := 0 var updateFiltersW []filter var updateFlagsW []bool updateCountW, updateFiltersW, updateFlagsW, netErrorW = f.refreshFiltersArray(&config.WhitelistFilters, force) updateCount += updateCountW updateFilters = append(updateFilters, updateFiltersW...) updateFlags = append(updateFlags, updateFlagsW...) } if netError && netErrorW { return 0, true } if updateCount != 0 { enableFilters(false) for i := range updateFilters { uf := &updateFilters[i] updated := updateFlags[i] if !updated { continue } _ = os.Remove(uf.Path() + ".old") } } log.Debug("Filters: update finished") return updateCount, false } // Allows printable UTF-8 text with CR, LF, TAB characters func isPrintableText(data []byte, len int) bool { for i := 0; i < len; i++ { c := data[i] if (c >= ' ' && c != 0x7f) || c == '\n' || c == '\r' || c == '\t' { continue } return false } return true } // A helper function that parses filter contents and returns a number of rules and a filter name (if there's any) func (f *Filtering) parseFilterContents(file io.Reader) (int, uint32, string) { rulesCount := 0 name := "" seenTitle := false r := bufio.NewReader(file) checksum := uint32(0) for { line, err := r.ReadString('\n') if err != nil { break } checksum = crc32.Update(checksum, crc32.IEEETable, []byte(line)) line = strings.TrimSpace(line) if len(line) == 0 { continue } if line[0] == '!' { m := f.filterTitleRegexp.FindAllStringSubmatch(line, -1) if len(m) > 0 && len(m[0]) >= 2 && !seenTitle { name = m[0][1] seenTitle = true } } else { rulesCount++ } } return rulesCount, checksum, name } // Perform upgrade on a filter and update LastUpdated value func (f *Filtering) update(filter *filter) (bool, error) { b, err := f.updateIntl(filter) filter.LastUpdated = time.Now() if !b { e := os.Chtimes(filter.Path(), filter.LastUpdated, filter.LastUpdated) if e != nil { log.Error("os.Chtimes(): %v", e) } } return b, err } func (f *Filtering) updateIntl(filter *filter) (bool, error) { log.Tracef("Downloading update for filter %d from %s", filter.ID, filter.URL) tmpFile, err := ioutil.TempFile(filepath.Join(Context.getDataDir(), filterDir), "") if err != nil { return false, err } defer func() { if tmpFile != nil { _ = tmpFile.Close() _ = os.Remove(tmpFile.Name()) } }() resp, err := Context.client.Get(filter.URL) if resp != nil && resp.Body != nil { defer resp.Body.Close() } if err != nil { log.Printf("Couldn't request filter from URL %s, skipping: %s", filter.URL, err) return false, err } if resp.StatusCode != 200 { log.Printf("Got status code %d from URL %s, skipping", resp.StatusCode, filter.URL) return false, fmt.Errorf("got status code != 200: %d", resp.StatusCode) } htmlTest := true firstChunk := make([]byte, 4*1024) firstChunkLen := 0 buf := make([]byte, 64*1024) total := 0 for { n, err := resp.Body.Read(buf) total += n if htmlTest { // gather full buffer firstChunk and perform its data tests num := util.MinInt(n, len(firstChunk)-firstChunkLen) copied := copy(firstChunk[firstChunkLen:], buf[:num]) firstChunkLen += copied if firstChunkLen == len(firstChunk) || err == io.EOF { if !isPrintableText(firstChunk, firstChunkLen) { return false, fmt.Errorf("data contains non-printable characters") } s := strings.ToLower(string(firstChunk)) if strings.Index(s, "= 0 || strings.Index(s, "= 0 { return false, fmt.Errorf("data is HTML, not plain text") } htmlTest = false firstChunk = nil } } _, err2 := tmpFile.Write(buf[:n]) if err2 != nil { return false, err2 } if err == io.EOF { break } if err != nil { log.Printf("Couldn't fetch filter contents from URL %s, skipping: %s", filter.URL, err) return false, err } } // Extract filter name and count number of rules _, _ = tmpFile.Seek(0, io.SeekStart) rulesCount, checksum, filterName := f.parseFilterContents(tmpFile) // Check if the filter has been really changed if filter.checksum == checksum { log.Tracef("Filter #%d at URL %s hasn't changed, not updating it", filter.ID, filter.URL) return false, nil } log.Printf("Filter %d has been updated: %d bytes, %d rules", filter.ID, total, rulesCount) if filterName != "" { filter.Name = filterName } filter.RulesCount = rulesCount filter.checksum = checksum filterFilePath := filter.Path() log.Printf("Saving filter %d contents to: %s", filter.ID, filterFilePath) // Closing the file before renaming it is necessary on Windows _ = tmpFile.Close() err = os.Rename(tmpFile.Name(), filterFilePath) if err != nil { return false, err } tmpFile = nil return true, nil } // loads filter contents from the file in dataDir func (f *Filtering) load(filter *filter) error { filterFilePath := filter.Path() log.Tracef("Loading filter %d contents to: %s", filter.ID, filterFilePath) if _, err := os.Stat(filterFilePath); os.IsNotExist(err) { // do nothing, file doesn't exist return err } file, err := os.Open(filterFilePath) if err != nil { return err } defer file.Close() st, _ := file.Stat() log.Tracef("File %s, id %d, length %d", filterFilePath, filter.ID, st.Size()) rulesCount, checksum, _ := f.parseFilterContents(file) filter.RulesCount = rulesCount filter.checksum = checksum filter.LastUpdated = filter.LastTimeUpdated() return nil } // Clear filter rules func (filter *filter) unload() { filter.RulesCount = 0 filter.checksum = 0 } // Path to the filter contents func (filter *filter) Path() string { return filepath.Join(Context.getDataDir(), filterDir, strconv.FormatInt(filter.ID, 10)+".txt") } // LastTimeUpdated returns the time when the filter was last time updated func (filter *filter) LastTimeUpdated() time.Time { filterFilePath := filter.Path() s, err := os.Stat(filterFilePath) if os.IsNotExist(err) { // if the filter file does not exist, return 0001-01-01 return time.Time{} } if err != nil { // if the filter file does not exist, return 0001-01-01 return time.Time{} } // filter file modified time return s.ModTime() } func enableFilters(async bool) { var filters []dnsfilter.Filter var whiteFilters []dnsfilter.Filter if config.DNS.FilteringEnabled { // convert array of filters userFilter := userFilter() f := dnsfilter.Filter{ ID: userFilter.ID, Data: userFilter.Data, } filters = append(filters, f) for _, filter := range config.Filters { if !filter.Enabled { continue } f := dnsfilter.Filter{ ID: filter.ID, FilePath: filter.Path(), } filters = append(filters, f) } for _, filter := range config.WhitelistFilters { if !filter.Enabled { continue } f := dnsfilter.Filter{ ID: filter.ID, FilePath: filter.Path(), } whiteFilters = append(whiteFilters, f) } } _ = Context.dnsFilter.SetFilters(filters, whiteFilters, async) }