package home import ( "fmt" "hash/crc32" "io/ioutil" "os" "path/filepath" "regexp" "strconv" "strings" "sync" "time" "github.com/AdguardTeam/AdGuardHome/dnsfilter" "github.com/AdguardTeam/golibs/file" "github.com/AdguardTeam/golibs/log" ) var ( nextFilterID = time.Now().Unix() // semi-stable way to generate an unique ID filterTitleRegexp = regexp.MustCompile(`^! Title: +(.*)$`) refreshStatus uint32 // 0:none; 1:in progress refreshLock sync.Mutex ) func initFiltering() { loadFilters() deduplicateFilters() updateUniqueFilterID(config.Filters) } func startFiltering() { // 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 periodicallyRefreshFilters() } 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 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 } // Enable or disable a filter func filterEnable(url string, enable bool) bool { r := false config.Lock() for i := range config.Filters { filter := &config.Filters[i] // otherwise we will be operating on a copy if filter.URL == url { filter.Enabled = enable if enable { e := filter.load() if e != nil { // This isn't a fatal error, // because it may occur when someone removes the file from disk. // In this case the periodic update task will try to download the file. filter.LastUpdated = time.Time{} log.Tracef("%s filter load: %v", url, e) } } else { filter.unload() } r = true break } } config.Unlock() return r } // Return TRUE if a filter with this URL exists func filterExists(url string) bool { r := false config.RLock() for i := range config.Filters { if config.Filters[i].URL == url { r = true break } } config.RUnlock() return r } // Add a filter // Return FALSE if a filter with this URL exists func filterAdd(f filter) bool { config.Lock() // Check for duplicates for i := range config.Filters { if config.Filters[i].URL == f.URL { config.Unlock() return false } } config.Filters = append(config.Filters, f) config.Unlock() return true } // Load filters from the disk // And if any filter has zero ID, assign a new one func loadFilters() { for i := range config.Filters { filter := &config.Filters[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 := filter.load() 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 periodicallyRefreshFilters() { for { if config.DNS.FiltersUpdateIntervalHours != 0 && refreshStatus == 0 { refreshStatus = 1 refreshLock.Lock() _ = refreshFiltersIfNecessary(false) refreshLock.Unlock() refreshStatus = 0 } time.Sleep(1 * time.Hour) } } // Refresh filters func refreshFilters() (int, error) { if refreshStatus != 0 { // we could use atomic cmpxchg here, but it's not really required return 0, fmt.Errorf("Filters update procedure is already running") } refreshStatus = 1 refreshLock.Lock() nUpdated := refreshFiltersIfNecessary(true) refreshLock.Unlock() refreshStatus = 0 return nUpdated, nil } // Checks filters updates if necessary // If force is true, it ignores the filter.LastUpdated field value // // Algorithm: // . Get the list of filters to be updated // . For each filter run the download and checksum check operation // . For each filter: // . If filter data hasn't changed, just set new update time on file // . If filter data has changed: // . rename the old file (1.txt -> 1.txt.old) // . store the new data on disk (1.txt) // . Pass new filters to dnsfilter object - it analyzes new data while the old filters are still active // . dnsfilter activates new filters // . Remove the old filter files (1.txt.old) func refreshFiltersIfNecessary(force bool) int { var updateFilters []filter var updateFlags []bool // 'true' if filter data has changed log.Debug("Filters: updating...") now := time.Now() config.RLock() for i := range config.Filters { f := &config.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() for i := range updateFilters { uf := &updateFilters[i] updated, err := uf.update() updateFlags = append(updateFlags, updated) if err != nil { log.Printf("Failed to update filter %s: %s\n", uf.URL, err) continue } uf.LastUpdated = now } updateCount := 0 for i := range updateFilters { uf := &updateFilters[i] updated := updateFlags[i] if updated { err := uf.saveAndBackupOld() if err != nil { log.Printf("Failed to save the updated filter %d: %s", uf.ID, err) continue } } else { e := os.Chtimes(uf.Path(), uf.LastUpdated, uf.LastUpdated) if e != nil { log.Error("os.Chtimes(): %v", e) } } config.Lock() for k := range config.Filters { f := &config.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.Data = nil f.RulesCount = uf.RulesCount f.checksum = uf.checksum updateCount++ } config.Unlock() } 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 } // Allows printable UTF-8 text with CR, LF, TAB characters func isPrintableText(data []byte) bool { for _, c := range data { 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 parseFilterContents(contents []byte) (int, string) { data := string(contents) rulesCount := 0 name := "" seenTitle := false // Count lines in the filter for len(data) != 0 { line := SplitNext(&data, '\n') if len(line) == 0 { continue } if line[0] == '!' { m := filterTitleRegexp.FindAllStringSubmatch(line, -1) if len(m) > 0 && len(m[0]) >= 2 && !seenTitle { name = m[0][1] seenTitle = true } } else { rulesCount++ } } return rulesCount, name } // Perform upgrade on a filter func (filter *filter) update() (bool, error) { log.Tracef("Downloading update for filter %d from %s", filter.ID, filter.URL) resp, err := config.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) } body, err := ioutil.ReadAll(resp.Body) if err != nil { log.Printf("Couldn't fetch filter contents from URL %s, skipping: %s", filter.URL, err) return false, err } // Check if the filter has been really changed checksum := crc32.ChecksumIEEE(body) if filter.checksum == checksum { log.Tracef("Filter #%d at URL %s hasn't changed, not updating it", filter.ID, filter.URL) return false, nil } var firstChunk []byte if len(body) <= 4096 { firstChunk = body } else { firstChunk = body[:4096] } if !isPrintableText(firstChunk) { 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") } // Extract filter name and count number of rules rulesCount, filterName := parseFilterContents(body) log.Printf("Filter %d has been updated: %d bytes, %d rules", filter.ID, len(body), rulesCount) if filterName != "" { filter.Name = filterName } filter.RulesCount = rulesCount filter.Data = body filter.checksum = checksum return true, nil } // saves filter contents to the file in dataDir // This method is safe to call during filters update, // because it creates a new file and then renames it, // so the currently opened file descriptors to the old filter file remain valid. func (filter *filter) save() error { filterFilePath := filter.Path() log.Printf("Saving filter %d contents to: %s", filter.ID, filterFilePath) err := file.SafeWrite(filterFilePath, filter.Data) // update LastUpdated field after saving the file filter.LastUpdated = filter.LastTimeUpdated() return err } func (filter *filter) saveAndBackupOld() error { filterFilePath := filter.Path() err := os.Rename(filterFilePath, filterFilePath+".old") if err != nil && !os.IsNotExist(err) { return err } return filter.save() } // loads filter contents from the file in dataDir func (filter *filter) load() 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 } filterFileContents, err := ioutil.ReadFile(filterFilePath) if err != nil { return err } log.Tracef("File %s, id %d, length %d", filterFilePath, filter.ID, len(filterFileContents)) rulesCount, _ := parseFilterContents(filterFileContents) filter.RulesCount = rulesCount filter.Data = nil filter.checksum = crc32.ChecksumIEEE(filterFileContents) filter.LastUpdated = filter.LastTimeUpdated() return nil } // Clear filter rules func (filter *filter) unload() { filter.Data = nil filter.RulesCount = 0 } // Path to the filter contents func (filter *filter) Path() string { return filepath.Join(config.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 map[int]string if config.DNS.FilteringEnabled { // convert array of filters filters = make(map[int]string) userFilter := userFilter() filters[int(userFilter.ID)] = string(userFilter.Data) for _, filter := range config.Filters { if !filter.Enabled { continue } filters[int(filter.ID)] = filter.Path() } } _ = Context.dnsFilter.SetFilters(filters, async) }