package main import ( "fmt" "hash/crc32" "io/ioutil" "os" "path/filepath" "regexp" "strconv" "strings" "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: +(.*)$`) ) // field ordering is important -- yaml fields will mirror ordering from here type filter struct { Enabled bool `json:"enabled"` URL string `json:"url"` Name string `json:"name" yaml:"name"` RulesCount int `json:"rulesCount" yaml:"-"` LastUpdated time.Time `json:"lastUpdated,omitempty" 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 { return filter{ // User filter always has constant ID=0 Enabled: true, Filter: dnsfilter.Filter{ Rules: config.UserRules, }, } } // 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 { // This is okay for the first start, the filter will be loaded later log.Debug("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 range time.Tick(time.Minute) { refreshFiltersIfNecessary(false) } } // 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 // . If filter data hasn't changed, set new update time // . If filter data has changed, parse it, save it on disk, set new update time // . Apply changes to the current configuration // . Restart server func refreshFiltersIfNecessary(force bool) int { var updateFilters []filter if config.firstRun { return 0 } config.RLock() for i := range config.Filters { f := &config.Filters[i] // otherwise we will be operating on a copy if !f.Enabled { continue } if !force && time.Since(f.LastUpdated) <= updatePeriod { 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() updateCount := 0 for i := range updateFilters { uf := &updateFilters[i] updated, err := uf.update() if err != nil { log.Printf("Failed to update filter %s: %s\n", uf.URL, err) continue } if updated { // Saving it to the filters dir now err = uf.save() if err != nil { log.Printf("Failed to save the updated filter %d: %s", uf.ID, err) continue } } else { mtime := time.Now() e := os.Chtimes(uf.Path(), mtime, mtime) if e != nil { log.Error("os.Chtimes(): %v", e) } uf.LastUpdated = mtime } 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.Rules = uf.Rules f.RulesCount = uf.RulesCount f.checksum = uf.checksum updateCount++ } config.Unlock() } if updateCount > 0 && isRunning() { err := reconfigureDNSServer() if err != nil { msg := fmt.Sprintf("SHOULD NOT HAPPEN: cannot reconfigure DNS server with the new filters: %s", err) panic(msg) } } return updateCount } // 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, []string) { lines := strings.Split(string(contents), "\n") rulesCount := 0 name := "" seenTitle := false // Count lines in the filter for _, line := range lines { line = strings.TrimSpace(line) 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, lines } // 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 := 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) } contentType := strings.ToLower(resp.Header.Get("content-type")) if !strings.HasPrefix(contentType, "text/plain") { log.Printf("Non-text response %s from %s, skipping", contentType, filter.URL) return false, fmt.Errorf("non-text response %s", contentType) } 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 } // Extract filter name and count number of rules rulesCount, filterName, rules := 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.Rules = rules filter.checksum = checksum return true, nil } // saves filter contents to the file in dataDir func (filter *filter) save() error { filterFilePath := filter.Path() log.Printf("Saving filter %d contents to: %s", filter.ID, filterFilePath) body := []byte(strings.Join(filter.Rules, "\n")) err := file.SafeWrite(filterFilePath, body) // update LastUpdated field after saving the file filter.LastUpdated = filter.LastTimeUpdated() return err } // 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, _, rules := parseFilterContents(filterFileContents) filter.RulesCount = rulesCount filter.Rules = rules filter.checksum = crc32.ChecksumIEEE(filterFileContents) filter.LastUpdated = filter.LastTimeUpdated() return nil } // Clear filter rules func (filter *filter) unload() { filter.Rules = []string{} filter.RulesCount = 0 } // Path to the filter contents func (filter *filter) Path() string { return filepath.Join(config.ourWorkingDir, dataDir, 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() }