package dnsfilter import ( "bytes" "compress/gzip" "encoding/json" "fmt" "log" "os" "sync" "time" "github.com/go-test/deep" ) var ( fileWriteLock sync.Mutex ) const enableGzip = false func flushToFile(buffer []*logEntry) error { if len(buffer) == 0 { return nil } start := time.Now() var b bytes.Buffer e := json.NewEncoder(&b) for _, entry := range buffer { err := e.Encode(entry) if err != nil { log.Printf("Failed to marshal entry: %s", err) return err } } elapsed := time.Since(start) log.Printf("%d elements serialized via json in %v: %d kB, %v/entry, %v/entry", len(buffer), elapsed, b.Len()/1024, float64(b.Len())/float64(len(buffer)), elapsed/time.Duration(len(buffer))) err := checkBuffer(buffer, b) if err != nil { log.Printf("failed to check buffer: %s", err) return err } var zb bytes.Buffer filename := queryLogFileName // gzip enabled? if enableGzip { filename += ".gz" zw := gzip.NewWriter(&zb) zw.Name = queryLogFileName zw.ModTime = time.Now() _, err = zw.Write(b.Bytes()) if err != nil { log.Printf("Couldn't compress to gzip: %s", err) zw.Close() return err } if err = zw.Close(); err != nil { log.Printf("Couldn't close gzip writer: %s", err) return err } } else { zb = b } fileWriteLock.Lock() defer fileWriteLock.Unlock() f, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644) if err != nil { log.Printf("failed to create file \"%s\": %s", filename, err) return err } defer f.Close() n, err := f.Write(zb.Bytes()) if err != nil { log.Printf("Couldn't write to file: %s", err) return err } log.Printf("ok \"%s\": %v bytes written", filename, n) return nil } func checkBuffer(buffer []*logEntry, b bytes.Buffer) error { l := len(buffer) d := json.NewDecoder(&b) i := 0 for d.More() { entry := &logEntry{} err := d.Decode(entry) if err != nil { log.Printf("Failed to decode: %s", err) return err } if diff := deep.Equal(entry, buffer[i]); diff != nil { log.Printf("decoded buffer differs: %s", diff) return fmt.Errorf("decoded buffer differs: %s", diff) } i++ } if i != l { err := fmt.Errorf("check fail: %d vs %d entries", l, i) log.Print(err) return err } log.Printf("check ok: %d entries", i) return nil } func rotateQueryLog() error { from := queryLogFileName to := queryLogFileName + ".1" if enableGzip { from = queryLogFileName + ".gz" to = queryLogFileName + ".gz.1" } if _, err := os.Stat(from); os.IsNotExist(err) { // do nothing, file doesn't exist return nil } err := os.Rename(from, to) if err != nil { log.Printf("Failed to rename querylog: %s", err) return err } log.Printf("Rotated from %s to %s successfully", from, to) return nil } func periodicQueryLogRotate() { for range time.Tick(queryLogRotationPeriod) { err := rotateQueryLog() if err != nil { log.Printf("Failed to rotate querylog: %s", err) // do nothing, continue rotating } } } func genericLoader(onEntry func(entry *logEntry) error, needMore func() bool, timeWindow time.Duration) error { now := time.Now() // read from querylog files, try newest file first files := []string{} if enableGzip { files = []string{ queryLogFileName + ".gz", queryLogFileName + ".gz.1", } } else { files = []string{ queryLogFileName, queryLogFileName + ".1", } } // read from all files for _, file := range files { if !needMore() { break } if _, err := os.Stat(file); os.IsNotExist(err) { // do nothing, file doesn't exist continue } f, err := os.Open(file) if err != nil { log.Printf("Failed to open file \"%s\": %s", file, err) // try next file continue } defer f.Close() var d *json.Decoder if enableGzip { trace("Creating gzip reader") zr, err := gzip.NewReader(f) if err != nil { log.Printf("Failed to create gzip reader: %s", err) continue } defer zr.Close() trace("Creating json decoder") d = json.NewDecoder(zr) } else { d = json.NewDecoder(f) } i := 0 // entries on file are in oldest->newest order // we want maxLen newest for d.More() { if !needMore() { break } var entry logEntry err := d.Decode(&entry) if err != nil { log.Printf("Failed to decode: %s", err) // next entry can be fine, try more continue } if now.Sub(entry.Time) > timeWindow { trace("skipping entry") continue } i++ err = onEntry(&entry) if err != nil { return err } } elapsed := time.Since(now) log.Printf("file \"%s\": read %d entries in %v, %v/entry", file, i, elapsed, elapsed/time.Duration(i)) } return nil } func appendFromLogFile(values []*logEntry, maxLen int, timeWindow time.Duration) []*logEntry { a := []*logEntry{} onEntry := func(entry *logEntry) error { a = append(a, entry) if len(a) > maxLen { toskip := len(a) - maxLen a = a[toskip:] } return nil } needMore := func() bool { return true } err := genericLoader(onEntry, needMore, timeWindow) if err != nil { log.Printf("Failed to load entries from querylog: %s", err) return values } // now that we've read all eligible entries, reverse the slice to make it go from newest->oldest for left, right := 0, len(a)-1; left < right; left, right = left+1, right-1 { a[left], a[right] = a[right], a[left] } // append it to values values = append(values, a...) // then cut off of it is bigger than maxLen if len(values) > maxLen { values = values[:maxLen] } return values }