147 lines
2.9 KiB
Go
147 lines
2.9 KiB
Go
package dnsfilter
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import (
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"bytes"
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"compress/gzip"
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"encoding/json"
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"fmt"
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"log"
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"os"
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"sync"
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"time"
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"github.com/go-test/deep"
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)
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const (
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queryLogRotationPeriod = time.Hour * 24 // rotate the log every 24 hours
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queryLogFileName = "querylog.json" // .gz added during compression
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)
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var (
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fileWriteLock sync.Mutex
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)
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func flushToFile(buffer []logEntry) error {
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if len(buffer) == 0 {
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return nil
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}
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start := time.Now()
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var b bytes.Buffer
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e := json.NewEncoder(&b)
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for _, entry := range buffer {
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err := e.Encode(entry)
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if err != nil {
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log.Printf("Failed to marshal entry: %s", err)
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return err
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}
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}
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elapsed := time.Since(start)
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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)))
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err := checkBuffer(buffer, b)
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if err != nil {
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log.Printf("failed to check buffer: %s", err)
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return err
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}
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filenamegz := queryLogFileName + ".gz"
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var zb bytes.Buffer
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zw := gzip.NewWriter(&zb)
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zw.Name = queryLogFileName
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zw.ModTime = time.Now()
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_, err = zw.Write(b.Bytes())
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if err != nil {
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log.Printf("Couldn't compress to gzip: %s", err)
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zw.Close()
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return err
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}
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if err = zw.Close(); err != nil {
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log.Printf("Couldn't close gzip writer: %s", err)
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return err
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}
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fileWriteLock.Lock()
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defer fileWriteLock.Unlock()
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f, err := os.OpenFile(filenamegz, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
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if err != nil {
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log.Printf("failed to create file \"%s\": %s", filenamegz, err)
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return err
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}
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defer f.Close()
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n, err := f.Write(zb.Bytes())
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if err != nil {
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log.Printf("Couldn't write to file: %s", err)
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return err
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}
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log.Printf("ok \"%s\": %v bytes written", filenamegz, n)
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return nil
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}
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func checkBuffer(buffer []logEntry, b bytes.Buffer) error {
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l := len(buffer)
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d := json.NewDecoder(&b)
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i := 0
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for d.More() {
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var entry logEntry
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err := d.Decode(&entry)
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if err != nil {
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log.Printf("Failed to decode: %s", err)
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return err
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}
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if diff := deep.Equal(entry, buffer[i]); diff != nil {
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log.Printf("decoded buffer differs: %s", diff)
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return fmt.Errorf("decoded buffer differs: %s", diff)
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}
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i++
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}
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if i != l {
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err := fmt.Errorf("check fail: %d vs %d entries", l, i)
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log.Print(err)
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return err
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}
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log.Printf("check ok: %d entries", i)
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return nil
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}
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func rotateQueryLog() error {
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from := queryLogFileName + ".gz"
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to := queryLogFileName + ".gz.1"
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if _, err := os.Stat(from); os.IsNotExist(err) {
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// do nothing, file doesn't exist
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return nil
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}
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err := os.Rename(from, to)
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if err != nil {
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log.Printf("Failed to rename querylog: %s", err)
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return err
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}
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log.Printf("Rotated from %s to %s successfully", from, to)
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return nil
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}
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func periodicQueryLogRotate(t time.Duration) {
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for range time.Tick(t) {
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err := rotateQueryLog()
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if err != nil {
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log.Printf("Failed to rotate querylog: %s", err)
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// do nothing, continue rotating
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}
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}
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}
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