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|
package log
import (
"io"
"log"
"net"
"sync"
"time"
"github.com/mpolden/zdns/sql"
)
// Logger wraps a standard log.Logger and an optional log database.
type Logger struct {
*log.Logger
Now func() time.Time
queue chan Entry
db *sql.Client
maintainer *maintainer
wg sync.WaitGroup
}
// RecordOptions configures recording of DNS requests.
type RecordOptions struct {
Database string
ExpiryInterval time.Duration
TTL time.Duration
}
// Entry represents a DNS request log entry.
type Entry struct {
Time time.Time
RemoteAddr net.IP
Qtype uint16
Question string
Answers []string
}
type maintainer struct {
interval time.Duration
ttl time.Duration
done chan bool
}
// New creates a new logger wrapping a standard log.Logger.
func New(w io.Writer, prefix string, options RecordOptions) (*Logger, error) {
logger := &Logger{
Logger: log.New(w, prefix, 0),
queue: make(chan Entry, 100),
Now: time.Now,
}
var err error
if options.Database != "" {
logger.db, err = sql.New(options.Database)
if err != nil {
return nil, err
}
}
logger.wg.Add(1)
go logger.readQueue()
if options.TTL > 0 {
if options.ExpiryInterval <= 0 {
options.ExpiryInterval = time.Minute
}
maintain(logger, options.ExpiryInterval, options.TTL)
}
return logger, nil
}
func maintain(logger *Logger, interval, ttl time.Duration) {
m := &maintainer{
interval: interval,
ttl: ttl,
done: make(chan bool),
}
logger.maintainer = m
logger.wg.Add(1)
go m.run(logger)
}
func (m *maintainer) run(logger *Logger) {
ticker := time.NewTicker(m.interval)
defer logger.wg.Done()
for {
select {
case <-ticker.C:
t := logger.Now().Add(-m.ttl)
if err := logger.db.DeleteLogBefore(t); err != nil {
logger.Printf("error deleting log entries before %v: %s", t, err)
}
case <-m.done:
ticker.Stop()
return
}
}
}
// Close consumes any outstanding log requests and closes the logger.
func (l *Logger) Close() error {
close(l.queue)
if l.maintainer != nil {
l.maintainer.done <- true
}
l.wg.Wait()
return nil
}
// Record records the given DNS request to the log database.
func (l *Logger) Record(remoteAddr net.IP, qtype uint16, question string, answers ...string) {
if l.db == nil {
return
}
l.queue <- Entry{
Time: l.Now(),
RemoteAddr: remoteAddr,
Qtype: qtype,
Question: question,
Answers: answers,
}
}
// Get returns the n most recent persisted log entries.
func (l *Logger) Get(n int) ([]Entry, error) {
logEntries, err := l.db.ReadLog(n)
if err != nil {
return nil, err
}
ids := make(map[int64]*Entry)
entries := make([]Entry, 0, len(logEntries))
for _, le := range logEntries {
entry, ok := ids[le.ID]
if !ok {
newEntry := Entry{
Time: time.Unix(le.Time, 0).UTC(),
RemoteAddr: le.RemoteAddr,
Qtype: le.Qtype,
Question: le.Question,
}
entries = append(entries, newEntry)
entry = &entries[len(entries)-1]
ids[le.ID] = entry
}
entry.Answers = append(entry.Answers, le.Answer)
}
return entries, nil
}
func (l *Logger) readQueue() {
defer l.wg.Done()
for entry := range l.queue {
if err := l.db.WriteLog(entry.Time, entry.RemoteAddr, entry.Qtype, entry.Question, entry.Answers...); err != nil {
l.Printf("write failed: %+v: %s", entry, err)
}
}
}
|
