dnstap_nats_output.go

/*
 * Copyright (c) 2019 Manabu Sonoda
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package dtap

import (
	"context"
	"encoding/json"
	"fmt"
	"sync"
	"time"

	dnstap "github.com/dnstap/golang-dnstap"
	framestream "github.com/farsightsec/golang-framestream"
	"github.com/golang/protobuf/proto"
	nats "github.com/nats-io/go-nats"
	"github.com/prometheus/common/log"
)

type DnstapNatsOutput struct {
	config          *OutputNatsConfig
	enc             *framestream.Encoder
	con             *nats.Conn
	mux             *sync.Mutex
	dataString      []byte
	data            []*DnstapFlatT
	flatOption      DnstapFlatOption
	flushCancelFunc context.CancelFunc
	flushErr        error
	closeCh         chan struct{}
}

func NewDnstapNatsOutput(config *OutputNatsConfig, params *DnstapOutputParams) *DnstapOutput {
	params.Handler = &DnstapNatsOutput{
		config:     config,
		flatOption: &config.Flat,
		data:       []*DnstapFlatT{},
		mux:        new(sync.Mutex),
	}
	return NewDnstapOutput(params)
}

func (o *DnstapNatsOutput) open() error {
	var err error
	if o.config.Token != "" {
		o.con, err = nats.Connect(o.config.GetHost(), nats.Token(o.config.GetToken()))
	} else if o.config.User != "" {
		o.con, err = nats.Connect(o.config.GetHost(), nats.UserInfo(o.config.GetUser(), o.config.GetPassword()))
	} else {
		o.con, err = nats.Connect(o.config.GetHost())
	}
	if err != nil {
		return fmt.Errorf("failed to create nats producer: %w", err)
	}
	o.closeCh = make(chan struct{})
	ctx, cancelFunc := context.WithCancel(context.Background())
	o.flushCancelFunc = cancelFunc
	o.flushErr = nil
	go o.flush(ctx)
	return nil
}

func (o *DnstapNatsOutput) write(frame []byte) error {
	if o.flushErr != nil {
		return o.flushErr
	}
	dt := dnstap.Dnstap{}
	if err := proto.Unmarshal(frame, &dt); err != nil {
		return err
	}
	data, err := FlatDnstap(&dt, o.flatOption)
	if err != nil {
		return err
	}
	o.mux.Lock()
	o.data = append(o.data, data)
	o.mux.Unlock()
	return nil
}

func (o *DnstapNatsOutput) flush(ctx context.Context) {
	ticker := time.NewTicker(10 * time.Millisecond)
	for {
		select {
		case <-ctx.Done():
			ticker.Stop()
			return
		case <-ticker.C:
			o.publish()
		}
	}
}

func (o *DnstapNatsOutput) publish() {
	o.mux.Lock()
	if len(o.data) == 0 {
		o.mux.Unlock()
		return
	}
	buf, err := json.Marshal(o.data)
	if err != nil {
		log.Debug(err)
		return
	}
	o.data = []*DnstapFlatT{}
	o.mux.Unlock()
	if err := o.con.Publish(o.config.GetSubject(), buf); err != nil {
		o.flushErr = fmt.Errorf("publish error: %w", err)
	}
}

func (o *DnstapNatsOutput) close() {
	close(o.closeCh)
	o.flushCancelFunc()
	o.publish()
	o.con.Close()
}