FrameStreamOutput.go

/*
 * Copyright (c) 2014 by Farsight Security, Inc.
 *
 * 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 dnstap

import "io"
import "log"
import "os"

import framestream "github.com/farsightsec/golang-framestream"

type FrameStreamOutput struct {
    outputChannel   chan []byte
    wait            chan bool
    enc             *framestream.Encoder
}

func NewFrameStreamOutput(w io.Writer) (o *FrameStreamOutput, err error) {
    o = new(FrameStreamOutput)
    o.outputChannel = make(chan []byte, outputChannelSize)
    o.enc, err = framestream.NewEncoder(w, &framestream.EncoderOptions{ContentType: FSContentType})
    if err != nil {
        return
    }
    o.wait = make(chan bool)
    return
}

func NewFrameStreamOutputFromFilename(fname string) (o *FrameStreamOutput, err error) {
    if fname == "" || fname == "-" {
        return NewFrameStreamOutput(os.Stdout)
    }
    w, err := os.Create(fname)
    if err != nil {
        return
    }
    return NewFrameStreamOutput(w)
}

func (o *FrameStreamOutput) GetOutputChannel() (chan []byte) {
    return o.outputChannel
}

func (o *FrameStreamOutput) RunOutputLoop() {
    for frame := range o.outputChannel {
        if _, err := o.enc.Write(frame); err != nil {
            log.Fatalf("framestream.Encoder.Write() failed: %s\n", err)
            break
        }
    }
    close(o.wait)
}

func (o *FrameStreamOutput) Close() {
    close(o.outputChannel)
    <-o.wait
    o.enc.Flush()
    o.enc.Close()
}