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file.go
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file.go
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// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you 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 sniffer
import (
"fmt"
"io"
"time"
"github.com/tsg/gopacket"
"github.com/tsg/gopacket/layers"
"github.com/tsg/gopacket/pcap"
"github.com/elastic/beats/libbeat/logp"
)
type fileHandler struct {
pcapHandle *pcap.Handle
file string
loopCount, maxLoopCount int
topSpeed bool
lastTS time.Time
}
func newFileHandler(file string, topSpeed bool, maxLoopCount int) (*fileHandler, error) {
h := &fileHandler{
file: file,
topSpeed: topSpeed,
maxLoopCount: maxLoopCount,
}
if err := h.open(); err != nil {
return nil, err
}
return h, nil
}
func (h *fileHandler) open() error {
tmp, err := pcap.OpenOffline(h.file)
if err != nil {
return err
}
h.pcapHandle = tmp
return nil
}
func (h *fileHandler) ReadPacketData() ([]byte, gopacket.CaptureInfo, error) {
data, ci, err := h.pcapHandle.ReadPacketData()
if err != nil {
if err != io.EOF {
return data, ci, err
}
h.pcapHandle.Close()
h.pcapHandle = nil
h.loopCount++
if h.loopCount >= h.maxLoopCount {
return data, ci, err
}
logp.Debug("sniffer", "Reopening the file")
if err = h.open(); err != nil {
return nil, ci, fmt.Errorf("Error reopening file: %s", err)
}
data, ci, err = h.pcapHandle.ReadPacketData()
h.lastTS = ci.Timestamp
return data, ci, err
}
if h.topSpeed {
return data, ci, nil
}
if !h.lastTS.IsZero() {
sleep := ci.Timestamp.Sub(h.lastTS)
if sleep > 0 {
time.Sleep(sleep)
} else {
logp.Warn("Time in pcap went backwards: %d", sleep)
}
}
h.lastTS = ci.Timestamp
ci.Timestamp = time.Now()
return data, ci, nil
}
func (h *fileHandler) LinkType() layers.LinkType {
return h.pcapHandle.LinkType()
}
func (h *fileHandler) Close() {
if h.pcapHandle != nil {
h.pcapHandle.Close()
h.pcapHandle = nil
}
}