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// Copyright 2019-2022 Graham Clark. All rights reserved. Use of this source
// code is governed by the MIT license that can be found in the LICENSE
// file.
package convs
import (
"bytes"
"context"
"fmt"
"os/exec"
"sync"
"github.com/gcla/gowid"
"github.com/gcla/termshark/v2"
"github.com/gcla/termshark/v2/pkg/pcap"
log "github.com/sirupsen/logrus"
)
//======================================================================
var Goroutinewg *sync.WaitGroup
//======================================================================
type ILoaderCmds interface {
Convs(pcapfile string, convs []string, filter string, abs bool, resolve bool) pcap.IPcapCommand
}
type commands struct{}
func MakeCommands() commands {
return commands{}
}
var _ ILoaderCmds = commands{}
func (c commands) Convs(pcapfile string, convs []string, filter string, abs bool, resolve bool) pcap.IPcapCommand {
args := []string{"-q", "-r", pcapfile}
if abs {
args = append(args, "-t", "a")
}
if !resolve {
args = append(args, "-n")
}
for _, conv := range convs {
args = append(args, "-z", fmt.Sprintf("conv,%s", conv))
if filter != "" {
args[len(args)-1] = fmt.Sprintf("%s,%s", args[len(args)-1], filter)
}
}
return &pcap.Command{
Cmd: exec.Command(termshark.TSharkBin(), args...),
}
}
//======================================================================
type Loader struct {
cmds ILoaderCmds
SuppressErrors bool // if true, don't report process errors e.g. at shutdown
mainCtx context.Context // cancelling this cancels the dependent contexts
mainCancelFn context.CancelFunc
convsCtx context.Context
convsCancelFn context.CancelFunc
convsCmd pcap.IPcapCommand
}
func NewLoader(cmds ILoaderCmds, ctx context.Context) *Loader {
res := &Loader{
cmds: cmds,
}
res.mainCtx, res.mainCancelFn = context.WithCancel(ctx)
return res
}
func (c *Loader) StopLoad() {
if c.convsCancelFn != nil {
c.convsCancelFn()
}
}
//======================================================================
type IConvsCallbacks interface {
OnData(data string)
AfterDataEnd(success bool)
}
func (c *Loader) StartLoad(pcap string, convs []string, filter string, abs bool, resolve bool, app gowid.IApp, cb IConvsCallbacks) {
termshark.TrackedGo(func() {
c.loadConvAsync(pcap, convs, filter, abs, resolve, app, cb)
}, Goroutinewg)
}
func (c *Loader) loadConvAsync(pcapf string, convs []string, filter string, abs bool, resolve bool, app gowid.IApp, cb IConvsCallbacks) {
c.convsCtx, c.convsCancelFn = context.WithCancel(c.mainCtx)
procChan := make(chan int)
pid := 0
defer func() {
if pid == 0 {
close(procChan)
}
}()
c.convsCmd = c.cmds.Convs(pcapf, convs, filter, abs, resolve)
termChan := make(chan error)
termshark.TrackedGo(func() {
var err error
cmd := c.convsCmd
cancelledChan := c.convsCtx.Done()
procChan := procChan
state := pcap.NotStarted
kill := func() {
err := termshark.KillIfPossible(cmd)
if err != nil {
log.Infof("Did not kill tshark conv process: %v", err)
}
}
loop:
for {
select {
case err = <-termChan:
state = pcap.Terminated
if !c.SuppressErrors && err != nil {
if _, ok := err.(*exec.ExitError); ok {
pcap.HandleError(pcap.ConvCode, app, pcap.MakeUsefulError(c.convsCmd, err), cb)
}
}
case pid := <-procChan:
procChan = nil
if pid != 0 {
state = pcap.Started
if cancelledChan == nil {
kill()
}
}
case <-cancelledChan:
cancelledChan = nil
if state == pcap.Started {
kill()
}
}
if state == pcap.Terminated || (procChan == nil && state == pcap.NotStarted) {
break loop
}
}
}, Goroutinewg)
convsOut, err := c.convsCmd.StdoutReader()
if err != nil {
pcap.HandleError(pcap.ConvCode, app, err, cb)
return
}
defer func() {
cb.AfterDataEnd(true)
}()
app.Run(gowid.RunFunction(func(app gowid.IApp) {
pcap.HandleBegin(pcap.ConvCode, app, cb)
}))
defer func() {
app.Run(gowid.RunFunction(func(app gowid.IApp) {
pcap.HandleEnd(pcap.ConvCode, app, cb)
}))
}()
err = c.convsCmd.Start()
if err != nil {
err = fmt.Errorf("Error starting %v: %v", c.convsCmd, err)
pcap.HandleError(pcap.ConvCode, app, err, cb)
return
}
log.Infof("Started command %v with pid %d", c.convsCmd, c.convsCmd.Pid())
termshark.TrackedGo(func() {
termChan <- c.convsCmd.Wait()
}, Goroutinewg)
pid = c.convsCmd.Pid()
procChan <- pid
buf := new(bytes.Buffer)
buf.ReadFrom(convsOut)
cb.OnData(buf.String())
c.convsCancelFn()
}
//======================================================================
// Local Variables:
// mode: Go
// fill-column: 78
// End:
|
