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// Copyright (C) MongoDB, Inc. 2014-present.
//
// 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
package mongoreplay
import (
"fmt"
"os"
"os/signal"
"syscall"
"github.com/google/gopacket/pcap"
)
// RecordCommand stores settings for the mongoreplay 'record' subcommand
type RecordCommand struct {
GlobalOpts *Options `no-flag:"true"`
OpStreamSettings
Gzip bool `long:"gzip" description:"compress output file with Gzip"`
FullReplies bool `long:"full-replies" description:"save full reply payload in playback file"`
PlaybackFile string `short:"p" description:"path to playback file to record to" long:"playback-file" required:"yes"`
}
// ErrPacketsDropped means that some packets were dropped
type ErrPacketsDropped struct {
Count int
}
func (e ErrPacketsDropped) Error() string {
return fmt.Sprintf("completed with %d packets dropped", e.Count)
}
type packetHandlerContext struct {
packetHandler *PacketHandler
mongoOpStream *MongoOpStream
pcapHandle *pcap.Handle
}
func getOpstream(cfg OpStreamSettings) (*packetHandlerContext, error) {
if cfg.PacketBufSize < 1 {
return nil, fmt.Errorf("invalid packet buffer size")
}
var pcapHandle *pcap.Handle
var err error
if len(cfg.PcapFile) > 0 {
pcapHandle, err = pcap.OpenOffline(cfg.PcapFile)
if err != nil {
return nil, fmt.Errorf("error opening pcap file: %v", err)
}
} else if len(cfg.NetworkInterface) > 0 {
inactive, err := pcap.NewInactiveHandle(cfg.NetworkInterface)
if err != nil {
return nil, fmt.Errorf("error creating a pcap handle: %v", err)
}
// This is safe; calling `Activate()` steals the underlying ptr.
defer inactive.CleanUp()
err = inactive.SetSnapLen(64 * 1024)
if err != nil {
return nil, fmt.Errorf("error setting snaplen on pcap handle: %v", err)
}
err = inactive.SetPromisc(false)
if err != nil {
return nil, fmt.Errorf("error setting promisc on pcap handle: %v", err)
}
err = inactive.SetTimeout(pcap.BlockForever)
if err != nil {
return nil, fmt.Errorf("error setting timeout on pcap handle: %v", err)
}
// CaptureBufSize is in KiB to match units on `tcpdump -B`.
err = inactive.SetBufferSize(cfg.CaptureBufSize * 1024)
if err != nil {
return nil, fmt.Errorf("error setting buffer size on pcap handle: %v", err)
}
pcapHandle, err = inactive.Activate()
if err != nil {
return nil, fmt.Errorf("error listening to network interface: %v", err)
}
} else {
return nil, fmt.Errorf("must specify either a pcap file or network interface to record from")
}
if len(cfg.Expression) > 0 {
err = pcapHandle.SetBPFFilter(cfg.Expression)
if err != nil {
return nil, fmt.Errorf("error setting packet filter expression: %v", err)
}
}
assemblerOptions := AssemblerOptions{
MaxBufferedPagesTotal: cfg.MaxBufferedPages,
}
h := NewPacketHandler(pcapHandle, assemblerOptions)
h.Verbose = userInfoLogger.isInVerbosity(DebugLow)
toolDebugLogger.Logvf(Info, "Created packet buffer size %d", cfg.PacketBufSize)
m := NewMongoOpStream(cfg.PacketBufSize)
return &packetHandlerContext{h, m, pcapHandle}, nil
}
// ValidateParams validates the settings described in the RecordCommand struct.
func (record *RecordCommand) ValidateParams(args []string) error {
switch {
case len(args) > 0:
return fmt.Errorf("unknown argument: %s", args[0])
case record.PcapFile != "" && record.NetworkInterface != "":
return fmt.Errorf("must only specify an interface or a pcap file")
}
if record.OpStreamSettings.PacketBufSize == 0 {
// default heap size
record.OpStreamSettings.PacketBufSize = 1000
}
if record.OpStreamSettings.CaptureBufSize == 0 {
// default capture buffer size to 2 MiB (same as libpcap)
record.OpStreamSettings.CaptureBufSize = 2 * 1024
}
if record.OpStreamSettings.MaxBufferedPages < 0 {
return fmt.Errorf("bufferedPagesMax cannot be less than 0")
}
return nil
}
// Execute runs the program for the 'record' subcommand
func (record *RecordCommand) Execute(args []string) error {
err := record.ValidateParams(args)
if err != nil {
return err
}
record.GlobalOpts.SetLogging()
ctx, err := getOpstream(record.OpStreamSettings)
if err != nil {
return err
}
// When a signal is received to kill the process, stop the packet handler so
// we gracefully flush all ops being processed before exiting.
sigChan := make(chan os.Signal, 1)
signal.Notify(sigChan, syscall.SIGTERM, syscall.SIGINT, syscall.SIGHUP)
go func() {
// Block until a signal is received.
s := <-sigChan
toolDebugLogger.Logvf(Info, "Got signal %v, closing PCAP handle", s)
ctx.packetHandler.Close()
}()
playbackFileWriter, err := NewPlaybackFileWriter(record.PlaybackFile, false, record.Gzip)
if err != nil {
return err
}
defer playbackFileWriter.Close()
return Record(ctx, playbackFileWriter, record.FullReplies)
}
// Record writes pcap data into a playback file
func Record(ctx *packetHandlerContext,
playbackWriter *PlaybackFileWriter,
noShortenReply bool) error {
ch := make(chan error)
go func() {
defer close(ch)
var fail error
for op := range ctx.mongoOpStream.Ops {
// since we don't currently have a way to shutdown packetHandler.Handle()
// continue to read from ctx.mongoOpStream.Ops even after a fatal error
if fail != nil {
toolDebugLogger.Logvf(DebugHigh, "not recording op because of record error %v", fail)
continue
}
if (op.Header.OpCode == OpCodeReply || op.Header.OpCode == OpCodeCommandReply) &&
!noShortenReply {
err := op.ShortenReply()
if err != nil {
userInfoLogger.Logvf(DebugLow, "stream %v problem shortening reply: %v", op.SeenConnectionNum, err)
continue
}
}
err := bsonToWriter(playbackWriter, op)
if err != nil {
fail = fmt.Errorf("error writing message: %v", err)
userInfoLogger.Logvf(Always, "%v", err)
continue
}
}
ch <- fail
}()
if err := ctx.packetHandler.Handle(ctx.mongoOpStream, -1); err != nil {
return fmt.Errorf("record: error handling packet stream: %s", err)
}
stats, err := ctx.pcapHandle.Stats()
if err != nil {
toolDebugLogger.Logvf(Always, "Warning: got err %v getting pcap handle stats", err)
} else {
toolDebugLogger.Logvf(Info, "PCAP stats: %#v", stats)
}
err = <-ch
if err == nil && stats != nil && stats.PacketsDropped != 0 {
err = ErrPacketsDropped{stats.PacketsDropped}
}
return err
}
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