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package main
import (
"context"
"errors"
"github.com/google/gopacket"
"github.com/google/gopacket/layers"
"github.com/google/gopacket/pcap"
"github.com/google/gopacket/tcpassembly"
log "github.com/sirupsen/logrus"
"net"
"sync"
"time"
)
const initialAssemblerPoolSize = 16
const flushOlderThan = 5 * time.Minute
const importUpdateProgressInterval = 100 * time.Millisecond
type PcapImporter struct {
storage Storage
streamPool *tcpassembly.StreamPool
assemblers []*tcpassembly.Assembler
sessions map[string]ImportingSession
mAssemblers sync.Mutex
mSessions sync.Mutex
serverIP gopacket.Endpoint
}
type ImportingSession struct {
ID string `json:"id" bson:"_id"`
CompletedAt time.Time `json:"completed_at" bson:"completed_at,omitempty"`
ProcessedPackets int `json:"processed_packets" bson:"processed_packets"`
InvalidPackets int `json:"invalid_packets" bson:"invalid_packets"`
PacketsPerService map[uint16]flowCount `json:"packets_per_service" bson:"packets_per_service"`
ImportingError string `json:"importing_error" bson:"importing_error,omitempty"`
cancelFunc context.CancelFunc
completed chan string
}
type flowCount [2]int
func NewPcapImporter(storage Storage, serverIP net.IP, rulesManager RulesManager) *PcapImporter {
serverEndpoint := layers.NewIPEndpoint(serverIP)
streamPool := tcpassembly.NewStreamPool(NewBiDirectionalStreamFactory(storage, serverEndpoint, rulesManager))
return &PcapImporter{
storage: storage,
streamPool: streamPool,
assemblers: make([]*tcpassembly.Assembler, 0, initialAssemblerPoolSize),
sessions: make(map[string]ImportingSession),
mAssemblers: sync.Mutex{},
mSessions: sync.Mutex{},
serverIP: serverEndpoint,
}
}
// Import a pcap file to the database. The pcap file must be present at the fileName path. If the pcap is already
// going to be imported or if it has been already imported in the past the function returns an error. Otherwise it
// create a new session and starts to import the pcap, and returns immediately the session name (that is the sha256
// of the pcap).
func (pi *PcapImporter) ImportPcap(fileName string) (string, error) {
hash, err := Sha256Sum(fileName)
if err != nil {
return "", err
}
pi.mSessions.Lock()
_, isPresent := pi.sessions[hash]
if isPresent {
pi.mSessions.Unlock()
return hash, errors.New("pcap already processed")
}
ctx, cancelFunc := context.WithCancel(context.Background())
session := ImportingSession{
ID: hash,
PacketsPerService: make(map[uint16]flowCount),
cancelFunc: cancelFunc,
completed: make(chan string),
}
pi.sessions[hash] = session
pi.mSessions.Unlock()
go pi.parsePcap(session, fileName, ctx)
return hash, nil
}
func (pi *PcapImporter) GetSession(sessionID string) (ImportingSession, bool) {
pi.mSessions.Lock()
defer pi.mSessions.Unlock()
session, isPresent := pi.sessions[sessionID]
return session, isPresent
}
func (pi *PcapImporter) CancelSession(sessionID string) error {
pi.mSessions.Lock()
defer pi.mSessions.Unlock()
if session, isPresent := pi.sessions[sessionID]; !isPresent {
return errors.New("session " + sessionID + " not found")
} else {
session.cancelFunc()
return nil
}
}
// Read the pcap and save the tcp stream flow to the database
func (pi *PcapImporter) parsePcap(session ImportingSession, fileName string, ctx context.Context) {
handle, err := pcap.OpenOffline(fileName)
if err != nil {
pi.progressUpdate(session, false, "failed to process pcap")
log.WithError(err).WithFields(log.Fields{"session": session, "fileName": fileName}).
Error("failed to open pcap")
return
}
packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
packetSource.NoCopy = true
assembler := pi.takeAssembler()
packets := packetSource.Packets()
firstPacketTime := time.Time{}
updateProgressInterval := time.Tick(importUpdateProgressInterval)
for {
select {
case <-ctx.Done():
handle.Close()
pi.releaseAssembler(assembler)
pi.progressUpdate(session, false, "import process cancelled")
return
default:
}
select {
case packet := <-packets:
if packet == nil { // completed
if !firstPacketTime.IsZero() {
assembler.FlushOlderThan(firstPacketTime.Add(-flushOlderThan))
}
handle.Close()
pi.releaseAssembler(assembler)
pi.progressUpdate(session, true, "")
return
}
timestamp := packet.Metadata().Timestamp
if firstPacketTime.IsZero() {
firstPacketTime = timestamp
}
session.ProcessedPackets++
if packet.NetworkLayer() == nil || packet.TransportLayer() == nil ||
packet.TransportLayer().LayerType() != layers.LayerTypeTCP { // invalid packet
session.InvalidPackets++
continue
}
tcp := packet.TransportLayer().(*layers.TCP)
var servicePort uint16
var index int
isDstServer := packet.NetworkLayer().NetworkFlow().Dst() == pi.serverIP
isSrcServer := packet.NetworkLayer().NetworkFlow().Src() == pi.serverIP
if isDstServer && !isSrcServer {
servicePort = uint16(tcp.DstPort)
index = 0
} else if isSrcServer && !isDstServer {
servicePort = uint16(tcp.SrcPort)
index = 1
} else {
session.InvalidPackets++
continue
}
fCount, isPresent := session.PacketsPerService[servicePort]
if !isPresent {
fCount = flowCount{0, 0}
}
fCount[index]++
session.PacketsPerService[servicePort] = fCount
assembler.AssembleWithTimestamp(packet.NetworkLayer().NetworkFlow(), tcp, timestamp)
case <-updateProgressInterval:
pi.progressUpdate(session, false, "")
}
}
}
func (pi *PcapImporter) progressUpdate(session ImportingSession, completed bool, err string) {
if completed {
session.CompletedAt = time.Now()
}
session.ImportingError = err
packetsPerService := session.PacketsPerService
session.PacketsPerService = make(map[uint16]flowCount, len(packetsPerService))
for key, value := range packetsPerService {
session.PacketsPerService[key] = value
}
pi.mSessions.Lock()
pi.sessions[session.ID] = session
pi.mSessions.Unlock()
if completed || session.ImportingError != "" {
if _, _err := pi.storage.Insert(ImportingSessions).One(session); _err != nil {
log.WithError(_err).WithField("session", session).Error("failed to insert importing stats")
}
session.completed <- session.ImportingError
}
}
func (pi *PcapImporter) takeAssembler() *tcpassembly.Assembler {
pi.mAssemblers.Lock()
defer pi.mAssemblers.Unlock()
if len(pi.assemblers) == 0 {
return tcpassembly.NewAssembler(pi.streamPool)
}
index := len(pi.assemblers) - 1
assembler := pi.assemblers[index]
pi.assemblers = pi.assemblers[:index]
return assembler
}
func (pi *PcapImporter) releaseAssembler(assembler *tcpassembly.Assembler) {
pi.mAssemblers.Lock()
pi.assemblers = append(pi.assemblers, assembler)
pi.mAssemblers.Unlock()
}
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