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package main
import (
"encoding/binary"
"github.com/flier/gohs/hyperscan"
"github.com/google/gopacket"
"github.com/google/gopacket/tcpassembly"
log "github.com/sirupsen/logrus"
"sync"
"time"
)
const initialConnectionsCapacity = 1024
const initialScannersCapacity = 1024
type BiDirectionalStreamFactory struct {
storage Storage
serverIP gopacket.Endpoint
connections map[StreamFlow]ConnectionHandler
mConnections sync.Mutex
rulesManager RulesManager
rulesDatabase RulesDatabase
mRulesDatabase sync.Mutex
scanners []Scanner
}
type StreamFlow [4]gopacket.Endpoint
type Scanner struct {
scratch *hyperscan.Scratch
version RowID
}
type ConnectionHandler interface {
Complete(handler *StreamHandler)
Storage() Storage
PatternsDatabase() hyperscan.StreamDatabase
PatternsDatabaseSize() int
}
type connectionHandlerImpl struct {
factory *BiDirectionalStreamFactory
connectionFlow StreamFlow
mComplete sync.Mutex
otherStream *StreamHandler
}
func NewBiDirectionalStreamFactory(storage Storage, serverIP gopacket.Endpoint,
rulesManager RulesManager) *BiDirectionalStreamFactory {
factory := &BiDirectionalStreamFactory{
storage: storage,
serverIP: serverIP,
connections: make(map[StreamFlow]ConnectionHandler, initialConnectionsCapacity),
mConnections: sync.Mutex{},
rulesManager: rulesManager,
mRulesDatabase: sync.Mutex{},
scanners: make([]Scanner, 0, initialScannersCapacity),
}
go factory.updateRulesDatabaseService()
return factory
}
func (factory *BiDirectionalStreamFactory) updateRulesDatabaseService() {
for {
select {
case rulesDatabase, ok := <-factory.rulesManager.DatabaseUpdateChannel():
if !ok {
return
}
factory.mRulesDatabase.Lock()
scanners := factory.scanners
factory.scanners = factory.scanners[:0]
for _, s := range scanners {
err := s.scratch.Realloc(rulesDatabase.database)
if err != nil {
log.WithError(err).Error("failed to realloc an existing scanner")
} else {
s.version = rulesDatabase.version
factory.scanners = append(factory.scanners, s)
}
}
factory.rulesDatabase = rulesDatabase
factory.mRulesDatabase.Unlock()
}
}
}
func (factory *BiDirectionalStreamFactory) takeScanner() Scanner {
factory.mRulesDatabase.Lock()
defer factory.mRulesDatabase.Unlock()
if len(factory.scanners) == 0 {
scratch, err := hyperscan.NewScratch(factory.rulesDatabase.database)
if err != nil {
log.WithError(err).Fatal("failed to alloc a new scratch")
}
return Scanner{
scratch: scratch,
version: factory.rulesDatabase.version,
}
}
index := len(factory.scanners) - 1
scanner := factory.scanners[index]
factory.scanners = factory.scanners[:index]
return scanner
}
func (factory *BiDirectionalStreamFactory) releaseScanner(scanner Scanner) {
factory.mRulesDatabase.Lock()
defer factory.mRulesDatabase.Unlock()
if scanner.version != factory.rulesDatabase.version {
err := scanner.scratch.Realloc(factory.rulesDatabase.database)
if err != nil {
log.WithError(err).Error("failed to realloc an existing scanner")
return
}
scanner.version = factory.rulesDatabase.version
}
factory.scanners = append(factory.scanners, scanner)
}
func (factory *BiDirectionalStreamFactory) New(net, transport gopacket.Flow) tcpassembly.Stream {
flow := StreamFlow{net.Src(), net.Dst(), transport.Src(), transport.Dst()}
invertedFlow := StreamFlow{net.Dst(), net.Src(), transport.Dst(), transport.Src()}
factory.mConnections.Lock()
connection, isPresent := factory.connections[invertedFlow]
if isPresent {
delete(factory.connections, invertedFlow)
} else {
var connectionFlow StreamFlow
if net.Src() == factory.serverIP {
connectionFlow = invertedFlow
} else {
connectionFlow = flow
}
connection = &connectionHandlerImpl{
connectionFlow: connectionFlow,
mComplete: sync.Mutex{},
factory: factory,
}
factory.connections[flow] = connection
}
factory.mConnections.Unlock()
streamHandler := NewStreamHandler(connection, flow, factory.takeScanner())
return &streamHandler
}
func (ch *connectionHandlerImpl) Complete(handler *StreamHandler) {
ch.factory.releaseScanner(handler.scanner)
ch.mComplete.Lock()
if ch.otherStream == nil {
ch.otherStream = handler
ch.mComplete.Unlock()
return
}
ch.mComplete.Unlock()
var startedAt, closedAt time.Time
if handler.firstPacketSeen.Before(ch.otherStream.firstPacketSeen) {
startedAt = handler.firstPacketSeen
} else {
startedAt = ch.otherStream.firstPacketSeen
}
if handler.lastPacketSeen.After(ch.otherStream.lastPacketSeen) {
closedAt = handler.lastPacketSeen
} else {
closedAt = ch.otherStream.lastPacketSeen
}
var client, server *StreamHandler
if handler.streamFlow == ch.connectionFlow {
client = handler
server = ch.otherStream
} else {
client = ch.otherStream
server = handler
}
connectionID := CustomRowID(ch.connectionFlow.Hash(), startedAt)
connection := Connection{
ID: connectionID,
SourceIP: ch.connectionFlow[0].String(),
DestinationIP: ch.connectionFlow[1].String(),
SourcePort: binary.BigEndian.Uint16(ch.connectionFlow[2].Raw()),
DestinationPort: binary.BigEndian.Uint16(ch.connectionFlow[3].Raw()),
StartedAt: startedAt,
ClosedAt: closedAt,
ClientBytes: client.streamLength,
ServerBytes: server.streamLength,
ClientDocuments: len(client.documentsIDs),
ServerDocuments: len(server.documentsIDs),
ProcessedAt: time.Now(),
}
ch.factory.rulesManager.FillWithMatchedRules(&connection, client.patternMatches, server.patternMatches)
_, err := ch.Storage().Insert(Connections).One(connection)
if err != nil {
log.WithError(err).WithField("connection", connection).Error("failed to insert a connection")
return
}
streamsIDs := append(client.documentsIDs, server.documentsIDs...)
if len(streamsIDs) > 0 {
n, err := ch.Storage().Update(ConnectionStreams).
Filter(OrderedDocument{{"_id", UnorderedDocument{"$in": streamsIDs}}}).
Many(UnorderedDocument{"connection_id": connectionID})
if err != nil {
log.WithError(err).WithField("connection", connection).Error("failed to update connection streams")
} else if int(n) != len(streamsIDs) {
log.WithError(err).WithField("connection", connection).Error("failed to update all connections streams")
}
}
}
func (ch *connectionHandlerImpl) Storage() Storage {
return ch.factory.storage
}
func (ch *connectionHandlerImpl) PatternsDatabase() hyperscan.StreamDatabase {
return ch.factory.rulesDatabase.database
}
func (ch *connectionHandlerImpl) PatternsDatabaseSize() int {
return ch.factory.rulesDatabase.databaseSize
}
func (sf StreamFlow) Hash() uint64 {
return sf[0].FastHash() ^ sf[1].FastHash() ^ sf[2].FastHash() ^ sf[3].FastHash()
}
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