/
tcpsniffer.go
182 lines (159 loc) · 4.74 KB
/
tcpsniffer.go
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package collectors
import (
"github.com/google/gopacket"
"github.com/google/gopacket/layers"
"github.com/google/gopacket/pcap"
"github.com/otterize/intents-operator/src/shared/errors"
sharedconfig "github.com/otterize/network-mapper/src/shared/config"
"github.com/otterize/network-mapper/src/sniffer/pkg/config"
"github.com/otterize/network-mapper/src/sniffer/pkg/ipresolver"
"github.com/otterize/nilable"
"github.com/sirupsen/logrus"
"github.com/spf13/viper"
"time"
)
type TCPSniffer struct {
NetworkCollector
resolver ipresolver.IPResolver
pending []pendingTCPCapture
lastRefresh time.Time
isRunningOnAWS bool
}
type pendingTCPCapture struct {
srcIp string
srcHostname string
destIp string
destPort int
time time.Time
ttl nilable.Nilable[int]
}
func NewTCPSniffer(resolver ipresolver.IPResolver, isRunningOnAWS bool) *TCPSniffer {
s := TCPSniffer{
NetworkCollector: NetworkCollector{},
resolver: resolver,
pending: make([]pendingTCPCapture, 0),
lastRefresh: time.Now().Add(-viper.GetDuration(config.HostsMappingRefreshIntervalKey)), // Should refresh immediately
isRunningOnAWS: isRunningOnAWS,
}
s.resetData()
return &s
}
func setCaptureIncomingTCPSYN(handle *pcap.Handle) error {
err := handle.SetDirection(pcap.DirectionIn)
if err != nil {
return err
}
err = handle.SetBPFFilter("tcp and tcp[tcpflags] == tcp-syn")
if err != nil {
return err
}
return nil
}
func (s *TCPSniffer) CreateTCPPacketStream() (chan gopacket.Packet, error) {
handle, err := pcap.OpenLive("any", 0, true, pcap.BlockForever)
if err != nil {
return nil, err
}
err = setCaptureIncomingTCPSYN(handle)
if err != nil {
return nil, err
}
packetSource := gopacket.NewPacketSource(handle, handle.LinkType())
return packetSource.Packets(), nil
}
func (s *TCPSniffer) HandlePacket(packet gopacket.Packet) {
if !viper.GetBool(sharedconfig.EnableTCPKey) {
return
}
captureTime := detectCaptureTime(packet)
ipLayer := packet.Layer(layers.LayerTypeIPv4)
if ipLayer == nil {
return
}
ip, ok := ipLayer.(*layers.IPv4)
if !ok {
logrus.Debugf("Failed to parse IP layer")
return
}
dstPort, portFound, err := s.getDestPort(packet, ip)
if err != nil {
logrus.Debugf("Failed to parse TCP/UDP port: %s", err)
return
}
if !portFound {
logrus.Debugf("Port not found, skipping packet")
return
}
logrus.Debugf("TCP SYN: %s to %s:%d", ip.SrcIP, ip.DstIP, dstPort)
srcIP := ip.SrcIP.String()
dstIP := ip.DstIP.String()
if !s.isRunningOnAWS {
s.addCapturedRequest(srcIP, "", dstIP, dstIP, captureTime, nilable.FromPtr[int](nil), &dstPort)
return
}
localHostname, err := s.resolver.ResolveIP(srcIP)
if err != nil {
logrus.Debugf("Can't resolve IP addr %s, sending IP only", srcIP)
s.addCapturedRequest(srcIP, "", dstIP, dstIP, captureTime, nilable.FromPtr[int](nil), &dstPort)
return
}
logrus.Debugf("Captured TCP SYN from %s to %s", srcIP, dstIP)
// Resolver cache could be outdated, verify same resolving result after next poll
s.pending = append(s.pending, pendingTCPCapture{
srcIp: srcIP,
srcHostname: localHostname,
destIp: dstIP,
destPort: dstPort,
time: captureTime,
})
}
func (s *TCPSniffer) getDestPort(packet gopacket.Packet, ip *layers.IPv4) (int, bool, error) {
layerType := ip.NextLayerType()
var portName string
var port int
switch layerType {
case layers.LayerTypeTCP:
tcpLayer := packet.Layer(layers.LayerTypeTCP)
if tcpLayer == nil {
return 0, false, errors.New("Failed to parse TCP layer")
}
tcp, ok := tcpLayer.(*layers.TCP)
if !ok {
return 0, false, errors.New("Failed to parse TCP layer")
}
port = int(tcp.DstPort)
portName = tcp.DstPort.String()
default:
return 0, false, errors.New("Unknown transport layer")
}
logrus.Debugf("Detected ip port %s: %s", ip.DstIP.String(), portName)
return port, true, nil
}
func (s *TCPSniffer) RefreshHostsMapping() error {
if !s.isRunningOnAWS {
return nil
}
err := s.resolver.Refresh()
if err != nil {
return errors.Wrap(err)
}
for _, p := range s.pending {
hostname, err := s.resolver.ResolveIP(p.srcIp)
if err != nil {
logrus.WithError(err).Debugf("Could not to resolve %s, skipping packet", p.srcIp)
continue
}
if p.srcHostname != hostname {
logrus.Debugf("IP %s was resolved to %s, but now resolves to %s. skipping packet", p.srcIp, p.srcHostname, hostname)
continue
}
s.addCapturedRequest(p.srcIp, hostname, p.destIp, p.destIp, p.time, p.ttl, &p.destPort)
}
s.pending = make([]pendingTCPCapture, 0)
return nil
}
func (s *TCPSniffer) GetTimeTilNextRefresh() time.Duration {
nextRefreshTime := s.lastRefresh.Add(viper.GetDuration(config.HostsMappingRefreshIntervalKey))
s.lastRefresh = time.Now()
return time.Until(nextRefreshTime)
}