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pkts_poller.go
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pkts_poller.go
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package main
import (
"fmt"
"sync"
"unsafe"
"github.com/cilium/ebpf/perf"
"github.com/go-errors/errors"
"github.com/kubeshark/gopacket"
"github.com/kubeshark/gopacket/layers"
"github.com/kubeshark/tracer/misc/ethernet"
"github.com/rs/zerolog/log"
)
type tracerPacketsData struct {
CgroupID uint64
ID uint64
Num uint16
Len uint16
Last uint16
Direction uint8
Data [4096]uint8
}
type tracerPktChunk struct {
cpu int
buf []byte
}
type pktBuffer struct {
id uint64
num uint16
len uint32
buf [64 * 1024]byte
}
type pktsPoller struct {
ethhdr *layers.Ethernet
mtx sync.Mutex
chunksReader *perf.Reader
sorter *PacketSorter
pktsMap map[int]*pktBuffer // CPU to packet
}
func newPktsPoller(
tls *Tracer,
procfs string,
sorter *PacketSorter,
) (*pktsPoller, error) {
poller := &pktsPoller{
ethhdr: ethernet.NewEthernetLayer(layers.EthernetTypeIPv4),
sorter: sorter,
pktsMap: make(map[int]*pktBuffer),
}
return poller, nil
}
func (p *pktsPoller) init(bpfObjects *tracerObjects, bufferSize int) error {
var err error
p.chunksReader, err = perf.NewReader(bpfObjects.PktsBuffer, bufferSize)
if err != nil {
return errors.Wrap(err, 0)
}
return nil
}
func (p *pktsPoller) close() error {
return p.chunksReader.Close()
}
func (p *pktsPoller) poll() {
// tracerPktsChunk is generated by bpf2go.
chunks := make(chan *tracerPktChunk)
go p.pollChunksPerfBuffer(chunks)
for chunk := range chunks {
if err := p.handlePktChunk(chunk); err != nil {
logError(err)
}
}
}
func (p *pktsPoller) handlePktChunk(chunk *tracerPktChunk) error {
p.mtx.Lock()
defer p.mtx.Unlock()
const expectedChunkSize = 4124
data := chunk.buf
if len(data) != expectedChunkSize {
return fmt.Errorf("bad pkt chunk: size %v expected: %v", len(data), expectedChunkSize)
}
ptr := (*tracerPacketsData)(unsafe.Pointer(&data[0]))
pkts, ok := p.pktsMap[chunk.cpu]
if !ok {
p.pktsMap[chunk.cpu] = &pktBuffer{}
pkts = p.pktsMap[chunk.cpu]
}
if ptr.Num != pkts.num {
if ptr.ID == pkts.id {
return fmt.Errorf("Lost packet message from %v to %v", pkts.id, ptr.ID)
}
pkts.len = 0
pkts.num = 0
pkts.id = ptr.ID
if ptr.Num != pkts.num {
return fmt.Errorf("Lost packet message from %v to %v", pkts.num, ptr.Num)
}
}
copy(pkts.buf[pkts.len:], ptr.Data[:ptr.Len])
pkts.len += uint32(ptr.Len)
if ptr.Last != 0 {
err := p.sorter.WritePlanePacket(ptr.CgroupID, ptr.Direction, layers.LayerTypeEthernet, p.ethhdr, gopacket.Payload(pkts.buf[:pkts.len]))
if err != nil {
return err
}
pkts.len = 0
pkts.num = 0
pkts.id++
} else {
pkts.num++
}
return nil
}
func (p *pktsPoller) pollChunksPerfBuffer(chunks chan<- *tracerPktChunk) {
log.Info().Msg("Start polling for tls events")
for {
record, err := p.chunksReader.Read()
if err != nil {
close(chunks)
if errors.Is(err, perf.ErrClosed) {
return
}
logError(errors.Errorf("Error reading chunks from pkts perf, aborting! %v", err))
return
}
if record.LostSamples != 0 {
log.Info().Msg(fmt.Sprintf("Buffer is full, dropped %d pkt chunks", record.LostSamples))
continue
}
chunk := tracerPktChunk{
cpu: record.CPU,
buf: record.RawSample,
}
chunks <- &chunk
}
}