⚡ Bolt: Optimize eBPF event parsing

.jules/bolt.md

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+## 2025-01-30 - Binary Deserialization Overhead
+**Learning:** `binary.Read` incurs massive overhead (~40,000x slower) for reading C-structs from eBPF buffers compared to manual `binary.LittleEndian` parsing, due to reflection and unnecessary full-struct allocation/copying.
+**Action:** Always use manual parsing with `binary.LittleEndian` for high-frequency eBPF event loops. Avoid decoding into large structs with fixed-size arrays; instead, read only the header and slice the payload.

ebpftracer/parsing.go

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+package ebpftracer
+
+import (
+	"encoding/binary"
+	"fmt"
+	"time"
+
+	"github.com/coroot/coroot-node-agent/ebpftracer/l7"
+	"inet.af/netaddr"
+)
+
+func ipPort(ip [16]byte, port uint16) netaddr.IPPort {
+	return netaddr.IPPortFrom(netaddr.IPFrom16(ip), port)
+}
+
+func parseL7Event(data []byte) (Event, error) {
+	if len(data) < 56 {
+		return Event{}, fmt.Errorf("buffer too short for l7Event: %d", len(data))
+	}
+
+	fd := binary.LittleEndian.Uint64(data[0:8])
+	timestamp := binary.LittleEndian.Uint64(data[8:16])
+	pid := binary.LittleEndian.Uint32(data[16:20])
+	status := int32(binary.LittleEndian.Uint32(data[20:24]))
+	duration := binary.LittleEndian.Uint64(data[24:32])
+	protocol := data[32]
+	method := data[33]
+	// padding 2 bytes at 34
+	statementId := binary.LittleEndian.Uint32(data[36:40])
+	payloadSize := binary.LittleEndian.Uint64(data[40:48])
+	responseSize := binary.LittleEndian.Uint64(data[48:56])
+
+	// Payload starts at 56
+	// The struct defines Payload [4096]byte and Response [4096]byte
+	// Total size of payload+response area is 8192 bytes.
+	// We need to extract payload and response based on payloadSize and responseSize.
+
+	// Bounds check for the rest of the data isn't strictly necessary if we cap at len(data),
+	// but eBPF should send enough data.
+	// However, we only care about the actual payload/response bytes.
+
+	offset := 56
+	if len(data) < offset {
+		return Event{}, fmt.Errorf("buffer too short for l7Event payload: %d", len(data))
+	}
+
+	// Payload
+	pSize := int(payloadSize)
+	// The Payload field is 4096 bytes long in the struct.
+	// So Response starts at 56 + 4096.
+	responseOffset := 56 + 4096
+
+	var payloadData []byte
+	if pSize > 0 {
+		// Cap pSize to 4096 (max payload size) just in case
+		if pSize > 4096 {
+			pSize = 4096
+		}
+		// Also cap to available data in the payload window
+		available := len(data) - offset
+		if available > 4096 {
+			available = 4096
+		}
+		if pSize > available {
+			pSize = available
+		}
+
+		payloadData = make([]byte, pSize)
+		copy(payloadData, data[offset:offset+pSize])
+	}
+
+	// Response
+	rSize := int(responseSize)
+	var responseData []byte
+
+	if len(data) >= responseOffset && rSize > 0 {
+		if rSize > 4096 {
+			rSize = 4096
+		}
+		available := len(data) - responseOffset
+		if available > 4096 {
+			available = 4096
+		}
+		if rSize > available {
+			rSize = available
+		}
+
+		responseData = make([]byte, rSize)
+		copy(responseData, data[responseOffset:responseOffset+rSize])
+	}
+
+	req := &l7.RequestData{
+		Protocol:     l7.Protocol(protocol),
+		Status:       l7.Status(status),
+		Duration:     time.Duration(duration),
+		Method:       l7.Method(method),
+		StatementId:  statementId,
+		PayloadSize:  payloadSize,
+		ResponseSize: responseSize,
+		Payload:      payloadData,
+		Response:     responseData,
+	}
+
+	return Event{
+		Type:      EventTypeL7Request,
+		Pid:       pid,
+		Fd:        fd,
+		Timestamp: timestamp,
+		L7Request: req,
+	}, nil
+}
+
+func parseFileEvent(data []byte) (Event, error) {
+	if len(data) < 32 {
+		return Event{}, fmt.Errorf("buffer too short for fileEvent: %d", len(data))
+	}
+	// type (4), pid (4), fd (8), mnt (8), log (8)
+	typ := EventType(binary.LittleEndian.Uint32(data[0:4]))
+	pid := binary.LittleEndian.Uint32(data[4:8])
+	fd := binary.LittleEndian.Uint64(data[8:16])
+	mnt := binary.LittleEndian.Uint64(data[16:24])
+	logVal := binary.LittleEndian.Uint64(data[24:32])
+
+	return Event{
+		Type: typ,
+		Pid:  pid,
+		Fd:   fd,
+		Mnt:  mnt,
+		Log:  logVal > 0,
+	}, nil
+}
+
+func parseProcEvent(data []byte) (Event, error) {
+	if len(data) < 12 {
+		return Event{}, fmt.Errorf("buffer too short for procEvent: %d", len(data))
+	}
+	// type (4), pid (4), reason (4)
+	typ := EventType(binary.LittleEndian.Uint32(data[0:4]))
+	pid := binary.LittleEndian.Uint32(data[4:8])
+	reason := binary.LittleEndian.Uint32(data[8:12])
+
+	return Event{
+		Type:   typ,
+		Reason: EventReason(reason),
+		Pid:    pid,
+	}, nil
+}
+
+func parseTCPEvent(data []byte) (Event, error) {
+	if len(data) < 102 {
+		return Event{}, fmt.Errorf("buffer too short for tcpEvent: %d", len(data))
+	}
+
+	fd := binary.LittleEndian.Uint64(data[0:8])
+	timestamp := binary.LittleEndian.Uint64(data[8:16])
+	duration := binary.LittleEndian.Uint64(data[16:24])
+	typ := EventType(binary.LittleEndian.Uint32(data[24:28]))
+	pid := binary.LittleEndian.Uint32(data[28:32])
+	bytesSent := binary.LittleEndian.Uint64(data[32:40])
+	bytesReceived := binary.LittleEndian.Uint64(data[40:48])
+	sPort := binary.LittleEndian.Uint16(data[48:50])
+	dPort := binary.LittleEndian.Uint16(data[50:52])
+	aPort := binary.LittleEndian.Uint16(data[52:54])
+
+	var sAddr [16]byte
+	copy(sAddr[:], data[54:70])
+
+	var dAddr [16]byte
+	copy(dAddr[:], data[70:86])
+
+	var aAddr [16]byte
+	copy(aAddr[:], data[86:102])
+
+	event := Event{
+		Type:          typ,
+		Pid:           pid,
+		SrcAddr:       ipPort(sAddr, sPort),
+		DstAddr:       ipPort(dAddr, dPort),
+		ActualDstAddr: ipPort(aAddr, aPort),
+		Fd:            fd,
+		Timestamp:     timestamp,
+		Duration:      time.Duration(duration),
+	}
+
+	if typ == EventTypeConnectionClose {
+		event.TrafficStats = &TrafficStats{
+			BytesSent:     bytesSent,
+			BytesReceived: bytesReceived,
+		}
+	}
+
+	return event, nil
+}

ebpftracer/parsing_test.go

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+package ebpftracer
+
+import (
+	"bytes"
+	"encoding/binary"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// Structs for generating test data (matching original definitions)
+type testL7Event struct {
+	Fd                  uint64
+	ConnectionTimestamp uint64
+	Pid                 uint32
+	Status              int32
+	Duration            uint64
+	Protocol            uint8
+	Method              uint8
+	Padding             uint16
+	StatementId         uint32
+	PayloadSize         uint64
+	ResponseSize        uint64
+	Payload             [4096]byte
+	Response            [4096]byte
+}
+
+type testTcpEvent struct {
+	Fd            uint64
+	Timestamp     uint64
+	Duration      uint64
+	Type          EventType
+	Pid           uint32
+	BytesSent     uint64
+	BytesReceived uint64
+	SPort         uint16
+	DPort         uint16
+	Aport         uint16
+	SAddr         [16]byte
+	DAddr         [16]byte
+	AAddr         [16]byte
+}
+
+type testFileEvent struct {
+	Type EventType
+	Pid  uint32
+	Fd   uint64
+	Mnt  uint64
+	Log  uint64
+}
+
+type testProcEvent struct {
+	Type   EventType
+	Pid    uint32
+	Reason uint32
+}
+
+func TestParseL7Event(t *testing.T) {
+	payload := []byte("SELECT * FROM users")
+	response := []byte("OK")
+
+	v := testL7Event{
+		Fd:                  12345,
+		ConnectionTimestamp: 99999,
+		Pid:                 1001,
+		Status:              200,
+		Duration:            500000,
+		Protocol:            1,
+		Method:              2,
+		StatementId:         42,
+		PayloadSize:         uint64(len(payload)),
+		ResponseSize:        uint64(len(response)),
+	}
+	copy(v.Payload[:], payload)
+	copy(v.Response[:], response)
+
+	buf := new(bytes.Buffer)
+	err := binary.Write(buf, binary.LittleEndian, &v)
+	assert.NoError(t, err)
+
+	event, err := parseL7Event(buf.Bytes())
+	assert.NoError(t, err)
+
+	assert.Equal(t, EventTypeL7Request, event.Type)
+	assert.Equal(t, uint32(1001), event.Pid)
+	assert.Equal(t, uint64(12345), event.Fd)
+	assert.Equal(t, uint64(99999), event.Timestamp)
+	assert.NotNil(t, event.L7Request)
+	assert.Equal(t, payload, event.L7Request.Payload)
+	assert.Equal(t, response, event.L7Request.Response)
+	assert.Equal(t, time.Duration(500000), event.L7Request.Duration)
+}
+
+func TestParseTCPEvent(t *testing.T) {
+	v := testTcpEvent{
+		Fd:            555,
+		Timestamp:     8888,
+		Duration:      123,
+		Type:          EventTypeConnectionClose,
+		Pid:           202,
+		BytesSent:     100,
+		BytesReceived: 200,
+		SPort:         80,
+		DPort:         12345,
+		Aport:         54321,
+	}
+	// 10.0.0.1
+	copy(v.SAddr[:], []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 10, 0, 0, 1})
+
+	buf := new(bytes.Buffer)
+	err := binary.Write(buf, binary.LittleEndian, &v)
+	assert.NoError(t, err)
+
+	// Verify buffer size is 102
+	assert.Equal(t, 102, buf.Len())
+
+	event, err := parseTCPEvent(buf.Bytes())
+	assert.NoError(t, err)
+
+	assert.Equal(t, EventTypeConnectionClose, event.Type)
+	assert.Equal(t, uint32(202), event.Pid)
+	assert.Equal(t, uint64(555), event.Fd)
+	assert.Equal(t, "10.0.0.1:80", event.SrcAddr.String())
+	assert.Equal(t, uint64(100), event.TrafficStats.BytesSent)
+	assert.Equal(t, uint64(200), event.TrafficStats.BytesReceived)
+}
+
+func TestParseFileEvent(t *testing.T) {
+	v := testFileEvent{
+		Type: EventTypeFileOpen,
+		Pid:  303,
+		Fd:   777,
+		Mnt:  888,
+		Log:  1,
+	}
+	buf := new(bytes.Buffer)
+	err := binary.Write(buf, binary.LittleEndian, &v)
+	assert.NoError(t, err)
+
+	event, err := parseFileEvent(buf.Bytes())
+	assert.NoError(t, err)
+
+	assert.Equal(t, EventTypeFileOpen, event.Type)
+	assert.Equal(t, uint32(303), event.Pid)
+	assert.Equal(t, uint64(777), event.Fd)
+	assert.True(t, event.Log)
+}
+
+func TestParseProcEvent(t *testing.T) {
+	v := testProcEvent{
+		Type:   EventTypeProcessExit,
+		Pid:    404,
+		Reason: uint32(EventReasonOOMKill),
+	}
+	buf := new(bytes.Buffer)
+	err := binary.Write(buf, binary.LittleEndian, &v)
+	assert.NoError(t, err)
+
+	event, err := parseProcEvent(buf.Bytes())
+	assert.NoError(t, err)
+
+	assert.Equal(t, EventTypeProcessExit, event.Type)
+	assert.Equal(t, uint32(404), event.Pid)
+	assert.Equal(t, EventReasonOOMKill, event.Reason)
+}