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monitor_payload.go
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/
monitor_payload.go
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// Copyright 2017 Authors of Cilium
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package payload
import (
"bytes"
"encoding/binary"
"encoding/gob"
"fmt"
"io"
"github.com/cilium/cilium/pkg/byteorder"
)
// Below constants are based on the ones from <linux/perf_event.h>.
const (
// EventSample is equivalent to PERF_RECORD_SAMPLE
EventSample = 9
// RecordLost is equivalent to PERF_RECORD_LOST
RecordLost = 2
)
// Meta is used by readers to get information about the payload.
type Meta struct {
Size uint32
_ [28]byte // Reserved 28 bytes for future fields.
}
// UnmarshalBinary decodes the metadata from its binary representation.
func (meta *Meta) UnmarshalBinary(data []byte) error {
return meta.ReadBinary(bytes.NewReader(data))
}
// MarshalBinary encodes the metadata into its binary representation.
func (meta *Meta) MarshalBinary() ([]byte, error) {
var buf bytes.Buffer
if err := meta.WriteBinary(&buf); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
// ReadBinary reads the metadata from its binary representation.
func (meta *Meta) ReadBinary(r io.Reader) error {
return binary.Read(r, byteorder.Native, meta)
}
// WriteBinary writes the metadata into its binary representation.
func (meta *Meta) WriteBinary(w io.Writer) error {
return binary.Write(w, byteorder.Native, meta)
}
// Payload is the structure used when copying events from the main monitor.
type Payload struct {
Data []byte
CPU int
Lost uint64
Type int
}
// Decode decodes the payload from its binary representation.
func (pl *Payload) Decode(data []byte) error {
// Note that this method can't be named UnmarshalBinary, because the gob encoder would call
// this method, resulting in infinite recursion.
return pl.ReadBinary(bytes.NewBuffer(data))
}
// Encode encodes the payload into its binary representation.
func (pl *Payload) Encode() ([]byte, error) {
// Note that this method can't be named MarshalBinary, because the gob encoder would call
// this method, resulting in infinite recursion.
var buf bytes.Buffer
if err := pl.WriteBinary(&buf); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
// ReadBinary reads the payload from its binary representation.
func (pl *Payload) ReadBinary(r io.Reader) error {
dec := gob.NewDecoder(r)
return pl.DecodeBinary(dec)
}
// WriteBinary writes the payload into its binary representation.
func (pl *Payload) WriteBinary(w io.Writer) error {
enc := gob.NewEncoder(w)
return pl.EncodeBinary(enc)
}
// EncodeBinary writes the payload into its binary representation.
func (pl *Payload) EncodeBinary(enc *gob.Encoder) error {
return enc.Encode(pl)
}
// DecodeBinary reads the payload from its binary representation.
func (pl *Payload) DecodeBinary(dec *gob.Decoder) error {
return dec.Decode(pl)
}
// ReadMetaPayload reads a Meta and Payload from a Cilium monitor connection.
func ReadMetaPayload(r io.Reader, meta *Meta, pl *Payload) error {
if err := meta.ReadBinary(r); err != nil {
return err
}
// Meta.Size is not necessary for framing/decoding, but is useful to validate the payload size.
return pl.ReadBinary(io.LimitReader(r, int64(meta.Size)))
}
// WriteMetaPayload writes a Meta and Payload into a Cilium monitor connection.
// meta.Size is set to the size of the encoded Payload.
func WriteMetaPayload(w io.Writer, meta *Meta, pl *Payload) error {
payloadBuf, err := pl.Encode()
if err != nil {
return err
}
meta.Size = uint32(len(payloadBuf))
meta.WriteBinary(w)
_, err = w.Write(payloadBuf)
return err
}
// BuildMessage builds the binary message to be sent and returns it
func (pl *Payload) BuildMessage() ([]byte, error) {
plBuf, err := pl.Encode()
if err != nil {
return nil, fmt.Errorf("unable to encode payload: %s", err)
}
meta := &Meta{Size: uint32(len(plBuf))}
metaBuf, err := meta.MarshalBinary()
if err != nil {
return nil, fmt.Errorf("unable to encode metadata: %s", err)
}
return append(metaBuf, plBuf...), nil
}