/
uds_common.go
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/
uds_common.go
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// Unless explicitly stated otherwise all files in this repository are licensed
// under the Apache License Version 2.0.
// This product includes software developed at Datadog (https://www.datadoghq.com/).
// Copyright 2016-present Datadog, Inc.
package listeners
import (
"encoding/binary"
"errors"
"expvar"
"fmt"
"io"
"net"
"os"
"strconv"
"strings"
"sync"
"time"
"github.com/DataDog/datadog-agent/comp/core/workloadmeta"
"github.com/DataDog/datadog-agent/comp/dogstatsd/listeners/ratelimit"
"github.com/DataDog/datadog-agent/comp/dogstatsd/packets"
"github.com/DataDog/datadog-agent/comp/dogstatsd/pidmap"
"github.com/DataDog/datadog-agent/comp/dogstatsd/replay"
"github.com/DataDog/datadog-agent/pkg/config"
"github.com/DataDog/datadog-agent/pkg/util/log"
"github.com/DataDog/datadog-agent/pkg/util/optional"
)
var (
udsExpvars = expvar.NewMap("dogstatsd-uds")
udsOriginDetectionErrors = expvar.Int{}
udsPacketReadingErrors = expvar.Int{}
udsPackets = expvar.Int{}
udsBytes = expvar.Int{}
)
func init() {
udsExpvars.Set("OriginDetectionErrors", &udsOriginDetectionErrors)
udsExpvars.Set("PacketReadingErrors", &udsPacketReadingErrors)
udsExpvars.Set("Packets", &udsPackets)
udsExpvars.Set("Bytes", &udsBytes)
}
// UDSListener implements the StatsdListener interface for Unix Domain
// Socket datagram protocol. It listens to a given socket path and sends
// back packets ready to be processed.
// Origin detection will be implemented for UDS.
type UDSListener struct {
packetOut chan packets.Packets
sharedPacketPoolManager *packets.PoolManager
oobPoolManager *packets.PoolManager
trafficCapture replay.Component
pidMap pidmap.Component
OriginDetection bool
config config.Reader
wmeta optional.Option[workloadmeta.Component]
transport string
dogstatsdMemBasedRateLimiter bool
packetBufferSize uint
packetBufferFlushTimeout time.Duration
telemetryWithListenerID bool
listenWg *sync.WaitGroup
}
// CloseFunction is a function that closes a connection
type CloseFunction func(unixConn *net.UnixConn) error
func setupUnixConn(conn *net.UnixConn, originDetection bool, config config.Reader) (bool, error) {
if originDetection {
err := enableUDSPassCred(conn)
if err != nil {
log.Errorf("dogstatsd-uds: error enabling origin detection: %s", err)
originDetection = false
} else {
log.Debugf("dogstatsd-uds: enabling origin detection on %s", conn.LocalAddr())
}
}
if rcvbuf := config.GetInt("dogstatsd_so_rcvbuf"); rcvbuf != 0 {
if err := conn.SetReadBuffer(rcvbuf); err != nil {
return originDetection, fmt.Errorf("could not set socket rcvbuf: %s", err)
}
}
return originDetection, nil
}
func setupSocketBeforeListen(socketPath string, transport string) (*net.UnixAddr, error) {
address, addrErr := net.ResolveUnixAddr(transport, socketPath)
if addrErr != nil {
return nil, fmt.Errorf("dogstatsd-uds: can't ResolveUnixAddr: %v", addrErr)
}
fileInfo, err := os.Stat(socketPath)
// Socket file already exists
if err == nil {
// Make sure it's a UNIX socket
if fileInfo.Mode()&os.ModeSocket == 0 {
return nil, fmt.Errorf("dogstatsd-uds: cannot reuse %s socket path: path already exists and is not a UNIX socket", socketPath)
}
err = os.Remove(socketPath)
if err != nil {
return nil, fmt.Errorf("dogstatsd-uds: cannot remove stale UNIX socket: %v", err)
}
}
return address, nil
}
func setSocketWriteOnly(socketPath string) error {
err := os.Chmod(socketPath, 0722)
if err != nil {
return fmt.Errorf("can't set the socket at write only: %s", err)
}
return nil
}
// NewUDSOobPoolManager returns an UDS OOB pool manager
func NewUDSOobPoolManager() *packets.PoolManager {
pool := &sync.Pool{
New: func() interface{} {
s := make([]byte, getUDSAncillarySize())
return &s
},
}
return packets.NewPoolManager(pool)
}
// NewUDSListener returns an idle UDS Statsd listener
func NewUDSListener(packetOut chan packets.Packets, sharedPacketPoolManager *packets.PoolManager, sharedOobPacketPoolManager *packets.PoolManager, cfg config.Reader, capture replay.Component, transport string, wmeta optional.Option[workloadmeta.Component], pidMap pidmap.Component) (*UDSListener, error) {
originDetection := cfg.GetBool("dogstatsd_origin_detection")
listener := &UDSListener{
OriginDetection: originDetection,
packetOut: packetOut,
sharedPacketPoolManager: sharedPacketPoolManager,
trafficCapture: capture,
pidMap: pidMap,
dogstatsdMemBasedRateLimiter: cfg.GetBool("dogstatsd_mem_based_rate_limiter.enabled"),
config: cfg,
transport: transport,
packetBufferSize: uint(cfg.GetInt("dogstatsd_packet_buffer_size")),
packetBufferFlushTimeout: cfg.GetDuration("dogstatsd_packet_buffer_flush_timeout"),
telemetryWithListenerID: cfg.GetBool("dogstatsd_telemetry_enabled_listener_id"),
listenWg: &sync.WaitGroup{},
wmeta: wmeta,
}
// Init the oob buffer pool if origin detection is enabled
if originDetection {
listener.oobPoolManager = sharedOobPacketPoolManager
if listener.oobPoolManager == nil {
listener.oobPoolManager = NewUDSOobPoolManager()
}
}
return listener, nil
}
// Listen runs the intake loop. Should be called in its own goroutine
func (l *UDSListener) handleConnection(conn *net.UnixConn, closeFunc CloseFunction) error {
listenerID := l.getListenerID(conn)
tlmListenerID := listenerID
telemetryWithFullListenerID := l.telemetryWithListenerID
if !telemetryWithFullListenerID {
// In case we don't want the full listener id, we only keep the transport.
tlmListenerID = "uds-" + conn.LocalAddr().Network()
}
packetsBuffer := packets.NewBuffer(
l.packetBufferSize,
l.packetBufferFlushTimeout,
l.packetOut,
tlmListenerID,
)
tlmUDSConnections.Inc(tlmListenerID, l.transport)
defer func() {
_ = closeFunc(conn)
packetsBuffer.Close()
if telemetryWithFullListenerID {
l.clearTelemetry(tlmListenerID)
}
tlmUDSConnections.Dec(tlmListenerID, l.transport)
}()
var err error
l.OriginDetection, err = setupUnixConn(conn, l.OriginDetection, l.config)
if err != nil {
return err
}
t1 := time.Now()
var t2 time.Time
log.Debugf("dogstatsd-uds: starting to handle %s", conn.LocalAddr())
var rateLimiter *ratelimit.MemBasedRateLimiter
if l.dogstatsdMemBasedRateLimiter {
var err error
rateLimiter, err = ratelimit.BuildMemBasedRateLimiter(l.config)
if err != nil {
log.Errorf("Cannot use DogStatsD rate limiter: %v", err)
rateLimiter = nil
} else {
log.Info("DogStatsD rate limiter enabled")
}
}
for {
var n int
var oobn int
var oob *[]byte
var oobS []byte
var err error
// retrieve an available packet from the packet pool,
// which will be pushed back by the server when processed.
packet := l.sharedPacketPoolManager.Get().(*packets.Packet)
udsPackets.Add(1)
var capBuff *replay.CaptureBuffer
if l.trafficCapture != nil && l.trafficCapture.IsOngoing() {
capBuff = replay.CapPool.Get().(*replay.CaptureBuffer)
capBuff.Pb.Ancillary = nil
capBuff.Pb.Payload = nil
capBuff.Pb.Pid = 0
capBuff.Pb.AncillarySize = int32(0)
capBuff.Pb.PayloadSize = int32(0)
capBuff.ContainerID = ""
}
if l.OriginDetection {
// Read datagram + credentials in ancillary data
oob = l.oobPoolManager.Get().(*[]byte)
oobS = *oob
}
if rateLimiter != nil {
if err = rateLimiter.MayWait(); err != nil {
log.Error(err)
}
}
t2 = time.Now()
tlmListener.Observe(float64(t2.Sub(t1).Nanoseconds()), tlmListenerID, l.transport, "uds")
var expectedPacketLength uint32
var maxPacketLength uint32
if l.transport == "unix" {
// Read the expected packet length (in stream mode)
b := []byte{0, 0, 0, 0}
_, err = io.ReadFull(conn, b)
expectedPacketLength := binary.LittleEndian.Uint32(b)
switch {
case err == io.EOF, errors.Is(err, io.ErrUnexpectedEOF):
log.Debugf("dogstatsd-uds: %s connection closed", l.transport)
return nil
}
if expectedPacketLength > uint32(len(packet.Buffer)) {
log.Info("dogstatsd-uds: packet length too large, dropping connection")
return nil
}
maxPacketLength = expectedPacketLength
} else {
maxPacketLength = uint32(len(packet.Buffer))
}
for err == nil {
if oob != nil {
n, oobn, _, _, err = conn.ReadMsgUnix(packet.Buffer[n:maxPacketLength], oobS[oobn:])
} else {
n, _, err = conn.ReadFromUnix(packet.Buffer[n:maxPacketLength])
}
if n == 0 && oobn == 0 && l.transport == "unix" {
log.Debugf("dogstatsd-uds: %s connection closed", l.transport)
return nil
}
// If framing is disabled (unixgram, unixpacket), we always will have read the whole packet
if expectedPacketLength == 0 {
break
}
// Otherwise see if we need to continue to accumulate bytes or not
if uint32(n) == expectedPacketLength {
break
}
if uint32(n) > expectedPacketLength {
log.Info("dogstatsd-uds: read length mismatch, dropping connection")
return nil
}
}
t1 = time.Now()
if oob != nil {
// Extract container id from credentials
pid, container, taggingErr := processUDSOrigin(oobS[:oobn], l.wmeta, l.pidMap)
if taggingErr != nil {
log.Warnf("dogstatsd-uds: error processing origin, data will not be tagged : %v", taggingErr)
udsOriginDetectionErrors.Add(1)
tlmUDSOriginDetectionError.Inc(tlmListenerID, l.transport)
} else {
packet.Origin = container
if capBuff != nil {
capBuff.ContainerID = container
}
}
if capBuff != nil {
capBuff.Oob = oob
capBuff.Pid = int32(pid)
capBuff.Pb.Pid = int32(pid)
capBuff.Pb.AncillarySize = int32(oobn)
capBuff.Pb.Ancillary = oobS[:oobn]
}
// Return the buffer back to the pool for reuse
l.oobPoolManager.Put(oob)
}
if capBuff != nil {
capBuff.Buff = packet
capBuff.Pb.Timestamp = time.Now().UnixNano()
capBuff.Pb.PayloadSize = int32(n)
capBuff.Pb.Payload = packet.Buffer[:n]
l.trafficCapture.Enqueue(capBuff)
}
if err != nil {
// connection has been closed
if strings.HasSuffix(err.Error(), " use of closed network connection") {
return nil
}
log.Errorf("dogstatsd-uds: error reading packet: %v", err)
udsPacketReadingErrors.Add(1)
tlmUDSPackets.Inc(tlmListenerID, l.transport, "error")
continue
}
tlmUDSPackets.Inc(tlmListenerID, l.transport, "ok")
udsBytes.Add(int64(n))
tlmUDSPacketsBytes.Add(float64(n), tlmListenerID, l.transport)
packet.Contents = packet.Buffer[:n]
packet.Source = packets.UDS
packet.ListenerID = listenerID
// packetsBuffer handles the forwarding of the packets to the dogstatsd server intake channel
packetsBuffer.Append(packet)
}
}
func (l *UDSListener) getConnID(conn *net.UnixConn) string {
// We use the file descriptor as a unique identifier for the connection. This might
// increase the cardinality in the backend, but this option is not designed to be enabled
// all the time. Plus is it useful to debug issues with the UDS listener since we will be
// able to use external tools to get additional stats about the socket/fd.
var fdConn uintptr
rawConn, err := conn.SyscallConn()
if err != nil {
log.Errorf("dogstatsd-uds: error getting file from connection: %s", err)
} else {
_ = rawConn.Control(func(fd uintptr) { fdConn = fd })
}
return strconv.Itoa(int(fdConn))
}
func (l *UDSListener) getListenerID(conn *net.UnixConn) string {
listenerID := "uds-" + conn.LocalAddr().Network()
connID := l.getConnID(conn)
if connID != "" {
listenerID += "-" + connID
}
return listenerID
}
// Stop closes the UDS connection and stops listening
func (l *UDSListener) Stop() {
// Socket cleanup on exit is not necessary as sockets are automatically removed by go.
l.listenWg.Wait()
}
func (l *UDSListener) clearTelemetry(id string) {
if id == "" {
return
}
// Since the listener id is volatile we need to make sure we clear the telemetry.
tlmListener.Delete(id, l.transport)
tlmUDSConnections.Delete(id, l.transport)
tlmUDSPackets.Delete(id, l.transport, "error")
tlmUDSPackets.Delete(id, l.transport, "ok")
tlmUDSPacketsBytes.Delete(id, l.transport)
}