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pinger.go
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pinger.go
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package main
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"log"
"net"
"os"
"strings"
"syscall"
"time"
"github.com/CloudDetail/node-agent/proc"
"github.com/vishvananda/netns"
"golang.org/x/net/icmp"
"golang.org/x/net/ipv4"
"golang.org/x/sys/unix"
"inet.af/netaddr"
"k8s.io/klog/v2"
)
const (
pingReplyPollTimeout = 10 * time.Millisecond
protocolICMP = 1 // Internet Control Message
maxRTT = 1.0
)
var (
pingerID = os.Getpid() & 0xFFFF
)
type sentPacket struct {
seq int
txTimestamp time.Time
}
func Ping(ns netns.NsHandle, originNs netns.NsHandle, targets []netaddr.IP, timeout time.Duration) (map[netaddr.IP]float64, error) {
if len(targets) < 1 {
return nil, nil
}
var conn *net.IPConn
err := proc.ExecuteInNetNs(ns, originNs, func() error {
c, err := openConn()
if err != nil {
return err
}
conn = c
return nil
})
if err != nil {
return nil, fmt.Errorf("failed to open IPConn: %s", err)
}
defer conn.Close()
f, err := conn.File()
if err != nil {
return nil, err
}
defer f.Close()
fd := int(f.Fd())
ids := make(map[netaddr.IP]*sentPacket, len(targets))
for seq, ip := range targets {
nowTime := time.Now()
pkt := &sentPacket{seq: seq + 1, txTimestamp: nowTime}
if err := send(conn, pkt.seq, ip.IPAddr()); err != nil {
if strings.HasPrefix(err.Error(), "resource temporarily unavailable") {
continue
}
return nil, fmt.Errorf("failed to send packet to %s: %s", ip, err)
}
if !Kernel317 {
if pkt.txTimestamp, err = getTxTimestamp(fd); err != nil {
if strings.HasPrefix(err.Error(), "resource temporarily unavailable") {
continue
}
return nil, fmt.Errorf("failed to get TX timestamp: %s", err)
}
} else {
pkt.txTimestamp = nowTime
}
ids[ip] = pkt
}
timeoutTicker := time.NewTimer(timeout)
defer timeoutTicker.Stop()
rttByIp := make(map[netaddr.IP]float64, len(targets))
for {
select {
case <-timeoutTicker.C:
for _, ip := range targets {
if _, ok := rttByIp[ip]; !ok {
rttByIp[ip] = maxRTT
}
}
return rttByIp, nil
default:
if len(rttByIp) == len(targets) {
return rttByIp, nil
}
remoteAddr, echoReply, rxTimestamp, err := receive(conn)
if err != nil {
if !strings.Contains(err.Error(), "interrupted system call") { // recvmsg timeout is not an issue
klog.Errorln(err)
}
continue
}
if echoReply == nil {
continue
}
if echoReply.ID != pingerID {
continue
}
ip, ok := netaddr.FromStdIP(remoteAddr.IP)
if !ok {
continue
}
if pkt, ok := ids[ip]; ok && pkt.seq == echoReply.Seq {
rtt := rxTimestamp.Sub(pkt.txTimestamp).Seconds()
if rtt < 0 { // a small negative value is possible if the clock has adjusted by ntpd
rtt = 0
}
rttByIp[ip] = rtt
}
}
}
}
func send(conn *net.IPConn, seq int, ip net.Addr) error {
msg := &icmp.Message{
Type: ipv4.ICMPTypeEcho,
Body: &icmp.Echo{
ID: pingerID,
Seq: seq,
},
}
data, err := msg.Marshal(nil)
if err != nil {
return err
}
_, err = conn.WriteTo(data, ip)
return err
}
func getTimestampFromOutOfBandData(oob []byte, oobn int) (time.Time, error) {
cms, err := syscall.ParseSocketControlMessage(oob[:oobn])
if err != nil {
return time.Time{}, err
}
for _, cm := range cms {
if cm.Header.Level == syscall.SOL_SOCKET || cm.Header.Type == syscall.SO_TIMESTAMPING {
var t unix.ScmTimestamping
if err := binary.Read(bytes.NewBuffer(cm.Data), binary.LittleEndian, &t); err != nil {
return time.Time{}, err
}
return time.Unix(t.Ts[0].Unix()), nil
}
}
return time.Time{}, fmt.Errorf("no timestamp found")
}
func getTimestampFromOutOfBandDataKernel317(oob []byte, oobn int) (time.Time, error) {
cms, err := syscall.ParseSocketControlMessage(oob[:oobn])
if err != nil {
return time.Time{}, err
}
for _, cm := range cms {
if cm.Header.Level == unix.SOL_SOCKET && (cm.Header.Type == unix.SO_TIMESTAMP || cm.Header.Type == unix.SO_TIMESTAMPNS) {
var t unix.Timeval
if err := binary.Read(bytes.NewBuffer(cm.Data), binary.LittleEndian, &t); err != nil {
return time.Time{}, err
}
return time.Unix(int64(t.Sec), int64(t.Usec)*1000), nil
}
}
return time.Time{}, fmt.Errorf("no timestamp found")
}
func getTxTimestamp(socketFd int) (time.Time, error) {
pktBuf := make([]byte, 1024)
oob := make([]byte, 1024)
var t time.Time
_, oobn, _, _, err := syscall.Recvmsg(socketFd, pktBuf, oob, syscall.MSG_ERRQUEUE)
if err != nil {
return t, err
}
if !Kernel317 {
return getTimestampFromOutOfBandData(oob, oobn)
} else {
return getTimestampFromOutOfBandDataKernel317(oob, oobn)
}
}
func receive(conn *net.IPConn) (*net.IPAddr, *icmp.Echo, time.Time, error) {
pktBuf := make([]byte, 1024)
oob := make([]byte, 1024)
var ts time.Time
_ = conn.SetReadDeadline(time.Now().Add(pingReplyPollTimeout))
n, oobn, _, ra, err := conn.ReadMsgIP(pktBuf, oob)
if err != nil {
if neterr, ok := err.(*net.OpError); ok && neterr.Timeout() {
return nil, nil, ts, nil
}
if strings.Contains(err.Error(), "no message of desired type") {
return nil, nil, ts, nil
}
return nil, nil, ts, err
}
if !Kernel317 {
if ts, err = getTimestampFromOutOfBandData(oob, oobn); err != nil {
return nil, nil, ts, fmt.Errorf("failed to get RX timestamp: %s", err)
}
} else {
if ts, err = getTimestampFromOutOfBandDataKernel317(oob, oobn); err != nil {
return nil, nil, ts, fmt.Errorf("failed to get RX timestamp: %s", err)
}
}
echo, err := extractEchoFromPacket(pktBuf, n)
if err != nil {
return nil, nil, ts, fmt.Errorf("failed to extract ICMP Echo from IPv4 packet %s: %s", ra, err)
}
return ra, echo, ts, nil
}
func extractEchoFromPacket(pktBuf []byte, n int) (*icmp.Echo, error) {
if n < ipv4.HeaderLen {
return nil, errors.New("malformed IPv4 packet")
}
pktBuf = pktBuf[ipv4.HeaderLen:]
var m *icmp.Message
m, err := icmp.ParseMessage(protocolICMP, pktBuf)
if err != nil {
return nil, err
}
if m.Type != ipv4.ICMPTypeEchoReply {
return nil, nil
}
echo, ok := m.Body.(*icmp.Echo)
if !ok {
return nil, fmt.Errorf("malformed ICMP message body: %T", m.Body)
}
return echo, nil
}
func openConn() (*net.IPConn, error) {
conn, err := net.ListenPacket("ip4:icmp", "0.0.0.0")
if err != nil {
return nil, err
}
ipconn := conn.(*net.IPConn)
f, err := ipconn.File()
if err != nil {
return nil, err
}
defer f.Close()
fd := int(f.Fd())
if !Kernel317 {
flags := unix.SOF_TIMESTAMPING_SOFTWARE | unix.SOF_TIMESTAMPING_RX_SOFTWARE | unix.SOF_TIMESTAMPING_TX_SCHED |
unix.SOF_TIMESTAMPING_OPT_CMSG | unix.SOF_TIMESTAMPING_OPT_TSONLY
if err := syscall.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_TIMESTAMPING, flags); err != nil {
log.Println(err)
return nil, err
}
} else {
if err := syscall.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_TIMESTAMP, 1); err != nil {
return nil, err
}
}
timeout := syscall.Timeval{Sec: 0, Usec: 1000}
if err := syscall.SetsockoptTimeval(fd, unix.SOL_SOCKET, unix.SO_RCVTIMEO, &timeout); err != nil {
return nil, err
}
if err := syscall.SetsockoptTimeval(fd, unix.SOL_SOCKET, unix.SO_SNDTIMEO, &timeout); err != nil {
return nil, err
}
return ipconn, nil
}