mig/modules/timedrift/timedrift.go

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Go

// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
//
// Contributor: Julien Vehent jvehent@mozilla.com [:ulfr]
/* The timedrift module evaluate the local time of a target against
network time retrieved using NTP.
Usage documentation is online at http://mig.mozilla.org/doc/module_timedrift.html
*/
package timedrift /* import "github.com/mozilla/mig/modules/timedrift" */
import (
"bufio"
"encoding/json"
"flag"
"fmt"
"github.com/mozilla/mig/modules"
"net"
"os"
"strings"
"time"
)
type module struct {
}
func (m *module) NewRun() modules.Runner {
return new(run)
}
func init() {
modules.Register("timedrift", new(module))
}
type run struct {
Parameters params
Results modules.Result
}
// a simple parameters structure, the format is arbitrary
type params struct {
Drift string `json:"drift"`
}
type elements struct {
HasCheckedDrift bool `json:"hascheckeddrift"`
IsWithinDrift bool `json:"iswithindrift,omitempty"`
Drifts []string `json:"drifts,omitempty"`
LocalTime string `json:"localtime"`
}
type statistics struct {
ExecTime string `json:"exectime"`
NtpStats []ntpstats `json:"ntpstats,omitempty"`
}
type ntpstats struct {
Host string `json:"host"`
Time time.Time `json:"time"`
Latency string `json:"latency"`
Drift string `json:"drift"`
Reachable bool `json:"reachable"`
}
var NtpBackupPool = []string{
`time.nist.gov`,
`0.pool.ntp.org`,
`1.pool.ntp.org`,
`2.pool.ntp.org`,
`3.pool.ntp.org`}
func (r *run) ValidateParameters() (err error) {
if r.Parameters.Drift != "" {
_, err = time.ParseDuration(r.Parameters.Drift)
}
return err
}
func (r *run) Run(in modules.ModuleReader) (out string) {
var (
stats statistics
el elements
drift time.Duration
ntpFile *os.File
ntpScan *bufio.Scanner
ntpPool []string
)
defer func() {
if e := recover(); e != nil {
r.Results.Errors = append(r.Results.Errors, fmt.Sprintf("%v", e))
r.Results.Success = false
buf, _ := json.Marshal(r.Results)
out = string(buf[:])
}
}()
el.LocalTime = time.Now().Format(time.RFC3339Nano)
t1 := time.Now()
err := modules.ReadInputParameters(in, &r.Parameters)
if err != nil {
panic(err)
}
err = r.ValidateParameters()
if err != nil {
panic(err)
}
// if drift is not set, skip the ntp test
if r.Parameters.Drift == "" {
r.Results.FoundAnything = true
goto done
}
drift, err = time.ParseDuration(r.Parameters.Drift)
if err != nil {
panic(err)
}
// assume host has synched time and set to false if not true
el.IsWithinDrift = true
//Load ntp servers from /etc/ntp.conf
ntpFile, err = os.Open("/etc/ntp.conf")
if err != nil {
r.Results.Errors = append(r.Results.Errors,
fmt.Sprintf("Using backup NTP hosts. Failed to read /etc/ntp.conf with error '%v'", err))
} else {
defer ntpFile.Close()
ntpScan = bufio.NewScanner(ntpFile)
for ntpScan.Scan() {
ntpFields := strings.Fields(ntpScan.Text())
if len(ntpFields) < 2 {
continue
}
if ntpFields[0] == "server" {
ntpPool = append(ntpPool, ntpFields[1])
}
}
}
//Add our hardcoded online servers to the end of our ntpPool as fallbacks
ntpPool = append(ntpPool, NtpBackupPool...)
// attempt to get network time from each of the NTP servers, and exit
// as soon as we get a valid result from one of them
for _, ntpsrv := range ntpPool {
t, lat, err := GetNetworkTime(ntpsrv)
if err != nil {
// failed to get network time, log a failure and try another one
stats.NtpStats = append(stats.NtpStats, ntpstats{
Host: ntpsrv,
Reachable: false,
})
continue
}
// compare network time to local time
localtime := time.Now()
if err != nil {
r.Results.Errors = append(r.Results.Errors, fmt.Sprintf("%v", err))
continue
}
if localtime.Before(t.Add(-drift)) {
el.IsWithinDrift = false
el.Drifts = append(el.Drifts, fmt.Sprintf("Local time is behind ntp host %s by %s", ntpsrv, t.Sub(localtime).String()))
} else if localtime.After(t.Add(drift)) {
el.IsWithinDrift = false
el.Drifts = append(el.Drifts, fmt.Sprintf("Local time is ahead of ntp host %s by %s", ntpsrv, localtime.Sub(t).String()))
}
stats.NtpStats = append(stats.NtpStats, ntpstats{
Host: ntpsrv,
Time: t,
Latency: lat,
Drift: localtime.Sub(t).String(),
Reachable: true,
})
el.HasCheckedDrift = true
// comparison succeeded, exit the loop
break
}
if !el.IsWithinDrift {
r.Results.FoundAnything = true
}
done:
stats.ExecTime = time.Now().Sub(t1).String()
out = r.buildResults(el, stats)
return
}
// GetNetworkTime queries a given NTP server to obtain the network time
func GetNetworkTime(host string) (t time.Time, latency string, err error) {
raddr, err := net.ResolveUDPAddr("udp", host+":123")
if err != nil {
return
}
// NTP request is 48 bytes long, we only set the first byte
data := make([]byte, 48)
// Flags: 0x1b (27)
// 00...... leap indicator (0)
// ..011... version number (3)
// .....011 mode: client (3)
data[0] = 3<<3 | 3
t1 := time.Now()
con, err := net.DialUDP("udp", nil, raddr)
if err != nil {
return
}
defer con.Close()
// send the request
_, err = con.Write(data)
if err != nil {
return
}
// wait up to 5 seconds for the response
con.SetDeadline(time.Now().Add(5 * time.Second))
// read up to 48 bytes from the response
_, err = con.Read(data)
if err != nil {
return
}
latency = time.Now().Sub(t1).String()
// Response format (from the RFC)
// 0 1 2 3
// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |LI | VN |Mode | Stratum | Poll | Precision |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Root Delay |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Root Dispersion |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Reference ID |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | |
// + Reference Timestamp (64) +
// | |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | |
// + Origin Timestamp (64) +
// | |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | |
// + Receive Timestamp (64) +
// | |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | |
// + Transmit Timestamp (64) +
// | |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
var sec, frac uint64
sec = uint64(data[43]) | uint64(data[42])<<8 | uint64(data[41])<<16 | uint64(data[40])<<24
frac = uint64(data[47]) | uint64(data[46])<<8 | uint64(data[45])<<16 | uint64(data[44])<<24
if sec == 0 || frac == 0 {
err = fmt.Errorf("null response received from NTP host")
return
}
nsec := sec * 1e9
nsec += (frac * 1e9) >> 32
t = time.Date(1900, 1, 1, 0, 0, 0, 0, time.UTC).Add(time.Duration(nsec)).Local()
return
}
// buildResults marshals the results
func (r *run) buildResults(el elements, stats statistics) string {
r.Results.Elements = el
r.Results.Statistics = stats
if len(r.Results.Errors) == 0 {
r.Results.Success = true
}
// if was supposed to check drift but hasn't, set success to false
if r.Parameters.Drift != "" && !el.HasCheckedDrift {
r.Results.Success = false
}
jsonOutput, err := json.Marshal(r.Results)
if err != nil {
panic(err)
}
return string(jsonOutput[:])
}
func (r *run) PrintResults(result modules.Result, foundOnly bool) (prints []string, err error) {
var (
el elements
stats statistics
)
err = result.GetElements(&el)
if err != nil {
return
}
prints = append(prints, "local time is "+el.LocalTime)
if el.HasCheckedDrift {
if el.IsWithinDrift {
prints = append(prints, "local time is within acceptable drift from NTP servers")
} else {
prints = append(prints, "local time is out of sync from NTP servers")
for _, drift := range el.Drifts {
prints = append(prints, drift)
}
}
}
// stop here if foundOnly is set, we don't want to see errors and stats
if foundOnly {
return
}
for _, e := range result.Errors {
prints = append(prints, "error:", e)
}
err = result.GetStatistics(&stats)
if err != nil {
panic(err)
}
prints = append(prints, "stat: execution time was "+stats.ExecTime)
for _, ntpstat := range stats.NtpStats {
if ntpstat.Reachable {
prints = append(prints, "stat: "+ntpstat.Host+" responded in "+ntpstat.Latency+" with time "+ntpstat.Time.UTC().String()+". local time drifts by "+ntpstat.Drift)
} else {
prints = append(prints, "stat: "+ntpstat.Host+" was unreachable")
}
}
if result.Success {
prints = append(prints, fmt.Sprintf("timedrift module has succeeded"))
} else {
prints = append(prints, fmt.Sprintf("timedrift module has failed"))
}
return
}
func printHelp(isCmd bool) {
dash := ""
if isCmd {
dash = "-"
}
fmt.Printf(`timedrift returns the local time of a system and, when %sdrift is set,
verifies that local time is within acceptable range of network time by querying NTP servers
%sdrift <duration> allowed time drift window. a value of "5s" compares local
time with ntp hosts and returns a drift failure if local
time is too far out of sync.
If no drift is set, the module only returns local time.
`, dash, dash)
}
func (r *run) ParamsCreator() (interface{}, error) {
fmt.Println("initializing timedrift parameters creation")
var err error
var p params
printHelp(false)
scanner := bufio.NewScanner(os.Stdin)
for {
fmt.Printf("drift> ")
scanner.Scan()
if err := scanner.Err(); err != nil {
fmt.Println("Invalid input. Try again")
continue
}
input := scanner.Text()
if input == "help" {
printHelp(false)
continue
}
if input != "" {
_, err = time.ParseDuration(input)
if err != nil {
fmt.Println("invalid drift duration. try again. ex: drift> 5s")
continue
}
}
p.Drift = input
break
}
r.Parameters = p
return r.Parameters, r.ValidateParameters()
}
func (r *run) ParamsParser(args []string) (interface{}, error) {
var (
err error
drift string
fs flag.FlagSet
)
if len(args) >= 1 && args[0] == "help" {
printHelp(true)
return nil, fmt.Errorf("help printed")
}
if len(args) == 0 {
return r.Parameters, nil
}
fs.Init("time", flag.ContinueOnError)
fs.StringVar(&drift, "drift", "", "see help")
err = fs.Parse(args)
if err != nil {
return nil, err
}
_, err = time.ParseDuration(drift)
if err != nil {
return nil, fmt.Errorf("invalid drift duration. try help.")
}
r.Parameters.Drift = drift
return r.Parameters, r.ValidateParameters()
}