prometheus-dnssec-exporter/main.go

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2022-04-08 03:02:20 +02:00
package main
import (
"fmt"
"net/http"
"os"
"sort"
"strings"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/miekg/dns"
prom "github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/prometheus/common/promlog"
"github.com/prometheus/common/promlog/flag"
"github.com/prometheus/common/version"
"github.com/prometheus/exporter-toolkit/web"
kingpin "gopkg.in/alecthomas/kingpin.v2"
)
const namespace = "dnssec"
type MetricsCollector struct {
Log log.Logger
signatureOkMetric *prom.GaugeVec
cdsPresentMetric *prom.GaugeVec
cdsDsMatchMetric *prom.GaugeVec
zones []string
DNS dns.Client
Resolver string
}
func NewMetricsCollector(zonelist []string, resolver string, logger log.Logger) *MetricsCollector {
signatureOkMetric := prom.NewGaugeVec(
prom.GaugeOpts{
Namespace: namespace,
Name: "signature_ok",
Help: "1 if the DNSSEC signature is present and valid, 0 otherwise",
},
[]string{"zone", "tld", "parent"},
)
cdsPresentMetric := prom.NewGaugeVec(
prom.GaugeOpts{
Namespace: namespace,
Name: "cds_present",
Help: "1 if a CDS record is present in the zone, 0 otherwise",
},
[]string{"zone", "tld", "parent"},
)
cdsDsMatchMetric := prom.NewGaugeVec(
prom.GaugeOpts{
Namespace: namespace,
Name: "cds_ds_match",
Help: "1 if the CDS and DS records match, 0 otherwise",
},
[]string{"zone", "tld", "parent"},
)
collector := MetricsCollector{
signatureOkMetric: signatureOkMetric,
cdsPresentMetric: cdsPresentMetric,
cdsDsMatchMetric: cdsDsMatchMetric,
zones: zonelist,
Resolver: resolver,
Log: logger,
}
return &collector
}
func (c *MetricsCollector) Describe(ch chan<- *prom.Desc) {
c.signatureOkMetric.Describe(ch)
c.cdsPresentMetric.Describe(ch)
c.cdsDsMatchMetric.Describe(ch)
}
func (c *MetricsCollector) Collect(ch chan<- prom.Metric) {
err := c.reportMetrics(ch)
if err != nil {
// TODO
c.Log.Log(err)
}
}
func (c *MetricsCollector) reportMetrics(ch chan<- prom.Metric) error {
for _, zone := range c.zones {
sok, err1 := c.signatureOk(zone)
if err1 != nil {
continue
}
cdp, cdm, err2 := c.cdsDsMatches(zone)
if err2 != nil {
continue
}
labels := strings.Split(zone, ".")
tld := strings.Join(labels[len(labels)-2:], ".")
parent := strings.Join(labels[1:], ".")
promlabels := prom.Labels{
"zone": zone,
"tld": tld,
"parent": parent,
}
signatureOkMetric := c.signatureOkMetric.With(promlabels)
cdsPresentMetric := c.cdsPresentMetric.With(promlabels)
cdsDsMatchMetric := c.cdsDsMatchMetric.With(promlabels)
if sok {
signatureOkMetric.Set(1)
} else {
signatureOkMetric.Set(0)
}
if cdp {
cdsPresentMetric.Set(1)
} else {
cdsPresentMetric.Set(0)
}
if cdm {
cdsDsMatchMetric.Set(1)
} else {
cdsDsMatchMetric.Set(0)
}
}
c.signatureOkMetric.Collect(ch)
c.cdsPresentMetric.Collect(ch)
c.cdsDsMatchMetric.Collect(ch)
return nil
}
type DsData struct {
KeyTag uint16
Algorithm uint8
DigestType uint8
Digest string
}
func Equal(a, b []DsData) bool {
if len(a) != len(b) {
return false
}
for i, v := range a {
if v != b[i] {
return false
}
}
return true
}
func (c *MetricsCollector) signatureOk(zone string) (bool, error) {
qsoa := new(dns.Msg)
// Request DNSSEC information
qsoa.SetEdns0(4096, true)
qsoa.SetQuestion(dns.Fqdn(zone), dns.TypeSOA)
rsoa, _, err := c.DNS.Exchange(qsoa, c.Resolver)
if err != nil {
return false, err
}
level.Debug(c.Log).Log(fmt.Sprintf("SOA header: %+v\n", rsoa.MsgHdr))
return rsoa.MsgHdr.AuthenticatedData, nil
}
func (c *MetricsCollector) cdsDsMatches(zone string) (bool, bool, error) {
qcds := new(dns.Msg)
qcds.SetQuestion(dns.Fqdn(zone), dns.TypeCDS)
rcds, _, err := c.DNS.Exchange(qcds, c.Resolver)
if err != nil {
return false, false, err
}
if len(rcds.Answer) == 0 {
// Zone doesn't publish CDS records
return false, false, nil
}
cdsdata := make([]DsData, len(rcds.Answer))
level.Debug(c.Log).Log(fmt.Sprintf("CDS data: %+v\n", rcds.Answer))
for i, a := range rcds.Answer {
ds := a.(*dns.CDS).DS
cdsdata[i] = DsData{
KeyTag: ds.KeyTag,
Algorithm: ds.Algorithm,
DigestType: ds.DigestType,
Digest: ds.Digest,
}
}
sort.SliceStable(cdsdata, func(a, b int) bool { return cdsdata[a].KeyTag < cdsdata[b].KeyTag })
qds := new(dns.Msg)
qds.SetQuestion(dns.Fqdn(zone), dns.TypeDS)
rds, _, err := c.DNS.Exchange(qds, c.Resolver)
if err != nil {
return true, false, err
}
dsdata := make([]DsData, len(rds.Answer))
level.Debug(c.Log).Log(fmt.Sprintf("DS data: %+v\n", rds.Answer))
for i, a := range rds.Answer {
ds := a.(*dns.DS)
dsdata[i] = DsData{
KeyTag: ds.KeyTag,
Algorithm: ds.Algorithm,
DigestType: ds.DigestType,
Digest: ds.Digest,
}
}
sort.SliceStable(dsdata, func(a, b int) bool { return dsdata[a].KeyTag < dsdata[b].KeyTag })
return true, Equal(dsdata, cdsdata), nil
}
func main() {
var (
listenAddress = kingpin.Flag(
"web.listen-address",
"Address on which to expose metrics.",
).Default(":9142").String()
metricsPath = kingpin.Flag(
"web.metrics-path",
"Path under which to expose metrics.",
).Default("/metrics").String()
resolver = kingpin.Flag(
"dns.resolver",
"DNS Resolver to use.",
).Default("127.0.0.1:53").String()
zones = kingpin.Flag(
"dns.zones",
"DNS zones to check, comma separated.",
).Default("example.org").String()
configFile = kingpin.Flag(
"web.config",
"[EXPERIMENTAL] Path to config yaml file that can enable TLS or authentication.",
).Default("").String()
)
promlogConfig := &promlog.Config{}
flag.AddFlags(kingpin.CommandLine, promlogConfig)
kingpin.Version(version.Print("dnssec_exporter"))
kingpin.CommandLine.UsageWriter(os.Stdout)
kingpin.HelpFlag.Short('h')
kingpin.Parse()
zonelist := strings.Split(*zones, ",")
// Always add trailing dot
for i, z := range zonelist {
if z[len(z)-1] != byte('.') {
zonelist[i] = z + "."
}
}
logger := promlog.New(promlogConfig)
logger = level.NewFilter(logger, level.AllowDebug())
logger = log.With(logger, "ts", log.DefaultTimestampUTC)
metricsCollector := NewMetricsCollector(zonelist, *resolver, logger)
prom.MustRegister(metricsCollector)
http.Handle(*metricsPath, promhttp.Handler())
server := &http.Server{Addr: *listenAddress}
logger.Log(web.ListenAndServe(server, *configFile, logger))
}