Feat: add support for domain based black lists

Makefile

@@ -8,6 +8,14 @@ run-dev:
  --log.debug \
  --config.dns-resolver 0.0.0.0:15353
 
+.PHONY: run-dev-domain
+run-dev-domain:
+ go run dnsbl_exporter.go \
+ --log.debug \
+ --config.rbls ./rbls-domain.ini \
+ --config.domain-based \
+ --config.dns-resolver 0.0.0.0:15353
+
 .PHONY: snapshot
 snapshot:
  goreleaser build --snapshot --clean

README.md

@@ -22,6 +22,7 @@ $ dnsbl-exporter -h
 --config.dns-resolver value IP address of the resolver to use. (default: "127.0.0.1:53")
 --config.rbls value Configuration file which contains RBLs (default: "./rbls.ini")
 --config.targets value Configuration file which contains the targets to check. (default: "./targets.ini")
+--config.domain-based RBLS are domain instead of IP based blacklists (default: false)
 --web.listen-address value Address to listen on for web interface and telemetry. (default: ":9211")
 --web.telemetry-path value Path under which to expose metrics. (default: "/metrics")
 --log.debug Enable more output in the logs, otherwise INFO.
@@ -85,6 +86,8 @@ luzilla_rbls_ips_blacklisted{hostname="mail.gmx.net",ip="212.227.17.168",rbl="ix
 
 This represent the server's hostname and the DNSBL in question. `0` for unlisted and `1` for listed. Requests to the DNSBL happen in real-time and are not cached. Take this into account and use accordingly.
 
+If the exporter is configured for DNS based blacklists, the ip label represents the return code of the blacklist.
+
 ### Caveat
 
 In order to use this, a _proper_ DNS resolver is needed. Proper means: not Google, not Cloudflare, OpenDNS, etc..

app/app.go

@@ -58,6 +58,11 @@ func NewApp(name string, version string) DNSBLApp {
  Usage: "Configuration file which contains the targets to check.",
  EnvVars: []string{"DNSBL_EXP_TARGETS"},
  },
+ &cli.BoolFlag{
+ Name: "config.domain-based",
+ Usage: "RBLS are domain based blacklists.",
+ Value: false,
+ },
  &cli.StringFlag{
  Name: "web.listen-address",
  Value: ":9211",
@@ -169,7 +174,7 @@ func (a *DNSBLApp) Bootstrap() {
  return err
  }
 
- rblCollector := setup.CreateCollector(rbls, targets, dnsUtil, log.With("area", "metrics"))
+ rblCollector := setup.CreateCollector(rbls, targets, ctx.Bool("config.domain-based"), dnsUtil, log.With("area", "metrics"))
  registry.MustRegister(rblCollector)
 
  registryExporter := setup.CreateRegistry()
@@ -191,9 +196,10 @@ func (a *DNSBLApp) Bootstrap() {
  http.Handle(ctx.String("web.telemetry-path"), mHandler.Handler())
 
  pHandler := prober.ProberHandler{
- DNS: dnsUtil,
- Rbls: rbls,
- Logger: log.With("area", "prober"),
+ DNS: dnsUtil,
+ Rbls: rbls,
+ DomainBased: ctx.Bool("config.domain-based"),
+ Logger: log.With("area", "prober"),
  }
  http.Handle("/prober", pHandler)
 

collector/collector.go

@@ -24,6 +24,7 @@ type RblCollector struct {
  rbls []string
  util *dns.DNSUtil
  targets []string
+ domainBased bool
  logger *slog.Logger
 }
 
@@ -32,7 +33,7 @@ func BuildFQName(metric string) string {
 }
 
 // NewRblCollector ... creates the collector
-func NewRblCollector(rbls []string, targets []string, util *dns.DNSUtil, logger *slog.Logger) *RblCollector {
+func NewRblCollector(rbls []string, targets []string, domainBased bool, util *dns.DNSUtil, logger *slog.Logger) *RblCollector {
  return &RblCollector{
  configuredMetric: prometheus.NewDesc(
  BuildFQName("used"),
@@ -70,10 +71,11 @@ func NewRblCollector(rbls []string, targets []string, util *dns.DNSUtil, logger
  nil,
  nil,
  ),
- rbls: rbls,
- util: util,
- targets: targets,
- logger: logger,
+ rbls: rbls,
+ util: util,
+ targets: targets,
+ domainBased: domainBased,
+ logger: logger,
  }
 }
 
@@ -116,7 +118,14 @@ func (c *RblCollector) Collect(ch chan<- prometheus.Metric) {
  close(targets)
  }()
  for _, host := range hosts {
- go resolver.Do(host, targets, wg.Done)
+ if c.domainBased {
+ go func(hostname string) {
+ targets <- rbl.Target{Host: hostname}
+ wg.Done()
+ }(host)
+ } else {
+ go resolver.Do(host, targets, wg.Done)
+ }
  }
  // run the check
  for target := range targets {
@@ -143,9 +152,12 @@ func (c *RblCollector) Collect(ch chan<- prometheus.Metric) {
  listed.Store(check.Rbl, val.(int)+1)
  }
 
- c.logger.Debug("listed?", slog.Int("v", metricValue), slog.String("rbl", check.Rbl))
-
- labelValues := []string{check.Rbl, check.Target.IP.String(), check.Target.Host}
+ c.logger.Debug("listed?", slog.Int("v", metricValue), slog.String("rbl", check.Rbl), slog.String("reason", check.Text))
+ ip := ""
+ if len(check.Target.IP) > 0 {
+ ip = check.Target.IP.String()
+ }
+ labelValues := []string{check.Rbl, ip, check.Target.Host}
 
  // this is an "error" from the RBL/transport
  if check.Error {

internal/prober/prober.go

@@ -10,9 +10,10 @@ import (
 )
 
 type ProberHandler struct {
- DNS *dns.DNSUtil
- Rbls []string
- Logger *slog.Logger
+ DNS *dns.DNSUtil
+ Rbls []string
+ DomainBased bool
+ Logger *slog.Logger
 }
 
 func (p ProberHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -26,7 +27,7 @@ func (p ProberHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
  targets = append(targets, r.URL.Query().Get("target"))
 
  registry := setup.CreateRegistry()
- collector := setup.CreateCollector(p.Rbls, targets, p.DNS, p.Logger)
+ collector := setup.CreateCollector(p.Rbls, targets, p.DomainBased, p.DNS, p.Logger)
  registry.MustRegister(collector)
 
  h := promhttp.HandlerFor(registry, promhttp.HandlerOpts{

internal/setup/setup.go

@@ -7,8 +7,8 @@ import (
  "golang.org/x/exp/slog"
 )
 
-func CreateCollector(rbls []string, targets []string, dnsUtil *dns.DNSUtil, logger *slog.Logger) *collector.RblCollector {
- return collector.NewRblCollector(rbls, targets, dnsUtil, logger)
+func CreateCollector(rbls []string, targets []string, domainBased bool, dnsUtil *dns.DNSUtil, logger *slog.Logger) *collector.RblCollector {
+ return collector.NewRblCollector(rbls, targets, domainBased, dnsUtil, logger)
 }
 
 func CreateRegistry() *prometheus.Registry {

internal/tests/tests.go

@@ -54,6 +54,13 @@ func CreateDNSMock(t *testing.T) *mockdns.Server {
  "10.0.0.127.zen.spamhaus.org.": {
  TXT: []string{"https://www.spamhaus.org/query/ip/127.0.0.10"},
  },
+ // domain based rbl responses
+ // https://www.spamhaus.org/faq/section/Spamhaus%20DBL#277
+ "dbltest.com.dbl.spamhaus.org.": {
+ A: []string{"127.0.1.2"},
+ TXT: []string{"https://www.spamhaus.org/query/domain/dbltest.com"},
+ },
+ "example.com.dbl.spamhaus.org.": {},
  }, true)
  if err != nil {
  assert.FailNow(t, "failed building mock", "error: %s", err)

pkg/rbl/rbl.go

@@ -44,18 +44,25 @@ func (rbl *RBL) Update(target Target, blocklist string, c chan<- Result) {
  slog.String("rbl", blocklist))))
 }
 
-func (r *RBL) lookup(blocklist string, ip Target, c chan<- Result, logger *slog.Logger) {
+func (r *RBL) lookup(blocklist string, target Target, c chan<- Result, logger *slog.Logger) {
  logger.Debug("next up")
 
  result := Result{
- Target: ip,
+ Target: target,
  Listed: false,
  Rbl: blocklist,
  }
+ domainBased := target.IP == nil
 
  logger.Debug("about to query RBL")
 
- lookup := godnsbl.Reverse(ip.IP) + "." + result.Rbl
+ var lookup string
+ if domainBased {
+ lookup = target.Host + "." + result.Rbl
+ } else {
+ lookup = godnsbl.Reverse(target.IP) + "." + result.Rbl
+ }
+
  logger.Debug("built lookup", slog.String("lookup", lookup))
 
  res, err := r.util.GetARecords(lookup)
@@ -69,12 +76,12 @@ func (r *RBL) lookup(blocklist string, ip Target, c chan<- Result, logger *slog.
  }
 
  if len(res) == 0 {
- // ip is not listed
+ // target (domain or ip) is not listed
  c <- result
  return
  }
 
- logger.Debug("ip is listed")
+ logger.Debug("target is listed")
 
  result.Listed = true
 
@@ -86,9 +93,18 @@ func (r *RBL) lookup(blocklist string, ip Target, c chan<- Result, logger *slog.
  c <- result
  return
  }
+ if domainBased {
+ // @see https://datatracker.ietf.org/doc/html/rfc5782
+ result.Target.IP = reason
+ }
 
  // fetch (potential) reason
- txt, err := r.util.GetTxtRecords(godnsbl.Reverse(reason) + "." + result.Rbl)
+ var txt []string
+ if domainBased {
+ txt, err = r.util.GetTxtRecords(lookup)
+ } else {
+ txt, err = r.util.GetTxtRecords(godnsbl.Reverse(reason) + "." + result.Rbl)
+ }
  if err != nil {
  logger.Error("error occurred fetching TXT record", slog.String("msg", err.Error()))
 

pkg/rbl/rbl_test.go

@@ -112,6 +112,41 @@ func TestRblSuite(t *testing.T) {
  assert.True(t, result.Listed)
  assert.Contains(t, result.Text, "https://www.spamhaus.org/")
  })
+
+ t.Run("run=domain", func(t *testing.T) {
+ dnsMock := tests.CreateDNSMock(t)
+ defer dnsMock.Close()
+
+ logger := tests.CreateTestLogger(t)
+ d := tests.CreateDNSUtil(t, dnsMock.LocalAddr())
+ r := rbl.New(d, logger)
+
+ // https://www.spamhaus.org/faq/section/Spamhaus%20DBL#277
+ targets := []rbl.Target{
+ {Host: "dbltest.com"},
+ {Host: "example.com"},
+ }
+
+ for _, target := range targets {
+ blocklist := "dbl.spamhaus.org"
+ c := make(chan rbl.Result)
+ defer close(c)
+
+ r.Update(target, blocklist, c)
+
+ res := <-c
+ assert.False(t, res.Error)
+ assert.NoError(t, res.ErrorType)
+ if target.Host == "dbltest.com" {
+ assert.True(t, res.Listed)
+ assert.Equal(t, "127.0.1.2", res.Target.IP.String())
+ assert.Equal(t, res.Text, "https://www.spamhaus.org/query/domain/dbltest.com")
+ } else {
+ assert.False(t, res.Listed)
+ assert.Nil(t, res.Target.IP)
+ }
+ }
+ })
 }
 
 func TestResolver(t *testing.T) {

rbls-domain.ini

@@ -0,0 +1,2 @@
+[rbl]
+server=dbl.spamhaus.org

targets.ini

@@ -6,3 +6,4 @@ server=smtp.gmail.com
 server=mail.gmx.net
 server=smtp.yahoo.com
 server=smtp.fastmail.com
+server=dbltest.com