Pause a registry's WHOIS server after it refuses a query (closes #218)

The fetcher kept one interval for every registry, so a registry that
refused a query was asked again within seconds. RIPE blocked the test
host's address that way.

The WHOIS client now pauses an RIR's or NIC.br's server for an hour
after the server refuses a query. A refused or reset connection is a
refusal, and so is an %ERROR:201: or %ERROR:202: line. Lookups at the
other servers go on. A lookup whose RIR is paused leaves the AS stale,
and counts as neither a success nor a failure. IANA is never paused,
because a pause of IANA would stop every lookup. NIC.br's hour-long
skip after its over-limit answer is now the same pause.

Model: opus-5-5

TODO.md

@@ -35,6 +35,14 @@ tested.
 
 # Completed Steps
 
+- 2026-11-02: RouteWatch pauses an RIR's or NIC.br's WHOIS server for an hour
+  after the server refuses a query. A refused or reset connection is a refusal.
+  So is an answer with an `%ERROR:201:` or `%ERROR:202:` line. Lookups at the
+  other servers go on. An AS whose RIR is paused is looked up after the pause.
+  IANA is never paused, because a pause of IANA would stop every lookup. A
+  refusal by IANA is an ordinary failure. NIC.br is also paused for an hour
+  after it says RouteWatch has passed NIC.br's query limit. Before, the fetcher
+  asked a server again within seconds of a refusal (closes #218)
 - 2026-10-27: the tests of `internal/routewatch` no longer fail on a loaded
   host. Five of them gave `HandleMessage` two seconds to apply a full prefix
   batch, which under the race detector can take longer. A test now waits up to

internal/routewatch/asnfetcher.go

@@ -287,6 +287,13 @@ func (f *ASNFetcher) fetchNextStale(ctx context.Context) {
 // so the AS stays stale. An AS IANA refers to no RIR is stored with no
 // WHOIS data, so it is not looked up again until it is stale; that counts
 // as neither a success nor a failure.
+//
+// The WHOIS client pauses an RIR's or NIC.br's server for whois.PauseTime
+// after the server refuses a query. Lookups at the other servers go on. IANA
+// is never paused, so a refusal by IANA is an ordinary failure. A lookup
+// whose RIR is paused fails with whois.ErrPaused. Such a lookup leaves the
+// AS stale, and counts as neither a success nor a failure. The lookups that
+// QueueImmediate asks for also run through fetchAndUpdate.
 func (f *ASNFetcher) fetchAndUpdate(ctx context.Context, asn int) bool {
 	ctx, cancel := context.WithTimeout(ctx, time.Minute)
 	defer cancel()
@@ -307,6 +314,13 @@ func (f *ASNFetcher) fetchAndUpdate(ctx context.Context, asn int) bool {
 		return false
 	}
 
+	if errors.Is(err, whois.ErrPaused) {
+		f.logger.Info("Skipped WHOIS lookup, the RIR's server is paused",
+			"asn", asn, "error", err)
+
+		return false
+	}
+
 	if err != nil {
 		f.logger.Error("WHOIS lookup failed", "asn", asn, "error", err)
 		f.recordFailure()

internal/routewatch/asnfetcher_internal_test.go

@@ -13,6 +13,7 @@ import (
 
 	"git.eeqj.de/sneak/routewatch/internal/database"
 	"git.eeqj.de/sneak/routewatch/internal/logger"
+	"git.eeqj.de/sneak/routewatch/internal/whois"
 )
 
 // The WHOIS servers a lookup asks: IANA first, then the RIR IANA refers it
@@ -131,6 +132,109 @@ func TestFetchAndUpdateKeepsTheRowWhenTheLookupFails(t *testing.T) {
 	}
 }
 
+// TestFetchAndUpdateWaitsOutAPause looks up an AS at RIPE while RIPE refuses
+// the query. The test sets the WHOIS client's clock. The next lookup comes a
+// second before whois.PauseTime has passed. It sends RIPE nothing and leaves
+// the AS never looked up. It counts as neither a success nor a failure. A
+// lookup at whois.PauseTime asks RIPE again.
+func TestFetchAndUpdateWaitsOutAPause(t *testing.T) {
+	t.Parallel()
+
+	f, db := newFetcherWithWHOISAnswers(t, map[string]string{
+		ianaWHOISServer: ianaRefersToRIPE,
+		ripeWHOISServer: ripeAccessDenied,
+	})
+
+	ripeAsks := 0
+	dial := f.whoisClient.DialContext
+	f.whoisClient.DialContext = func(
+		ctx context.Context, network, address string,
+	) (net.Conn, error) {
+		if address == ripeWHOISServer {
+			ripeAsks++
+		}
+
+		return dial(ctx, network, address)
+	}
+
+	start := time.Date(2026, 11, 2, 0, 0, 0, 0, time.UTC)
+	now := start
+	f.whoisClient.Now = func() time.Time { return now }
+
+	f.fetchAndUpdate(t.Context(), testASNA)
+
+	now = start.Add(whois.PauseTime - time.Second)
+
+	f.fetchAndUpdate(t.Context(), testASNA)
+
+	if ripeAsks != 1 {
+		t.Errorf("RIPE was asked %d times during its pause, want 1", ripeAsks)
+	}
+
+	stats, err := db.GetWHOISStats(t.Context(), whoisStaleThreshold)
+	if err != nil {
+		t.Fatalf("GetWHOISStats: %v", err)
+	}
+
+	if stats.NeverFetched != 1 {
+		t.Errorf("never looked up = %d, want 1", stats.NeverFetched)
+	}
+
+	got := f.GetStats()
+	if got.ConsecutiveFails != 1 || got.ErrorsLastHour != 1 ||
+		got.SuccessesLastHour != 0 {
+		t.Errorf("%d failures in a row, %d errors, %d successes; want 1, 1, 0",
+			got.ConsecutiveFails, got.ErrorsLastHour, got.SuccessesLastHour)
+	}
+
+	now = start.Add(whois.PauseTime)
+
+	f.fetchAndUpdate(t.Context(), testASNA)
+
+	if ripeAsks != 2 {
+		t.Errorf("RIPE was asked %d times after its pause, want 2", ripeAsks)
+	}
+}
+
+// TestFetchAndUpdateKeepsAskingIANA looks up an AS while IANA's server
+// refuses the connection. The test sets the WHOIS client's clock. The next
+// lookup comes a second before whois.PauseTime has passed. IANA is never
+// paused, so that lookup asks IANA again. Each refusal counts as a failure.
+func TestFetchAndUpdateKeepsAskingIANA(t *testing.T) {
+	t.Parallel()
+
+	// With no answers, every server refuses the connection.
+	f, _ := newFetcherWithWHOISAnswers(t, map[string]string{})
+
+	ianaAsks := 0
+	dial := f.whoisClient.DialContext
+	f.whoisClient.DialContext = func(
+		ctx context.Context, network, address string,
+	) (net.Conn, error) {
+		if address == ianaWHOISServer {
+			ianaAsks++
+		}
+
+		return dial(ctx, network, address)
+	}
+
+	start := time.Date(2026, 11, 2, 0, 0, 0, 0, time.UTC)
+	now := start
+	f.whoisClient.Now = func() time.Time { return now }
+
+	f.fetchAndUpdate(t.Context(), testASNA)
+
+	now = start.Add(whois.PauseTime - time.Second)
+
+	f.fetchAndUpdate(t.Context(), testASNA)
+
+	got := f.GetStats()
+	if ianaAsks != 2 || got.ConsecutiveFails != 2 {
+		t.Errorf("IANA was asked %d times, with %d failures in a row; "+
+			"want 2 and 2", ianaAsks, got.ConsecutiveFails)
+	}
+}
+
 // TestRecordStepsTheInterval has the fetcher fail from its base interval of
 // 15 seconds, then succeed. Each failure makes the interval 1.5 times as
 // long, up to one minute, and each success halves it, down to one second.

internal/whois/whois.go

@@ -12,6 +12,7 @@ import (
 	"regexp"
 	"strings"
 	"sync"
+	"syscall"
 	"time"
 	"unicode/utf8"
 
@@ -70,12 +71,12 @@ const nicbrHeader = "% Copyright (c) Nic.br"
 // queries to stop the data being taken in bulk.
 const nicbrLimitReached = "Query rate limit exceeded"
 
-// NICbrSkipTime is how long the client stops asking NIC.br after NIC.br
+// PauseTime is how long the client sends an RIR's or NIC.br's server no
-// answers that the client is over its query limit. NIC.br publishes
+// query after that server refuses a query. queryRegistry says what a
-// neither the limit nor how long it lasts. An hour outlasts a limit
+// refusal is. RIPE refuses an address for good when the address keeps
-// counted per minute or per hour. The ASes looked up meanwhile get
+// passing RIPE's limit (see noPersonalFlag). An hour outlasts a limit
-// NIC.br's fields when they are next refreshed.
+// counted per minute or per hour.
-const NICbrSkipTime = time.Hour
+const PauseTime = time.Hour
 
 // RIR identifiers.
 const (
@@ -125,6 +126,10 @@ var (
 	errAnswerTooLarge = errors.New("WHOIS answer reached the size cap")
 )
 
+// ErrPaused is returned when a lookup needs a server that refused a query
+// less than PauseTime ago. The client sends that server nothing meanwhile.
+var ErrPaused = errors.New("WHOIS server paused after refusing a query")
+
 // ASNInfo contains parsed WHOIS information for an ASN.
 type ASNInfo struct {
 	ASN         int
@@ -156,12 +161,12 @@ type Client struct {
 
 	logger *slog.Logger
 
-	// mu guards nicbrSkipUntil.
+	// mu guards pausedUntil.
 	mu sync.Mutex
 
-	// nicbrSkipUntil is when the client next asks NIC.br, after NIC.br
+	// pausedUntil maps a server, given as host:port, to the time the client
-	// answered that the client is over its query limit.
+	// may ask it again.
-	nicbrSkipUntil time.Time
+	pausedUntil map[string]time.Time
 }
 
 // NewClient creates a new WHOIS client that logs to logger.
@@ -172,23 +177,29 @@ func NewClient(logger *slog.Logger) *Client {
 		DialContext: dialer.DialContext,
 		Now:         time.Now,
 		logger:      logger,
+		pausedUntil: make(map[string]time.Time),
 	}
 }
 
 // LookupASN asks IANA which RIR holds the given ASN, asks that RIR, and
 // returns what the RIR's answer says. When LACNIC's answer is NIC.br's, it
 // returns what NIC.br's own server says instead, unless that query fails or
-// is skipped, as askNICbr says.
+// NIC.br is paused, as askNICbr says.
 //
-// It returns ErrNoReferral when IANA refers the AS to no RIR, and another
+// It returns ErrNoReferral when IANA refers the AS to no RIR. Its error
-// error when the query to IANA or to the RIR fails, when the RIR refuses
+// wraps ErrPaused when the RIR is paused. It returns another error in each
-// it, when IANA's answer has neither a referral nor the AS's block, when
+// of these cases:
-// IANA refers the AS to a server none of the five RIRs run, or when the
+//
-// answer carries none of ASNInfo's fields.
+//   - the query to IANA or to the RIR fails
+//   - the RIR refuses the query
+//   - IANA's answer has neither a referral nor the AS's block
+//   - IANA refers the AS to a server none of the five RIRs run
+//   - the answer carries none of ASNInfo's fields
 func (c *Client) LookupASN(ctx context.Context, asn int) (*ASNInfo, error) {
 	// Query IANA first to find the authoritative RIR
 	query := fmt.Sprintf("AS%d", asn)
 
+	// IANA is never paused, because a pause of IANA would stop every lookup.
 	ianaResp, err := c.query(ctx, whoisServerIANA, query)
 	if err != nil {
 		return nil, fmt.Errorf("IANA query failed: %w", err)
@@ -211,7 +222,7 @@ func (c *Client) LookupASN(ctx context.Context, asn int) (*ASNInfo, error) {
 	}
 
 	// Query the authoritative RIR
-	rirResp, err := c.queryRIR(ctx, whoisServer, rirQuery(rir, query))
+	rirResp, err := c.queryRegistry(ctx, whoisServer, rirQuery(rir, query))
 	if err != nil {
 		return nil, fmt.Errorf("RIR query failed: %w", err)
 	}
@@ -241,22 +252,19 @@ func (c *Client) LookupASN(ctx context.Context, asn int) (*ASNInfo, error) {
 // askNICbr returns lacnicInfo, what LACNIC's answer says, and logs a
 // warning when the query fails, when NIC.br sends the reduced answer for a
 // client over its limit, or when NIC.br's answer carries none of ASNInfo's
-// fields. After the reduced answer, it returns lacnicInfo without asking
+// fields. The reduced answer pauses NIC.br, as a refusal does. While NIC.br
-// NIC.br until NICbrSkipTime has passed.
+// is paused, askNICbr returns lacnicInfo without a warning. The ASes looked
+// up meanwhile get NIC.br's fields when they are next refreshed.
 func (c *Client) askNICbr(
 	ctx context.Context, asQuery string, lacnicInfo *ASNInfo,
 ) *ASNInfo {
 	asn := lacnicInfo.ASN
 
-	c.mu.Lock()
+	answer, err := c.queryRegistry(ctx, whoisServerNICbr, asQuery)
-	skipping := c.Now().Before(c.nicbrSkipUntil)
+	if errors.Is(err, ErrPaused) {
-	c.mu.Unlock()
-
-	if skipping {
 		return lacnicInfo
 	}
 
-	answer, err := c.query(ctx, whoisServerNICbr, asQuery)
 	if err != nil {
 		c.logger.Warn("NIC.br query failed, keeping LACNIC's fields",
 			"asn", asn, "error", err)
@@ -265,13 +273,11 @@ func (c *Client) askNICbr(
 	}
 
 	if strings.Contains(answer, nicbrLimitReached) {
-		c.mu.Lock()
+		c.pause(whoisServerNICbr)
-		c.nicbrSkipUntil = c.Now().Add(NICbrSkipTime)
-		c.mu.Unlock()
 
 		c.logger.Warn("NIC.br answered that the client is over its query "+
-			"limit, keeping LACNIC's fields and skipping NIC.br",
+			"limit, keeping LACNIC's fields and pausing NIC.br",
-			"asn", asn, "skip_for", NICbrSkipTime)
+			"asn", asn, "pause_for", PauseTime)
 
 		return lacnicInfo
 	}
@@ -309,25 +315,65 @@ func rirQuery(rir, asQuery string) string {
 	}
 }
 
-// queryRIR sends query to an RIR's server and returns the answer. An answer
+// queryRegistry sends query to the server of an RIR or of NIC.br, and
-// holding an error line with which the server refuses the query is an
+// returns the answer. The client pauses the server for PauseTime when the
-// error, and the error holds that line.
+// server refuses the query. Each of these is a refusal:
-func (c *Client) queryRIR(
+//
+//   - a refused connection
+//   - a reset connection
+//   - an %ERROR:201: or %ERROR:202: line in the answer
+//
+// A refusal is returned as an error. While the server is paused,
+// queryRegistry sends it nothing and returns an error that wraps ErrPaused.
+func (c *Client) queryRegistry(
 	ctx context.Context, server, query string,
 ) (string, error) {
+	c.mu.Lock()
+	pausedUntil := c.pausedUntil[server]
+	c.mu.Unlock()
+
+	if c.Now().Before(pausedUntil) {
+		return "", fmt.Errorf("%w: %s until %s", ErrPaused, server,
+			pausedUntil.UTC().Format(time.RFC3339))
+	}
+
 	answer, err := c.query(ctx, server, query)
+	if err == nil {
+		err = checkRefusal(answer)
+	}
+
+	if errors.Is(err, errRefused) || errors.Is(err, syscall.ECONNREFUSED) ||
+		errors.Is(err, syscall.ECONNRESET) {
+		c.pause(server)
+	}
+
 	if err != nil {
 		return "", err
 	}
 
+	return answer, nil
+}
+
+// checkRefusal returns an error holding the first line of answer that
+// starts with accessDeniedError or accessLimitError. It returns nil when
+// answer has no such line.
+func checkRefusal(answer string) error {
 	for line := range strings.SplitSeq(answer, "\n") {
 		if strings.HasPrefix(line, accessDeniedError) ||
 			strings.HasPrefix(line, accessLimitError) {
-			return "", fmt.Errorf("%w: %s", errRefused, line)
+			return fmt.Errorf("%w: %s", errRefused, line)
 		}
 	}
 
-	return answer, nil
+	return nil
+}
+
+// pause stops queryRegistry from querying server until PauseTime has passed.
+func (c *Client) pause(server string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.pausedUntil[server] = c.Now().Add(PauseTime)
 }
 
 // query performs a raw WHOIS query to the specified server and returns the

internal/whois/whois_test.go

@@ -718,9 +718,10 @@ func TestLookupASNKeepsLACNICsAnswerWhenNICbrFails(t *testing.T) {
 
 // TestLookupASNSkipsNICbrAfterItsLimit looks up an AS that NIC.br
 // registers three times with one client, while NIC.br answers that the
-// client is over its query limit. The first lookup asks NIC.br. The
+// client is over its query limit. The test sets the client's clock. The
-// second, a second before NICbrSkipTime has passed, does not. The third,
+// first lookup asks NIC.br. The next comes a second before PauseTime has
-// once NICbrSkipTime has passed, asks again. Each keeps LACNIC's fields.
+// passed, and does not ask NIC.br. The last comes at PauseTime and asks
+// NIC.br again. Each keeps LACNIC's fields.
 func TestLookupASNSkipsNICbrAfterItsLimit(t *testing.T) {
 	t.Parallel()
 
@@ -740,8 +741,8 @@ func TestLookupASNSkipsNICbrAfterItsLimit(t *testing.T) {
 		wantAsks int
 	}{
 		{after: 0, wantAsks: 1},
-		{after: whois.NICbrSkipTime - time.Second, wantAsks: 1},
+		{after: whois.PauseTime - time.Second, wantAsks: 1},
-		{after: whois.NICbrSkipTime, wantAsks: 2},
+		{after: whois.PauseTime, wantAsks: 2},
 	} {
 		now = start.Add(step.after)
 
@@ -785,6 +786,142 @@ func TestLookupASNReportsARefusal(t *testing.T) {
 	}
 }
 
+// resetServer starts a TCP server on the loopback address and returns the
+// server's address. The server reads one query on each connection, then
+// resets the connection.
+func resetServer(t *testing.T) string {
+	t.Helper()
+
+	var listenConfig net.ListenConfig
+
+	listener, err := listenConfig.Listen(t.Context(), "tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+
+	t.Cleanup(func() { _ = listener.Close() })
+
+	go func() {
+		for {
+			conn, err := listener.Accept()
+			if err != nil {
+				return
+			}
+
+			_, _ = bufio.NewReader(conn).ReadString('\n')
+
+			// Closing a connection whose linger time is zero resets it.
+			if tcpConn, ok := conn.(*net.TCPConn); ok {
+				_ = tcpConn.SetLinger(0)
+			}
+
+			_ = conn.Close()
+		}
+	}()
+
+	return listener.Addr().String()
+}
+
+// newRIPEClient returns a client whose fake servers send answers. The
+// client adds one to *ripeAsks each time it connects to RIPE's server. When
+// reset is true, RIPE's server resets the connection instead of answering.
+func newRIPEClient(
+	t *testing.T, answers map[string]string, reset bool, ripeAsks *int,
+) *whois.Client {
+	t.Helper()
+
+	dial := fakeServers(t, answers)
+	resetAddress := resetServer(t)
+
+	client := whois.NewClient(slog.New(slog.DiscardHandler))
+	client.DialContext = func(
+		ctx context.Context, network, address string,
+	) (net.Conn, error) {
+		if address == ripeServer {
+			*ripeAsks++
+		}
+
+		if address == ripeServer && reset {
+			var dialer net.Dialer
+
+			return dialer.DialContext(ctx, network, resetAddress)
+		}
+
+		return dial(ctx, network, address)
+	}
+
+	return client
+}
+
+// TestLookupASNPausesAServerThatRefuses looks up an AS at RIPE while RIPE
+// refuses the query, in each of the ways a server refuses. The test sets
+// the client's clock. A lookup a second before PauseTime has passed fails
+// with ErrPaused and asks RIPE nothing. A lookup of an AS at APNIC succeeds
+// during the pause. A lookup at PauseTime asks RIPE again.
+func TestLookupASNPausesAServerThatRefuses(t *testing.T) {
+	t.Parallel()
+
+	for name, test := range map[string]struct {
+		// ripeAnswer is RIPE's answer. With none, RIPE's server refuses
+		// the connection, or resets it when reset is true.
+		ripeAnswer string
+		reset      bool
+	}{
+		"access denied":      {ripeAnswer: ripeRefusal},
+		"limit reached":      {ripeAnswer: ripeLimitReached + "\n"},
+		"refused connection": {},
+		"reset connection":   {reset: true},
+	} {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			answers := map[string]string{
+				ianaQuery:      ianaReferral,
+				apnicIANAQuery: "refer:        whois.apnic.net\n",
+				apnicQuery:     apnicRecord,
+			}
+			if test.ripeAnswer != "" {
+				answers[ripeQuery] = test.ripeAnswer
+			}
+
+			ripeAsks := 0
+			client := newRIPEClient(t, answers, test.reset, &ripeAsks)
+
+			start := time.Date(2026, 11, 2, 0, 0, 0, 0, time.UTC)
+			now := start
+			client.Now = func() time.Time { return now }
+
+			_, err := client.LookupASN(t.Context(), testASN)
+			if err == nil || errors.Is(err, whois.ErrPaused) {
+				t.Fatalf("LookupASN while RIPE refuses: error %v, want a "+
+					"refusal", err)
+			}
+
+			now = start.Add(whois.PauseTime - time.Second)
+
+			_, err = client.LookupASN(t.Context(), testASN)
+			if !errors.Is(err, whois.ErrPaused) || ripeAsks != 1 {
+				t.Errorf("LookupASN during the pause: error %v after %d "+
+					"queries to RIPE, want ErrPaused after 1", err, ripeAsks)
+			}
+
+			_, err = client.LookupASN(t.Context(), apnicASN)
+			if err != nil {
+				t.Errorf("LookupASN of an AS at APNIC during RIPE's "+
+					"pause: %v", err)
+			}
+
+			now = start.Add(whois.PauseTime)
+
+			_, _ = client.LookupASN(t.Context(), testASN)
+			if ripeAsks != 2 {
+				t.Errorf("RIPE was asked %d times after the pause, want 2",
+					ripeAsks)
+			}
+		})
+	}
+}
+
 // TestLookupASNFailsWhenTheRIRGivesNoAnswer looks up an AS IANA refers to
 // RIPE when RIPE's server refuses the connection, and when it answers only
 // with an error. Neither is a lookup that found the AS.