AS number and country looked up for every client (closes #95)

GeoJS's geo.json is asked about every new visitor unless
SWWAF_LOOKUP_SOURCE is off. A request waits for its client's first
answer only while a country list or SWWAF_ADD_LOOKUP_HEADERS needs it;
otherwise the answer reaches the client's history and ban notes when it
comes. The AS number and name go beside the country in the request log,
history, ban notes, alerts and lookups.json, with metrics by AS number;
64512 counts as unknown. A client's own X-Client-ASN and
X-Client-Country never reach the app, whatever the setting says, and
make example-app sends no address to GeoJS.

Judgement call: AS numbers are written AS64496, as SPEC's settings write them.
Judgement call: SWWAF_LOOKUP_TIMEOUT is added, default 1s, and cannot be off.

Model: opus-5-5

internal/proxy/lookup_test.go

@@ -1,11 +1,14 @@
 package proxy_test
 
 import (
+	"net"
 	"net/http"
+	"net/http/httptest"
 	"net/netip"
 	"slices"
 	"sync"
 	"testing"
+	"testing/synctest"
 	"time"
 
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
@@ -237,6 +240,65 @@ func TestClientsOwnLookupHeadersAreRemovedWhileTheSettingIsOff(t *testing.T) {
 	}
 }
 
+func TestRequestWaitsAsLongAsTheLookupTimeoutSays(t *testing.T) {
+	t.Parallel()
+
+	// The test runs in a synctest bubble, where the time package runs on a
+	// clock of the test's own: the wait lasts exactly as long as it should,
+	// however slowly the test process runs. Nothing in it may wait on the
+	// network, which would keep that clock from moving on: the request is
+	// handed to the proxy's handler, and GeoJS is one that never answers.
+	synctest.Test(t, func(t *testing.T) {
+		// Not the default second. The exclusive list needs the answer, and
+		// the app is never reached.
+		const timeout = 3 * time.Second
+
+		server, out, _ := newProxy(t, "http://app.invalid", unansweredGeoJSURL,
+			time.Now, map[string]string{
+				lookupTimeout:    timeout.String(),
+				allowedCountries: "DE",
+			})
+
+		req := httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/",
+			http.NoBody)
+		req.RemoteAddr = net.JoinHostPort(fromDE, "1234")
+		began := time.Now()
+
+		server.Handler.ServeHTTP(httptest.NewRecorder(), req)
+
+		if waited := time.Since(began); waited != timeout {
+			t.Errorf("the request waited %s for its answer, want %s", waited, timeout)
+		}
+
+		// Without an answer, the client is in no country the list allows.
+		wantLine(t, out.requestLine(t), http.StatusForbidden,
+			requestlog.ActionCountryDenied)
+	})
+}
+
+// unansweredGeoJSURL is where a GeoJS that never answers is asked: a
+// request to it waits, without the network, until it is abandoned.
+// TestMain registers it with Go's default transport, through which GeoJS
+// is asked.
+const unansweredGeoJSURL = "unanswered://geojs/v1/ip/geo.json"
+
+func TestMain(m *testing.M) {
+	transport, _ := http.DefaultTransport.(*http.Transport)
+	transport.RegisterProtocol("unanswered", unansweredGeoJS{})
+
+	m.Run()
+}
+
+// unansweredGeoJS is the GeoJS at unansweredGeoJSURL.
+type unansweredGeoJS struct{}
+
+// RoundTrip waits until req is abandoned.
+func (unansweredGeoJS) RoundTrip(req *http.Request) (*http.Response, error) {
+	<-req.Context().Done()
+
+	return nil, req.Context().Err()
+}
+
 // clientsOwnLookupHeaders are the X-Client-ASN and X-Client-Country a
 // client sends of its own, each twice, in two cases.
 const clientsOwnLookupHeaders = "X-Client-ASN: AS1\r\nx-client-asn: AS2\r\n" +

internal/proxy/proxy_test.go

@@ -235,16 +235,43 @@ func startProxyWithClock(
 }
 
 // startProxyWithAlerts is startProxyWithClock, and returns the queue of
-// the alerts the proxy raises as well, as the settings in env make it. No
+// the alerts the proxy raises as well, as newProxy makes them.
-// alert is sent from it: they wait in it, for the test to look at. With
-// no geojsURL, there is no stand-in for GeoJS to look clients up at, and
-// SWWAF_LOOKUP_SOURCE is off unless env sets it.
 func startProxyWithAlerts(
 	t *testing.T, appURL, geojsURL string, now func() time.Time,
 	env map[string]string,
 ) (string, *output, *proxy.Server, *alerts.Queue) {
 	t.Helper()
 
+	server, out, alertQueue := newProxy(t, appURL, geojsURL, now, env)
+
+	listener, err := (&net.ListenConfig{}).Listen(t.Context(), "tcp", localhost+":0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+
+	go func() {
+		_ = server.Serve(listener)
+	}()
+
+	t.Cleanup(func() {
+		_ = server.Close()
+	})
+
+	return listener.Addr().String(), out, server, alertQueue
+}
+
+// newProxy makes the server startProxyWithClock starts, without starting
+// it, and returns it, what it writes, and the queue of the alerts the
+// proxy raises, as the settings in env make it. No alert is sent from the
+// queue: they wait in it, for the test to look at. With no geojsURL, there
+// is no stand-in for GeoJS to look clients up at, and SWWAF_LOOKUP_SOURCE
+// is off unless env sets it.
+func newProxy(
+	t *testing.T, appURL, geojsURL string, now func() time.Time,
+	env map[string]string,
+) (*proxy.Server, *output, *alerts.Queue) {
+	t.Helper()
+
 	settings := map[string]string{
 		"SWWAF_UPSTREAM_URL": appURL, rulesDir: t.TempDir(), instanceName: "app",
 	}
@@ -293,20 +320,7 @@ func startProxyWithAlerts(
 		Alerts:     alertQueue,
 	})
 
-	listener, err := (&net.ListenConfig{}).Listen(t.Context(), "tcp", localhost+":0")
+	return server, out, alertQueue
-	if err != nil {
-		t.Fatalf("listen: %v", err)
-	}
-
-	go func() {
-		_ = server.Serve(listener)
-	}()
-
-	t.Cleanup(func() {
-		_ = server.Close()
-	})
-
-	return listener.Addr().String(), out, server, alertQueue
 }
 
 // newClient returns an HTTP client that sends requests as they are made,