ctcloud: CertSpotter-backed CT cloud-resource monitor

Single stateless Go process that consumes CT logs via embedded (patched)
CertSpotter internals, classifies cloud/database/storage DNS identifiers
in-process with a zero-allocation classifier, enriches via round-robin DNS
resolvers with CNAME following, and batch-writes useful findings to PostgreSQL.

- third_party/certspotter: 2-hunk IdentifierSink patch, no stdout/JSON/files
- internal/classify: AWS/Azure/GCP/Firebase/Cloudflare R2/DigitalOcean/Supabase/OCI
- internal/dns: sharded bounded TTL cache, multi-resolver load balancing + failover
- internal/pipeline: bounded queues, dedup, direct-priority load shedding
- internal/store: pgx batch writer, Postgres CT checkpoints (no cert contents)
- internal/probe: optional non-destructive reachability checks (off by default)
- Docker: distroless non-root, read-only rootfs, no app volume, resource limits
- tests enforce 0 allocs/op on the classifier and sink hot path

internal/dns/resolver_test.go

@@ -0,0 +1,142 @@
+package dns
+
+import (
+	"context"
+	"errors"
+	"net"
+	"testing"
+	"time"
+)
+
+type fakeResolver struct {
+	cnames map[string]string
+	ips    map[string][]net.IP
+	err    error
+}
+
+func (f *fakeResolver) LookupCNAME(ctx context.Context, host string) (string, error) {
+	if f.err != nil {
+		return "", f.err
+	}
+	if c, ok := f.cnames[host]; ok {
+		return c, nil
+	}
+	return host, nil
+}
+
+func (f *fakeResolver) LookupIP(ctx context.Context, host string) ([]net.IP, error) {
+	if f.err != nil {
+		return nil, f.err
+	}
+	return f.ips[host], nil
+}
+
+func TestFollowChain(t *testing.T) {
+	r := &fakeResolver{cnames: map[string]string{
+		"a.example.com":      "b.example.com",
+		"b.example.com":      "c.s3.amazonaws.com",
+		"c.s3.amazonaws.com": "c.s3.amazonaws.com",
+	}}
+	chain, err := Follow(context.Background(), r, "a.example.com", 8)
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := []string{"a.example.com", "b.example.com", "c.s3.amazonaws.com"}
+	if len(chain) != len(want) {
+		t.Fatalf("chain = %v, want %v", chain, want)
+	}
+	for i := range want {
+		if chain[i] != want[i] {
+			t.Fatalf("chain = %v, want %v", chain, want)
+		}
+	}
+}
+
+func TestFollowLoop(t *testing.T) {
+	r := &fakeResolver{cnames: map[string]string{
+		"a.example.com": "b.example.com",
+		"b.example.com": "a.example.com",
+	}}
+	chain, err := Follow(context.Background(), r, "a.example.com", 8)
+	if !errors.Is(err, ErrCNAMELoop) {
+		t.Fatalf("err = %v, want ErrCNAMELoop", err)
+	}
+	if len(chain) < 2 {
+		t.Fatalf("chain = %v, want at least 2 entries", chain)
+	}
+}
+
+func TestFollowDepth(t *testing.T) {
+	r := &fakeResolver{cnames: map[string]string{
+		"h1.example.com": "h2.example.com",
+		"h2.example.com": "h3.example.com",
+		"h3.example.com": "h4.example.com",
+	}}
+	chain, err := Follow(context.Background(), r, "h1.example.com", 2)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(chain) != 3 {
+		t.Fatalf("chain = %v, want 3 entries (host + 2 hops)", chain)
+	}
+}
+
+func TestEnricherCaches(t *testing.T) {
+	r := &fakeResolver{
+		cnames: map[string]string{"a.example.com": "b.s3.amazonaws.com"},
+		ips:    map[string][]net.IP{"a.example.com": {net.ParseIP("1.2.3.4")}},
+	}
+	e := &Enricher{Resolver: r, Cache: NewTTLCache[Result](16, 2), PositiveTTL: time.Minute, NegativeTTL: time.Minute, MaxDepth: 8}
+	if _, ok := e.Resolve(context.Background(), "a.example.com"); !ok {
+		t.Fatal("first resolve failed")
+	}
+	r.cnames = nil // a cached lookup must not hit the resolver
+	res, ok := e.Resolve(context.Background(), "a.example.com")
+	if !ok || len(res.IPs) != 1 {
+		t.Fatalf("cached resolve = %+v ok=%v", res, ok)
+	}
+}
+
+func TestEnricherNegativeCache(t *testing.T) {
+	r := &fakeResolver{err: &net.DNSError{Err: "no such host", IsNotFound: true}}
+	e := &Enricher{Resolver: r, Cache: NewTTLCache[Result](16, 2), PositiveTTL: time.Minute, NegativeTTL: time.Minute, MaxDepth: 8}
+	if _, ok := e.Resolve(context.Background(), "missing.example.com"); ok {
+		t.Fatal("expected failure")
+	}
+	if _, ok := e.Resolve(context.Background(), "missing.example.com"); ok {
+		t.Fatal("expected cached failure")
+	}
+}
+
+type ctxResolver struct{}
+
+func (ctxResolver) LookupCNAME(ctx context.Context, host string) (string, error) {
+	return "", ctx.Err()
+}
+func (ctxResolver) LookupIP(ctx context.Context, host string) ([]net.IP, error) {
+	return nil, ctx.Err()
+}
+
+func TestResolveContextCancellation(t *testing.T) {
+	e := &Enricher{Resolver: ctxResolver{}, Cache: NewTTLCache[Result](16, 2), PositiveTTL: time.Minute, NegativeTTL: time.Minute, MaxDepth: 8}
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	if _, ok := e.Resolve(ctx, "example.com"); ok {
+		t.Fatal("expected cancellation to fail resolution")
+	}
+}
+
+func TestCacheBoundAndExpiry(t *testing.T) {
+	c := NewTTLCache[int](8, 2)
+	for i := 0; i < 100; i++ {
+		c.Set(string(rune('a'+i%26))+string(rune('0'+i%10)), i, time.Minute)
+	}
+	if c.Len() > 8 {
+		t.Fatalf("cache len = %d, want <= 8", c.Len())
+	}
+	c.Set("k", 1, time.Millisecond)
+	time.Sleep(5 * time.Millisecond)
+	if _, ok := c.Get("k"); ok {
+		t.Fatal("expected expired entry to be gone")
+	}
+}