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

third_party/certspotter/monitor/statedir.go

@@ -0,0 +1,167 @@
+// Copyright (C) 2023 Opsmate, Inc.
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License, v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+//
+// This software is distributed WITHOUT A WARRANTY OF ANY KIND.
+// See the Mozilla Public License for details.
+
+package monitor
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"software.sslmate.com/src/certspotter/cttypes"
+	"software.sslmate.com/src/certspotter/merkletree"
+	"strconv"
+	"strings"
+	"time"
+)
+
+func readVersion(stateDir string) (int, error) {
+	path := filepath.Join(stateDir, "version")
+
+	fileBytes, err := os.ReadFile(path)
+	if errors.Is(err, fs.ErrNotExist) {
+		if fileExists(filepath.Join(stateDir, "evidence")) {
+			return 0, nil
+		} else {
+			return -1, nil
+		}
+	} else if err != nil {
+		return -1, err
+	}
+
+	version, err := strconv.Atoi(strings.TrimSpace(string(fileBytes)))
+	if err != nil {
+		return -1, fmt.Errorf("version file %q is malformed: %w", path, err)
+	}
+
+	return version, nil
+}
+
+func writeVersion(stateDir string) error {
+	return writeFile(filepath.Join(stateDir, "version"), []byte{'2', '\n'}, 0666)
+}
+
+func migrateLogStateDirV1(dir string) error {
+	var sth cttypes.SignedTreeHead
+	var tree merkletree.CollapsedTree
+
+	sthPath := filepath.Join(dir, "sth.json")
+	sthData, err := os.ReadFile(sthPath)
+	if errors.Is(err, fs.ErrNotExist) {
+		return nil
+	} else if err != nil {
+		return err
+	}
+
+	treePath := filepath.Join(dir, "tree.json")
+	treeData, err := os.ReadFile(treePath)
+	if errors.Is(err, fs.ErrNotExist) {
+		return nil
+	} else if err != nil {
+		return err
+	}
+
+	if err := json.Unmarshal(sthData, &sth); err != nil {
+		return fmt.Errorf("error unmarshaling %s: %w", sthPath, err)
+	}
+	if err := json.Unmarshal(treeData, &tree); err != nil {
+		return fmt.Errorf("error unmarshaling %s: %w", treePath, err)
+	}
+
+	stateFile := LogState{
+		DownloadPosition: &tree,
+		VerifiedPosition: &tree,
+		VerifiedSTH:      &sth,
+		LastSuccess:      time.Now(),
+	}
+	if err := writeJSONFile(filepath.Join(dir, "state.json"), stateFile, 0666); err != nil {
+		return err
+	}
+
+	if err := os.Remove(sthPath); err != nil {
+		return err
+	}
+	if err := os.Remove(treePath); err != nil {
+		return err
+	}
+	return nil
+}
+
+func migrateStateDirV1(stateDir string) error {
+	if lockfile := filepath.Join(stateDir, "lock"); fileExists(lockfile) {
+		return fmt.Errorf("directory is locked by another instance of certspotter; remove %s if this is not the case", lockfile)
+	}
+
+	if logDirs, err := os.ReadDir(filepath.Join(stateDir, "logs")); err == nil {
+		for _, logDir := range logDirs {
+			if strings.HasPrefix(logDir.Name(), ".") || !logDir.IsDir() {
+				continue
+			}
+			if err := migrateLogStateDirV1(filepath.Join(stateDir, "logs", logDir.Name())); err != nil {
+				return fmt.Errorf("error migrating log state: %w", err)
+			}
+		}
+	} else if !errors.Is(err, fs.ErrNotExist) {
+		return err
+	}
+
+	if err := writeVersion(stateDir); err != nil {
+		return err
+	}
+
+	if err := os.Remove(filepath.Join(stateDir, "once")); err != nil && !errors.Is(err, fs.ErrNotExist) {
+		return err
+	}
+
+	return nil
+}
+
+func prepareStateDir(stateDir string) error {
+	if err := os.Mkdir(stateDir, 0777); err != nil && !errors.Is(err, fs.ErrExist) {
+		return err
+	}
+
+	if version, err := readVersion(stateDir); err != nil {
+		return err
+	} else if version == -1 {
+		if err := writeVersion(stateDir); err != nil {
+			return err
+		}
+	} else if version == 0 {
+		return fmt.Errorf("%s was created by a very old version of certspotter; run any version of certspotter after 0.2 and before 0.15.0 to upgrade this directory, or remove it to start from scratch", stateDir)
+	} else if version == 1 {
+		if err := migrateStateDirV1(stateDir); err != nil {
+			return err
+		}
+	} else if version > 2 {
+		return fmt.Errorf("%s was created by a newer version of certspotter; upgrade to the latest version of certspotter or remove this directory to start from scratch", stateDir)
+	}
+
+	for _, subdir := range []string{"certs", "logs", "healthchecks", "errors"} {
+		if err := os.Mkdir(filepath.Join(stateDir, subdir), 0777); err != nil && !errors.Is(err, fs.ErrExist) {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func prepareCacheDir(cacheDir string) error {
+	if err := os.MkdirAll(cacheDir, 0777); err != nil {
+		return err
+	}
+	for _, subdir := range []string{"issuers"} {
+		if err := os.Mkdir(filepath.Join(cacheDir, subdir), 0777); err != nil && !errors.Is(err, fs.ErrExist) {
+			return err
+		}
+	}
+	return nil
+}