Save malformed entries, and put paths in environment variables

To allow scripts to access them.

man/certspotter-script.md

@@ -138,6 +138,14 @@ The following environment variables are set for `malformed_cert` events:
 
 :    A human-readable string describing why the certificate is malformed.
 
+`ENTRY_FILENAME`
+
+:    Path to a file containing the JSON log entry.  The file contains a JSON object with two fields, `leaf_input` and `extra_data`, as described in RFC 6962 Section 4.6.
+
+`TEXT_FILENAME`
+
+:    Path to a file containing a text message describing the malformed certificate.  This file contains the same text that certspotter uses in emails.
+
 # JSON FILE FORMAT
 
 Unless `-no_save` is used, certspotter saves a JSON file for every discovered certificate

monitor/malformed.go

@@ -15,8 +15,30 @@ import (
 )
 
 type malformedLogEntry struct {
-	Entry *logEntry
-	Error string
+	Entry     *logEntry
+	Error     string
+	EntryPath string
+	TextPath  string
+}
+
+func (malformed *malformedLogEntry) entryJSON() any {
+	return struct {
+		LeafInput []byte `json:"leaf_input"`
+		ExtraData []byte `json:"extra_data"`
+	}{
+		LeafInput: malformed.Entry.LeafInput,
+		ExtraData: malformed.Entry.ExtraData,
+	}
+}
+
+func (malformed *malformedLogEntry) save() error {
+	if err := writeJSONFile(malformed.EntryPath, malformed.entryJSON(), 0666); err != nil {
+		return err
+	}
+	if err := writeTextFile(malformed.TextPath, malformed.Text(), 0666); err != nil {
+		return err
+	}
+	return nil
 }
 
 func (malformed *malformedLogEntry) Environ() []string {
@@ -27,6 +49,8 @@ func (malformed *malformedLogEntry) Environ() []string {
 		"ENTRY_INDEX=" + fmt.Sprint(malformed.Entry.Index),
 		"LEAF_HASH=" + malformed.Entry.LeafHash.Base64String(),
 		"PARSE_ERROR=" + malformed.Error,
+		"ENTRY_FILENAME=" + malformed.EntryPath,
+		"TEXT_FILENAME=" + malformed.TextPath,
 		"CERT_PARSEABLE=no", // backwards compat with pre-0.15.0; not documented
 	}
 }

monitor/monitor.go

@@ -74,11 +74,12 @@ func monitorLog(ctx context.Context, config *Config, ctlog *loglist.Log, logClie
 	defer cancel()
 
 	var (
-		stateDirPath  = filepath.Join(config.StateDir, "logs", ctlog.LogID.Base64URLString())
-		stateFilePath = filepath.Join(stateDirPath, "state.json")
-		sthsDirPath   = filepath.Join(stateDirPath, "unverified_sths")
+		stateDirPath     = filepath.Join(config.StateDir, "logs", ctlog.LogID.Base64URLString())
+		stateFilePath    = filepath.Join(stateDirPath, "state.json")
+		sthsDirPath      = filepath.Join(stateDirPath, "unverified_sths")
+		malformedDirPath = filepath.Join(stateDirPath, "malformed_entries")
 	)
-	for _, dirPath := range []string{stateDirPath, sthsDirPath} {
+	for _, dirPath := range []string{stateDirPath, sthsDirPath, malformedDirPath} {
 		if err := os.Mkdir(dirPath, 0777); err != nil && !errors.Is(err, fs.ErrExist) {
 			return fmt.Errorf("error creating state directory: %w", err)
 		}

monitor/process.go

@@ -157,12 +157,18 @@ func processCertificate(ctx context.Context, config *Config, entry *logEntry, ce
 }
 
 func processMalformedLogEntry(ctx context.Context, config *Config, entry *logEntry, parseError error) error {
-	// TODO-4: save the malformed entry (in get-entries format) in the state directory so user can inspect it
-
+	dirPath := filepath.Join(config.StateDir, "logs", entry.Log.LogID.Base64URLString(), "malformed_entries")
 	malformed := &malformedLogEntry{
-		Entry: entry,
-		Error: parseError.Error(),
+		Entry:     entry,
+		Error:     parseError.Error(),
+		EntryPath: filepath.Join(dirPath, fmt.Sprintf("%d.json", entry.Index)),
+		TextPath:  filepath.Join(dirPath, fmt.Sprintf("%d.txt", entry.Index)),
 	}
+
+	if err := malformed.save(); err != nil {
+		return fmt.Errorf("error saving malformed log entry %d in %s (%q): %w", entry.Index, entry.Log.URL, parseError, err)
+	}
+
 	if err := notify(ctx, config, malformed); err != nil {
 		return fmt.Errorf("error notifying about malformed log entry %d in %s (%q): %w", entry.Index, entry.Log.URL, parseError, err)
 	}