fix: project inline binary metadata and protect private markup attributes

internal/logging/binary_uri.go

@@ -0,0 +1,81 @@
+package logging
+
+import (
+	"encoding/base64"
+	"fmt"
+	"mime"
+	"net/url"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+// Inline attachments remain opaque in every log format, regardless of the
+// carrier field or element. Only standard-decoded media type and byte count
+// are projected; malformed declarations never restore their payload.
+var inlineDataURI = regexp.MustCompile(`(?i)\bdata:[^,\s<>"']*,[^\s<>"']*`)
+
+func redactInlineBinary(s string) string {
+	if strings.HasPrefix(strings.ToLower(strings.TrimSpace(s)), "data:") {
+		return inlineBinarySummary(strings.TrimSpace(s))
+	}
+	return inlineDataURI.ReplaceAllStringFunc(s, inlineBinarySummary)
+}
+
+// Repeated formatting must retain only our typed attachment projection.
+func isInlineBinarySummary(s string) bool {
+	if !strings.HasPrefix(s, "[BINARY ") || !strings.HasSuffix(s, "]") {
+		return false
+	}
+	fields := strings.Fields(s[len("[BINARY ") : len(s)-1])
+	if len(fields) != 2 && len(fields) != 3 {
+		return false
+	}
+	if !strings.HasPrefix(fields[0], "type=") || !strings.HasPrefix(fields[1], "bytes=") {
+		return false
+	}
+	kind := strings.TrimPrefix(fields[0], "type=")
+	if kind != "unknown" {
+		media, params, err := mime.ParseMediaType(kind)
+		if err != nil || media != kind || !strings.Contains(media, "/") || len(params) != 0 {
+			return false
+		}
+	}
+	count := strings.TrimPrefix(fields[1], "bytes=")
+	if count != "unknown" {
+		if _, err := strconv.ParseUint(count, 10, 64); err != nil {
+			return false
+		}
+	}
+	return len(fields) == 2 || fields[2] == "error=invalid_data_uri"
+}
+
+func inlineBinarySummary(uri string) string {
+	header, payload, ok := strings.Cut(uri[5:], ",")
+	if !ok {
+		return "[BINARY type=unknown bytes=unknown error=invalid_data_uri]"
+	}
+	encoded := strings.HasSuffix(strings.ToLower(header), ";base64")
+	if encoded {
+		header = header[:len(header)-7]
+	}
+	if header == "" {
+		header = "text/plain;charset=US-ASCII"
+	}
+	media, _, err := mime.ParseMediaType(header)
+	if err != nil || !strings.Contains(media, "/") {
+		return "[BINARY type=unknown bytes=unknown error=invalid_data_uri]"
+	}
+	raw, err := url.PathUnescape(payload)
+	if err != nil {
+		return fmt.Sprintf("[BINARY type=%s bytes=unknown error=invalid_data_uri]", media)
+	}
+	data := []byte(raw)
+	if encoded {
+		data, err = base64.StdEncoding.DecodeString(raw)
+		if err != nil {
+			return fmt.Sprintf("[BINARY type=%s bytes=unknown error=invalid_data_uri]", media)
+		}
+	}
+	return fmt.Sprintf("[BINARY type=%s bytes=%d]", media, len(data))
+}