1 files changed, 6 insertions, 0 deletions
diff --git a/src/shared/dns-domain.h b/src/shared/dns-domain.h
index 99c72574db..44a9975541 100644
--- a/src/shared/dns-domain.h
+++ b/src/shared/dns-domain.h
@@ -25,9 +25,15 @@
 #include "hashmap.h"
 #include "in-addr-util.h"
 
+/* Length of a single label, with all escaping removed, excluding any trailing dot or NUL byte */
 #define DNS_LABEL_MAX 63
+
+/* Worst case length of a single label, with all escaping applied and room for a trailing NUL byte. */
 #define DNS_LABEL_ESCAPED_MAX (DNS_LABEL_MAX*4+1)
 
+/* Maximum length of a full hostname, consisting of a series of unescaped labels, and no trailing dot or NUL byte */
+#define DNS_HOSTNAME_MAX 253
+
 int dns_label_unescape(const char **name, char *dest, size_t sz);
 int dns_label_unescape_suffix(const char *name, const char **label_end, char *dest, size_t sz);
 int dns_label_escape(const char *p, size_t l, char *dest, size_t sz);