- Test for nonstring attribute in configure and add

nonstring attribute annotations.

acx_nlnetlabs.m4

@@ -490,7 +490,7 @@ AC_DEFUN([AHX_CONFIG_FORMAT_ATTRIBUTE],
 ])
 
 dnl Check how to mark function arguments as unused.
-dnl result in HAVE_ATTR_UNUSED.  
+dnl result in HAVE_ATTR_UNUSED.
 dnl Make sure you include AHX_CONFIG_UNUSED_ATTRIBUTE also.
 AC_DEFUN([ACX_CHECK_UNUSED_ATTRIBUTE],
 [AC_REQUIRE([AC_PROG_CC])
@@ -525,6 +525,45 @@ if test $ac_cv_c_unused_attribute = yes; then
 fi
 ])dnl
 
+dnl Check how to mark function arguments as nonstring.
+dnl result in HAVE_ATTR_NONSTRING.
+dnl Make sure you include AHX_CONFIG_NONSTRING_ATTRIBUTE also.
+AC_DEFUN([ACX_CHECK_NONSTRING_ATTRIBUTE],
+[AC_REQUIRE([AC_PROG_CC])
+AC_MSG_CHECKING(whether the C compiler (${CC-cc}) accepts the "nonstring" attribute)
+AC_CACHE_VAL(ac_cv_c_nonstring_attribute,
+[ac_cv_c_nonstring_attribute=no
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>
+struct test {
+    char __attribute__((nonstring)) s[1];
+};
+]], [[
+   struct test t = { "1" };
+   (void) t;
+]])],[ac_cv_c_nonstring_attribute="yes"],[ac_cv_c_nonstring_attribute="no"])
+])
+
+dnl Setup ATTR_NONSTRING config.h parts.
+dnl make sure you call ACX_CHECK_NONSTRING_ATTRIBUTE also.
+AC_DEFUN([AHX_CONFIG_NONSTRING_ATTRIBUTE],
+[
+#if defined(DOXYGEN)
+#  define ATTR_NONSTRING(x)  x
+#elif defined(__cplusplus)
+#  define ATTR_NONSTRING(x)  __attribute__((nonstring)) x
+#elif defined(HAVE_ATTR_NONSTRING)
+#  define ATTR_NONSTRING(x)  __attribute__((nonstring)) x
+#else /* !HAVE_ATTR_NONSTRING */
+#  define ATTR_NONSTRING(x)  x
+#endif /* !HAVE_ATTR_NONSTRING */
+])
+
+AC_MSG_RESULT($ac_cv_c_nonstring_attribute)
+if test $ac_cv_c_nonstring_attribute = yes; then
+  AC_DEFINE(HAVE_ATTR_NONSTRING, 1, [Whether the C compiler accepts the "nonstring" attribute])
+fi
+])dnl
+
 dnl Pre-fun for ACX_LIBTOOL_C_ONLY
 AC_DEFUN([ACX_LIBTOOL_C_PRE], [
 # skip these tests, we do not need them.

config.h.in

@@ -72,6 +72,9 @@
 /* Whether the C compiler accepts the "unused" attribute */
 #undef HAVE_ATTR_UNUSED
 
+/* Whether the C compiler accepts the "nonstring" attribute */
+#undef HAVE_ATTR_NONSTRING
+
 /* Whether the C compiler accepts the "weak" attribute */
 #undef HAVE_ATTR_WEAK
 
@@ -1381,6 +1384,17 @@
 #endif /* !HAVE_ATTR_UNUSED */
 
 
+#if defined(DOXYGEN)
+#  define ATTR_NONSTRING(x)  x
+#elif defined(__cplusplus)
+#  define ATTR_NONSTRING(x)  __attribute__((nonstring)) x
+#elif defined(HAVE_ATTR_NONSTRING)
+#  define ATTR_NONSTRING(x)  __attribute__((nonstring)) x
+#else /* !HAVE_ATTR_NONSTRING */
+#  define ATTR_NONSTRING(x)  x
+#endif /* !HAVE_ATTR_NONSTRING */
+
+
 #ifndef HAVE_FSEEKO
 #define fseeko fseek
 #define ftello ftell

configure.ac

@@ -329,6 +329,7 @@ fi
 AC_C_INLINE
 ACX_CHECK_FORMAT_ATTRIBUTE
 ACX_CHECK_UNUSED_ATTRIBUTE
+ACX_CHECK_NONSTRING_ATTRIBUTE
 
 AC_DEFUN([CHECK_WEAK_ATTRIBUTE],
 [AC_REQUIRE([AC_PROG_CC])
@@ -2292,6 +2293,7 @@ dnl includes
 
 AHX_CONFIG_FORMAT_ATTRIBUTE
 AHX_CONFIG_UNUSED_ATTRIBUTE
+AHX_CONFIG_NONSTRING_ATTRIBUTE
 AHX_CONFIG_FSEEKO
 AHX_CONFIG_MAXHOSTNAMELEN
 #if !defined(HAVE_SNPRINTF) || defined(SNPRINTF_RET_BROKEN)

doc/Changelog

@@ -1,3 +1,7 @@
+26 September 2025: Yorgos
+	- Test for nonstring attribute in configure and add
+	  nonstring attribute annotations.
+
 24 September 2025: Yorgos
 	- Avoid calling mesh_detect_cycle_found() when there is no mesh state
 	  to begin with.

util/data/msgreply.h

@@ -577,7 +577,7 @@ void log_query_info(enum verbosity_value v, const char* str,
 	struct query_info* qinf);
 
 /**
- * Append edns option to edns option list
+ * Append edns option to edns option list.
  * @param list: the edns option list to append the edns option to.
  * @param code: the edns option's code.
  * @param len: the edns option's length.
@@ -589,17 +589,20 @@ int edns_opt_list_append(struct edns_option** list, uint16_t code, size_t len,
         uint8_t* data, struct regional* region);
 
 /**
- * Append edns EDE option to edns options list
+ * Append edns EDE option to edns options list.
+ * We need ATTR_NONSTRING because we are trimming the trailing \0 of static
+ * string (TXT) when assigning to ede.text; it silences compiler nonstring
+ * warnings.
  * @param LIST: the edns option list to append the edns option to.
  * @param REGION: region to allocate the new edns option.
  * @param CODE: the EDE code.
- * @param TXT: Additional text for the option
+ * @param TXT: Additional text for the option.
  */
 #define EDNS_OPT_LIST_APPEND_EDE(LIST, REGION, CODE, TXT) 		\
 	do {								\
 		struct {						\
 			uint16_t code;					\
-			char text[sizeof(TXT) - 1];			\
+			char ATTR_NONSTRING(text[sizeof(TXT) - 1]) ;	\
 		} ede = { htons(CODE), TXT };				\
                 verbose(VERB_ALGO, "attached EDE code: %d with"		\
                         " message: '%s'", CODE, TXT);			\