detect/iponly: address format truncation warnings

This appears to be a FP. Work around it to allow for using this warning
as an error.

detect-engine-iponly.c: In function 'IPOnlyCIDRListParse2':
detect-engine-iponly.c:721:35: warning: 'snprintf' output may be truncated before the last format character [-Wformat-truncation=]
  721 |                              "[%s]", rule_var_address);
      |                                   ^
detect-engine-iponly.c:720:21: note: 'snprintf' output 3 or more bytes (assuming 4) into a destination of size 3
  720 |                     snprintf(temp_rule_var_address, strlen(rule_var_address) + 3,
      |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  721 |                              "[%s]", rule_var_address);
      |                              ~~~~~~~~~~~~~~~~~~~~~~~~~
detect-engine-iponly.c:782:34: warning: 'snprintf' output may be truncated before the last format character [-Wformat-truncation=]
  782 |                             "[%s]", rule_var_address);
      |                                  ^
detect-engine-iponly.c:781:21: note: 'snprintf' output 3 or more bytes (assuming 4) into a destination of size 3
  781 |                     snprintf(temp_rule_var_address, strlen(rule_var_address) + 3,
      |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  782 |                             "[%s]", rule_var_address);
      |                             ~~~~~~~~~~~~~~~~~~~~~~~~~

Ticket: #7905.

src/detect-engine-iponly.c

@@ -712,13 +712,14 @@ static IPOnlyCIDRItem *IPOnlyCIDRListParse2(
                     goto error;
 
                 if ((negate + n_set) % 2) {
-                    temp_rule_var_address = SCMalloc(strlen(rule_var_address) + 3);
+                    /* add +1 to safisfy gcc 15 + -Wformat-truncation=2 */
+                    const size_t str_size = strlen(rule_var_address) + 3 + 1;
+                    temp_rule_var_address = SCMalloc(str_size);
                     if (unlikely(temp_rule_var_address == NULL)) {
                         goto error;
                     }
 
-                    snprintf(temp_rule_var_address, strlen(rule_var_address) + 3,
-                             "[%s]", rule_var_address);
+                    snprintf(temp_rule_var_address, str_size, "[%s]", rule_var_address);
                 } else {
                     temp_rule_var_address = SCStrdup(rule_var_address);
                     if (unlikely(temp_rule_var_address == NULL)) {
@@ -774,12 +775,13 @@ static IPOnlyCIDRItem *IPOnlyCIDRListParse2(
                     goto error;
 
                 if ((negate + n_set) % 2) {
-                    temp_rule_var_address = SCMalloc(strlen(rule_var_address) + 3);
+                    /* add +1 to safisfy gcc 15 + -Wformat-truncation=2 */
+                    const size_t str_size = strlen(rule_var_address) + 3 + 1;
+                    temp_rule_var_address = SCMalloc(str_size);
                     if (unlikely(temp_rule_var_address == NULL)) {
                         goto error;
                     }
-                    snprintf(temp_rule_var_address, strlen(rule_var_address) + 3,
-                            "[%s]", rule_var_address);
+                    snprintf(temp_rule_var_address, str_size, "[%s]", rule_var_address);
                 } else {
                     temp_rule_var_address = SCStrdup(rule_var_address);
                     if (unlikely(temp_rule_var_address == NULL)) {