detect: warn on missing closing parenthesis

Ticket: 8579

src/detect-parse.c

@@ -2058,8 +2058,12 @@ static int SigParseBasics(DetectEngineCtx *de_ctx, Signature *s, const char *sig
     while (isspace(*index) || *index == '(') {
         index++;
     }
+    bool closing = false;
     for (size_t i = strlen(index); i > 0; i--) {
-        if (isspace(index[i - 1]) || index[i - 1] == ')') {
+        if (index[i - 1] == ')') {
+            closing = true;
+            index[i - 1] = '\0';
+        } else if (isspace(index[i - 1])) {
             index[i - 1] = '\0';
         } else {
             break;
@@ -2071,6 +2075,11 @@ static int SigParseBasics(DetectEngineCtx *de_ctx, Signature *s, const char *sig
         return 0;
     }
 
+    if (!closing && de_ctx->rule_file) {
+        SCLogWarning(
+                "Rule missing closing parenthesis at %s:%u", de_ctx->rule_file, de_ctx->rule_line);
+    }
+
     /* Parse Action */
     if (SigParseAction(s, parser->action) < 0)
         goto error;