Merge pull request owasp-modsecurity#3139 from marcstern/v2/mst/SecArgumentsLimit_log

Enhanced logging [Issue owasp-modsecurity#3107]

Author: airween

CHANGES

@@ -1,6 +1,8 @@
 DD mmm YYYY - 2.9.x (to be released)
 -------------------
 
+ * Enhance logging
+   [Issue #3107 - @marcstern]
  * Fix possible segfault in collection_unpack
    [Issue #3072 - @twouters]
  * Set the minimum security protocol version for SecRemoteRules

apache2/msc_json.c

@@ -65,6 +65,7 @@ int json_add_argument(modsec_rec *msr, const char *value, unsigned length)
                     log_escape_ex(msr->mp, arg->value, arg->value_len));
         }
         msr->msc_reqbody_error = 1;
+        msr->json->yajl_error = apr_psprintf(msr->mp, "More than %ld JSON keys", msr->txcfg->arguments_limit);
         return 0;
     }
 
@@ -374,9 +375,12 @@ int json_process_chunk(modsec_rec *msr, const char *buf, unsigned int size, char
 	if (msr->json->depth_limit_exceeded) {
            *error_msg = "JSON depth limit exceeded";
 	} else {
-           char *yajl_err = yajl_get_error(msr->json->handle, 0, buf, size);
-           *error_msg = apr_pstrdup(msr->mp, yajl_err);
-           yajl_free_error(msr->json->handle, yajl_err);
+        if (msr->json->yajl_error) *error_msg = msr->json->yajl_error;
+        else {
+             char* yajl_err = yajl_get_error(msr->json->handle, 0, buf, size);
+             *error_msg = apr_pstrdup(msr->mp, yajl_err);
+             yajl_free_error(msr->json->handle, yajl_err);
+        }
 	}
         return -1;
     }