api: verify message size on receipt

When a message is received, verify that it's sufficiently large to
accomodate any VLAs within message. To do that, we need a way to
calculate message size including any VLAs. This patch adds such
funcionality to vppapigen and necessary C code to use those to validate
message size on receipt. Drop messages which are malformed.

Type: improvement
Signed-off-by: Klement Sekera <ksekera@cisco.com>
Change-Id: I2903aa21dee84be6822b064795ba314de46c18f4

src/vat/api_format.c

@@ -64,6 +64,10 @@
 #include <vlibmemory/memclnt.api.h>
 #undef vl_endianfun
 
+#define vl_calcsizefun
+#include <vlibmemory/memclnt.api.h>
+#undef vl_calcsizefun
+
 /* instantiate all the print functions we know about */
 #if VPP_API_TEST_BUILTIN == 0
 #define vl_print(handle, ...)
@@ -2737,11 +2741,11 @@ void
 vat_api_hookup (vat_main_t * vam)
 {
 #define _(N, n)                                                               \
-  vl_msg_api_set_handlers (VL_API_##N + 1, #n, vl_api_##n##_t_handler_uni,    \
-			   vl_noop_handler, vl_api_##n##_t_endian,            \
-			   vl_api_##n##_t_print, sizeof (vl_api_##n##_t), 1,  \
-			   vl_api_##n##_t_print_json, vl_api_##n##_t_tojson,  \
-			   vl_api_##n##_t_fromjson);
+  vl_msg_api_set_handlers (                                                   \
+    VL_API_##N + 1, #n, vl_api_##n##_t_handler_uni, vl_noop_handler,          \
+    vl_api_##n##_t_endian, vl_api_##n##_t_print, sizeof (vl_api_##n##_t), 1,  \
+    vl_api_##n##_t_print_json, vl_api_##n##_t_tojson,                         \
+    vl_api_##n##_t_fromjson, vl_api_##n##_t_calc_size);
   foreach_vpe_api_reply_msg;
 #if VPP_API_TEST_BUILTIN == 0
   foreach_standalone_reply_msg;