api: enforce vla is last and fixed string type

Enforce that variable length fields are the last element of API messages.

Add a 'fixed' version of string type, since dealing with
multiple variable length strings turned out too painful
for the C language bindings.

The string type is now:
{
  string name[64]; // NUL terminated C-string. Essentially decays to u8 name[64]
  string name[];   // Variable length string with embedded len field (vl_api_string_t)
};

The latter notation could be made available to other types as well.
e.g.
{
  vl_api_address_t addresses[];
}
instead of

{
  u32 n_addr;
  vl_api_address_t addresses[n_addr];
};

Type: fix
Change-Id: I18fa17ef47227633752ab50453e8d20a652a9f9b
Signed-off-by: Ole Troan <ot@cisco.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/extras/vom/vom/interface_cmds.cpp b/extras/vom/vom/interface_cmds.cpp
index 8c47b9f4c45..691040dd5f1 100644
--- a/extras/vom/vom/interface_cmds.cpp
+++ b/extras/vom/vom/interface_cmds.cpp
@@ -635,8 +635,8 @@ set_tag::issue(connection& con)
   auto& payload = req.get_request().get_payload();
   payload.is_add = 1;
   payload.sw_if_index = m_hw_item.data().value();
-  memset(payload.tag.buf, 0, payload.tag.length);
-  memcpy(payload.tag.buf, m_name.c_str(), m_name.length());
+  memset(payload.tag, 0, sizeof(payload.tag));
+  memcpy(payload.tag, m_name.c_str(), m_name.length());
 
   VAPI_CALL(req.execute());