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>

3 files changed, 7 insertions, 7 deletions

diff --git a/extras/vom/vom/interface.cpp b/extras/vom/vom/interface.cpp
index c80dc793604..70035648d06 100644
--- a/extras/vom/vom/interface.cpp
+++ b/extras/vom/vom/interface.cpp
@@ -647,8 +647,8 @@ interface::event_handler::handle_populate(const client_db::key_t& key)
   for (auto& itf_record : *cmd) {
     auto payload = itf_record.get_payload();
     VOM_LOG(log_level_t::DEBUG) << "dump: [" << payload.sw_if_index
-                                << " name:" << (char*)payload.interface_name.buf
-                                << " tag:" << (char*)payload.tag.buf << "]";
+                                << " name:" << (char*)payload.interface_name
+                                << " tag:" << (char*)payload.tag << "]";
 
     std::shared_ptr<interface> itf = interface_factory::new_interface(payload);
 
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());
 
diff --git a/extras/vom/vom/interface_factory.cpp b/extras/vom/vom/interface_factory.cpp
index 750df96b025..2c64e321330 100644
--- a/extras/vom/vom/interface_factory.cpp
+++ b/extras/vom/vom/interface_factory.cpp
@@ -30,7 +30,7 @@ interface_factory::new_interface(const vapi_payload_sw_interface_details& vd)
   /**
    * Determine the interface type from the name and VLAN attributes
    */
-  std::string name = reinterpret_cast<const char*>(vd.interface_name.buf);
+  std::string name = reinterpret_cast<const char*>(vd.interface_name);
   interface::type_t type = interface::type_t::from_string(name);
   interface::admin_state_t state = interface::admin_state_t::from_int(
     vd.flags & vapi_enum_if_status_flags::IF_STATUS_API_FLAG_ADMIN_UP);
@@ -64,8 +64,8 @@ interface_factory::new_interface(const vapi_payload_sw_interface_details& vd)
    * if the tag is set, then we wrote that to specify a name to make
    * the interface type more specific
    */
-  if (vd.tag.buf[0] != 0) {
-    tag = std::string(reinterpret_cast<const char*>(vd.tag.buf));
+  if (vd.tag[0] != 0) {
+    tag = std::string(reinterpret_cast<const char*>(vd.tag));
   }
 
   if (!tag.empty() && interface::type_t::LOOPBACK == type) {