MINOR: lua: Create the global 'act' object to register all action return codes

ACT_RET_* code are now available from lua scripts. The gloabl object "act" is
used to register these codes as constant. Now, lua actions can return any of
following codes :

  * act.CONTINUE for ACT_RET_CONT
  * act.STOP for ACT_RET_STOP
  * act.YIELD for ACT_RET_YIELD
  * act.ERROR for ACT_RET_ERR
  * act.DONE for ACT_RET_DONE
  * act.DENY for ACT_RET_DENY
  * act.ABORT for ACT_RET_ABRT
  * act.INVALID for ACT_RET_INV

For instance, following script denied all requests :

  core.register_action("deny", { "http-req" }, function (txn)
      return act.DENY
  end)

Thus "http-request lua.deny" do exactly the same than "http-request deny".

doc/lua-api/index.rst

@@ -2560,6 +2560,87 @@ StickTable class
       {"gpc0", "gt", 30}, {"gpc1", "gt", 20}}, {"conn_rate", "le", 10}
     }
 
+.. _action_class:
+
+Action class
+=============
+
+.. js:class:: Act
+
+  **context**: action
+
+  This class contains all return codes an action may return. It is the lua
+  equivalent to HAProxy "ACT_RET_*" code.
+
+.. code-block:: lua
+
+  core.register_action("deny", { "http-req" }, function (txn)
+      return act.DENY
+   end)
+..
+.. js:attribute:: act.CONTINUE
+
+  This attribute is an integer (0). It instructs HAProxy to continue the current
+  ruleset processing on the message. It is the default return code for a lua
+  action.
+
+  :returns: integer
+
+.. js:attribute:: act.STOP
+
+  This attribute is an integer (1). It instructs HAProxy to stop the current
+  ruleset processing on the message.
+
+.. js:attribute:: act.YIELD
+
+  This attribute is an integer (2). It instructs HAProxy to temporarily pause
+  the message processing. It will be resumed later on the same rule. The
+  corresponding lua script is re-executed for the start.
+
+.. js:attribute:: act.ERROR
+
+  This attribute is an integer (3). It triggers an internal errors The message
+  processing is stopped and the transaction is terminated. For HTTP streams, an
+  HTTP 500 error is returned to the client.
+
+  :returns: integer
+
+.. js:attribute:: act.DONE
+
+  This attribute is an integer (4). It instructs HAProxy to stop the message
+  processing.
+
+  :returns: integer
+
+.. js:attribute:: act.DENY
+
+  This attribute is an integer (5). It denies the current message. The message
+  processing is stopped and the transaction is terminated. For HTTP streams, an
+  HTTP 403 error is returned to the client if the deny is returned during the
+  request analysis. During the response analysis, an HTTP 502 error is returned
+  and the server response is discarded.
+
+  :returns: integer
+
+.. js:attribute:: act.ABORT
+
+  This attribute is an integer (6). It aborts the current message. The message
+  processing is stopped and the transaction is terminated. For HTTP streams,
+  HAproxy assumes a response was already sent to the client. From the Lua
+  actions point of view, when this code is used, the transaction is terminated
+  with no reply.
+
+  :returns: integer
+
+.. js:attribute:: act.INVALID
+
+  This attribute is an integer (7). It triggers an internal errors. The message
+  processing is stopped and the transaction is terminated. For HTTP streams, an
+  HTTP 400 error is returned to the client if the error is returned during the
+  request analysis. During the response analysis, an HTTP 502 error is returned
+  and the server response is discarded.
+
+  :returns: integer
 
 External Lua libraries
 ======================

src/hlua.c

@@ -7618,6 +7618,27 @@ void hlua_init(void)
 
 	lua_setglobal(gL.T, "core");
 
+	/*
+	 *
+	 * Create "act" object.
+	 *
+	 */
+
+	/* This table entry is the object "act" base. */
+	lua_newtable(gL.T);
+
+	/* push action return constants */
+	hlua_class_const_int(gL.T, "CONTINUE", ACT_RET_CONT);
+	hlua_class_const_int(gL.T, "STOP",     ACT_RET_STOP);
+	hlua_class_const_int(gL.T, "YIELD",    ACT_RET_YIELD);
+	hlua_class_const_int(gL.T, "ERROR",    ACT_RET_ERR);
+	hlua_class_const_int(gL.T, "DONE",     ACT_RET_DONE);
+	hlua_class_const_int(gL.T, "DENY",     ACT_RET_DENY);
+	hlua_class_const_int(gL.T, "ABORT",    ACT_RET_ABRT);
+	hlua_class_const_int(gL.T, "INVALID",  ACT_RET_INV);
+
+	lua_setglobal(gL.T, "act");
+
 	/*
 	 *
 	 * Register class Map