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Merge pull request #8982 from dlqs/lua-func-stack

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Quentin Young 2021-08-02 13:51:35 +00:00 committed by GitHub
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33
bgpd/bgp_routemap.c
View File

@ -366,38 +366,37 @@ static enum route_map_cmd_result_t
route_match_script(void *rule, const struct prefix *prefix, void *object)
{
const char *scriptname = rule;
const char *routematch_function = "route_match";
struct bgp_path_info *path = (struct bgp_path_info *)object;
struct frrscript *fs = frrscript_load(scriptname, NULL);
struct frrscript *fs = frrscript_new(scriptname);
if (!fs) {
zlog_err("Issue loading script rule; defaulting to no match");
if (frrscript_load(fs, routematch_function, NULL)) {
zlog_err(
"Issue loading script or function; defaulting to no match");
return RMAP_NOMATCH;
}
enum frrlua_rm_status lrm_status = LUA_RM_FAILURE,
status_nomatch = LUA_RM_NOMATCH,
status_match = LUA_RM_MATCH,
status_match_and_change = LUA_RM_MATCH_AND_CHANGE;
struct attr newattr = *path->attr;
int result = frrscript_call(
fs, ("RM_FAILURE", (long long *)&lrm_status),
("RM_NOMATCH", (long long *)&status_nomatch),
("RM_MATCH", (long long *)&status_match),
("RM_MATCH_AND_CHANGE", (long long *)&status_match_and_change),
("action", (long long *)&lrm_status), ("prefix", prefix),
("attributes", &newattr), ("peer", path->peer));
fs, routematch_function, ("prefix", prefix),
("attributes", &newattr), ("peer", path->peer),
("RM_FAILURE", LUA_RM_FAILURE), ("RM_NOMATCH", LUA_RM_NOMATCH),
("RM_MATCH", LUA_RM_MATCH),
("RM_MATCH_AND_CHANGE", LUA_RM_MATCH_AND_CHANGE));
if (result) {
zlog_err("Issue running script rule; defaulting to no match");
return RMAP_NOMATCH;
}
long long *action = frrscript_get_result(fs, routematch_function,
"action", lua_tointegerp);
int status = RMAP_NOMATCH;
switch (lrm_status) {
switch (*action) {
case LUA_RM_FAILURE:
zlog_err(
"Executing route-map match script '%s' failed; defaulting to no match",
@ -428,7 +427,9 @@ route_match_script(void *rule, const struct prefix *prefix, void *object)
break;
}
frrscript_unload(fs);
XFREE(MTYPE_SCRIPT_RES, action);
frrscript_delete(fs);
return status;
}

534
doc/developer/scripting.rst
View File

@ -14,8 +14,8 @@ is implemented using the standard Lua C bindings. The supported version of Lua
is 5.3.
C objects may be passed into Lua and Lua objects may be retrieved by C code via
a marshalling system. In this way, arbitrary data from FRR may be passed to
scripts. It is possible to pass C functions as well.
a encoding/decoding system. In this way, arbitrary data from FRR may be passed to
scripts.
The Lua environment is isolated from the C environment; user scripts cannot
access FRR's address space unless explicitly allowed by FRR.
@ -53,150 +53,290 @@ Reasons against supporting multiple scripting languages:
with which a given script can be shared
General
^^^^^^^
-------
FRR's concept of a script is somewhat abstracted away from the fact that it is
Lua underneath. A script in has two things:
- name
- state
In code:
FRR's scripting functionality is provided in the form of Lua functions in Lua
scripts (``.lua`` files). One Lua script may contain many Lua functions. These
are respectively encapsulated in the following structures:
.. code-block:: c
struct frrscript {
/* Script name */
/* Lua file name */
char *name;
/* Lua state */
struct lua_State *L;
/* hash of lua_function_states */
struct hash *lua_function_hash;
};
struct lua_function_state {
/* Lua function name */
char *name;
lua_State *L;
};
``name`` is simply a string. Everything else is in ``state``, which is itself a
Lua library object (``lua_State``). This is an opaque struct that is
manipulated using ``lua_*`` functions. The basic ones are imported from
``lua.h`` and the rest are implemented within FRR to fill our use cases. The
thing to remember is that all operations beyond the initial loading the script
take place on this opaque state object.
`struct frrscript`: Since all Lua functions are contained within scripts, the
following APIs manipulates this structure. ``name`` contains the
Lua script name and a hash of Lua functions to their function names.
There are four basic actions that can be done on a script:
`struct lua_function_state` is an internal structure, but it essentially contains
the name of the Lua function and its state (a stack), which is run using Lua
library functions.
- load
- execute
- query state
- unload
In general, to run a Lua function, these steps must take place:
They are typically done in this order.
- Initialization
- Load
- Call
- Delete
Loading
^^^^^^^
A snippet of Lua code is referred to as a "chunk". These are simply text. FRR
presently assumes chunks are located in individual files specific to one task.
These files are stored in the scripts directory and must end in ``.lua``.
A script object is created by loading a script. This is done with
``frrscript_load()``. This function takes the name of the script and an
optional callback function. The string ".lua" is appended to the script name,
and the resultant filename is looked for in the scripts directory.
For example, to load ``/etc/frr/scripts/bingus.lua``:
.. code-block:: c
struct frrscript *fs = frrscript_load("bingus", NULL);
During loading the script is validated for syntax and its initial environment
is setup. By default this does not include the Lua standard library; there are
security issues to consider, though for practical purposes untrusted users
should not be able to write the scripts directory anyway. If desired the Lua
standard library may be added to the script environment using
``luaL_openlibs(fs->L)`` after loading the script. Further information on
setting up the script environment is in the Lua manual.
Executing
^^^^^^^^^
After loading, scripts may be executed. A script may take input in the form of
variable bindings set in its environment prior to being run, and may provide
results by setting the value of variables. Arbitrary C values may be
transferred into the script environment, including functions.
A typical execution call looks something like this:
.. code-block:: c
struct frrscript *fs = frrscript_load(...);
int status_ok = 0, status_fail = 1;
struct prefix p = ...;
int result = frrscript_call(fs,
("STATUS_FAIL", &status_fail),
("STATUS_OK", &status_ok),
("prefix", &p));
To execute a loaded script, we need to define the inputs. These inputs are
passed in by binding values to variable names that will be accessible within the
Lua environment. Basically, all communication with the script takes place via
global variables within the script, and to provide inputs we predefine globals
before the script runs. This is done by passing ``frrscript_call()`` a list of
parenthesized pairs, where the first and second fields identify, respectively,
the name of the global variable within the script environment and the value it
is bound to.
The script is then executed and returns a general status code. In the success
case this will be 0, otherwise it will be nonzero. The script itself does not
determine this code, it is provided by the Lua interpreter.
Querying State
Initialization
^^^^^^^^^^^^^^
.. todo::
The ``frrscript`` object encapsulates the Lua function state(s) from
one Lua script file. To create, use ``frrscript_new()`` which takes the
name of the Lua script.
The string ".lua" is appended to the script name, and the resultant filename
will be used to look for the script when we want to load a Lua function from it.
This section will be updated once ``frrscript_get_result`` has been
updated to work with the new ``frrscript_call`` and the rest of the new API.
Unloading
^^^^^^^^^
To destroy a script and its associated state:
For example, to create ``frrscript`` for ``/etc/frr/scripts/bingus.lua``:
.. code-block:: c
frrscript_unload(fs);
struct frrscript *fs = frrscript_new("bingus");
.. _marshalling:
The script is *not* read at this stage.
This function cannot be used to test for a script's presence.
Marshalling
^^^^^^^^^^^
Load
^^^^
The function to be called must first be loaded. Use ``frrscript_load()``
which takes a ``frrscript`` object, the name of the Lua function
and a callback function.
For example, to load the Lua function ``on_foo``
in ``/etc/frr/scripts/bingus.lua``:
.. code-block:: c
int ret = frrscript_load(fs, "on_foo", NULL);
This function returns 0 if and only if the Lua function was successfully loaded.
A non-zero return could indicate either a missing Lua script, a missing
Lua function, or an error when loading the function.
During loading the script is validated for syntax and its environment
is set up. By default this does not include the Lua standard library; there are
security issues to consider, though for practical purposes untrusted users
should not be able to write the scripts directory anyway.
Call
^^^^
After loading, Lua functions may be called.
Input
"""""
Inputs to the Lua script should be given by providing a list of parenthesized
pairs,
where the first and second field identify the name of the variable and the
value it is bound to, respectively.
The types of the values must have registered encoders (more below); the compiler
will warn you otherwise.
These variables are first encoded in-order, then provided as arguments
to the Lua function. In the example, note that ``c`` is passed in as a value
while ``a`` and ``b`` are passed in as pointers.
.. code-block:: c
int a = 100, b = 200, c = 300;
frrscript_call(fs, "on_foo", ("a", &a), ("b", &b), ("c", c));
.. code-block:: lua
function on_foo(a, b, c)
-- a is 100, b is 200, c is 300
...
Output
""""""
.. code-block:: c
int a = 100, b = 200, c = 300;
frrscript_call(fs, "on_foo", ("a", &a), ("b", &b), ("c", c));
// a is 500, b is 200, c is 300
int* d = frrscript_get_result(fs, "on_foo", "d", lua_tointegerp);
// d is 800
.. code-block:: lua
function on_foo(a, b, c)
b = 600
return { ["a"] = 500, ["c"] = 700, ["d"] = 800 }
end
**Lua functions being called must return a single table of string names to
values.**
(Lua functions should return an empty table if there is no output.)
The keys of the table are mapped back to names of variables in C. Note that
the values in the table can also be tables. Since tables are Lua's primary
data structure, this design lets us return any Lua value.
After the Lua function returns, the names of variables to ``frrscript_call()``
are matched against keys of the returned table, and then decoded. The types
being decoded must have registered decoders (more below); the compiler will
warn you otherwise.
In the example, since ``a`` was in the returned table and ``b`` was not,
``a`` was decoded and its value modified, while ``b`` was not decoded.
``c`` was decoded as well, but its decoder is a noop.
What modifications happen given a variable depends whether its name was
in the returned table and the decoder's implementation.
.. warning::
Always keep in mind that non const-qualified pointers in
``frrscript_call()`` may be modified - this may be a source of bugs.
On the other hand, const-qualified pointers and other values cannot
be modified.
.. tip::
You can make a copy of a data structure and pass that in instead,
so that modifications only happen to that copy.
``frrscript_call()`` returns 0 if and only if the Lua function was successfully
called. A non-zero return could indicate either a missing Lua script, a missing
Lua function, or an error from the Lua interpreter.
In the above example, ``d`` was not an input to ``frrscript_call()``, so its
value must be explicitly retrieved with ``frrscript_get_result``.
``frrscript_get_result()`` takes a
decoder and string name which is used as a key to search the returned table.
Returns the pointer to the decoded value, or NULL if it was not found.
In the example, ``d`` is a "new" value in C space,
so memory allocation might take place. Hence the caller is
responsible for memory deallocation.
Delete
^^^^^^
To delete a script and the all Lua states associated with it:
.. code-block:: c
frrscript_delete(fs);
A complete example
""""""""""""""""""
So, a typical execution call, with error checking, looks something like this:
.. code-block:: c
struct frrscript *fs = frrscript_new("my_script"); // name *without* .lua
int ret = frrscript_load(fs, "on_foo", NULL);
if (ret != 0)
goto DONE; // Lua script or function might have not been found
int a = 100, b = 200, c = 300;
ret = frrscript_call(fs, "on_foo", ("a", &a), ("b", &b), ("c", c));
if (ret != 0)
goto DONE; // Lua function might have not successfully run
// a and b might be modified
assert(a == 500);
assert(b == 200);
// c could not have been modified
assert(c == 300);
// d is new
int* d = frrscript_get_result(fs, "on_foo", "d", lua_tointegerp);
if (!d)
goto DONE; // "d" might not have been in returned table
assert(*d == 800);
XFREE(MTYPE_SCRIPT_RES, d); // caller responsible for free
DONE:
frrscript_delete(fs);
.. code-block:: lua
function on_foo(a, b, c)
b = 600
return { a = 500, c = 700, d = 800 }
end
Note that ``{ a = ...`` is same as ``{ ["a"] = ...``; it is Lua shorthand to
use the variable name as the key in a table.
Encoding and Decoding
^^^^^^^^^^^^^^^^^^^^^
Earlier sections glossed over the types of values that can be passed into
``frrscript_call`` and how data is passed between C and Lua. Lua, as a dynamically
typed, garbage collected language, cannot directly use C values without some
kind of marshalling / unmarshalling system to translate types between the two
runtimes.
``frrscript_call()`` and how data is passed between C and Lua. Lua, as a
dynamically typed, garbage collected language, cannot directly use C values
without some kind of encoding / decoding system to
translate types between the two runtimes.
Lua communicates with C code using a stack. C code wishing to provide data to
Lua scripts must provide a function that marshalls the C data into a Lua
Lua scripts must provide a function that encodes the C data into a Lua
representation and pushes it on the stack. C code wishing to retrieve data from
Lua must provide a corresponding unmarshalling function that retrieves a Lua
value from the stack and converts it to the corresponding C type. These
functions are known as encoders and decoders in FRR.
Lua must provide a corresponding decoder function that retrieves a Lua
value from the stack and converts it to the corresponding C type.
An encoder is a function that takes a ``lua_State *`` and a C type and pushes
onto the Lua stack a value representing the C type. For C structs, the usual
case, this will typically be a Lua table (tables are the only datastructure Lua
has). For example, here is the encoder function for ``struct prefix``:
Encoders and decoders are provided for common data types.
Developers wishing to pass their own data structures between C and Lua need to
create encoders and decoders for that data type.
We try to keep them named consistently.
There are three kinds of encoders and decoders:
1. lua_push*: encodes a value onto the Lua stack.
Required for ``frrscript_call``.
2. lua_decode*: decodes a value from the Lua stack.
Required for ``frrscript_call``.
Only non const-qualified pointers may be actually decoded (more below).
3. lua_to*: allocates memory and decodes a value from the Lua stack.
Required for ``frrscript_get_result``.
This design allows us to combine typesafe *modification* of C values as well as
*allocation* of new C values.
In the following sections, we will use the encoders/decoders for ``struct prefix`` as an example.
Encoding
""""""""
An encoder function takes a ``lua_State *``, a C type and pushes that value onto
the Lua state (a stack).
For C structs, the usual case,
this will typically be encoded to a Lua table, then pushed onto the Lua stack.
Here is the encoder function for ``struct prefix``:
.. code-block:: c
@ -204,8 +344,6 @@ has). For example, here is the encoder function for ``struct prefix``:
{
char buffer[PREFIX_STRLEN];
zlog_debug("frrlua: pushing prefix table");
lua_newtable(L);
lua_pushstring(L, prefix2str(prefix, buffer, PREFIX_STRLEN));
lua_setfield(L, -2, "network");
@ -215,7 +353,7 @@ has). For example, here is the encoder function for ``struct prefix``:
lua_setfield(L, -2, "family");
}
This function pushes a single value onto the Lua stack. It is a table whose
This function pushes a single value, a table, onto the Lua stack, whose
equivalent in Lua is:
.. code-block:: c
@ -223,16 +361,23 @@ equivalent in Lua is:
{ ["network"] = "1.2.3.4/24", ["prefixlen"] = 24, ["family"] = 2 }
Decoding
""""""""
Decoders are a bit more involved. They do the reverse; a decoder function takes
a ``lua_State *``, pops a value off the Lua stack and converts it back into its
C type.
However, since Lua programs have the ability to directly modify their inputs
(i.e. values passed in via ``frrscript_call``), we need two separate decoder
functions, called ``lua_decode_*`` and ``lua_to*``.
A ``lua_decode_*`` function takes a ``lua_State*``, an index, and a C type, and
unmarshalls a Lua value into that C type.
Again, for ``struct prefix``:
There are two: ``lua_decode*`` and ``lua_to*``. The former does no mememory
allocation and is needed for ``frrscript_call``.
The latter performs allocation and is optional.
A ``lua_decode_*`` function takes a ``lua_State*``, an index, and a pointer
to a C data structure, and directly modifies the structure with values from the
Lua stack. Note that only non const-qualified pointers may be modified;
``lua_decode_*`` for other types will be noops.
Again, for ``struct prefix *``:
.. code-block:: c
@ -240,29 +385,52 @@ Again, for ``struct prefix``:
{
lua_getfield(L, idx, "network");
(void)str2prefix(lua_tostring(L, -1), prefix);
/* pop the netork string */
lua_pop(L, 1);
/* pop the table */
/* pop the prefix table */
lua_pop(L, 1);
}
Note:
- Before ``lua_decode*`` is run, the "prefix" table is already on the top of
the stack. ``frrscript_call`` does this for us.
- However, at the end of ``lua_decode*``, the "prefix" table should be popped.
- The other two fields in the "network" table are disregarded, meaning that any
modification to them is discarded in C space. In this case, this is desired
behavior.
.. warning::
``lua_decode_prefix`` functions should leave the Lua stack completely empty
when they return.
For decoders that unmarshall fields from tables, remember to pop the table
at the end.
``lua_decode*`` functions should pop all values that ``lua_to*`` pushed onto
the Lua stack.
For encoders that pushed a table, its decoder should pop the table at the end.
The above is an example.
A ``lua_to*`` function perform a similar role except that it first allocates
memory for the new C type before decoding the value from the Lua stack, then
returns a pointer to the newly allocated C type.
``int`` is not a non const-qualified pointer, so for ``int``:
.. code-block:: c
void lua_decode_int_noop(lua_State *L, int idx, int i)
{ //noop
}
A ``lua_to*`` function provides identical functionality except that it first
allocates memory for the new C type before decoding the value from the Lua stack,
then returns a pointer to the newly allocated C type. You only need to implement
this function to use with ``frrscript_get_result`` to retrieve a result of
this type.
This function can and should be implemented using ``lua_decode_*``:
.. code-block:: c
void *lua_toprefix(lua_State *L, int idx)
{
struct prefix *p = XCALLOC(MTYPE_TMP, sizeof(struct prefix));
struct prefix *p = XCALLOC(MTYPE_SCRIPT_RES, sizeof(struct prefix));
lua_decode_prefix(L, idx, p);
return p;
@ -270,22 +438,15 @@ This function can and should be implemented using ``lua_decode_*``:
The returned data must always be copied off the stack and the copy must be
allocated with ``MTYPE_TMP``. This way it is possible to unload the script
allocated with ``MTYPE_SCRIPT_RES``. This way it is possible to unload the script
(destroy the state) without invalidating any references to values stored in it.
Note that it is the caller's responsibility to free the data.
For consistency, we should always name functions of the first type
``lua_decode_*``.
Functions of the second type should be named ``lua_to*``, as this is the
naming convention used by the Lua C library for the basic types e.g.
``lua_tointeger`` and ``lua_tostring``.
This two-function design allows the compiler to warn if a value passed into
``frrscript_call`` does not have a encoder and decoder for that type.
The ``lua_to*`` functions enable us to easily create decoders for nested
structures.
Registering encoders and decoders for frrscript_call
""""""""""""""""""""""""""""""""""""""""""""""""""""
To register a new type with its corresponding encoding and decoding functions,
To register a new type with its ``lua_push*`` and ``lua_decode*`` functions,
add the mapping in the following macros in ``frrscript.h``:
.. code-block:: diff
@ -296,7 +457,7 @@ add the mapping in the following macros in ``frrscript.h``:
- struct peer * : lua_pushpeer \
+ struct peer * : lua_pushpeer, \
+ struct prefix * : lua_pushprefix \
)(L, value)
)((L), (value))
#define DECODE_ARGS_WITH_STATE(L, value) \
_Generic((value), \
@ -304,7 +465,7 @@ add the mapping in the following macros in ``frrscript.h``:
- struct peer * : lua_decode_peer \
+ struct peer * : lua_decode_peer, \
+ struct prefix * : lua_decode_prefix \
)(L, -1, value)
)((L), -1, (value))
At compile time, the compiler will search for encoders/decoders for the type of
@ -331,11 +492,12 @@ For that, use ``lua_decode_noop``:
.. note::
Marshalled types are not restricted to simple values like integers, strings
and tables. It is possible to marshall a type such that the resultant object
in Lua is an actual object-oriented object, complete with methods that call
back into defined C functions. See the Lua manual for how to do this; for a
code example, look at how zlog is exported into the script environment.
Encodable/decodable types are not restricted to simple values like integers,
strings and tables.
It is possible to encode a type such that the resultant object in Lua
is an actual object-oriented object, complete with methods that call
back into defined C functions. See the Lua manual for how to do this;
for a code example, look at how zlog is exported into the script environment.
Script Environment
@ -364,10 +526,11 @@ Examples
For a complete code example involving passing custom types, retrieving results,
and doing complex calculations in Lua, look at the implementation of the
``match script SCRIPT`` command for BGP routemaps. This example calls into a
script with a route prefix and attributes received from a peer and expects the
script to return a match / no match / match and update result.
script with a function named ``route_match``,
provides route prefix and attributes received from a peer and expects the
function to return a match / no match / match and update result.
An example script to use with this follows. This script matches, does not match
An example script to use with this follows. This function matches, does not match
or updates a route depending on how many BGP UPDATE messages the peer has
received when the script is called, simply as a demonstration of what can be
accomplished with scripting.
@ -378,48 +541,59 @@ accomplished with scripting.
-- Example route map matching
-- author: qlyoung
--
-- The following variables are available to us:
-- The following variables are available in the global environment:
-- log
-- logging library, with the usual functions
-- prefix
--
-- route_match arguments:
-- table prefix
-- the route under consideration
-- attributes
-- table attributes
-- the route's attributes
-- peer
-- table peer
-- the peer which received this route
-- RM_FAILURE
-- integer RM_FAILURE
-- status code in case of failure
-- RM_NOMATCH
-- integer RM_NOMATCH
-- status code for no match
-- RM_MATCH
-- integer RM_MATCH
-- status code for match
-- RM_MATCH_AND_CHANGE
-- integer RM_MATCH_AND_CHANGE
-- status code for match-and-set
--
-- We need to set the following out values:
-- action
-- Set to the appropriate status code to indicate what we did
-- attributes
-- Setting fields on here will propagate them back up to the caller if
-- 'action' is set to RM_MATCH_AND_CHANGE.
-- route_match returns table with following keys:
-- integer action, required
-- resultant status code. Should be one of RM_*
-- table attributes, optional
-- updated route attributes
--
function route_match(prefix, attributes, peer,
RM_FAILURE, RM_NOMATCH, RM_MATCH, RM_MATCH_AND_CHANGE)
log.info("Evaluating route " .. prefix.network .. " from peer " .. peer.remote_id.string)
function on_match (prefix, attrs)
function on_match (prefix, attributes)
log.info("Match")
action = RM_MATCH
return {
attributes = RM_MATCH
}
end
function on_nomatch (prefix, attrs)
function on_nomatch (prefix, attributes)
log.info("No match")
return {
action = RM_NOMATCH
}
end
function on_match_and_change (prefix, attrs)
action = RM_MATCH_AND_CHANGE
function on_match_and_change (prefix, attributes)
log.info("Match and change")
attrs["metric"] = attrs["metric"] + 7
attributes["metric"] = attributes["metric"] + 7
return {
action = RM_MATCH_AND_CHANGE,
attributes = attributes
}
end
special_routes = {
@ -430,12 +604,12 @@ accomplished with scripting.
if special_routes[prefix.network] then
special_routes[prefix.network](prefix, attributes)
return special_routes[prefix.network](prefix, attributes)
elseif peer.stats.update_in % 3 == 0 then
on_match(prefix, attributes)
return on_match(prefix, attributes)
elseif peer.stats.update_in % 2 == 0 then
on_nomatch(prefix, attributes)
return on_nomatch(prefix, attributes)
else
on_match_and_change(prefix, attributes)
return on_match_and_change(prefix, attributes)
end
end

26
lib/command.c
View File

@ -2422,27 +2422,29 @@ DEFUN(find,
}
#if defined(DEV_BUILD) && defined(HAVE_SCRIPTING)
DEFUN(script,
script_cmd,
"script SCRIPT",
"Test command - execute a script\n"
"Script name (same as filename in /etc/frr/scripts/\n")
DEFUN(script, script_cmd, "script SCRIPT FUNCTION",
"Test command - execute a function in a script\n"
"Script name (same as filename in /etc/frr/scripts/)\n"
"Function name (in the script)\n")
{
struct prefix p;
(void)str2prefix("1.2.3.4/24", &p);
struct frrscript *fs = frrscript_load(argv[1]->arg, NULL);
struct frrscript *fs = frrscript_new(argv[1]->arg);
if (fs == NULL) {
vty_out(vty, "Script '/etc/frr/scripts/%s.lua' not found\n",
argv[1]->arg);
} else {
int ret = frrscript_call(fs, ("p", &p));
if (frrscript_load(fs, argv[2]->arg, NULL)) {
vty_out(vty,
"/etc/frr/scripts/%s.lua or function '%s' not found\n",
argv[1]->arg, argv[2]->arg);
}
int ret = frrscript_call(fs, argv[2]->arg, ("p", &p));
char buf[40];
prefix2str(&p, buf, sizeof(buf));
vty_out(vty, "p: %s\n", buf);
vty_out(vty, "Script result: %d\n", ret);
}
frrscript_delete(fs);
return CMD_SUCCESS;
}

30
lib/frrlua.c
View File

@ -29,6 +29,8 @@
#include "log.h"
#include "buffer.h"
DEFINE_MTYPE(LIB, SCRIPT_RES, "Scripting results");
/* Lua stuff */
/*
@ -81,7 +83,7 @@ void lua_decode_prefix(lua_State *L, int idx, struct prefix *prefix)
void *lua_toprefix(lua_State *L, int idx)
{
struct prefix *p = XCALLOC(MTYPE_TMP, sizeof(struct prefix));
struct prefix *p = XCALLOC(MTYPE_SCRIPT_RES, sizeof(struct prefix));
lua_decode_prefix(L, idx, p);
return p;
}
@ -153,7 +155,8 @@ void lua_decode_interface(lua_State *L, int idx, struct interface *ifp)
}
void *lua_tointerface(lua_State *L, int idx)
{
struct interface *ifp = XCALLOC(MTYPE_TMP, sizeof(struct interface));
struct interface *ifp =
XCALLOC(MTYPE_SCRIPT_RES, sizeof(struct interface));
lua_decode_interface(L, idx, ifp);
return ifp;
@ -183,7 +186,8 @@ void lua_decode_inaddr(lua_State *L, int idx, struct in_addr *inaddr)
void *lua_toinaddr(lua_State *L, int idx)
{
struct in_addr *inaddr = XCALLOC(MTYPE_TMP, sizeof(struct in_addr));
struct in_addr *inaddr =
XCALLOC(MTYPE_SCRIPT_RES, sizeof(struct in_addr));
lua_decode_inaddr(L, idx, inaddr);
return inaddr;
}
@ -213,7 +217,8 @@ void lua_decode_in6addr(lua_State *L, int idx, struct in6_addr *in6addr)
void *lua_toin6addr(lua_State *L, int idx)
{
struct in6_addr *in6addr = XCALLOC(MTYPE_TMP, sizeof(struct in6_addr));
struct in6_addr *in6addr =
XCALLOC(MTYPE_SCRIPT_RES, sizeof(struct in6_addr));
lua_decode_in6addr(L, idx, in6addr);
return in6addr;
}
@ -243,7 +248,8 @@ void lua_decode_sockunion(lua_State *L, int idx, union sockunion *su)
void *lua_tosockunion(lua_State *L, int idx)
{
union sockunion *su = XCALLOC(MTYPE_TMP, sizeof(union sockunion));
union sockunion *su =
XCALLOC(MTYPE_SCRIPT_RES, sizeof(union sockunion));
lua_decode_sockunion(L, idx, su);
return su;
@ -262,7 +268,7 @@ void lua_decode_timet(lua_State *L, int idx, time_t *t)
void *lua_totimet(lua_State *L, int idx)
{
time_t *t = XCALLOC(MTYPE_TMP, sizeof(time_t));
time_t *t = XCALLOC(MTYPE_SCRIPT_RES, sizeof(time_t));
lua_decode_timet(L, idx, t);
return t;
@ -283,7 +289,7 @@ void lua_decode_integerp(lua_State *L, int idx, long long *num)
void *lua_tointegerp(lua_State *L, int idx)
{
long long *num = XCALLOC(MTYPE_TMP, sizeof(long long));
long long *num = XCALLOC(MTYPE_SCRIPT_RES, sizeof(long long));
lua_decode_integerp(L, idx, num);
return num;
@ -297,7 +303,7 @@ void lua_decode_stringp(lua_State *L, int idx, char *str)
void *lua_tostringp(lua_State *L, int idx)
{
char *string = XSTRDUP(MTYPE_TMP, lua_tostring(L, idx));
char *string = XSTRDUP(MTYPE_SCRIPT_RES, lua_tostring(L, idx));
return string;
}
@ -309,6 +315,14 @@ void lua_decode_noop(lua_State *L, int idx, const void *ptr)
{
}
/*
* Noop decoder for int.
*/
void lua_decode_integer_noop(lua_State *L, int idx, int i)
{
}
/*
* Logging.
*

6
lib/frrlua.h
View File

@ -34,6 +34,8 @@
extern "C" {
#endif
DECLARE_MTYPE(SCRIPT_RES);
/*
* gcc-10 is complaining about the wrapper function
* not being compatible with lua_pushstring returning
@ -162,10 +164,12 @@ void lua_decode_stringp(lua_State *L, int idx, char *str);
void *lua_tostringp(lua_State *L, int idx);
/*
* No-op decocder
* No-op decoders
*/
void lua_decode_noop(lua_State *L, int idx, const void *ptr);
void lua_decode_integer_noop(lua_State *L, int idx, int i);
/*
* Retrieve an integer from table on the top of the stack.
*

205
lib/frrscript.c
View File

@ -102,67 +102,136 @@ static void codec_free(struct codec *c)
}
#endif
/* Generic script APIs */
/* Lua function hash utils */
int _frrscript_call(struct frrscript *fs)
unsigned int lua_function_hash_key(const void *data)
{
const struct lua_function_state *lfs = data;
return string_hash_make(lfs->name);
}
bool lua_function_hash_cmp(const void *d1, const void *d2)
{
const struct lua_function_state *lfs1 = d1;
const struct lua_function_state *lfs2 = d2;
return strmatch(lfs1->name, lfs2->name);
}
void *lua_function_alloc(void *arg)
{
struct lua_function_state *tmp = arg;
struct lua_function_state *lfs =
XCALLOC(MTYPE_SCRIPT, sizeof(struct lua_function_state));
lfs->name = tmp->name;
lfs->L = tmp->L;
return lfs;
}
static void lua_function_free(struct hash_bucket *b, void *data)
{
struct lua_function_state *lfs = (struct lua_function_state *)b->data;
lua_close(lfs->L);
XFREE(MTYPE_SCRIPT, lfs);
}
/* internal frrscript APIs */
int _frrscript_call_lua(struct lua_function_state *lfs, int nargs)
{
int ret = lua_pcall(fs->L, 0, 0, 0);
int ret;
ret = lua_pcall(lfs->L, nargs, 1, 0);
switch (ret) {
case LUA_OK:
break;
case LUA_ERRRUN:
zlog_err("Script '%s' runtime error: %s", fs->name,
lua_tostring(fs->L, -1));
zlog_err("Lua hook call '%s' : runtime error: %s", lfs->name,
lua_tostring(lfs->L, -1));
break;
case LUA_ERRMEM:
zlog_err("Script '%s' memory error: %s", fs->name,
lua_tostring(fs->L, -1));
zlog_err("Lua hook call '%s' : memory error: %s", lfs->name,
lua_tostring(lfs->L, -1));
break;
case LUA_ERRERR:
zlog_err("Script '%s' error handler error: %s", fs->name,
lua_tostring(fs->L, -1));
zlog_err("Lua hook call '%s' : error handler error: %s",
lfs->name, lua_tostring(lfs->L, -1));
break;
case LUA_ERRGCMM:
zlog_err("Script '%s' garbage collector error: %s", fs->name,
lua_tostring(fs->L, -1));
zlog_err("Lua hook call '%s' : garbage collector error: %s",
lfs->name, lua_tostring(lfs->L, -1));
break;
default:
zlog_err("Script '%s' unknown error: %s", fs->name,
lua_tostring(fs->L, -1));
zlog_err("Lua hook call '%s' : unknown error: %s", lfs->name,
lua_tostring(lfs->L, -1));
break;
}
if (ret != LUA_OK) {
lua_pop(fs->L, 1);
lua_pop(lfs->L, 1);
goto done;
}
if (lua_gettop(lfs->L) != 1) {
zlog_err(
"Lua hook call '%s': Lua function should return only 1 result",
lfs->name);
ret = 1;
goto done;
}
if (lua_istable(lfs->L, 1) != 1) {
zlog_err(
"Lua hook call '%s': Lua function should return a Lua table",
lfs->name);
ret = 1;
}
done:
/* LUA_OK is 0, so we can just return lua_pcall's result directly */
return ret;
}
void *frrscript_get_result(struct frrscript *fs,
const struct frrscript_env *result)
void *frrscript_get_result(struct frrscript *fs, const char *function_name,
const char *name,
void *(*lua_to)(lua_State *L, int idx))
{
void *r;
struct frrscript_codec c = {.typename = result->typename};
void *p;
struct lua_function_state *lfs;
struct lua_function_state lookup = {.name = function_name};
struct frrscript_codec *codec = hash_lookup(codec_hash, &c);
assert(codec && "No encoder for type");
lfs = hash_lookup(fs->lua_function_hash, &lookup);
if (!codec->decoder) {
zlog_err("No script decoder for type '%s'", result->typename);
if (lfs == NULL)
return NULL;
/* At this point, the Lua state should have only the returned table.
* We will then search the table for the key/value we're interested in.
* Then if the value is present (i.e. non-nil), call the lua_to*
* decoder.
*/
assert(lua_gettop(lfs->L) == 1);
assert(lua_istable(lfs->L, -1) == 1);
lua_getfield(lfs->L, -1, name);
if (lua_isnil(lfs->L, -1)) {
lua_pop(lfs->L, 1);
zlog_warn(
"frrscript: '%s.lua': '%s': tried to decode '%s' as result but failed",
fs->name, function_name, name);
return NULL;
}
p = lua_to(lfs->L, 2);
lua_getglobal(fs->L, result->name);
r = codec->decoder(fs->L, -1);
lua_pop(fs->L, 1);
/* At the end, the Lua state should be same as it was at the start
* i.e. containing soley the returned table.
*/
assert(lua_gettop(lfs->L) == 1);
assert(lua_istable(lfs->L, -1) == 1);
return r;
return p;
}
void frrscript_register_type_codec(struct frrscript_codec *codec)
@ -183,61 +252,99 @@ void frrscript_register_type_codecs(struct frrscript_codec *codecs)
frrscript_register_type_codec(&codecs[i]);
}
struct frrscript *frrscript_load(const char *name,
int (*load_cb)(struct frrscript *))
struct frrscript *frrscript_new(const char *name)
{
struct frrscript *fs = XCALLOC(MTYPE_SCRIPT, sizeof(struct frrscript));
fs->name = XSTRDUP(MTYPE_SCRIPT, name);
fs->L = luaL_newstate();
frrlua_export_logging(fs->L);
fs->lua_function_hash =
hash_create(lua_function_hash_key, lua_function_hash_cmp,
"Lua function state hash");
return fs;
}
char fname[MAXPATHLEN * 2];
snprintf(fname, sizeof(fname), "%s/%s.lua", scriptdir, fs->name);
int frrscript_load(struct frrscript *fs, const char *function_name,
int (*load_cb)(struct frrscript *))
{
int ret = luaL_loadfile(fs->L, fname);
/* Set up the Lua script */
lua_State *L = luaL_newstate();
frrlua_export_logging(L);
char script_name[MAXPATHLEN];
if (snprintf(script_name, sizeof(script_name), "%s/%s.lua", scriptdir,
fs->name)
>= (int)sizeof(script_name)) {
zlog_err("frrscript: path to script %s/%s.lua is too long",
scriptdir, fs->name);
goto fail;
}
int ret = luaL_dofile(L, script_name);
switch (ret) {
case LUA_OK:
break;
case LUA_ERRSYNTAX:
zlog_err("Failed loading script '%s': syntax error: %s", fname,
lua_tostring(fs->L, -1));
zlog_err(
"frrscript: failed loading script '%s.lua': syntax error: %s",
script_name, lua_tostring(L, -1));
break;
case LUA_ERRMEM:
zlog_err("Failed loading script '%s': out-of-memory error: %s",
fname, lua_tostring(fs->L, -1));
zlog_err(
"frrscript: failed loading script '%s.lua': out-of-memory error: %s",
script_name, lua_tostring(L, -1));
break;
case LUA_ERRGCMM:
zlog_err(
"Failed loading script '%s': garbage collector error: %s",
fname, lua_tostring(fs->L, -1));
"frrscript: failed loading script '%s.lua': garbage collector error: %s",
script_name, lua_tostring(L, -1));
break;
case LUA_ERRFILE:
zlog_err("Failed loading script '%s': file read error: %s",
fname, lua_tostring(fs->L, -1));
zlog_err(
"frrscript: failed loading script '%s.lua': file read error: %s",
script_name, lua_tostring(L, -1));
break;
default:
zlog_err("Failed loading script '%s': unknown error: %s", fname,
lua_tostring(fs->L, -1));
zlog_err(
"frrscript: failed loading script '%s.lua': unknown error: %s",
script_name, lua_tostring(L, -1));
break;
}
if (ret != LUA_OK)
goto fail;
if (load_cb && (*load_cb)(fs) != 0)
/* Push the Lua function we want */
lua_getglobal(L, function_name);
if (lua_isfunction(L, lua_gettop(L)) == 0) {
zlog_err("frrscript: loaded script '%s.lua' but %s not found",
script_name, function_name);
goto fail;
}
return fs;
if (load_cb && (*load_cb)(fs) != 0) {
zlog_err(
"frrscript: '%s.lua': %s: loaded but callback returned non-zero exit code",
script_name, function_name);
goto fail;
}
/* Add the Lua function state to frrscript */
struct lua_function_state key = {.name = function_name, .L = L};
hash_get(fs->lua_function_hash, &key, lua_function_alloc);
return 0;
fail:
frrscript_unload(fs);
return NULL;
lua_close(L);
return 1;
}
void frrscript_unload(struct frrscript *fs)
void frrscript_delete(struct frrscript *fs)
{
lua_close(fs->L);
hash_iterate(fs->lua_function_hash, lua_function_free, NULL);
XFREE(MTYPE_SCRIPT, fs->name);
XFREE(MTYPE_SCRIPT, fs);
}

148
lib/frrscript.h
View File

@ -25,7 +25,7 @@
#include <lua.h>
#include "frrlua.h"
#include "../bgpd/bgp_script.h"
#include "bgpd/bgp_script.h" // for peer and attr encoders/decoders
#ifdef __cplusplus
extern "C" {
@ -40,14 +40,30 @@ struct frrscript_codec {
decoder_func decoder;
};
struct lua_function_state {
const char *name;
lua_State *L;
};
struct frrscript {
/* Script name */
char *name;
/* Lua state */
struct lua_State *L;
/* Hash of Lua function name to Lua function state */
struct hash *lua_function_hash;
};
/*
* Hash related functions for lua_function_hash
*/
void *lua_function_alloc(void *arg);
unsigned int lua_function_hash_key(const void *data);
bool lua_function_hash_cmp(const void *d1, const void *d2);
struct frrscript_env {
/* Value type */
const char *typename;
@ -60,15 +76,24 @@ struct frrscript_env {
};
/*
* Create new FRR script.
* Create new struct frrscript for a Lua script.
* This will hold the states for the Lua functions in this script.
*
* scriptname
* Name of the Lua script file, without the .lua
*/
struct frrscript *frrscript_load(const char *name,
struct frrscript *frrscript_new(const char *scriptname);
/*
* Load a function into frrscript, run callback if any
*/
int frrscript_load(struct frrscript *fs, const char *function_name,
int (*load_cb)(struct frrscript *));
/*
* Destroy FRR script.
* Delete Lua function states and frrscript
*/
void frrscript_unload(struct frrscript *fs);
void frrscript_delete(struct frrscript *fs);
/*
* Register a Lua codec for a type.
@ -97,16 +122,31 @@ void frrscript_register_type_codecs(struct frrscript_codec *codecs);
*/
void frrscript_init(const char *scriptdir);
#define ENCODE_ARGS(name, value) \
do { \
ENCODE_ARGS_WITH_STATE(L, value); \
lua_setglobal(L, name); \
} while (0)
/*
* This macro is mapped to every (name, value) in frrscript_call,
* so this in turn maps them onto their encoders
*/
#define ENCODE_ARGS(name, value) ENCODE_ARGS_WITH_STATE(lfs->L, (value))
/*
* This macro is also mapped to every (name, value) in frrscript_call, but
* not every value can be mapped to its decoder - only those that appear
* in the returned table will. To find out if they appear in the returned
* table, first pop the value and check if its nil. Only call the decoder
* if non-nil.
*
* At the end, the only thing left on the stack should be the
* returned table.
*/
#define DECODE_ARGS(name, value) \
do { \
lua_getglobal(L, name); \
DECODE_ARGS_WITH_STATE(L, value); \
lua_getfield(lfs->L, 1, (name)); \
if (lua_isnil(lfs->L, 2)) { \
lua_pop(lfs->L, 1); \
} else { \
DECODE_ARGS_WITH_STATE(lfs->L, (value)); \
} \
assert(lua_gettop(lfs->L) == 1); \
} while (0)
/*
@ -120,6 +160,7 @@ void frrscript_init(const char *scriptdir);
*/
#define ENCODE_ARGS_WITH_STATE(L, value) \
_Generic((value), \
int : lua_pushinteger, \
long long * : lua_pushintegerp, \
struct prefix * : lua_pushprefix, \
struct interface * : lua_pushinterface, \
@ -131,10 +172,11 @@ char * : lua_pushstring_wrapper, \
struct attr * : lua_pushattr, \
struct peer * : lua_pushpeer, \
const struct prefix * : lua_pushprefix \
)(L, value)
)((L), (value))
#define DECODE_ARGS_WITH_STATE(L, value) \
_Generic((value), \
int : lua_decode_integer_noop, \
long long * : lua_decode_integerp, \
struct prefix * : lua_decode_prefix, \
struct interface * : lua_decode_interface, \
@ -146,56 +188,84 @@ char * : lua_decode_stringp, \
struct attr * : lua_decode_attr, \
struct peer * : lua_decode_noop, \
const struct prefix * : lua_decode_noop \
)(L, -1, value)
)((L), -1, (value))
/*
* Call script.
* Call Lua function state (abstraction for a single Lua function)
*
* fs
* The script to call; this is obtained from frrscript_load().
* lfs
* The Lua function to call; this should have been loaded in by
* frrscript_load(). nargs Number of arguments the function accepts
*
* Returns:
* 0 if the script ran successfully, nonzero otherwise.
*/
int _frrscript_call(struct frrscript *fs);
int _frrscript_call_lua(struct lua_function_state *lfs, int nargs);
/*
* Wrapper for call script. Maps values passed in to their encoder
* and decoder types.
* Wrapper for calling Lua function state. Maps values passed in to their
* encoder and decoder types.
*
* fs
* The script to call; this is obtained from frrscript_load().
* The struct frrscript in which the Lua fuction was loaded into
* f
* Name of the Lua function.
*
* Returns:
* 0 if the script ran successfully, nonzero otherwise.
*/
#define frrscript_call(fs, ...) \
#define frrscript_call(fs, f, ...) \
({ \
lua_State *L = fs->L; \
struct lua_function_state lookup = {.name = (f)}; \
struct lua_function_state *lfs; \
lfs = hash_lookup((fs)->lua_function_hash, &lookup); \
lfs == NULL ? ({ \
zlog_err( \
"frrscript: '%s.lua': '%s': tried to call this function but it was not loaded", \
(fs)->name, (f)); \
1; \
}) \
: ({ \
MAP_LISTS(ENCODE_ARGS, ##__VA_ARGS__); \
int ret = _frrscript_call(fs); \
if (ret == 0) { \
MAP_LISTS(DECODE_ARGS, ##__VA_ARGS__); \
} \
ret; \
_frrscript_call_lua( \
lfs, PP_NARG(__VA_ARGS__)); \
}) != 0 \
? ({ \
zlog_err( \
"frrscript: '%s.lua': '%s': this function called but returned non-zero exit code. No variables modified.", \
(fs)->name, (f)); \
1; \
}) \
: ({ \
MAP_LISTS(DECODE_ARGS, \
##__VA_ARGS__); \
0; \
}); \
})
/*
* Get result from finished script.
* Get result from finished function
*
* fs
* The script. This script must have been run already.
*
* result
* The result to extract from the script.
* This reuses the frrscript_env type, but only the typename and name fields
* need to be set. The value is returned directly.
* function_name
* Name of the Lua function.
* name
* Name of the result.
* This will be used as a string key to retrieve from the table that the
* Lua function returns.
* The name here should *not* appear in frrscript_call.
* lua_to
* Function pointer to a lua_to decoder function.
* This function should allocate and decode a value from the Lua state.
*
* Returns:
* The script result of the specified name and type, or NULL.
* A pointer to the decoded value from the Lua state, or NULL if no such
* value.
*/
void *frrscript_get_result(struct frrscript *fs,
const struct frrscript_env *result);
void *frrscript_get_result(struct frrscript *fs, const char *function_name,
const char *name,
void *(*lua_to)(lua_State *L, int idx));
#ifdef __cplusplus
}

55
tests/lib/script1.lua
View File

@ -1 +1,54 @@
a = a + b
-- Positive testing
function foo(a, b)
a = a + 1
b = b + 1
return {
a = a,
b = b,
}
end
function bar(a, b)
a = a + 1
b = b + 1
c = 303
return {
b = b,
c = c,
}
end
function fact(n)
-- outer function must return a table
-- inner functions can be used to recurse or as helpers
function helper(m)
if m == 0 then
return 1
else
return m * helper(m - 1)
end
end
return {
ans = helper(n)
}
end
-- Negative testing
function bad_return1()
end
function bad_return2()
return 123
end
function bad_return3()
return {}
end
function bad_return4()
error("Something bad!")
end

75
tests/lib/test_frrscript.c
View File

@ -20,18 +20,85 @@
#include <zebra.h>
#include "lib/frrscript.h"
#include "lib/frrlua.h"
int main(int argc, char **argv)
{
frrscript_init("./lib");
struct frrscript *fs = frrscript_new("script1");
int result;
/* Positive testing */
struct frrscript *fs = frrscript_load("script1", NULL);
long long a = 100, b = 200;
int result = frrscript_call(fs, ("a", &a), ("b", &b));
result = frrscript_load(fs, "foo", NULL);
assert(result == 0);
assert(a == 300);
assert(b == 200);
result = frrscript_call(fs, "foo", ("a", &a), ("b", &b));
assert(result == 0);
assert(a == 101);
assert(b == 201);
a = 100, b = 200;
result = frrscript_load(fs, "bar", NULL);
assert(result == 0);
result = frrscript_call(fs, "bar", ("a", &a), ("b", &b));
assert(result == 0);
long long *cptr = frrscript_get_result(fs, "bar", "c", lua_tointegerp);
/* a should not occur in the returned table in script */
assert(a == 100);
assert(b == 201);
assert(*cptr == 303);
XFREE(MTYPE_SCRIPT_RES, cptr);
long long n = 5;
result = frrscript_load(fs, "fact", NULL);
assert(result == 0);
result = frrscript_call(fs, "fact", ("n", &n));
assert(result == 0);
long long *ansptr =
frrscript_get_result(fs, "fact", "ans", lua_tointegerp);
assert(*ansptr == 120);
XFREE(MTYPE_SCRIPT_RES, ansptr);
/* Negative testing */
/* Function does not exist in script file*/
result = frrscript_load(fs, "does_not_exist", NULL);
assert(result == 1);
/* Function was not (successfully) loaded */
result = frrscript_call(fs, "does_not_exist", ("a", &a), ("b", &b));
assert(result == 1);
/* Get result from a function that was not loaded */
long long *llptr =
frrscript_get_result(fs, "does_not_exist", "c", lua_tointegerp);
assert(llptr == NULL);
/* Function returns void */
result = frrscript_call(fs, "bad_return1");
assert(result == 1);
/* Function returns number */
result = frrscript_call(fs, "bad_return2");
assert(result == 1);
/* Get non-existent result from a function */
result = frrscript_call(fs, "bad_return3");
assert(result == 1);
long long *cllptr =
frrscript_get_result(fs, "bad_return3", "c", lua_tointegerp);
assert(cllptr == NULL);
/* Function throws exception */
result = frrscript_call(fs, "bad_return4");
assert(result == 1);
frrscript_delete(fs);
return 0;
}