130 lines
4.0 KiB
ReStructuredText
130 lines
4.0 KiB
ReStructuredText
.. _example_handler:
|
|
|
|
Fundamentals
|
|
================
|
|
|
|
This basic example shows how to create simple python module which will pass on the requests to the iterator.
|
|
|
|
How to enable python module
|
|
----------------------------
|
|
If you look into unbound configuration file, you can find the option `module-config` which specifies the names and the order of modules to be used.
|
|
Example configuration::
|
|
|
|
module-config: "validator python iterator"
|
|
|
|
As soon as the DNS query arrives, Unbound calls modules starting from leftmost - the validator *(it is the first module on the list)*.
|
|
The validator does not know the answer *(it can only validate)*, thus it will pass on the event to the next module.
|
|
Next module is python which can
|
|
|
|
a) generate answer *(response)*
|
|
When python module generates the response unbound calls validator. Validator grabs the answer and determines the security flag.
|
|
|
|
b) pass on the event to the iterator.
|
|
When iterator resolves the query, Unbound informs python module (event :data:`module_event_moddone`). In the end, when the python module is done, validator is called.
|
|
|
|
Note that the python module is called with :data:`module_event_pass` event, because new DNS event was already handled by validator.
|
|
|
|
Another situation occurs when we use the following configuration::
|
|
|
|
module-config: "python validator iterator"
|
|
|
|
Python module is the first module here, so it's invoked with :data:`module_event_new` event *(new query)*.
|
|
|
|
On Python module initialization, module loads script from `python-script` option::
|
|
|
|
python-script: "/unbound/test/ubmodule.py"
|
|
|
|
Simple python module step by step
|
|
---------------------------------
|
|
|
|
Script file must contain four compulsory functions:
|
|
|
|
.. function:: init(id, cfg)
|
|
|
|
Initialize module internals, like database etc.
|
|
Called just once on module load.
|
|
|
|
:param id: module identifier (integer)
|
|
:param cfg: :class:`config_file` configuration structure
|
|
|
|
::
|
|
|
|
def init(id, cfg):
|
|
log_info("pythonmod: init called, module id is %d port: %d script: %s" % (id, cfg.port, cfg.python_script))
|
|
return True
|
|
|
|
|
|
.. function:: deinit(id)
|
|
|
|
Deinitialize module internals.
|
|
Called just once on module unload.
|
|
|
|
:param id: module identifier (integer)
|
|
|
|
::
|
|
|
|
def deinit(id):
|
|
log_info("pythonmod: deinit called, module id is %d" % id)
|
|
return True
|
|
|
|
|
|
.. function:: inform_super(id, qstate, superqstate, qdata)
|
|
|
|
Inform super querystate about the results from this subquerystate.
|
|
Is called when the querystate is finished.
|
|
|
|
:param id: module identifier (integer)
|
|
:param qstate: :class:`module_qstate` Query state
|
|
:param superqstate: :class:`pythonmod_qstate` Mesh state
|
|
:param qdata: :class:`query_info` Query data
|
|
|
|
::
|
|
|
|
def inform_super(id, qstate, superqstate, qdata):
|
|
return True
|
|
|
|
|
|
|
|
.. function:: operate(id, event, qstate, qdata)
|
|
|
|
Perform action on pending query. Accepts a new query, or work on pending query.
|
|
|
|
You have to set qstate.ext_state on exit.
|
|
The state informs unbound about result and controls the following states.
|
|
|
|
:param id: module identifier (integer)
|
|
:param qstate: :class:`module_qstate` query state structure
|
|
:param qdata: :class:`query_info` per query data, here you can store your own data
|
|
|
|
::
|
|
|
|
def operate(id, event, qstate, qdata):
|
|
log_info("pythonmod: operate called, id: %d, event:%s" % (id, strmodulevent(event)))
|
|
if event == MODULE_EVENT_NEW:
|
|
qstate.ext_state[id] = MODULE_WAIT_MODULE
|
|
return True
|
|
|
|
if event == MODULE_EVENT_MODDONE:
|
|
qstate.ext_state[id] = MODULE_FINISHED
|
|
return True
|
|
|
|
if event == MODULE_EVENT_PASS:
|
|
qstate.ext_state[id] = MODULE_ERROR
|
|
return True
|
|
|
|
log_err("pythonmod: BAD event")
|
|
qstate.ext_state[id] = MODULE_ERROR
|
|
return True
|
|
|
|
|
|
Complete source code
|
|
--------------------
|
|
|
|
.. literalinclude:: example0-1.py
|
|
:language: python
|
|
|
|
As you can see, the source code is much more flexible in contrast to C modules.
|
|
Moreover, compulsory functions called on appropriate module events allows to handle almost
|
|
anything from web control to query analysis.
|
|
|