clixon/example

Clixon example

This directory contains a Clixon example which includes a simple routing example. It contains the following files:

• example.xml The configuration file. See yang/clixon-config@.yang for all available fields.
• example.yang The yang spec of the example. It mainly includes ietf routing and IP modules.
• example_cli.cli CLIgen specification.
• example_cli.c CLI callback plugin containing functions called in the cli file above: a generic callback (mycallback) and an RPC (fib_route_rpc).
• example_backend.c Backend callback plugin including example of:
  • transaction callbacks (validate/commit),
  • notification,
  • rpc handler
  • state-data handler, ie non-config data
• example_backend_nacm.c Secondary backend plugin. Plugins are loaded alphabetically.
• example_restconf.c Restconf callback plugin containing an HTTP basic authentication callback
• example_netconf.c Netconf callback plugin
• Makefile.in Example makefile where plugins are built and installed

Compile and run

    cd example
    make && sudo make install

Start backend:

    clixon_backend -f /usr/local/etc/example.xml -I

Edit cli:

    clixon_cli -f /usr/local/etc/example.xml

Send netconf command:

    clixon_netconf -f /usr/local/etc/example.xml

Start clixon restconf daemon

> sudo su -c "/www-data/clixon_restconf -f /usr/local/etc/example.xml " -s /bin/sh www-data

Send restconf command

    curl -G http://127.0.0.1/restconf/data

Setting data example using netconf

<rpc><edit-config><target><candidate/></target><config>
      <interfaces>
         <interface>
            <name>eth1</name>
            <enabled>true</enabled>
            <ipv4>
               <address>
                  <ip>9.2.3.4</ip>
                  <prefix-length>24</prefix-length>
               </address>
            </ipv4>
         </interface>
      </interfaces>
</config></edit-config></rpc>]]>]]>

Getting data using netconf

<rpc><get-config><source><candidate/></source></get-config></rpc>]]>]]>
<rpc><get-config><source><candidate/></source><filter/></get-config></rpc>]]>]]>
<rpc><get-config><source><candidate/></source><filter type="xpath"/></get-config></rpc>]]>]]>
<rpc><get-config><source><candidate/></source><filter type="subtree"><configuration><interfaces><interface><ipv4/></interface></interfaces></configuration></filter></get-config></rpc>]]>]]>
<rpc><get-config><source><candidate/></source><filter type="xpath" select="/interfaces/interface/ipv4"/></get-config></rpc>]]>]]>
<rpc><validate><source><candidate/></source></validate></rpc>]]>]]>

Creating notification

The example has an example notification triggering every 10s. To start a notification stream in the session, create a subscription:

<rpc><create-subscription><stream>ROUTING</stream></create-subscription></rpc>]]>]]>
<rpc-reply><ok/></rpc-reply>]]>]]>
<notification><event>Routing notification</event></notification>]]>]]>
<notification><event>Routing notification</event></notification>]]>]]>
...

This can also be triggered via the CLI:

cli> notify 
cli> Routing notification
Routing notification
...

Initializing a plugin

The example includes a restonf, netconf, CLI and two backend plugins. Each plugin is initiated with an API struct followed by a plugin init function. The content of the API struct is different depending on what kind of plugin it is. The plugin init function may also include registering RPC functions, see below is for a backend.

static clixon_plugin_api api = {
    "example",          /* name */
    clixon_plugin_init, 
    plugin_start,       
    plugin_exit,        
    .ca_reset=plugin_reset,/* reset */          
    .ca_statedata=plugin_statedata, /* statedata */
    .ca_trans_begin=NULL, /* trans begin */
    .ca_trans_validate=transaction_validate,/* trans validate */
    .ca_trans_complete=NULL,                /* trans complete */
    .ca_trans_commit=transaction_commit,    /* trans commit */
    .ca_trans_end=NULL,                     /* trans end */
    .ca_trans_abort=NULL                    /* trans abort */
};

clixon_plugin_api *
clixon_plugin_init(clicon_handle h)
{
    /* Optional callback registration for RPC calls */
    rpc_callback_register(h, fib_route, NULL, "fib-route");
    /* Return plugin API */
    return &api; /* Return NULL on error */
}

Operation data

Clixon implements Yang RPC operations by an extension mechanism. The extension mechanism enables you to add application-specific operations. It works by adding user-defined callbacks for added netconf operations. It is possible to use the extension mechanism independent of the yang rpc construct, but it is recommended. The example includes an example:

Example:

cli> rpc ipv4
<rpc-reply>
   <ok/>
</rpc-reply>

The example works by creating a netconf rpc call and sending it to the backend: (see the fib_route_rpc() function).

  <rpc>
    <fib-route>
      <routing-instance-name>ipv4</routing-instance-name>
    </fib-route>
   </rpc>

In the backend, a callback is registered (fib_route()) which handles the RPC.

static int 
fib_route(clicon_handle h, 
	  cxobj        *xe,           /* Request: <rpc><xn></rpc> */
	  cbuf         *cbret,        /* Reply eg <rpc-reply>... */
	  void         *arg,          /* Client session */
	  void         *regarg)       /* Argument given at register */
{
    cprintf(cbret, "<rpc-reply><ok/></rpc-reply>");    
    return 0;
}
int
clixon_plugin_init(clicon_handle h)
{
...
   rpc_callback_register(h, fib_route, NULL, "fib-route");
...
}

State data

Netconf and restconf GET also returns state data, in contrast to config data. p In YANG state data is specified with "config false;". In the example, interface-state is state data.

To return state data, you need to write a backend state data callback with the name "plugin_statedata" where you return an XML tree with state. This is then merged with config data by the system.

A static example of returning state data is in the example. Note that a real example would poll or get the interface counters via a system call, as well as use the "xpath" argument to identify the requested state data.

Authentication and NACM

The example contains some stubs for authorization according to RFC8341(NACM):

• A basic auth HTTP callback, see: example_restconf_credentials() containing three example users: adm1, wilma, and guest, according to the examples in Appendix A in the RFC.
• A NACM backend plugin reporting the mandatory NACM state variables.

Run as docker container

(Note not updated)

cd docker
# look in README