ospfclient

This is an Erlang/OTP client for accessing the link-state database (LSDB) of the OSPF daemon from FRRouting routing protocol suite.

Using this client, an Erlang application could:

monitor the LSDB from OSPF daemon
get informed from NSM, ISM, Router ID changes
sync or resync LSDB, ISM, NSM

How to use

You can register callbacks and get notified when something changed in OSPF daemon.

    Callbacks = #{
        'MSG_NSM_CHANGE' => fun my/3
        % 'MSG_LSA_UPDATE_NOTIFY' => fun my/3,
        % 'MSG_LSA_DELETE_NOTIFY' => fun my/3
    },
    Opts = [{callbacks, Callbacks}, {callback_data, self()}],

    {ok, Handle} = ospfclient:connect({192, 168, 56, 102}, Opts),

For now, the default OSPF client daemon is: 2607. And is not possible to define an alternative port.

All callbacks follow the type (ospfclient:async_handler()):

    -type async_handler() :: fun((string(), term(), any()) -> ok).

The follow async messages are supported:

'MSG_READY_NOTIFY'
'MSG_LSA_UPDATE_NOTIFY'
'MSG_LSA_DELETE_NOTIFY'
'MSG_NEW_IF'
'MSG_DEL_IF'
'MSG_ISM_CHANGE'
'MSG_NSM_CHANGE'
'MSG_REACHABLE_CHANGE'
'MSG_ROUTER_ID_CHANGE'

Design

The module ospfclient spawns two erlang process responsible for handle sync and async messages.

sync messages are to OSPF daemon
async messages are messages from OSPF daemon

The sync and async process are linked for safe reasons. Each process manages a specific Socket.

flowchart LR
    sync((Sync))-. link .-async((Async))

There is a small connection protocol in order to get the async socket working:

4001/tcp port is open and waits for connection from OSPF daemon, this is the async socket
next, a connection is made to OSPF daemon through dest 2607/tcp port and having the port 4000/tcp as source port
the OSPF daemon receives the connection and also makes another connection to ospfclient which is listening connections to 4001/tcp port
now both sockets are up and running.

The function ospfclient:do_connect/2 is responsible for implementing that logic.

When calling: ospfclient:connect/1 function, the caller receives back a Handle. That handle (which is a process id) should be used for further interactions with ospfclient.

If callbacks were registered when calling ospfclient:connect/2 function, then the async process will call these callbacks for registered messages. In this context the caller will receive notifications for OSPF events like ISM, NSM, etc.

Build

$ rebar3 compile

Test Environment

There is no secret and all what we need is some FRR hosts in order to configure OSPF routes. My environment was made using 3 virtual machines with Ubuntu 24 and FF installed from packages. Then I made OSPF configuration and connect to one of virtual hosts. That is all.

Test

This project does not support unit test yet. It's a challenge to implement tests because it depends on FRR ospf daemon.

$ rebar3 as test shell
Erlang/OTP 26 [erts-14.2.5] [source] [64-bit] [smp:32:12] [ds:32:12:10] [async-threads:1] [jit:ns]

Eshell V14.2.5 (press Ctrl+G to abort, type help(). for help)

1> H = ospfclient_test:test().

2> ospfclinet:sync_nsm(H).

callback mt "NSM_CHANGE" data <0.483.0> payload {msg_nsm_change,
                                             {10,90,0,1},
                                             {10,90,0,2},
                                             {192,168,56,101},
                                             4}
callback mt "NSM_CHANGE" data <0.483.0> payload {msg_nsm_change,
                                             {10,90,0,1},
                                             {10,90,0,2},
                                             {192,168,56,101},
                                             6}
callback mt "NSM_CHANGE" data <0.483.0> payload {msg_nsm_change,
                                             {10,90,0,1},
                                             {10,90,0,2},
                                             {192,168,56,101},
                                             7}
callback mt "NSM_CHANGE" data <0.483.0> payload {msg_nsm_change,
                                             {10,90,0,1},
                                             {10,90,0,2},
                                             {192,168,56,101},
                                             9}