mqlobber-access-control   

Access control for mqlobber message queues. Specify to which topics clients can (and can't) subscribe, publish and receive.

The API is described here.

Example:

Here's a server program which listens on a TCP port specified on the command line. It allows clients to:

• Publish messages to topics matching foo.bar.# (i.e. any topic beginning with foo.bar.) but not to foo.bar.reserved
• Subscribe to messages with topics matching foo.# (i.e. any topic beginning with foo.)

// server.js
var net = require('net'),
    QlobberFSQ = require('qlobber-fsq').QlobberFSQ,
    MQlobberServer = require('mqlobber').MQlobberServer,
    AccessControl = require('mqlobber-access-control').AccessControl,
    fsq = new QlobberFSQ();
 
fsq.on('start', function ()
{
    var server = net.createServer().listen(parseInt(process.argv[2]));
    server.on('connection', function (c)
    {
        new AccessControl(
        {
            publish: { allow: [ 'foo.bar.#' ],
                       disallow: [ 'foo.bar.reserved' ] },
            subscribe: { allow: [ 'foo.#' ] }
        }).attach(new MQlobberServer(fsq, c));
    });
});

Next, a program which connects to the server and subscribes to messages published to a topic:

// client_subscribe.js
var assert = require('assert'),
    MQlobberClient = require('mqlobber').MQlobberClient,
    c = require('net').createConnection(parseInt(process.argv[2])),
    mq = new MQlobberClient(c),
    topic = process.argv[3];
 
mq.subscribe(topic, function (s, info)
{
    var msg = '';
    s.on('readable', function ()
    {
        var data;
        while ((data = this.read()) !== null)
        {
            msg += data.toString();
        }
    });
    s.on('finish', function ()
    {
        c.end();
    });
    s.on('end', function ()
    {
        console.log('received', info.topic, msg);
        assert.equal(msg, 'hello');
    });
}, assert.ifError);

Finally, a program which connects to the server and publishes a message to a topic:

// client_publish.js
var assert = require('assert'),
    MQlobberClient = require('mqlobber').MQlobberClient,
    c = require('net').createConnection(parseInt(process.argv[2])),
    mq = new MQlobberClient(c);
 
mq.publish(process.argv[3], function (err)
{
    assert.ifError(err);
    c.end();
}).end('hello');

Run two servers listening on ports 8600 and 8601:

$ node server.js 8600 &
$ node server.js 8601 &

Try to subscribe to topic test:

$ node client_subscribe.js 8600 test
[Error: blocked subscribe to topic: test]
assert.js:362
assert.ifError = function(err) { if (err) throw err; };
                                          ^
 
Error: server error
    at BPDuplex.<anonymous> (/tmp/wup/node_modules/mqlobber/lib/client.js:423:27)
    at emitTwo (events.js:87:13)
    at BPDuplex.emit (events.js:172:7)
    at BPMux._process_header (/tmp/wup/node_modules/mqlobber/node_modules/bpmux/index.js:652:20)
    at null.<anonymous> (/tmp/wup/node_modules/mqlobber/node_modules/bpmux/index.js:514:29)
    at emitNone (events.js:67:13)
    at emit (events.js:166:7)
    at emitReadable_ (_stream_readable.js:419:10)
    at emitReadable (_stream_readable.js:413:7)
    at readableAddChunk (_stream_readable.js:164:13)

Subscribe to two topics, foo.bar and wildcard topic foo.*, one against each server:

$ node client_subscribe.js 8600 foo.bar &
$ node client_subscribe.js 8601 'foo.*' &

Try to publish to topic foo.bar.reserved:

$ node client_publish.js 8600 foo.bar.reserved
node client_publish.js 8600 foo.bar.reserved
[Error: blocked publish to topic: foo.bar.reserved]
assert.js:362
assert.ifError = function(err) { if (err) throw err; };
                                          ^
 
Error: server error
    at BPDuplex.<anonymous> (/tmp/wup/node_modules/mqlobber/lib/client.js:633:27)
    at emitTwo (events.js:87:13)
    at BPDuplex.emit (events.js:172:7)
    at BPMux._process_header (/tmp/wup/node_modules/mqlobber/node_modules/bpmux/index.js:652:20)
    at null.<anonymous> (/tmp/wup/node_modules/mqlobber/node_modules/bpmux/index.js:514:29)
    at emitNone (events.js:67:13)
    at emit (events.js:166:7)
    at emitReadable_ (_stream_readable.js:419:10)
    at emitReadable (_stream_readable.js:413:7)
    at readableAddChunk (_stream_readable.js:164:13)

Then publish a message to the topic foo.bar:

$ node client_publish.js 8600 foo.bar
received foo.bar hello
received foo.bar hello
 
[3]-  Done                    node client_subscribe.js 8600 foo.bar
[4]+  Done                    node client_subscribe.js 8601 'foo.*'

Only the servers should still be running and you can now terminate them:

$ jobs
[1]-  Running                 node server.js 8600 &
[2]+  Running                 node server.js 8601 &
$ kill %1 %2
[1]-  Terminated              node server.js 8600
[2]+  Terminated              node server.js 8601

Installation

npm install mqlobber-access-control

Licence

MIT

Test

grunt test

Lint

grunt lint

Code Coverage

grunt coverage

Istanbul results are available here.

Coveralls page is here.

API

• AccessControl
• AccessControl.prototype.reset
• AccessControl.prototype.attach
• AccessControl.prototype.detach
• AccessControl.events.subscribe_blocked
• AccessControl.events.publish_blocked
• AccessControl.events.message_blocked

AccessControl(options)

Create a new AccessControl object for applying access control on publish and subscribe requests to MQlobberServer objects and messages delivered to clients.

Calls reset after creating the object.

Parameters:

• {Object} options See reset for valid options.

_{Go: TOC}

AccessControl.prototype.reset(options)

Reset the access control applied by this object to client publish and subscribe requests on attached MQlobberServer objects and messages delivered to clients.

Parameters:

• {Object} options Specifies to which topics clients should be allowed and disallowed to publish, subscribe and receive messages. It supports the following properties:

  • {Object} [publish] Allowed and disallowed topics for publish requests, with the following properties:

    • {Array} [allow] Clients can publish messages to these topics.
    • {Array} [disallow] Clients cannot publish messages to these topics.
    • {Integer} [max_data_length] Maximum number of bytes allowed in a published message.
    • {Integer} [max_publications] Maximum number of messages each client can publish at any one time.
    • {Boolean} [disallow_single] Whether to allow messages to be published to a single subscriber.
    • {Boolean} [disallow_multi] Whether to allow messages to be published to multiple subscribers.

  • {Object} [subscribe] Allowed and disallowed topics for subscribe requests, with the following properties:

    • {Array} [allow] Clients can subscribe to messages published to these topics.
    • {Array} [disallow] Clients cannot subscribe to messages published to these topics.
    • {Integer} [max_subscriptions] Maximum number of topics to which each client can be subscribed at any one time.

  • {Array} [block] Clients cannot receive messages published to these topics. This is useful if subscribe.allow is a superset of subscribe.disallow but you don't want messages matching (a subset of) subscribe.disallow sent to clients.

  • {Integer} [max_topic_length] Maximum topic length for publish, subscribe and unsubscribe requests.

Topics are the same as mqlobber topics and qlobber-fsq topics. They're split into words using . as the separator. You can use * to match exactly one word in a topic or # to match zero or more words. For example, foo.* would match foo.bar whereas foo.# would match foo, foo.bar and foo.bar.wup.

Note these are the default separator and wildcard characters. They can be changed when constructing the QlobberFSQ instance or QlobberPG instance passed to MQlobberServer's constructor. If you do change them, make sure you specify the changed values in options too.

There's also a limit on the number of words and # words, imposed by Qlobber. For defaults, see max_words and max_wildcard_somes here. You can change the limits by specifying max_words and/or max_wildcard_somes in options.

Note also that for subscribe requests, AccessControl matches topics you specify here against topics in the requests, which can themselves contain wildcard specifiers.

Disallowed topics take precedence over allowed ones. So if a topic in a publish or subscribe request matches a disallowed topic specifier, it's blocked even if it also matches an allowed topic specifier.

Access control is only applied where topics are specified.

_{Go: TOC | AccessControl.prototype}

AccessControl.prototype.attach(server)

Start applying access control to a MQlobberServer object.

Only one AccessControl object can be attached to a MQlobberServer object at a time. Trying to attach more than one will throw an exception.

If a conflict is detected between server's configuration and the AccessControl object's configuration (for example different separators or different word limit) then an exception will be thrown.

Parameters:

• {MQlobberServer} server Object to which to apply access control.

_{Go: TOC | AccessControl.prototype}

AccessControl.prototype.detach(server)

Stop applying access control to a MQlobberServer object.

Parameters:

• {MQlobberServer} server Object to which to stop applying access control.

_{Go: TOC | AccessControl.prototype}

AccessControl.events.subscribe_blocked(topic, server)

subscribe_blocked event

Emitted by an AccessControl object after it blocks a subscribe request from a client.

Parameters:

• {String} topic The topic that was blocked.
• {MQlobberServer} server The MQlobberServer object which received the subscription request.

_{Go: TOC | AccessControl.events}

AccessControl.events.publish_blocked(topic, server)

publish_blocked event

Emitted by an AccessControl object after it blocks a publish request from a client.

Parameters:

• {String} topic The topic that was blocked.
• {MQlobberServer} server The MQlobberServer object which received the publication request.

_{Go: TOC | AccessControl.events}

AccessControl.events.message_blocked(topic, server)

message_blocked event

Emitted by an AccessControl object after it blocks a message being sent to a client.

Parameters:

• {String} topic The topic that was blocked.
• {MQlobberServer} server The MQlobberServer object which was handling the message.

_{Go: TOC | AccessControl.events}

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