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PHP client library for XMPP (Jabber) protocol

This is low level socket implementation for enabling PHP to communicate with XMPP due to lack of such libraries online (at least ones I could find that had decent documentation).

XMPP core documentation can be found here.

Installation requirements and example

Project requirements are given in composer.json ( Composer website):

You can use this library in your project by running:

You can see usage example in Example.php file by changing credentials to point to your XMPP server and from project root run php Example.php.

Library usage

Initialization

In order to start using the library you first need to instantiate a new Options class. Host, username and password are mandatory fields, while port number, if omitted, will default to 5222 which is XMPP default.

Username can be either bare JID or in JID/resource form. If you are using a bare JID the resource will be added automatically. You can override this by explicitly setting a resource with $client->iq->setResource(). In the second case the username will be automatically parsed to username and resource variables. In case of JID/resource/xyz format, everything after second slash will be ignored. If both JID/resource is present as well as using the $client->iq->setResource() method, which ever was defined last will take precedence.

Options object is required for establishing the connection and every other subsequent request, so once set it should not be changed.

Once this is set you can instantiate a new XmppClient object and pass the Options object in.

XMPP client class explanation

Since XMPP is all about 3 major stanzas, (IQ, Message and Presence), I've created separate classes which are dependant on socket implementation so that you can directly send XML by calling a stanza method.

This means that 3 stanzas have been made available from XmppClient class constructor to be used like a chained method on client's concrete class.

Current logic thus is $client->STANZA->METHOD(). For example:

Connecting to the server

Beside being a stanza wrapper, XmppClient class offers a few public methods.

$client->connect() method does a few things:

1. Connects to the socket which was initialized in XmppClient constructor
2. Opens an XML stream to exchange with the XMPP server
3. Tries to authenticate with the server based on provided credentials
4. Starts the initial communication with the server, bare minimum to get you started

Current version supports PLAIN and DIGEST-MD5 auth methods.

TLS is supported by default. If server has support for TLS, library will automatically try to connect with TLS and make the connection secure.

If you'd like to explicitly disable this functionality, you can use setUseTls(false) function on the Options instance so that TLS communication is disabled. Note that this will function in environments where TLS is supported but not required. If TLS is required, program will connect to it independently of the option you set.

Sending raw data

send() message is exposed as being public in XmppClient class, and its intention is to send raw XML data to the server. For it to work correctly, XML which you send has to be valid XML.

Getting raw response

Server responses (or server side continuous XML session to be exact) can be retrieved with $client->getResponse(). This should be used in an infinite loop or for more sustainable solution in some WebSocket solution like Ratchet if you'd like to see continuous stream of everything coming from the server.

If you would like to see the output of the received response in the console you can call the $client->prettyPrint($response) method.

Receiving messages and other responses

In case you are not interested in complete response which comes from server, you may also use $client->message->receive() ($client->getMessages() was removed because it was just a shorthand method for this one) which will match message tags with regex and return array of matched messages. In case you'd like to see the response in the terminal, you can do something like this:

Disconnect

Disconnect method sends closing XML to the server to end the currently open session and closes the open socket.

Stanza method breakdown

Remember from here -> $client->STANZA->METHOD()

Message

send() - sending a message to someone. Takes 3 parameters of which the last one is optional. First parameter is the actual message you'd like to send (body), second one is recipient of the message and third one is type of message to be sent. This defaults to chat.

You can find possible types in this RFC document

receive() - covered in this section

IQ

getRoster() - takes no arguments and fetches current authenticated user roster.

setGroup() - puts a given user in group you provide. Method takes two arguments: first one being the group name which you will attach to given user, and other being JID of that user.

Presence

setPriority() - sets priority for given resource. First argument is an integer -128 <> 127. If no second argument is given, priority will be set for currently used resource. Other resource can be provided as a second argument whereas the priority will be set for that specific resource.

subscribe() - takes JID as an argument and asks that user for presence.

acceptSubscription() - takes JID as an argument and accepts presence from that user.

declineSubscription() - takes JID as an argument and declines presence from that user.

Sessions

Sessions are currently being used only to differentiate logs if multiple connections are being made.

XmppClient class takes in second optional parameter $sessionId to which you can forward session ID from your system, or it will be assigned automatically.

You can disable sessions through Options object ($options->setSessionManager(false)), as they can cause collision with already established sessions if being used inside frameworks or similar. Needless to say if this is disabled, forwarding a second parameter to XmppClient will not establish a new session.

More options (not required)

Options object can take more options which may be chained but are not required. These are explained and commented in the code directly in the Options class:

Socket options

Most of the socket options are set by default so there is no need to tamper with this class, however you can additionally change the timeout for the period the socket will be alive when doing a socket_read(), and you can do that with $socket->setTimeout().

Logging

Upon new established session the library is creating a xmpp.log log file in logs/ folder:

You can manually set logger when instantiating Options with setLogger($logger). The method accepts any object which implements Loggable interface so you can create your own implementation.

Fun fact: this used to be a PSR-3 logger interface, but I decided it was an overkill for this stage of development.

Other

Example.php has a sendRawXML() method which can be helpful with debugging. Method works in a way that you can provide hand-written XML and send it to the server. On the other hand you can also trigger a method by providing method name instead of XML.

Some valid XMPP XML will be declined (like sending <presence/>) because simplexml_load_string() is not able to parse it as being a valid XML. In cases you need to do some custom stuff like that and you are sure it is a XMPP valid XML, you can remove the parsing line and just let the send() method do its magic.

Be aware! Be very aware! sending an invalid XML to the server will probably invalidate currently open XML session and you will probably need to restart the script. This is highly experimental and not maintained really. It is a poor orphan method whose parents have abandoned it and left in a hurry. It may prove to be Harry Potter one day, but hey... we all clearly doubt it. You may be a special snowflake but no one likes you. Onward to orphanagemobil! Begone method (just kidding, I won't delete it)!

Who says readme's are boring.

Dev documentation

For anyone willing to contribute, a quick breakdown of the structure:

• Options.php - everything that is variable about the library
• Socket.php - socket related implementation (connecting, reading, writing etc.)

• XmppClient.php - user friendly methods to interact with the library and stanza wrapper enabling users to call stanza methods through instantiated class. This should contain as little logic as possible, turns out it's not so easy :)

• AuthTypes - contains methods to authenticate yourself to XMPP server. Besides concrete implementations there is also an abstract class with minor logic to avoid duplication and interface having all the necessary methods should the need for new auth type arise.

• Buffers - implementation of buffer (or should I say a simple array) which gets filled when socket is calling the receive() method, and it flushes on any read, which happens when calling getResponse() method for example. A brief history of why: I had issues when a non-recoverable error would be thrown. In this situation I had to do 2 things: try to reconnect, show the error to the user. The thing is that getResponse() returns string, and in case of reconnection the program execution would continue returning either nothing or returning error string after the server already connected for the second time, thus misinforming the user of the error which occurred before reconnection. Buffer was born.

• Exceptions - this is more or less a standard. I am just overriding constructors so I can get my message in.

• Loggers - containing logic to store logs to the logs/xmpp.log file. The idea was to keep several log types inside (full, simple, no logger), but I found the one made to be sufficient.

Xml

• Xml.php - a trait consisting of way too many regex matching. This should be reformatted.
• Stanzas - main logic for all stanza communication with the server. This used to be just plain XML, but I have decided to forward a socket dependency inside so that when you call the method, you actually also send it to the server. That used to be something like $this->socket->send($this->iq->getRoster()) which is correct from the programming perspective, but for the simplicity sake, I like the $client->iq->getRoster() more. I'm open to other suggestions.

CI

Continuous integration is done through Travis CI, and each push goes through a process which is currently as simple as:

• check unit tests (and god knows I have them)
• check for syntax errors
• run phpcs (configuration in phpcs.xml)
• run phpmd (configuration in phpmd.xml)

TODO's

• unit testing - unfortunately I have been prolonging this for far too long, maybe there is a good soul out there who enjoys writing tests.
• throttling - when an unrecoverable error occurs (currently I am catching <stream:error> ones which break the stream) reconnect is being made automatically. In case this is happening over and over again, program will try connecting indefinitely, which is fine to any aspect except logs which will get clogged. I would like to throttle the connection so that it increases the connection time each time it is unsuccessful. Problem here is that I can only catch the error when getting the response, and response can be successful on the first XML exchange (for example when you send opening stream request), while breaking on the second request. With this in mind my only idea was to implement throttling with timestamps or something.
• sessions - I presume this part is working correctly but should be tested from a framework
• multiple connections - I think this part works fine, but I am worried that triggering getRoster() while simultaneously fetching a message may delete one server response. If you get in one batch both roster and message, it will be added to the buffer. Calling back the response will get either roster or message, not both. And then buffer will be flushed. This is something that needs thinking.
• structure of XmppClient - in order to enable the $client->stanza->method I need to instantiate all stanzas within the class. I feel as this could be simplified.