Php Inside - confoo 2011 - Derick Rethans

Welcome!

PHP Inside

ConFoo - Montréal, Canada - March 10th, 2011
Derick Rethans - derick@php.net - twitter: @derickr
http://derickrethans.nl/talks.html
http://joind.in/2823

About Me

Derick Rethans

● Dutchman living in London
● PHP development
● Author of the mcrypt, input_filter, dbus, translit
and date/time extensions
● Author of Xdebug
● Contributor to the Apache Zeta Components
Incubator project (formerly eZ Components)
● Freelancer doing PHP (internals) development

My First Application

● is the new hello world
● Simple web API to get data
● Authentication with HTTP basic auth
● Simple interface: some buttons, an edit box and a
list of tweets

GUI toolset

● is a PHP binding for the GTK+ widget set
● It comes as an extension for PHP
● It wraps around many GTK+ widgets
● GUI can be created from PHP:
<?php
$tb = new GtkToolbar();
$tb->set_show_arrow( false );
$tb->set_property( 'toolbar-style', Gtk::TOOLBAR_BOTH );
$tb->set_property( 'icon-size', 6 );
$this->updatebutton = GtkToolButton::new_from_stock( Gtk::STOCK_REFRESH );
$lbl = new GtkLabel();
$lbl->set_markup( '<span underline="single">U</span>pdate' );
$this->updatebutton->set_label_widget( $lbl );
$this->updatebutton->connect_simple( 'clicked', array( $this, 'update' ) );
$this->updatebutton->add_accelerator( 'clicked', $accels, Gdk::KEY_U, Gdk::MOD1_MASK, 0 );
$this->updatebutton->set_use_underline( true );
$tb->insert( $this->updatebutton, -1 );

Getting PHP on the device

● It's an ARM processor
● Cross compiling vs compiling on the device

Cross-compiling:
● Requires cross-compilation set-up

● Tricky, and caused libtool problems for me

Compiling on the device
● All packages need to be found and installed

● Compiling PHP is really slow, you really don't

want to use make clean

Data Storage

● You can't really run a database server on the
phone
● SQLite is part of PHP, and self-contained
● Indexes are vital on this platform
● Clever use of SQL/Data manipulation is required
for performance

Twitter App Experiences

● Starting the app is not fast
● Styling with GTK is tricky, especially if you want
to run the app on the desktop too
● Twitter API is very unstable, and inaccessible at
times; it's also badly designed
● You pull in way too much data than you need
● My fingers are really fat
● Can't really have the app running for a long time

Transport for London

● Provides status updates through
● If you're traveling, it's really handy to have this
information with you
● There is no API, so you need to scrape
● Widget provided for embedding:
● Strict rules about colours etc.:

● It's probably not totally legal

Scraping the Tube status

● It's a ~25kb download; with GPRS the download
time is about 5 seconds
● It has lots of mark-up and JavaScript that we're
not interested in
● Using PHP to get the data we want from it is
relatively slow
● If the format changes, all the installed apps need
to be updated

Web API

● The download with status is only 0.5kb
● The API caches the download
● It only provides the data in JSON that we require:
{
"date":1273835118,
"status":[
["Bakerloo",["Good service",""]],["Central",["Good service",""]],
["Circle",["Good service",""]],["District",["Good service",""]],
["H'smith & City",["Good service",""]],["Jubilee",["Good service",""]],
["Metropolitan",["Good service",""]],["Northern",["Good service",""]],
["Piccadilly",["Good service",""]],["Victoria",["Good service",""]],
["Waterloo & City",["Good service",""]]
]
}

● Parsing the JSON is fast, very little processing
needed in the app, just display
● If the HTML changes, only the scraping algorithm
needs to be changed

Talking to the hardware

● Many applications (phonebook, sending SMS) that
came with the phone where suboptimal
● Writing a new GUI is possible, but talking to the
hardware requires D-BUS
● D-BUS APIs are exposed by the freesmartphone
project that the Linux distribution uses
● PHP didn't have a D-BUS extension

PHP DBUS extension

● DBUS bindings using the low-level C library
(libdbus)
● Provides proxy objects
● Implements automatic-marshalling of data
● Provides specific classes for full control
● Support for method invocation, method calls,
sending and receiving signals
● (Basic) support for introspection

Talking to a DBUS object from PHP
Activating the screensaver

screensaver.php:
<?php
$d = new Dbus;
$n = $d->createProxy(
"org.gnome.ScreenSaver",
"/org/gnome/ScreenSaver",
"org.gnome.ScreenSaver"
);

var_dump($n->GetActive());
$n->SetActive( true );
var_dump($n->GetActive());
sleep(5);
$n->SetActive( false );
?>

Kindle Hacking

Playing around with your Kindle can make Amazon
angry

Kindle Hacking

In order to get shell, you have to do the following:
● Install a jailbreak

● Install USB networking

● Install Launchpad

● http://www.mobileread.com/forums/showthread.ph

p?t=88004

Kindle Hacking
Getting PHP on the Kindle

● Install the cross compilers from Emdebian:
echo "deb http://www.emdebian.org/debian/ testing main"
>> /etc/apt/sources.list
apt-get update
apt-get install gcc-4.3-arm-linux-gnueabi
● Cross compile PHP
● Copy it over and run:
scp sapi/cli/php root@kindle:/tmp
ssh root@kindle /tmp/php
[root@kindle root]# /tmp/php -v PHP 5.3.6-dev (cli) (built:
Mar 7 2011 13:42:56) Copyright (c) 1997-2011 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2011 Zend
Technologies

Kindle Hacking
Cross-compiling

● Install the cross compilers from Emdebian:
echo "deb http://www.emdebian.org/debian/ testing main" >>
/etc/apt/sources.list
apt-get update
apt-get install gcc-4.3-arm-linux-gnueabi
● Configure "like normal":
CC='arm-linux-gnueabi-gcc' '/home/derick/dev/php/php-
src/branches/PHP_5_3/configure' '--disable-all' '--
prefix=/home/derick/install/kindle/cross/target' '--enable-
sockets' '--enable-pcntl' '--with-pcre-regex'
● make
● Edit the last line, remove everything until arm-
linux-gnueabi-gcc
● Add -static after -fvisibility=hidden
● Replace every .lo with .o
● Run
arm-linux-gnueabi-gcc -export-dynamic -g -O2 -fvisibility=hidden
-static ext/date/php_date.o .... -lcrypt -o sapi/cli/php

Kindle Hacking

The Kindle:
● Runs Linux

● Does not run X, but a framebuffer

● Has WiFi (and 3G), but requires a proxy to work

Getting GTK to run on framebuffer is a pain, and so
far I have not managed to get PHP-GTK running on
it.

Kindle Hacking
Accessing the screen

● Open framebuffer /dev/fb0
● mmap the open file
● Screen data is stored with every two pixels stored
in one byte, in total 800 rows, with 300 bytes per
row (600 pixels)
(40 more)
66 55 55 65 66 54 45 68 CF FF (290 more)
77 77 66 78 77 65 65 55 7B FF (290 more)
(858 more)

7B = 0111 1011
`--´ `--´
| `---- 2nd nibble: 11/15
`----------1st nibble: 7/15

Kindle Hacking
Downloading files from PHP

You need to use Amazon's proxy
● Each request with the proxy needs to be

authenticated, otherwise:
HTTP/1.1 403 Forbidden+for+Client3A+amz5F2020
Date: Thu, 03 Mar 2011 20:54:10 GMT
Content-Type: text/html
Transfer-Encoding: chunked
x-kn-retry: 300

There is a problem with your Kindle account. Please call Customer Service at 1-866-321-8851 or 1-206-266-0927. For UK
customers, please call +44(0)800 496 2449.

<?php
$url = "tcp://87.238.83.84:80";
$fp = stream_socket_client($url, $errno, $errstr, 1);
if (!$fp) {
echo "$errstr ($errno)<br />n";
} else {
fwrite($fp, <<<ENDREQ
GET http://derickrethans.nl/ws/tubestatus.ws.php HTTP/1.1r
Host: derickrethans.nlr
User-Agent: Mozilla/5.0 (Linux; U; en-US) AppleWebKit/528.5+ (KHTML, like Gecko, Safari/528.5+) Version/4.0 Kindle/3.0
(screen 600x800; rotate)r
Referer: http://mobile.twitter.com/r
Cache-Control: max-age=0r
Accept-Encoding: gzipr
Accept-Language: en-USr
x-fsn: R0pdR...personal-key...qpxX1Jr
x-kn-appId: BBookletV3r
r
r
ENDREQ
);
while (!feof($fp)) {
echo fgets($fp, 1024);
}
fclose($fp);
}?>

Kindle Hacking

What is left?
● A PHP extension to talk to the screen

● Figure out how to stop the Kindle's main

application from running when our own app is
going
● How to write an interface, and or interface with

the keyboard just like the Kindle does

Conclusion

● Mobile devices have little memory and CPU power
● Bandwidth is a real issue
● Lack of APIs
● PHP can run on them, but whether it's smart is to
be seen
● Issues with proprietary systems
● Next experiment: PHP on Android/WebOS/Meego?

Thanks!

Derick Rethans - derick@php.net - twitter: @derickr
http://derickrethans.nl/talks.html
http://joind.in/2823

Php Inside - confoo 2011 - Derick Rethans

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