veracruz

PHP - Advanced Tutorial

Gulev

December 6, 2002. Veracruz, Mexico

Rasmus Lerdorf <rasmus@php.net>

http://lerdorf.com/veracruz.pdf

/64 December 6, 2002
Agenda
o PHP-MySQL
o Cookie Handling
o Dynamic Images
o PDF
o Flash
o Sessions
o Security
o Tips & Tricks
o Optimization
o Latest Developments
o Future

-2-

Setup
Check your PHP Setup for MySQL support
<? phpinfo() ?>

If not enabled
Very rare since a MySQL client library is distributed with PHP and built into PHP by default.
However, it is possible to build PHP without MySQL support. Some possible fixes:
apt-get install php-mysql

rpm -Uvh php-mysql-4.2.2-1.i386.rpm

./configure --with-mysql=shared,/usr
cp modules/mysql.so /usr/local/lib/php

extension_dir=/usr/local/lib/php
extension=mysql.so

-3-

Sanity Check
Make sure MySQL is running
prompt:~> mysqlshow
+-----------+
| Databases |
+-----------+
| mysql |
| test |
+-----------+

Or with the latest PHP
<? echo mysql_stat() ?>

Output:
Uptime: 6717 Threads: 1 Questions: 1 Slow queries: 0 Opens: 6 Flush tables: 1
Open tables: 0 Queries per second avg: 0.000

-4-

Connecting to MySQL
The simple connection
<?
$conn = mysql_connect('localhost');
echo $conn;
?>

Output:
Resource id #28

Other variations
<?
mysql_connect('db.domain.com:33306','rasmus','foobar');
mysql_connect('localhost:/tmp/mysql.sock');
mysql_connect('localhost','rasmus','foobar',
true,MYSQL_CLIENT_SSL|MYSQL_CLIENT_COMPRESS);
?>

-5-

Persistent Connections
The simple connection
<?
$conn = mysql_pconnect('localhost');
echo $conn;
?>

Output:
Resource id #31

Caveats
o Watch out for multi-credential connections
o Make sure you match up max_connections and MaxClients

-6-

Creating a Database
Create a DB
<?
mysql_connect('localhost');
if(mysql_query("CREATE DATABASE foo")) {
echo "Database foo created";
} else {
echo mysql_error();
}
?>

Output:
Database foo created

Create a Table
<?
mysql_select_db('foo');
$result = mysql_query("CREATE TABLE users (
id varchar(16) binary NOT NULL default '',
Password varchar(16) NOT NULL default '',
Name varchar(64) default NULL,
email varchar(64) default NULL,
ts timestamp(14) NOT NULL,
PRIMARY KEY (id)
)");
if($result) {
echo "Table created";
} else {
echo mysql_error();
}
?>

Output:
Table created

-7-

Inserting Data
INSERT Query
<?php
function add_user($id, $pass, $name, $email) {
$result=mysql_query("insert into users values
('$id',ENCRYPT('$pass'),'$name','$email',NULL)");
if($result) {
echo "Row inserted<br />";
} else {
echo mysql_error()."<br />";
}
}


add_user('rasmus','foobar','Rasmus Lerdorf','rasmus@php.net');
add_user('carl','carlspass','Carl AlexandeR Lerdorf','carl@lerdorf.com');
?>

Output:
Row insertedRow inserted

-8-

Selecting Data
SELECT Query
<?
$result = mysql_query("select * from users");
if(!$result) echo mysql_error();
else {
while($row = mysql_fetch_row($result)) {
echo "$row[0] - $row[1] - $row[2] - $row[3] - $row[4]<br />n";
}
}
?>

Output:
rasmus - aVOtbUF2LODnw - Rasmus Lerdorf - rasmus@php.net - 20021206142646
carl - aVOnaDJh48k7o - Carl AlexandeR Lerdorf - carl@lerdorf.com - 20021206142646

mysql_fetch_array()
<?
$result = mysql_query("select * from users order by id");
if(!$result) echo mysql_error();
else {
while($row = mysql_fetch_array($result,MYSQL_ASSOC)) {
echo "$row[id] - $row[Password] - $row[Name] -
$row[email] - $row[ts]<br />n";
}
}
?>

Output:
carl - aVOnaDJh48k7o - Carl AlexandeR Lerdorf -
carl@lerdorf.com - 20021206142646
rasmus - aVOtbUF2LODnw - Rasmus Lerdorf -
rasmus@php.net - 20021206142646

-9-

Dealing with timestamps
Using DATE_FORMAT
<?
$result = mysql_query(
"select id, email,
date_format(ts,'%W %M %D, %Y %r') as d
from users order by ts");
if($result) {
while($row = mysql_fetch_assoc($result)) {
echo "$row[id] - $row[email] - $row[d]<br />n";
}
} else {
echo mysql_error();
}
?>

Output:
rasmus - rasmus@php.net - Friday December 6th, 2002 02:26:46 PM
carl - carl@lerdorf.com - Friday December 6th, 2002 02:26:46 PM

- 10 -

Changing Existing Rows
Using UPDATE
<?
$result = mysql_query(
"update users set email = 'babycarl@lerdorf.com'
where id = 'carl'");
if($result) {
echo mysql_affected_rows();
} else {
echo mysql_error();
}
?>

Output:
1

REPLACE INTO
You can also use REPLACE INTO to update a row if it exists and insert it if it doesn't.

- 11 -

Magic Quotes
Escaping troublesome characters
When you are inserting data into a MySQL database, certain characters have a special meaning and
must therefore be escaped if you wish to insert these characters literally.

By default, PHP will escape these characters for you in any data coming from the user in GET, Post
or Cookie data. This magic escaping is known as Magic Quotes and can be configured in your php.ini
file by setting the magic_quotes_gpc directive.

The characters affected are ' " and NUL (char 0). If these characters appear in user-supplied data
they will be escaped with a (backslash).

Some people prefer to turn this feature off and handle escaping data manually using the addslashes()
function. There is a converse function, stripslashes(), which removes the backslash characters in an
escaped string.

- 12 -

A Simple Guestbook
Guestbook Example
A very simple guestbook example to illustrate basic file handling.
<html><head><title>My Guestbook</title></head>
<body>
<h1>Welcome to my Guestbook</h1>
<h2>Please write me a little note below</h2>
<form action="<?="$PHP_SELF#results"?>" method="POST">
<textarea cols=40 rows=5 name=note wrap=virtual></textarea>
<input type=submit value=" Send it ">
</form>
<?if(isset($note)) {
$fp = fopen("/tmp/notes.txt","a");
fputs($fp,nl2br($note).'<br>');
fclose($fp);
}
?><h2>The entries so far:</h2>
<? @ReadFile("/tmp/notes.txt") ?>
</body></html>

Output:
My Guestbook

Welcome to my Guestbook
Please write me a little note below

The entries so far:

- 13 -

DB-driven Guestbook
SQL'izing the Guestbook Example
We are going to convert this into an SQL-driven guestbook by first creating a database, then a
schema for the table where we will store the data and then we will modify the code.

Create a database
mysqladmin create mydb

Create a Schema
CREATE TABLE comments (
id int(8) DEFAULT '0' NOT NULL auto_increment,
comment text,
ts datetime,
PRIMARY KEY (id)
);

- 14 -

DB-driven Guestbook
SQL'izing the Guestbook Example
Here we add the necessary code to store our guestbook comments in an SQL database
<html><head><title>My Guestbook</title></head>
<body>
<h1>Welcome to my Guestbook</h1>
<h2>Please write me a little note below</h2>
<form action="<? echo "$PHP_SELF#results"?>" method="POST">
<textarea cols=40 rows=5 name="note" wrap=virtual></textarea>
<input type="submit" value=" Send it ">
</form>
<?
mysql_select_db('mydb');
if(isset($note)) {
$ts = date("Y-m-d H:i:s");
mysql_query("insert into comments values
(0,'$note','$ts')");
}
?>
<h2>The entries so far:</h2>
<? $result = mysql_query("select * from comments");
while($row=mysql_fetch_row($result)) {
echo $row[0] ." " . $row[1] . " " . $row[2] . "<br>n";
} ?>
</body></html>

Output:
My Guestbook

Welcome to my Guestbook
Please write me a little note below

The entries so far:

- 15 -

DB Abstraction
A database abstraction layer is bundled with PHP 4. In the example below, the only thing you would
need to change to use a different database is the odbc word on the third line.
<?php
require_once 'DB.php';
$db = DB::connect('odbc://user:pw@host/mydb');
$stmt = $db->prepare('SELECT * FROM comments');
$result = $db->execute($stmt);
while($row = $db->fetchrow($result)) {
while($row as $field => $value ) {
echo "$field: $value<br>n";
}
}
$db->disconnect();
?>

- 16 -

HTTP Headers
You can add headers to the HTTP response in PHP using the Header() function. Since the response
headers are sent before any of the actual response data, you have to send these headers before
outputting any data. So, put any such header calls at the top of your script.

Redirection
<?header('Location: http://www.php.net')?>

Setting a Last-Modified Header
<?header('Last-Modified: '.
gmdate('D, d M Y H:i:s',getlastmod()).' GMT')?>

Avoid all Caching
<?php
Header('Cache-Control: no-cache, must-revalidate');
Header('Pragma: no-cache');
Header('Expires: Mon,26 Jul 1980 05:00:00 GMT');
?>

- 17 -

Cookies
Setting a Session Cookie
<? SetCookie('Cookie_Name','value'); ?>

Setting a Persistent Cookie
<? SetCookie('Cookie_Name','value',
mktime(12,0,0,22,11,2002) ); ?>

Reading a Cookie
<? echo $Cookie_Name; ?>

<? echo $HTTP_COOKIE_VARS['Cookie_Name']; ?>

Deleting the Cookies
<? SetCookie('Cookie_Name',''); ?>

<? SetCookie('Cookie_Name','',
mktime(12,0,0,22,11,1970) ); ?>

Other Optional Paramters
Path, Domain, and Secure parameters can also be set to restrict a cookie to a certain path, domain or
in the case of the Secure parameter, limit the cookie to only be set if the request came in over an SSL
connection.

- 18 -

Cookie Expiry
Problem
Short expiry cookies depend on users having their system clocks set correctly.

Solution
Don't depend on the users having their clocks set right. Embed the timeout based on your server's
clock in the cookie.
<?php
$value = time()+3600 . ':' . $variable;
SetCookie('Cookie_Name',$value);
?>

Then when you receive the cookie, decode it and determine if it is still valid.
<?php
list($ts,$variable) = explode(':',$Cookie_Name,2);
if($ts < time()) {
...
} else {
SetCookie('Cookie_Name','');
}
?>

- 19 -

GD 1/2
Creating a PNG with a TrueType font
<?
Header("Content-type: image/png");
$im = ImageCreate(630,80);
$blue = ImageColorAllocate($im,0x5B,0x69,0xA6);
$white = ImageColorAllocate($im,255,255,255);
$black = ImageColorAllocate($im,0,0,0);
ImageTTFText($im, 45, 0, 10, 57, $black, "CANDY", $text);
ImageTTFText($im, 45, 0, 6, 54, $white, "CANDY", $text);
ImagePNG($im);
?>

<IMG src="txt.php?text=<?echo urlencode($text)?>">

!

- 20 -

Colours
Color Handling
For images with an 8-bit indexed palette it can be tricky to manage colors.
<?
for($r=0; $r<256; $r++) {
$col = ImageColorAllocate($im,$r,0,0);
ImageLine($im, 0,$r, 100, $r, $col);
}
for($g=0; $g<256; $g++) {
$col = ImageColorAllocate($im,0,$g,0);
ImageLine($im, 100,255-$g, 200, 255-$g, $col);
}
for($b=0; $b<256; $b++) {
$col = ImageColorAllocate($im,0,0,$b);
ImageLine($im, 200,$b, 300, $b, $col);
}
Header('Content-Type: image/png');
ImagePNG($im);
?>

Output:

For paletted images the following functions can be useful:
o ImageColorClosest
o ImageColorExact
o ImageColorDeallocate

- 21 -

Colours
Colour Handling
For Truecolor images we have no such issues.
<?
$im = ImageCreateTruecolor(300,256);
for($r=0; $r<256; $r++) {
$col = ImageColorAllocate($im,$r,0,0);
ImageLine($im, 0,$r, 100, $r, $col);
}
for($g=0; $g<256; $g++) {
$col = ImageColorAllocate($im,0,$g,0);
ImageLine($im, 100,255-$g, 200, 255-$g, $col);
}
for($b=0; $b<256; $b++) {
$col = ImageColorAllocate($im,0,0,$b);
ImageLine($im, 200,$b, 300, $b, $col);
}
ImagePNG($im);
?>

Output:

- 22 -

Truecolor Colors
Truecolor color handling
For Truecolor images the colors are actually simple 31-bit longs. Or, think of them as being
composed of 4 bytes arranged like this:

The highest or leftmost bit in the alpha channel is not used which means the alpha channel can only
have values from 0 to 127. You can use the ImageColorAllocate() as with paletted images, but you
can also specify the color directly.

For example:
<?
ImageFilledRectangle($im,0,0,399,299,0x00ffffff);
ImageFilledEllipse($im,200,150,300,300,0x00000000);
ImageAlphaBlending($im,true);
ImageFilledRectangle($im,100,0,400,100,0x60ff1111);
ImagePNG($im);
?>

Output:

This example could also be written like this:
<?php
ImageFilledRectangle($im,0,0,399,299,$white);
ImageFilledEllipse($im,200,150,300,300,$black);
$col = ImageColorResolveAlpha($im,0xff,0x11,0x11,0x60);
ImageFilledRectangle($im,100,0,400,100,$col);

- 23 -

ImagePNG($im);
?>

- 24 -

Truecolor Colors
Truecolor Color Handling
Given the nature of the way truecolor colors are constructed, we can rewrite our color testing strip
using PHP's bitshift operator:
<?
$im = ImageCreateTrueColor(256,60);
for($x=0; $x<256; $x++) {
ImageLine($im, $x, 0, $x, 19, $x);
ImageLine($im, 255-$x, 20, 255-$x, 39, $x<<8);
ImageLine($im, $x, 40, $x, 59, $x<<16);
}
ImagePNG($im);
?>

Output:

- 25 -

ImageColorAt
Using ImageColorAt()

<? $image = "presentations/slides/intro/php-tiny.jpg"; ?>
<img src="<?=$image?>"><br />
<?
$im = imagecreatefromjpeg($image);
$dx = imagesx($im);
$dy = imagesy($im);
for($y = 0; $y < $dy; $y++) {
for($x=0; $x < $dx; $x++) {
$col = imagecolorat($im, $x, $y);
$rgb = imagecolorsforindex($im,$col);
printf("<font color=#%02x%02x%02x>#</font>",
$rgb['red'],$rgb['green'],$rgb['blue']);
}
echo "<br />n";
}
imagedestroy($im);
?>

Output:
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################
################################################################

- 26 -

GD 1/2
CreateFrom and Bounding Box Math
<?
Header("Content-type: image/png");
$font = 'phpi';
if(!$si) $si = 66;
$im = ImageCreateFromPNG('php-blank.png');
$tsize = imagettfbbox($si,0,$font,$text);
$dx = abs($tsize[2]-$tsize[0]);
$dy = abs($tsize[5]-$tsize[3]);
$x = ( imagesx($im) - $dx ) / 2;
$y = ( imagesy($im) - $dy ) / 2 + 3*$dy/4;
$blue = ImageColorAllocate($im,0x5B,0x69,0xA6);
ImageTTFText($im, $si, 0, $x, $y, $white, $font, $text);
ImageTTFText($im, $si, 0, $x+2, $y, $white, $font, $text);
ImageTTFText($im, $si, 0, $x, $y+2, $white, $font, $text);
ImageTTFText($im, $si, 0, $x+2, $y+2, $white, $font, $text);
ImageTTFText($im, $si, 0, $x+1, $y+1, $black, $font, $text);
ImagePNG($im);
?>

<IMG src="txt2.php?text=<?echo urlencode($text)?>&si=<?echo $si?>">

Text: Size: !

- 27 -

Text
Built-in Fonts
GD comes with 5 built-in fonts. They aren't all that useful.
<?
ImageString($im,1,10,20,"Font 1: ABCdef",$black);
ImageStringUp($im,5,150,118,"Vertical Text",$black);
ImagePNG($im);
?>

Output:

- 28 -

TTF Text
TrueType Fonts
You can use any TrueType Font that includes a Unicode mapping table. Fonts such as Wingdings
will not work.
<?
$dir = opendir('/usr/share/fonts/truetype');
$y=30;
while($file = readdir($dir)) {
if(substr($file,strrpos($file,'.'))=='.ttf') {
ImageString($im,5,5,$y-20,substr($file,0,-4),$black);
ImageTTFText($im,30,0,100,$y,$black, substr($file,0,-4),"ABCdéf123");
$y+=40;
}
}
ImagePNG($im);
?>

Output:

- 29 -

EXIF
Reading EXIF Headers from a JPEG
<?php
$data = exif_read_data('presentations/slides/intro/img_resize.jpg');
foreach($data as $key=>$val) {
if(is_array($val)) {
foreach($val as $k=>$v) {
echo $key."[$k]: $v<br />n";
}
} else
echo "$key: ".@substr($val,0,40)."<br />n";
}
?>

Output:
FileName: img_resize.jpg
FileDateTime: 1027351588
FileSize: 669158
FileType: 2
MimeType: image/jpeg
SectionsFound: ANY_TAG, IFD0, THUMBNAIL, EXIF
COMPUTED[html]: width="1536" height="1024"
COMPUTED[Height]: 1024
COMPUTED[Width]: 1536
COMPUTED[IsColor]: 1
COMPUTED[ByteOrderMotorola]: 0
COMPUTED[ApertureFNumber]: f/4.0
COMPUTED[FocusDistance]: 1.07m
COMPUTED[Thumbnail.FileType]: 8
COMPUTED[Thumbnail.MimeType]: image/tiff
COMPUTED[Thumbnail.Height]: 64
COMPUTED[Thumbnail.Width]: 96
Make: Eastman Kodak Company
Model: KODAK DC265 ZOOM DIGITAL CAMERA (V01.00)
Orientation: 1
XResolution: 150/1
YResolution: 150/1
ResolutionUnit: 2
YCbCrPositioning: 1
Exif_IFD_Pointer: 190
THUMBNAIL[ImageWidth]: 96
THUMBNAIL[ImageLength]: 64
THUMBNAIL[BitsPerSample]: Array
THUMBNAIL[Compression]: 1
THUMBNAIL[PhotometricInterpretation]: 2
THUMBNAIL[StripOffsets]: 1748
THUMBNAIL[Orientation]: 1
THUMBNAIL[SamplesPerPixel]: 3
THUMBNAIL[RowsPerStrip]: 64
THUMBNAIL[StripByteCounts]: 18432
THUMBNAIL[XResolution]: 72/1
THUMBNAIL[YResolution]: 72/1
THUMBNAIL[PlanarConfiguration]: 1
THUMBNAIL[ResolutionUnit]: 2
ExposureTime: 1/250
FNumber: 400/100
ExifVersion: 0200
DateTimeOriginal: 1999:01:31 04:17:59
ComponentsConfiguration:

Fetching an embedded thumbnail
<?

- 31 -

Header('Content-type: image/tiff');
echo exif_thumbnail('p0004557.jpg');
?>

- 32 -

PDFs on-the-fly
A PDF Invoice
<?php
$pdf = pdf_new();
pdf_open_file($pdf);
pdf_set_info($pdf, "Author","Rasmus Lerdorf");
pdf_set_info($pdf, "Title","Sample Invoice");
pdf_set_info($pdf, "Creator", "See Author");
pdf_set_info($pdf, "Subject", "Sample Invoice");

$sizes = array('a4'=>'595x842', 'letter'=>'612x792', 'legal'=>'612x1008');

if(!isset($type)) $type='letter';
list($x,$y) = explode('x',$sizes[$type]);

$items = array(array('Our special low-cost widget that does everything','299.99'),
array('Our special high-cost widget that does more','1899'),
array('A blue widget','29.95'),
array('And a red widget','49.95'),
array('A yellow widget that makes noise','49.9'),
array('And one that doesn't','999.95'),
);

pdf_begin_page($pdf, $x, $y);

$im = pdf_open_jpeg($pdf, "php-big.jpg");
pdf_place_image($pdf, $im, 5, $y-72, 0.5);
pdf_close_image ($pdf,$im);

pdf_set_value($pdf, 'textrendering', 0); // fill

pdf_set_font($pdf, "Helvetica" , 12, winansi);
pdf_show_xy($pdf, 'Generic Evil Company Inc.',145,$y-20);
pdf_continue_text($pdf, '123 Main Street');
pdf_continue_text($pdf, 'Dark City, CA 98765');

pdf_show_xy($pdf, 'Helpless Customer Ltd.',20,$y-100);
pdf_continue_text($pdf, '2 Small Street');
pdf_continue_text($pdf, 'Little Town, ID 56789');

pdf_show_xy($pdf, 'Terms: Net 30',150,$y-100);
pdf_continue_text($pdf, 'PO #: 12345');

pdf_set_font($pdf, "Helvetica-Bold" , 30, winansi);
pdf_show_xy($pdf, "* I N V O I C E *",$x-250,$y-112);

pdf_setcolor($pdf,'fill','gray',0.9,0,0,0);
pdf_rect($pdf,20,80,$x-40,$y-212);
pdf_fill_stroke($pdf);

$offset = 184; $i=0;
while($y-$offset > 80) {
pdf_setcolor($pdf,'fill','gray',($i%2)?0.8:1,0,0,0);
pdf_setcolor($pdf,'stroke','gray',($i%2)?0.8:1,0,0,0);
pdf_rect($pdf,21,$y-$offset,$x-42,24);
pdf_fill_stroke($pdf);
$i++; $offset+=24;
}

pdf_setcolor($pdf,'fill','gray',0,0,0,0);
pdf_setcolor($pdf,'stroke','gray',0,0,0,0);
pdf_moveto($pdf, 20,$y-160);
pdf_lineto($pdf, $x-20,$y-160);

- 33 -

pdf_stroke($pdf);

pdf_moveto($pdf, $x-140,$y-160);
pdf_lineto($pdf, $x-140,80);
pdf_stroke($pdf);

pdf_set_font($pdf, "Times-Bold" , 18, winansi);
pdf_show_xy($pdf, "Item",30,$y-150);
pdf_show_xy($pdf, "Price",$x-100,$y-150);

pdf_set_font($pdf, "Times-Italic" , 15, winansi);

$offset = 177;
foreach($items as $item) {
pdf_show_xy($pdf, $item[0],30,$y-$offset);
pdf_show_boxed($pdf, '$'.number_format($item[1],2), $x-55, $y-$offset, 0, 0,
'right');
$offset+=24;
$total += $item[1];
}

pdf_set_font($pdf, "Times-Bold" , 17, winansi);
$offset+=24;
pdf_show_xy($pdf, 'Total',30,$y-$offset);
pdf_show_boxed($pdf, '$'.number_format($total,2), $x-55, $y-$offset, 0, 0,
'right');

pdf_end_page($pdf);
pdf_close($pdf);

$data = pdf_get_buffer($pdf);
header('Content-type: application/pdf');
header("Content-disposition: inline; filename=invoice.pdf");
header("Content-length: " . strlen($data));
echo $data;
?>

Output:

- 34 -

Ming-Flash
See http://www.opaque.net/ming/
<?
$s = new SWFShape();
$fp = fopen('php-big.jpg','r');
$jpg = new SWFBitmap($fp);
$w = $jpg->getWidth(); $h = $jpg->getHeight();

$f = $s->addFill($jpg);
$f->moveTo(-$w/2, -$h/2);
$s->setRightFill($f);

$s->movePenTo(-$w/2, -$h/2);
$s->drawLine($w, 0);
$s->drawLine(0, $h);
$s->drawLine(-$w, 0);
$s->drawLine(0, -$h);

$p = new SWFSprite();
$i = $p->add($s);

for($step=0; $step<360; $step+=2) {
$p->nextFrame();
$i->rotate(-2);
}

$m = new SWFMovie();
$i = $m->add($p);
$i->moveTo(230,120);
$m->setRate(100);
$m->setDimension($w*1.8, $h*1.8);

header('Content-type: application/x-shockwave-flash');
$m->output();
?>

Output:

- 35 -

More Ming
Flash + RSS/XML
<?php
require 'XML/RSS.php';

$r =& new XML_RSS('slashdot.rdf');
$r->parse();

$allItems = $r->getItems();
$itemCount = count($allItems);
$width = 1000;
$m = new SWFMovie();
$m->setDimension($width, 70);
$m->setBackground(0xcf, 0xcf, 0xcf);

$f = new SWFFont("../../../fonts/Techno.fdb");

$hit = new SWFShape();
$hit->setRightFill($hit->addFill(0,0,0));
$hit->movePenTo(-($width/2), -30);
$hit->drawLine($width, 0);
$hit->drawLine(0, 60);
$hit->drawLine(-$width, 0);
$hit->drawLine(0, -60);
$x = 0;

// build the buttons
foreach($allItems as $Item) {

$title = $Item['title'];
$link = $Item['link'];

// get the text
$t = new SWFText();
$t->setFont($f);
$t->setHeight(50);
$t->setColor(0,0,0);
$t->moveTo(-$f->getWidth($title)/2, 25);
$t->addString($title);

// make a button
$b[$x] = new SWFButton();
$b[$x]->addShape($hit, SWFBUTTON_HIT);
$b[$x]->addShape($t, SWFBUTTON_OVER | SWFBUTTON_UP | SWFBUTTON_DOWN);
$b[$x++]->addAction(new SWFAction("getURL('$link','_new');"), SWFBUTTON_MOUSEUP);
}

// display them
for($x=0; $x<$itemCount; $x++) {

$i = $m->add($b[$x]);
$i->moveTo($width/2,30);

for($j=0; $j<=30; ++$j) {
$i->scaleTo(sqrt(sqrt($j/30)));
$i->multColor(1.0, 1.0, 1.0, $j/30);
$m->nextFrame();
}

for($j=0; $j<=30; ++$j) {
$i->scaleTo(sqrt(sqrt(1+($j/30))));
$i->multColor(1.0, 1.0, 1.0, (30-$j)/30);
$m->nextFrame();
}

- 36 -

$m->remove($i);

}

header('Content-type: application/x-shockwave-flash');
$m->output();
?>

Output:

- 37 -

Cool!
Super-cool Dynamic Image Generator
Want to be cooler than all your friends? Well here it is!

First, set up an ErrorDocument 404 handler for your images directory.
<Directory /home/doc_root/images>
ErrorDocument 404 /images/generate.php
</Directory>')

Then generate.php looks like this:
<?php
$filename = basename($_SERVER['REDIRECT_URL']);
if(preg_match('/^([^_]*?)_([^_]*?)_([^_]*?).(.*?)$/',$filename, $reg)) {
$type = $reg[1];
$text = $reg[2];
$rgb = $reg[3];
$ext = $reg[4];
}

if(strlen($rgb)==6) {
$r = hexdec(substr($rgb,0,2));
$g = hexdec(substr($rgb,2,2));
$b = hexdec(substr($rgb,4,2));
} else $r = $g = $b = 0;

switch(strtolower($ext)) {
case 'jpg':
Header("Content-Type: image/jpg");
break;
case 'png':
case 'gif': /* We don't do gif - send a png instead */
Header("Content-Type: image/png");
break;
default:
break;
}

switch($type) {
case 'solid':
$im = imagecreatetruecolor(80,80);
$bg = imagecolorallocate($im, $r, $g, $b);
imagefilledrectangle($im,0,0,80,80,$bg);
break;
case 'button':
$si = 32; $font = "php";
$im = imagecreatefrompng('blank_wood.png');
$tsize = imagettfbbox($si,0,$font,$text);
$dx = abs($tsize[2]-$tsize[0]);
$dy = abs($tsize[5]-$tsize[3]);
$x = ( imagesx($im) - $dx ) / 2;
$y = ( imagesy($im) - $dy ) / 2 + $dy;
$black = ImageColorAllocate($im,$r,$g, $b);
ImageTTFText($im, $si, 0, $x, $y, $white, $font, $text);
ImageTTFText($im, $si, 0, $x+2, $y, $white, $font, $text);
ImageTTFText($im, $si, 0, $x, $y+2, $white, $font, $text);
ImageTTFText($im, $si, 0, $x+2, $y+2, $white, $font, $text);
ImageTTFText($im, $si, 0, $x+1, $y+1, $black, $font, $text);
break;
}
Header("HTTP/1.1 200 OK");
$dest_file = dirname($_SERVER['SCRIPT_FILENAME']).'/'.$filename;
switch(strtolower($ext)) {

- 38 -

case 'png':
case 'gif':
@ImagePNG($im,$dest_file);
ImagePNG($im);
break;
case 'jpg':
@ImageJPEG($im,$dest_file);
ImageJPEG($im);
break;
}
?>

The URL, http://localhost/images/button_test_000000.png produces this image:

- 39 -

Sessions
Starting a Session
To start a session use session_start() and to register a variable in this session use the $_SESSION
array.
<?php
session_start();
$_SESSION['my_var'] = 'Hello World';
?>

If register_globals is enabled then your session variables will be available as normal variables on
subsequent pages. Otherwise they will only be in the $_SESSION array.
<?php
session_start();
echo $_SESSION['my_var'];
?>

- 40 -

Session Configuration
Default session settings are set in your php.ini file:
session.save_handler = files ; Flat file backend
session.save_path=/tmp ; where to store flat files
session.name = PHPSESSID ; Name of session (cookie name)
session.auto_start = 0 ; init session on req startup
session.use_cookies = 1 ; whether cookies should be used
session.use_only_cookies = 0 ; force only cookies to be used
session.cookie_lifetime = 0 ; 0 = session cookie
session.cookie_path = / ; path for which cookie is valid
session.cookie_domain = ; the cookie domain
session.serialize_handler = php ; serialization handler (wddx|php)
session.gc_probability = 1 ; garbage collection prob.
session.gc_dividend = 100 ; If 100, then above is in %
session.gc_maxlifetime = 1440 ; garbage collection max lifetime
session.referer_check = ; filter out external URL's
session.entropy_length = 0 ; # of bytes from entropy source
session.entropy_file = ; addtional entropy source
session.use_trans_sid = 1 ; use automatic url rewriting
url_rewriter.tags = "a=href,area=href,frame=src,input=src"
session.cache_limiter = nocache ; Set cache-control headers
session.cache_expire = 180 ; expiry for private/public caching

Cache-control is important when it comes to sessions. You have to be careful that end-user client
caches aren't caching invalid pages and also that intermediary proxy-cache mechanisms don't sneak in
and cache pages on you. When cache-limiter is set to the default, no-cache, PHP generates a set of
response headers that look like this:
HTTP/1.1 200 OK
Date: Sat, 10 Feb 2001 10:21:59 GMT
Server: Apache/1.3.13-dev (Unix) PHP/4.0.5-dev
X-Powered-By: PHP/4.0.5-dev
Set-Cookie: PHPSESSID=9ce80c83b00a4aefb384ac4cd85c3daf; path=/
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Connection: close
Content-Type: text/html

For cache_limiter = private the cache related headers look like this:
Set-Cookie: PHPSESSID=b02087ce4225987870033eba2b6d78c3; path=/
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: private, max-age=10800, pre-check=10800

For cache_limiter = public they look like this:
Set-Cookie: PHPSESSID=37421e3d0283c667f75481745b25b9ad; path=/
Expires: Tue, 12 Feb 2001 13:57:16 GMT
Cache-Control: public, max-age=10800

- 41 -

Custom Backend
You can change the session backend datastore from a script using session_module_name().
<?php
session_module_name("files"); // ASCII files

session_module_name("mm"); // Shared memory

session_module_name("user"); // Custom session backend
?>

You can also define your own custom session backend datastore using the
session_set_save_handler() function.
<?php
session_set_save_handler("myOpen", "myClose",
"myRead", "myWrite",
"myDestroy", "myGC");
?>

You would then write these 6 functions.

- 42 -

Custom Backend
Let's have a look at an actual custom session backend. This uses MySQL to store the session data.
We could set these right in the script, but let's make use of Apache's httpd.conf file to set our custom
save handler for a portion of our web site.
<Directory "/var/html/test">
php_value session.save_handler user
php_value session.save_path mydb
php_value session.name sessions
</Directory>

The MySQL schema looks like this:
CREATE TABLE sessions (
id char(32) NOT NULL,
data text,
ts timestamp,
PRIMARY KEY (id)
)

We can now write our handler. It looks like this:
<?php
function open($db,$name) {
global $table;
mysql_select_db($db);
$table = $name;
return true;
}

function close() {
mysql_close();
return true;
}

function read($id) {
global $table;
$result = mysql_query("select data from $table where id='$id'");
if($result && mysql_num_rows($result)) {
return mysql_result($result,0);
} else {
error_log("read: ".mysql_error()."n",3,"/tmp/errors.log");
return "";
}
}

function write($id, $data) {
global $table;
$data = addslashes($data);
mysql_query("replace into $table (id,data) values('$id','$data')")
or error_log("write: ".mysql_error()."n",3,"/tmp/errors.log");
return true;
}

function destroy($id) {
global $table;
mysql_query("delete from $table where where id='$id'");
}

function gc($max_time) {
global $table;
mysql_query(
"delete from $table where UNIX_TIMESTAMP(ts)<UNIX_TIMESTAMP()-$max_time")

- 43 -

or error_log("gc: ".mysql_error()."n",3,"/tmp/errors.log");
return true;
}

session_set_save_handler('open','close','read','write','destroy','gc');
?>

Our PHP files under /var/html/test then simply need to look something like this:
<?php
require 'handler.php';

session_start();
session_register('var');
$var = "Hello World";
?>

- 44 -

register_globals
PHP automatically creates global variables containing data from a variety of external sources. This
feature can be turned off by turning off the register_globals setting. With register_globals you can
access this data via a number of special associative arrays listed below.

$_GET['foo']='bar'
http://www.php.net/index.php?foo=bar

$_POST['foo']='bar'
<form action="script.php" method="POST">
<input type="text" name="foo" value="bar">
</form>

$_COOKIE['foo']='bar'
<?php
SetCookie('foo','bar');
?>

$_REQUEST['foo']='bar'
<?php
SetCookie('foo','bar');
?>

$_SERVER
Special variables set by your web server. You can get a list of what is set by running this code on
your server:
<?php
foreach($_SERVER as $key=>$val) {
echo '$_SERVER['.$key."] = $val<br>n";
}
?>
$_SERVER[DOCUMENT_ROOT] = /home/rasmus/phpweb
$_SERVER[HTTP_ACCEPT] = text/xml,application/xml,application/xht...
$_SERVER[HTTP_ACCEPT_CHARSET] = ISO-8859-1, utf-8;q=0.66, *;q=0.66
$_SERVER[HTTP_ACCEPT_ENCODING] = gzip, deflate, compress;q=0.9
$_SERVER[HTTP_ACCEPT_LANGUAGE] = en-us, en;q=0.50
$_SERVER[HTTP_CACHE_CONTROL] = max-age=0
$_SERVER[HTTP_CONNECTION] = keep-alive
$_SERVER[HTTP_COOKIE] = dims=1014_690; PHPSESSID=c1c486d22f970af...
$_SERVER[HTTP_HOST] = localhost
$_SERVER[HTTP_KEEP_ALIVE] = 300
$_SERVER[HTTP_REFERER] = http://localhost/pres2/index.php/PHP
$_SERVER[HTTP_USER_AGENT] = Mozilla/5.0 (X11; U; Linux i686; en-US; ...
$_SERVER[PATH] = /usr/local/bin:/bin:/usr/bin:/usr/sbin:/...
$_SERVER[REMOTE_ADDR] = 127.0.0.1
$_SERVER[REMOTE_PORT] = 1099
$_SERVER[SCRIPT_FILENAME] = /home/rasmus/phpweb/pres2/show.php
$_SERVER[SERVER_ADDR] = 127.0.0.1
$_SERVER[SERVER_ADMIN] = rasmus@lerdorf.com
$_SERVER[SERVER_NAME] = localhost
$_SERVER[SERVER_PORT] = 80
$_SERVER[SERVER_SIGNATURE] = Apache/1.3.28-dev Server at localhost Po...
$_SERVER[SERVER_SOFTWARE] = Apache/1.3.28-dev (Unix) PHP/4.4.0-dev
$_SERVER[GATEWAY_INTERFACE] = CGI/1.1
$_SERVER[SERVER_PROTOCOL] = HTTP/1.1

- 45 -

$_SERVER[REQUEST_METHOD] = GET
$_SERVER[QUERY_STRING] =
$_SERVER[REQUEST_URI] = /pres2/show.php/veracruz
$_SERVER[SCRIPT_NAME] = /pres2/show.php
$_SERVER[PATH_INFO] = /veracruz
$_SERVER[PATH_TRANSLATED] = /home/rasmus/phpweb/veracruz
$_SERVER[PHP_SELF] = /pres2/show.php/veracruz
$_SERVER[argv] = Array
$_SERVER[argc] = 0

$_ENV
Environment variables that were present at server startup time. Note that environment variables
created by PHP using putenv() will not be shown here, nor do they persist beyond the request.
$_ENV[MANPATH] = /usr/man:/usr/local/man:/usr/share/man
$_ENV[SUPPORTED] = en_US:en
$_ENV[SSH_AGENT_PID] = 855
$_ENV[HOSTNAME] = thinkpad.lerdorf.com
$_ENV[HOST] = thinkpad.lerdorf.com
$_ENV[TERM] = xterm
$_ENV[SHELL] = /bin/tcsh
$_ENV[GTK_RC_FILES] = /etc/gtk/gtkrc:/home/rasmus/.gtkrc-1.2-g...
$_ENV[WINDOWID] = 27263119
$_ENV[QTDIR] = /usr/lib/qt3-gcc3.2
$_ENV[BK_HOST] = mysql.com
$_ENV[USER] = root
$_ENV[GROUP] = rasmus
$_ENV[LS_COLORS] = no=00:fi=00:di=00;34:ln=00;36:pi=40;33:s...
$_ENV[SUDO_USER] = rasmus
$_ENV[GDK_USE_XFT] = 1
$_ENV[SUDO_UID] = 500
$_ENV[HOSTTYPE] = i386-linux
$_ENV[SSH_AUTH_SOCK] = /tmp/ssh-XXpcCouR/agent.843
$_ENV[SESSION_MANAGER] = local/thinkpad.lerdorf.com:/tmp/.ICE-uni...
$_ENV[PAGER] = /usr/bin/less
$_ENV[BK_LICENSE] = ACCEPTED
$_ENV[BK_USER] = rasmus
$_ENV[PATH] = /usr/local/bin:/bin:/usr/bin:/usr/sbin:/...
$_ENV[MAIL] = /var/mail/rasmus
$_ENV[PWD] = /home/rasmus/phpweb/pres2/presentations
$_ENV[XMODIFIERS] = @im=none
$_ENV[EDITOR] = vi
$_ENV[LANG] = en_US
$_ENV[NPROMPT] = %{[34;1m%}%t %m:%~>%{[0m%} >
$_ENV[SSH_ASKPASS] = /usr/libexec/openssh/gnome-ssh-askpass
$_ENV[SUDO_COMMAND] = /bin/tcsh
$_ENV[HOME] = /home/rasmus
$_ENV[SHLVL] = 5
$_ENV[OSTYPE] = linux
$_ENV[GNOME_DESKTOP_SESSION_ID] = Default
$_ENV[VENDOR] = intel
$_ENV[LOGNAME] = root
$_ENV[MACHTYPE] = i386
$_ENV[MOZILLA_XFT] = 1
$_ENV[VISUAL] = vi
$_ENV[LESSOPEN] = |/usr/bin/lesspipe.sh %s
$_ENV[SUDO_GID] = 500
$_ENV[DISPLAY] = :0
$_ENV[G_BROKEN_FILENAMES] = 1
$_ENV[COLORTERM] = gnome-terminal
$_ENV[XAUTHORITY] = /home/rasmus/.Xauthority
$_ENV[_] = /usr/sbin/httpd

$_FILES
Used for the RFC1867 file upload feature.
$_FILES['userfile']['name']

- 46 -

$_FILES['userfile']['type']
$_FILES['userfile']['size']
$_FILES['userfile']['tmp_name']

$HTTP_RAW_POST_DATA
When the mime type associated with the POST data is unrecognized or not set, the raw post data is
available in this variable.

- 47 -

Safe Mode
Safe Mode is an attempt to solve the shared-server security problem. It is architecturally incorrect to
try to solve this problem at the PHP level, but since the alternatives at the web server and OS levels
aren't very realistic, many people, especially ISP's, use safe mode for now.

The configuration directives that control safe mode are:
safe_mode = Off
open_basedir =
safe_mode_exec_dir =
safe_mode_allowed_env_vars = PHP_
safe_mode_protected_env_vars = LD_LIBRARY_PATH
disable_functions =

When safe_mode is on, PHP checks to see if the owner of the current script matches the owner of the
file to be operated on by a file function.

For example:
-rw-rw-r-- 1 rasmus rasmus 33 Jul 1 19:20 script.php
-rw-r--r-- 1 root root 1116 May 26 18:01 /etc/passwd

Running this script.php
<?php
readfile('/etc/passwd');
?>

results in this error when safe mode is enabled:
<b>Warning</b>: SAFE MODE Restriction in effect. The script whose uid is 500 is
not allowed to access /etc/passwd owned by uid 0 in <b>/docroot/script.php</b> on
line <b>2</b>

If instead of safe_mode, you set an open_basedir directory then all file operations will be limited to
files under the specified directory. For example (Apache httpd.conf example):
<Directory /docroot>
php_admin_value open_basedir /docroot
</Directory>

If you run the same script.php with this open_basedir setting then this is the result:
<b>Warning</b>: open_basedir restriction in effect. File is in wrong directory in
<b>/docroot/script.php</b> on line <b>2</b>

You can also disable individual functions. If we add this to our php.ini file:
disable_functions readfile,system

Then we get this output:
<b>Warning</b>: readfile() has been disabled for security reasons in
<b>/docroot/script.php</b> on line <b>2</b>

- 48 -

Security
Watch for uninitialized variables
<?php
if($user=='rasmus') {
$ok = true;
}

if($ok) {
echo "$user logged in";
}
?>

Catch these by setting the error_reporting level to E_ALL. The above script would generate this
warning (assuming $user is set):
<b>Warning</b>: Undefined variable: ok in <b>script.php</b> on line <b>6</b>

You can of course also turn off register_globals, but that addresses the symptom rather than the
problem.

- 49 -

Security
Never trust user data!
<?php
readfile($filename);
?>

Turning off register_globals doesn't make this any more secure. The script would instead look like
this:
<?php
readfile($HTTP_POST_VARS['filename']);
?>

The only way to secure something like this is to be really paranoid about cleaning user input. In this
case if you really want the user to be able to specify a filename that gets used in any of PHP's file
functions, do something like this:
<?php
$doc_root = $HTTP_SERVER_VARS['DOCUMENT_ROOT'];
$filename = realpath($filename);
readfile($doc_root.$filename);
?>

You may also want to strip out any path and only take the filename component. An easy way to do
that is to use the basename() function. Or perhaps check the extension of the file. You can get the
extension using this code:
<?php
$ext = substr($str,strrpos($str,'.'));
?>

- 50 -

Security
Again, never trust user data!
<?php
system("ls $dir");
?>

In this example you want to make sure that the user can't pass in $dir set to something like: ".;cat
/etc/passwd" The remedy is to use escapeshellarg() which places the argument inside single quotes
and escapes any single quote characters in the string.
<?php
$dir=escapeshellarg($dir);
system("ls $dir");
?>

Beyond making sure users can't pass in arguments that executes other system calls, make sure that
the argument itself is ok and only accesses data you want the users to have access to.

- 51 -

Security
Many users place code in multiple files and include these files:
<?php
require 'functions.inc';
?>

Or perhaps
<?php
require 'functions.php';
?>

Both of these can be problematic if the included file is accessible somewhere under the
DOCUMENT_ROOT directory. The best solution is to place these files outside of the
DOCUMENT_ROOT directory where they are not accessible directly. You can add this external
directory to your include_path configuration setting.

Another option is to reject any direct requests for these files in your Apache configuration. You can
use a rule like this in your "httpd.conf" file:
<Files ~ ".inc$">
Order allow,deny
Deny from all
</Files>

- 52 -

Security
Take this standard file upload form:
<FORM ENCTYPE="multipart/form-data" ACTION="upload.php" METHOD=POST>
<INPUT TYPE="hidden" name="MAX_FILE_SIZE" value="100000">
Send this file: <INPUT NAME="myfile" TYPE="file">
<INPUT TYPE="submit" VALUE="Send File">
</FORM>

The correct way to put the uploaded file in the right place:
<?php
/* Not under DOCUMENT_ROOT */
$destination = "/some/path/$myfile_name";

move_uploaded_file($myfile, $destination);
?>

If you are uploading files to be placed somewhere under the DOCUMENT_ROOT then you need to
be very paranoid in checking what you are putting there. For example, you wouldn't want to let people
upload arbitrary PHP scripts that they can then browse to in order to execute them. Here we get
paranoid about checking that only image files can be uploaded. We even look at the contents of the
file and ensure that the file extension matches the content.
<?php
$type = $HTTP_POST_FILES['myfile']['type'];
$file = $HTTP_POST_FILES['myfile']['tmp_name'];
$name = $HTTP_POST_FILES['myfile']['name'];
$types = array(0,'.gif','.jpg','.png','.swf');
list(,,$type) = getimagesize($file);
if($type) {
$name = substr($name,0,strrpos($str,'.'));
$name .= $types[$type];
}
move_uploaded_file($myfile, "$DOCUMENT_ROOT/images/$name");
?>

- 53 -

References
References are not pointers!
<?php
$foo = 'Hello';
$bar = 'World';
?>

<?php
$bar = & $foo;
?>

- 54 -

Returning References
Passing arguments to a function by reference
<?php
function inc(& $b) {
$b++;
}
$a = 1;
inc($a);
echo $a;
?>

Output:
2

A function may return a reference to data as opposed to a copy
<?php
function & get_data() {
$data = "Hello World";
return $data;
}
$foo = & get_data();
?>

- 55 -

Adding an extension
Problem
You need PHP's built-in ftp functions for the ultra-cool script you are writing, but your service
provider does not have PHP compiled with the --enable-ftp option.

Solution
If you have a shell account on a system with the same operating system as your web server, grab the
PHP source tarball and build using:
--with-apxs --enable-ftp=shared

You can check which flags your provider used by putting a phpinfo() call in a script on your server.
<?phpinfo()?>

Once compiled, you will find a "modules/ftp.so" file which you can copy to your web server and
enable either by putting:
extension=ftp.so

in your php.ini file or by adding this to the top of your script:
<?php dl("ftp.so") ?>

- 56 -

$PATH_INFO
$PATH_INFO is your friend when it comes to creating clean URLS. Take for example this URL:
http://www.company.com/products/routers

If the Apache configuration contains this block:
<Location "/products">
ForceType application/x-httpd-php
</Location>

Then all you have to do is create a PHP script in your DOCUMENT_ROOT named 'products' and
you can use the $PATH_INFO variable which will contain the string, '/routers', to make a DB query.

- 57 -

ErrorDocument
Apache's ErrorDocument directive can come in handy. For example, this line in your Apache
configuration file:
ErrorDocument 404 /error.php

Can be used to redirect all 404 errors to a PHP script. The following server variables are of interest:
o $REDIRECT_ERROR_NOTES - File does not exist: /docroot/bogus
o $REDIRECT_REQUEST_METHOD - GET
o $REDIRECT_STATUS - 404
o $REDIRECT_URL - /docroot/bogus
Don't forget to send a 404 status if you choose not to redirect to a real page.
<? Header('HTTP/1.0 404 Not Found'); ?>

Interesting uses
o Search for closest matching valid URL and redirect
o Use attempted url text as a DB keyword lookup
o Funky caching

- 58 -

Funky Caching
An interesting way to handle caching is to have all 404's redirected to a PHP script.
ErrorDocument 404 /generate.php

Then in your generate.php script use the contents of $REDIRECT_URI to determine which URL the
person was trying to get to. In your database you would then have fields linking content to the URL
they affect and from that you should be able to generate the page. Then in your generate.php script do
something like:
<?php
$s = $REDIRECT_URI;
$d = $DOCUMENT_ROOT;
// determine requested uri
$uri = substr($s, strpos($s,$d) + strlen($d) + 1);
ob_start(); // Start buffering output
// ... code to fetch and output content from DB ...
$data = ob_get_contents();
$fp = fopen("$DOCUMENT_ROOT/$uri",'w');
fputs($fp,$data);
fclose($fp);
ob_end_flush(); // Flush and turn off buffering
?>

So, the way it works, when a request comes in for a page that doesn't exist, generate.php checks the
database and determines if it should actually exist and if so it will create it and respond with this
generated data. The next request for that same URL will get the generated page directly. So in order
to refresh your cache you simply have to delete the files.

- 59 -

Variable variables
A variable variable looks like this: $$var

So, if $var = 'foo' and $foo = 'bar' then $$var would contain the value 'bar' because $$var can be
thought of as $'foo' which is simply $foo which has the value 'bar'.

Variable variables sound like a cryptic a useless concept, but they can be useful sometimes. For
example, if we have a configuration file consisting of configuration directives and values in this
format:
foo=bar
abc=123

Then it is very easy to read this file and create corresponding variables:
<?php
$fp = fopen('config.txt','r');
while(true) {
$line = fgets($fp,80);
if(!feof($fp)) {
if($line[0]=='#' || strlen($line)<2) continue;
list($name,$val)=explode('=',$line,2);
$$name=trim($val);
} else break;
}
fclose($fp);
?>

Along the same lines as variable variables, you can create compound variables and variable
functions.
<?php
$str = 'var';
$var_toaster = "Hello World";
echo ${$str.'_toaster'};

$str(); // Calls a function named var()
${$str.'_abc'}(); // Calls a function named var_abc()
?>

- 60 -

Optimization
Don't use a regex if you don't have to
PHP has a rich set of string manipulation functions - use them!
BAD: <? $new = ereg_replace("-","_",$str); ?>

GOOD:<? $new = str_replace("-","_",$str); ?>

BAD: <? preg_match('/(..*?)$/',$str,$reg);?>

GOOD:<? substr($str,strrpos($str,'.')); ?>

Use References if you are passing large data structs around to save memory
There is a tradeoff here. Manipulating references is actually a bit slower than making copies of your
data, but with references you will be using less memory. So you need to determine if you are cpu or
memory bound to decide whether to go through and look for places to pass references to data instead
of copies.

Use Persistent Database connections
Some database are slower than others at establising new connections. The slower it is, the more of an
impact using persistent connections will have. But, keep in mind that persistent connections will sit
and tie up resources even when not in use. Watch your resource limits as well. For example, by
default Apache's

Using MySQL? Check out mysql_unbuffered_query()
Use it exactly like you would mysql_query(). The difference is that instead of waiting for the entire
query to finish and storing the result in the client API, an unbuffered query makes results available to
you as soon as possible and they are not allocated in the client API. You potentially get access to
your data quicker, use a lot less memory, but you can't use mysql_num_rows() on the result resource
and it is likely to be slightly slower for small selects.

Hey Einstein!
Don't over-architect things. If your solution seems complex to you, there is probably a simpler and
more obvious approach. Take a break from the computer and go out into the big (amazingly realistic)
room and think about something else for a bit.

- 61 -

PHP Opcode Caches
Standard PHP

PHP with an Opcode Cache

- 62 -

PHP Opcode Caches
There are a number of them out there.
o APC - open source
o IonCube Accelerator - free, but closed source
o Zend Cache - commercial
Installation
Typically very trivial. For IonCube, for example, in your php.ini add:

zend_extension = "/usr/local/lib/php/php_accelerator_1.3.3r2.so"

So why isn't this just built into standard PHP?

This gets asked often, and although not a good answer, the answer is that since it wasn't in PHP from
the start a number of competing plugin cache systems were developed and choosing one over another
at this point would effectively chop these projects, both commercial and free, off at their knees. This
way they can compete and innovate against each other at the cost of duplicated effort.

- 64 -

Profiling PHP
www:~> cd /usr/local/lib/php
www:/usr/local/lib/php> ln -s extensions/no-debug-non-zts-20020429/apd.so apd.so

Then in your php.ini file:
zend_extension = "/usr/local/lib/php/apd.so"
apd.dumpdir = /tmp

It isn't completely transparent. You need to tell the profiler when to start profiling. At the top of a
script you want to profile, add this call:
<?php
apd_set_pprof_trace();
?>

The use the command-line tool called pprofp:
wwww: ~> pprofp
pprofp <flags> <trace file>
Sort options
-a Sort by alphabetic names of subroutines.
-l Sort by number of calls to subroutines
-m Sort by memory used in a function call.
-r Sort by real time spent in subroutines.
-R Sort by real time spent in subroutines (inclusive of child calls).
-s Sort by system time spent in subroutines.
-S Sort by system time spent in subroutines (inclusive of child
calls).
-u Sort by user time spent in subroutines.
-U Sort by user time spent in subroutines (inclusive of child calls).
-v Sort by average amount of time spent in subroutines.
-z Sort by user+system time spent in subroutines. (default)

Display options
-c Display Real time elapsed alongside call tree.
-i Suppress reporting for php builtin functions
-O <cnt> Specifies maximum number of subroutines to display. (default 15)
-t Display compressed call tree.
-T Display uncompressed call tree.

www: ~> ls -latr /tmp/pprofp.*
-rw-r--r-- 1 nobody nobody 16692 Dec 3 01:19 /tmp/pprof.04545

www: ~> pprofp -z /tmp/pprof.04545

Trace for /home/rasmus/phpweb/index.php
Total Elapsed Time = 0.69
Total System Time = 0.01
Total User Time = 0.08

Real User System secs/ cumm
%Time (excl/cumm) (excl/cumm) (excl/cumm) Calls call s/call Memory Usage
Name
--------------------------------------------------------------------------------------
33.3 0.11 0.13 0.02 0.03 0.01 0.01 7 0.0043 0.0057 298336
require_once
22.2 0.02 0.02 0.02 0.02 0.00 0.00 183 0.0001 0.0001 -33944
feof
11.1 0.01 0.01 0.01 0.01 0.00 0.00 3 0.0033 0.0033 -14808
define
11.1 0.04 0.04 0.01 0.01 0.00 0.00 182 0.0001 0.0001 112040
fgetcsv

- 67 -

11.1 0.25 0.25 0.01 0.01 0.00 0.00 6 0.0017 0.0017 3768
getimagesize
11.1 0.01 0.01 0.01 0.01 0.00 0.00 55 0.0002 0.0002 2568
sprintf
0.0 0.00 0.00 0.00 0.00 0.00 0.00 7 0.0000 0.0000 -136
printf
0.0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.0000 0.0000 136
htmlspecialchars
0.0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.0000 0.0000 -16
mirror_provider_url
0.0 0.00 0.00 0.00 0.00 0.00 0.00 7 0.0000 0.0000 112
spacer
0.0 0.00 0.00 0.00 0.00 0.00 0.00 10 0.0000 0.0000 -552
delim
0.0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.0000 0.0000 112
mirror_provider
0.0 0.00 0.00 0.00 0.00 0.00 0.00 20 0.0000 0.0000 -624
print_link
0.0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.0000 0.0000 24
have_stats
0.0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.0000 0.0000 -72
make_submit
0.0 0.00 0.00 0.00 0.00 0.00 0.00 2 0.0000 0.0000 112
strrchr
0.0 0.08 0.08 0.00 0.00 0.00 0.00 2 0.0000 0.0000 168
filesize
0.0 0.00 0.00 0.00 0.00 0.00 0.00 1 0.0000 0.0000 -16
commonfooter
0.0 0.00 0.11 0.00 0.00 0.00 0.00 2 0.0000 0.0000 0
download_link
0.0 0.00 0.25 0.00 0.01 0.00 0.00 6 0.0000 0.0017 208
make_image

- 68 -

debug_backtrace
debug_backtrace() is a new function in PHP 4.3

Custom error handler
<?
function short($str) {
if(strstr($str,'/'))
return substr(strrchr($str,'/'),1);
else return $str;
}
function myErrorHandler($errno,$errstr,$errfile,$errline)
{
echo "$errno: $errstr in ".short($errfile)." at line $errline<br />n";
echo "Backtrace<br />n";
$trace = debug_backtrace();
foreach($trace as $ent) {
if(isset($ent['file'])) $ent['file'].':';
if(isset($ent['function'])) {
echo $ent['function'].'(';
if(isset($ent['args'])) {
$args='';
foreach($ent['args'] as $arg) { $args.=$arg.','; }
echo rtrim(short($args),',');
}
echo ') ';
}
if(isset($ent['line'])) echo 'at line '.$ent['line'].' ';
if(isset($ent['file'])) echo 'in '.short($ent['file']);
echo "<br />n";
}
}

set_error_handler('myErrorHandler');
include 'file2.php';
test2(1,0);
?>

Custom error handler
<?
function test1($b,$a) {
$a/$b;
}

function test2($a,$b) {
test1($b,$a);
}
?>

- 69 -

Squid
For really busy sites, a reverse proxy like Squid is magical! Either run it as a single-server
accelerator:

Or as a front-end cache to a number of local or remote servers:

Note:
Watch out for any use of $REMOTE_ADDR in your PHP scripts. Use
$HTTP_X_FORWARDED_FOR instead.

- 70 -

Squid Configuration
Make it listen to port 80 on our external interface:
http_port 198.186.203.51:80

If we don't do cgi-bin stuff, comment these out:
#acl QUERY urlpath_regex cgi-bin
#no_cache deny QUERY

If we have plenty of RAM, bump this up a bit:
cache_mem 16MB
maximum_object_size 14096 KB

Specify where to store cached files (size in Megs, level 1 subdirs, level 2 subdirs)
cache_dir ufs /local/squid/cache 500 16 256

Get rid of the big store.log file:
cache_store_log none

Set our SNMP public community string:
acl snmppublic snmp_community public

Get rid of "allow all" and use list of hosts we are blocking (1 ip per line):
#http_access allow all
acl forbidden src "/local/squid/etc/forbidden"
http_access allow !forbidden

Set user/group squid should run as:
cache_effective_user squid
cache_effective_group daemon

Single-server reverse proxy setup (set up Apache to listen to port 80 on the loopback):
httpd_accel_host 127.0.0.1
httpd_accel_port 80
httpd_accel_single_host on
httpd_accel_uses_host_header on

Only allow localhost access through snmp:
snmp_access allow snmppublic localhost

- 71 -

MySQL Replication
As of version 3.23.15 (try to use 3.23.29 or later), MySQL supports one-way replication. Since most
web applications usually have more reads than writes, an architecture which distributes reads across
multiple servers can be very beneficial.

In typical MySQL fashion, setting up replication is trivial. On your master server add this to your
"my.cnf" file:
[mysqld]
log-bin
server-id=1

And add a replication user id for slaves to log in as:
GRANT FILE ON *.* TO repl@"%" IDENTIFIED BY 'foobar';

If you are using MySQL 4.0.2 or later, replace FILE with REPLICATION SLAVE in the above.
Then on your slave servers:
[mysqld]
set-variable = max_connections=200
log-bin
master-host=192.168.0.1
master-user=repl
master-password=foobar
master-port=3306
server-id=2

Make sure each slave has its own unique server-id. And since these will be read-only slaves, you
can start them with these options to speed them up a bit:
--skip-bdb --low-priority-updates
--delay-key-write-for-all-tables

Stop your master server. Copy the table files to each of your slave servers. Restart the master, then
start all the slaves. And you are done. Combining MySQL replication with a Squid reverse cache and
redirector and you might have an architecture like this:

- 72 -

You would then write your application to send all database writes to the master server and all reads to
the local slave. It is also possible to set up two-way replication, but you would need to supply your
own application-level logic to maintain atomicity of distributed writes. And you lose a lot of the
advantages of this architecture if you do this as the writes would have to go to all the slaves anyway.

- 73 -

Load Balancing
The Easy (And Expensive) Solution
You can buy dedicated boxes that do all sorts of advanced load balancing for you. Some popular
ones are:
o Cisco CSS
o Foundry ServerIron
o Intel Netstructure
o F5 BIG-IP
If you are on Linux you could also try LVS. See www.LinuxVirtualServer.org.

- 74 -

Load Balancing with Squid
There are two primary ways to configure Squid to be a load balancer.

Private /etc/hosts
The easiest is to simply list multiple ips for the httpd_accel_host in your /etc/hosts file and Squid will
automatically round-robin across the backend servers.

Use cache_peer
This is more complex. Squid has advanced support for communicating with other caches. It just so
happens that this communication happens over HTTP so you can set Squid up to treat the web servers
you wish to load balance as peer caches. The configuration would look something like this:
httpd_accel_host www.visible-domain.com
httpd_accel_uses_host_header on
never_direct allow all
cache_peer server1 parent 80 0 no-query round-robin

no-query in the above tells Squid not to try to send ICP (Internet Cache Protocol) requests to the
Apache servers. You could turn on the echo port on each server and redirect these ICP requests to
there which would make this system automatically detect a server that is down.

Avoiding Redirectors
It is generally a good idea to avoid external redirectors. A lot of things can be done directly in
Squid's config file. For example:
acl domain1 dstdomain www.domain1.com
cache_peer_access server1 allow domain1
cache_peer_access server1 deny all

This would configure Squid to send requests for pages on certain domains to certain backend servers.
These backend servers could actually be aliases to different ips on the same server if you wanted to
run multiple Apache instances on different ports on the same box.

- 75 -

Latest Developments

o PEAR and PECL
o SOAP
o Zend Engine 2
o New Object model
o Unified Constructors and Destructors
o Objects are references
o Exceptions
o User-space overloading
o SRM

- 76 -

Future

o Apache 2.0
o Extensions to talk to everything!
o php-soap
o Parrot

- 77 -

Resources

Home Page: http://www.php.net
Manual: http://php.net/manual
Tutorial: http://php.net/tut.php
Books: http://php.net/books.php

- 78 -

Index
Agenda ............................................................................................................ 2
Setup ............................................................................................................... 3
Sanity Check ................................................................................................... 4
Connecting to MySQL .................................................................................... 5
Persistent Connections .................................................................................... 6
Creating a Database ........................................................................................ 7
Inserting Data .................................................................................................. 8
Selecting Data ................................................................................................. 9
Dealing with timestamps ................................................................................ 10
Changing Existing Rows ................................................................................ 11
Magic Quotes .................................................................................................. 12
A Simple Guestbook ....................................................................................... 13
DB-driven Guestbook ..................................................................................... 14
DB-driven Guestbook ..................................................................................... 15
DB Abstraction ............................................................................................... 16
HTTP Headers ................................................................................................ 17
Cookies ........................................................................................................... 18
Cookie Expiry ................................................................................................. 19
GD 1/2 ............................................................................................................. 20
Colours ............................................................................................................ 21
Colours ............................................................................................................ 22
Truecolor Colors ............................................................................................. 23
Truecolor Colors ............................................................................................. 25
ImageColorAt ................................................................................................. 26
GD 1/2 ............................................................................................................. 27
Text ................................................................................................................. 28
TTF Text ......................................................................................................... 29
EXIF ................................................................................................................ 31
PDFs on-the-fly ............................................................................................... 33
Ming-Flash ...................................................................................................... 35
More Ming ...................................................................................................... 36
Cool! ............................................................................................................... 38
Sessions ........................................................................................................... 40
Session Configuration ..................................................................................... 41
Custom Backend ............................................................................................. 42
Custom Backend ............................................................................................. 43
register_globals ............................................................................................... 45
Safe Mode ....................................................................................................... 48
Security ........................................................................................................... 49
Security ........................................................................................................... 50
Security ........................................................................................................... 51
Security ........................................................................................................... 52
Security ........................................................................................................... 53
References ....................................................................................................... 54

Returning References ...................................................................................... 55
Adding an extension ....................................................................................... 56
$PATH_INFO ................................................................................................. 57
ErrorDocument ............................................................................................... 58
Funky Caching ................................................................................................ 59
Variable variables ........................................................................................... 60
Optimization ................................................................................................... 61
PHP Opcode Caches ....................................................................................... 62
PHP Opcode Caches ....................................................................................... 64
Profiling PHP .................................................................................................. 65
Profiling PHP .................................................................................................. 67
debug_backtrace ............................................................................................. 69
Squid ............................................................................................................... 70
Squid Configuration ........................................................................................ 71
MySQL Replication ........................................................................................ 72
Load Balancing ............................................................................................... 74
Load Balancing with Squid ............................................................................. 75
Latest Developments ....................................................................................... 76
Future .............................................................................................................. 77
Resources ........................................................................................................ 78

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