Archive for the ‘Net: Techy: PHP’ category

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Snippet: PHP, MySQL and IDN Email addresses

November 20th, 2008

Here’s something to look out for if you are building an international website where you are handling email addresses…

Email addresses, as you are probably aware, comprise of two parts. The “local part” (the bit before the @ sign) and the “domain part” (the bit after the @ sign). Therefore with the email address richard@example.invalid , “richard” is the local part and “example.invalid” is the domain part.

The domain part of the email address can actually be 255 characters in length theoretically (it’s 63 characters for the actually domain name, then the TLD: however, you could have sub domains in force which can take it up to the 255 limit.

The local part of the email address can be 64 characters: bringing the count up to 319 characters. Allow an extra one for the “@” sign and 320… Just slightly too big to fit within the standard 255/256 character string field that has tended to be used. I’ve seen rumours that this section may be expanded to 128 characters, so plan for 383 characters.

Oh – don’t forget that Internationalised/Internationalized Domain Names are becoming popular in some countries and unless you want to handle conversion to/from Punycode or another storage format for the IDNs, then you’ll need to make your database store the email address in Unicode… However, that appears to cause a problem in some version of MySQL if you store it all in a Varchar field.

So in your programming language (such as PHP), you’re going to have to keep all the above in mind and then split the email address into two parts for storing in the database for sanity.

See http://www.faqs.org/rfcs/rfc2821.html, http://en.wikipedia.org/wiki/E-mail_address, http://www.santosj.name/general/stop-doing-email-validation-the-wrong-way/ and http://askville.amazon.com/maximum-length-allowed-email-address/AnswerViewer.do?requestId=1166932.

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Posted in Net: Techy: PHP, Snippet

PHP: Avoiding “Headers already sent by…” errors

March 3rd, 2008

Just a quick post inspired by Techgirl, here’s how to avoid the annoying PHP errors “Headers already sent by…” when working with multiple files.

Basically, a PHP script usually looks like:

<?php
include "my.lib.php";
include "otherstuff.php";
....
?>

however, if my.lib.php (for example) looks like:

<?php
....
...
?>


(do you see the hidden “new line at the end”), you’ll get the “Warning: Cannot modify header information – headers already sent by (output started at my.lib.php:6) in index.php on line 2? error.

So how do you simpley avoid this? Easy! Omit the closing ?> from the library/include files. My.lib.php now looks like:

<?php
....
...

and the problem is solved.

Simple, quick solution which is worth remembering!

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PHP: Making use of Object Orientated PHP

February 22nd, 2008

Just a quickie: From Tim of Sacratee there is a post on Jatecblog about Making use of Object Oriented PHP which provides a good simple example of how to use OOP in PHP5 to build a module-based system.

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Posted in Net: Techy: PHP

PHP: Making faster PHP scripts

February 18th, 2008

Making the web has a couple of articles about how to make PHP scripts run faster and more efficiently. Checking the lists show I’m already doing quite a few of the items listed:

Page one

Multiple arguments with echo (i.e. using “,” instead of “.”)
I don’t currently do this, but it’s only 0.396% faster
Reduce function calls (i.e. find out the size of an array before a loop, not in the “for statement”)
I do do this, but not as much as I should – especially with a 54.095% difference!
Avoid using variables if they aren’t needed and unset them once you’ve finished with them
I try to do this, but there doesn’t appear (from the site) to be any speed penalties in not doing this.
Use single quotes (instead of double quotes – ” )
I’ve done this for ages as I knew PHP didn’t have to parse the string – but I didn’t know it was only a 0.696% speed difference.
str_replace() vs ereg_replace() and preg_replace()
I tend to use preg_replace instead of ereg_replace anyway, and I’m aware that using any sort of regular expressions is slow. Therefore I do try and use str_replace instead – after all, it’s a 59.224% saving in speed!

» Read more: PHP: Making faster PHP scripts

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Posted in Net: Techy: PHP

Coding: Password Security in Cookies

December 22nd, 2007

Via boren.nu, I came across a nice detailed section on how to create a secure cookie and password system (which will be implemented in WordPress 2.4):

Cookies will be based on the secure cookie protocol described here. The cookie is structured like so:

user name|expiration time|HMAC( user name|expiration time, k)
where k = HMAC(user name|expiration time, sk)
and where sk is a secret key

The new cookie protocol will allow us to enforce expirations server-side, mass invalidate all cookies, and offer high-level confidentiality. Read the Liu paper for details on the protocol… …In conjunction with the new cookies, password hashing will be improved by moving to phpass. phpass provides password stretching and salting. These make brute-forcing your password hashes impractical should someone get access to your database.

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