<?php

/**
 * Validates an IPv6 address.
 * @author Feyd @ forums.devnetwork.net (public domain)
 * @note This function requires brackets to have been removed from address
 *       in URI.
 */
class HTMLPurifier_AttrDef_URI_IPv6 extends HTMLPurifier_AttrDef_URI_IPv4 {
	
	/**
	 *
	 * @param string $aIP        	
	 * @param HTMLPurifier_Config $config        	
	 * @param HTMLPurifier_Context $context        	
	 * @return bool|string
	 */
	public function validate($aIP, $config, $context) {
		if (! $this->ip4) {
			$this->_loadRegex ();
		}
		
		$original = $aIP;
		
		$hex = '[0-9a-fA-F]';
		$blk = '(?:' . $hex . '{1,4})';
		$pre = '(?:/(?:12[0-8]|1[0-1][0-9]|[1-9][0-9]|[0-9]))'; // /0 - /128
		                                                        
		// prefix check
		if (strpos ( $aIP, '/' ) !== false) {
			if (preg_match ( '#' . $pre . '$#s', $aIP, $find )) {
				$aIP = substr ( $aIP, 0, 0 - strlen ( $find [0] ) );
				unset ( $find );
			} else {
				return false;
			}
		}
		
		// IPv4-compatiblity check
		if (preg_match ( '#(?<=:' . ')' . $this->ip4 . '$#s', $aIP, $find )) {
			$aIP = substr ( $aIP, 0, 0 - strlen ( $find [0] ) );
			$ip = explode ( '.', $find [0] );
			$ip = array_map ( 'dechex', $ip );
			$aIP .= $ip [0] . $ip [1] . ':' . $ip [2] . $ip [3];
			unset ( $find, $ip );
		}
		
		// compression check
		$aIP = explode ( '::', $aIP );
		$c = count ( $aIP );
		if ($c > 2) {
			return false;
		} elseif ($c == 2) {
			list ( $first, $second ) = $aIP;
			$first = explode ( ':', $first );
			$second = explode ( ':', $second );
			
			if (count ( $first ) + count ( $second ) > 8) {
				return false;
			}
			
			while ( count ( $first ) < 8 ) {
				array_push ( $first, '0' );
			}
			
			array_splice ( $first, 8 - count ( $second ), 8, $second );
			$aIP = $first;
			unset ( $first, $second );
		} else {
			$aIP = explode ( ':', $aIP [0] );
		}
		$c = count ( $aIP );
		
		if ($c != 8) {
			return false;
		}
		
		// All the pieces should be 16-bit hex strings. Are they?
		foreach ( $aIP as $piece ) {
			if (! preg_match ( '#^[0-9a-fA-F]{4}$#s', sprintf ( '%04s', $piece ) )) {
				return false;
			}
		}
		return $original;
	}
}

// vim: et sw=4 sts=4