<?php

/*  PowerAdmin, a friendly web-based admin tool for PowerDNS.

 *  See <https://rejo.zenger.nl/poweradmin> for more details.

 *

 *  Copyright 2007, 2008  Rejo Zenger <rejo@zenger.nl>

 *

 *  This program is free software: you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation, either version 3 of the License, or

 *  (at your option) any later version.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

/*

 * Validates an IPv4 IP.

 * returns true if valid.

 */

function validate_input($zoneid, $type, &$content, &$name, &$prio, &$ttl)

{

	global $db;

	// Has to validate content first then it can do the rest

	// Since if content is invalid already it can aswell be just removed

	// Check first if content is IPv4, IPv6 or Hostname

	// We accomplish this by just running all tests over it

	// We start with IPv6 since its not able to have these ip's in domains.

	//

	// <TODO>

	// The nocheck has to move to the configuration file

	// </TODO>

	//

	$domain = get_domain_name_from_id($zoneid);

	$nocheck = array('SOA', 'HINFO', 'NAPTR', 'URL', 'MBOXFW', 'TXT');

	$hostname = false;

	$ip4 = false;

	$ip6 = false;

	if(!in_array(strtoupper($type), $nocheck))

	{

		if(!is_valid_ip6($content))

		{

			if(!is_valid_ip($content))

			{

				if(!is_valid_hostname($content))

				{

					error(ERR_DNS_CONTENT);

				}

				else

				{

					$hostname = true;

				}

			}

			else

			{

				$ip4 = true;

			}

		}

		else

		{

			$ip6 = true;

		}

	}

	// Prepare total hostname.

	if($name == '*')

	{

		$wildcard = true;

	}

	if ($name=="0") {

	   $name=$name.".".$domain;

	} else {

	   $name = ($name) ? $name.".".$domain : $domain;

	}

	if (preg_match('!@\.!i', $name))

	{

		$name = str_replace('@.', '@', $name);

	}

	if(!$wildcard)

	{

		if(!is_valid_hostname($name))

		{

			error(ERR_DNS_HOSTNAME);

		}

	}

	// Check record type (if it exists in our allowed list.

	if (!in_array(strtoupper($type), get_record_types()))

	{

		error(ERR_DNS_RECORDTYPE);

	}

	// Start handling the demands for the functions.

	// Validation for IN A records. Can only have an IP. Nothing else.

	if ($type == 'A' && !$ip4)

	{

		error(ERR_DNS_IPV4);

	}

	if ($type == 'AAAA' && !$ip6)

	{

		error(ERR_DNS_IPV6);

	}

	if ($type == 'CNAME' && $hostname)

	{

		if(!is_valid_cname($name))

		{

			error(ERR_DNS_CNAME);

		}

	}

	if ($type == 'NS')

	{

		$status = is_valid_ns($content, $hostname);

		if($status == -1)

		{

			error(ERR_DNS_NS_HNAME);

		}

		elseif($status == -2)

		{

			error(ERR_DNS_NS_CNAME);

		}

		// Otherwise its ok

	}

	if ($type == 'SOA')

	{

		$status = is_valid_soa($content, $zoneid);

		if($status == -1)

		{

			error(ERR_DNS_SOA_UNIQUE);

			// Make nicer error

		}

		elseif($status == -2)

		{

			error(ERR_DNS_SOA_NUMERIC);

		}

	}

	// HINFO and TXT require no validation.

	if ($type == 'URL')

	{

		if(!is_valid_url($content))

		{

			error(ERR_INV_URL);

		}

	}

	if ($type == 'MBOXFW')

	{

		if(!is_valid_mboxfw($content))

		{

			error(ERR_INV_EMAIL);

		}

	}

	// NAPTR has to be done.

	// Do we want that?

	// http://www.ietf.org/rfc/rfc2915.txt

	// http://www.zvon.org/tmRFC/RFC2915/Output/chapter2.html

	// http://www.zvon.org/tmRFC/RFC3403/Output/chapter4.html

	// See if the prio field is valid and if we have one.

	// If we dont have one and the type is MX record, give it value '10'

	if($type == 'NAPTR')

	{

	}

	if($type == 'MX')

	{

		if($hostname)

		{

			$status = is_valid_mx($content, $prio);

			if($status == -1)

			{

				error(ERR_DNS_MX_CNAME);

			}

			elseif($status == -2)

			{

				error(ERR_DNS_MX_PRIO);

			}

		}

		else

		{

			error( _('If you specify an MX record it must be a hostname.') );

		}

	}

	else

	{

		$prio=0;

	}

	// Validate the TTL, it has to be numeric.

	$ttl = (!isset($ttl) || !is_numeric($ttl)) ? $DEFAULT_TTL : $ttl;

}

		/****************************************

		 *					*

		 * RECORD VALIDATING PART.		*

		 * CHANGES HERE SHOULD BE CONSIDERED	*

		 * THEY REQUIRE KNOWLEDGE ABOUT THE 	*

		 * DNS SPECIFICATIONS			*

		 *					*

		 ***************************************/

/*

 * Validatis a CNAME record by the name it will have and its destination

 *

 */

function is_valid_cname($dest)

{

	/*

	 * This is really EVIL.

	 * If the new record (a CNAME) record is being pointed to by a MX record or NS record we have to bork.

	 * this is the idea.

	 *

	 * MX record: blaat.nl MX mail.blaat.nl

	 * Now we look what mail.blaat.nl is

	 * We discover the following:

	 * mail.blaat.nl CNAME bork.blaat.nl

	 * This is NOT allowed! mail.onthanet.nl can not be a CNAME!

	 * The same goes for NS. mail.blaat.nl must have a normal IN A record.

	 * It MAY point to a CNAME record but its not wished. Lets not support it.

	 */

	global $db;

	// Check if there are other records with this information of the following types.

	// P.S. we might add CNAME to block CNAME recursion and chains.

	$blockedtypes = " AND (type='MX' OR type='NS')";

	$cnamec = "SELECT type, content FROM records WHERE content=".$db->quote($dest) . $blockedtypes;

	$result = $db->query($cnamec);

	if($result->numRows() > 0)

	{

		return false;

		// Lets inform the user he is doing something EVIL.

		// Ok we found a record that has our content field in their content field.

	}

	return true;

}

/*

 * Checks if something is a valid domain.

 * Checks for domainname with the allowed characters <a,b,...z,A,B,...Z> and - and _.

 * This part must be followed by a 2 to 4 character TLD.

 */

function is_valid_domain($domain)

{

	if ((eregi("^[0-9a-z]([-.]?[0-9a-z])*\\.[a-z]{2,4}$", $domain)) && (strlen($domain) <= 128))

	{

		return true;

	}

	return false;

}

/*

 * Validates if given hostname is allowed.

 * returns true if allowed.

 */

function is_valid_hostname($host)

{

	if(count(explode(".", $host)) == 1)

	{

		return false;

	}

	// Its not perfect (in_addr.int is allowed) but works for now.

	if(preg_match('!(ip6|in-addr).(arpa|int)$!i', $host))

	{

		if(preg_match('!^(([A-Z\d]|[A-Z\d][A-Z\d-]*[A-Z\d])\.)*[A-Z\d]+$!i', $host))

		{

			return true;

		}

		return false;

	}

	// Validate further.

	return (preg_match('!^(([A-Z\d]|[A-Z\d][A-Z\d-]*[A-Z\d])\.)*[A-Z\d]+$!i', $host)) ? true : false;

}

/*

 * Validates an IPv4 IP.

 * returns true if valid.

 */

function is_valid_ip($ip)

{

	// Stop reading at this point. Scroll down to the next function...

	// Ok... you didn't stop reading... now you have to rewrite the whole function! enjoy ;-)

	// Trance unborked it. Twice even!

	return ($ip == long2ip(ip2long($ip))) ? true : false;

}

/*

 * Validates an IPv6 IP.

 * returns true if valid.

 */

function is_valid_ip6($ip)

{

	// Validates if the given IP is truly an IPv6 address.

	// Precondition: have a string

	// Postcondition: false: Error in IP

	//                true: IP is correct

	// Requires: String

	// Date: 10-sep-2002

	if(preg_match('!^[A-F0-9:]{1,39}$!i', $ip) == true)

	{

		// Not 3 ":" or more.

		$p = explode(':::', $ip);

		if(sizeof($p) > 1)

		{

			return false;

		}

		// Find if there is only one occurence of "::".

		$p = explode('::', $ip);

		if(sizeof($p) > 2)

		{

			return false;

		}

		// Not more than 8 octects

		$p = explode(':', $ip);

		if(sizeof($p) > 8)

		{

			return false;

		}

		// Check octet length

		foreach($p as $checkPart)

		{

			if(strlen($checkPart) > 4)

			{

				return false;

			}

		}

		return true;

	}

	return false;

}

/*

 * FANCY RECORD.

 * Validates if the fancy record mboxfw is an actual email address.

 */

function is_valid_mboxfw($email)

{

	return is_valid_email($email);

}

/*

 * Validates MX records.

 * an MX record cant point to a CNAME record. This has to be checked.

 * this function also sets a proper priority.

 */

function is_valid_mx($content, &$prio)

{

	global $db;

	// See if the destination to which this MX is pointing is NOT a CNAME record.

	// Check inside our dns server.

	if($db->queryOne("SELECT count(id) FROM records WHERE name=".$db->quote($content)." AND type='CNAME'") > 0)

	{

		return -1;

	}

	else

	{

		// Fix the proper priority for the record.

		// Bugfix, thanks Oscar :)

		if(!isset($prio))

		{

			$prio = 10;

		}

		if(!is_numeric($prio))

		{

			if($prio == '')

			{

				$prio = 10;

			}

			else

			{

				return -2;

			}

		}

	}

	return 1;

}

/*

 * Validates NS records.

 * an NS record cant point to a CNAME record. This has to be checked.

 * $hostname directive means if its a hostname or not (this to avoid that NS records get ip fields)

 * NS must have a hostname, it is not allowed to have an IP.

 */

function is_valid_ns($content, $hostname)

{

	global $db;

	// Check if the field is a hostname, it MUST be a hostname.

	if(!$hostname)

	{

		return -1;

		// "an IN NS field must be a hostname."

	}

	if($db->queryOne("SELECT count(id) FROM records WHERE name=".$db->quote($content)." AND type='CNAME'") > 0)

	{

		return -2;

		// "You can not point a NS record to a CNAME record. Remove/rename the CNAME record first or take another name."

	}

	return 1;

}

/*

 * Function to check the validity of SOA records.

 * return values: true if succesful

 */

function is_valid_soa(&$content, $zoneid)

{

	/*

	 * SOA (start of authority)

	 * there is only _ONE_ SOA record allowed in every zone.

	 * Validate SOA record

	 * The Start of Authority record is one of the most complex available. It specifies a lot

	 * about a domain: the name of the master nameserver ('the primary'), the hostmaster and

	 * a set of numbers indicating how the data in this domain expires and how often it needs

	 * to be checked. Further more, it contains a serial number which should rise on each change

	 * of the domain.