<? php

/**
 *
 * DNSLookup class
 *  This class works only with UDP protocol without ipv6 support. Parse only A and SRV records. Don't support truncated queries. Instructions and recomendations from RFC are considered
 *  Returned data format depends from what you ask i.e. what query type you pass in class (A, AAAA, NS, MX, etc). Function which define data format is DNSLookup::getResult()
 *
 * Usage:
 *     $dnsinfo = new DNSLookup('www.google.com') or $dnsinfo = new DNSLookup('_xmpp-client._tcp.google.com', 'SRV') or $dnsinfo = new DNSLookup('_xmpp-client._tcp.google.com', 'SRV', '216.87.84.211');
 *     if($dnsinfo->error == FALSE)
 *       echo $dnsinfo->getResult();
 *  For more information set $debug to 1
 *
 * References:
 *  http://tools.ietf.org/html/rfc1035
 *  http://www.phpclasses.org/browse/file/17457.html
 *  http://www.zytrax.com/books/dns/ch15/
 *  http://www.dnspython.org/docs/1.11.1/dns.rdtypes.IN.SRV-pysrc.html#SRV
 *
 * Capabilities may added in future:
 *  IPv6 support
 *  Working with TCP for responses with length more than 512 bytes and for Zone Transfer
 *  Working with truncated queries
 *  Adding more RRs formats
 *
 **/

class DNSLookup {
    public $dnsserver = '8.8.8.8';
    public $qclass;
    public $qtype;
    public $recursion = 1; //Set RD because if us SRV queries won't be recursive then we dont get information
    public $opcode = 0;
    public $domain_name;
    public $debug = 0;
    public $error = FALSE;
    private $qclasses = array("IN" = > 1, "CS" = > 2, "CH" = > 3, "HS" = > 4, "*" = > 255);
    private $qtypes = array("A" = > 1, "NS" = > 2, "ND" = > 3, "NF" = > 4, "CNAME" = > 5, "SOA" = > 6, "MB" = > 7, "MG" = > 8, "MR" = > 9, "NULL" = > 10, "WKS" = > 11, "PTR" = > 12, "HINFO" = > 13, "MINFO" = > 14, "MX" = > 15, "TXT" = > 16, "RP" = > 17, "SIG" = > 24, "KEY" = > 25, "LOC" = > 29, "NXT" = > 30, "AAAA" = > 28, "SRV" = > 33, "CERT" = > 37, "A6" = > 38, "AXFR" = > 252, "IXFR" = > 251, "*" = > 255);
    private $query;
    private $response;
    private $response_header;
    private $response_body;
    public $RR;
    public $result;


    public
    function DNSLookup($domain_name, $qtype = 'A', $dnsserver = '8.8.8.8') {
        $this - > error = FALSE;
        $this - > result = FALSE;
        $this - > dnsserver = $dnsserver;
        $this - > domain_name = $domain_name;
        $this - > qclass = $this - > qclasses['IN'];
        $this - > qtype = $this - > qtypes[$qtype];

        if ($this - > debug == TRUE) {
            echo "<pre>n";
            echo "DNS Server: ".$dnsserver."n";
            echo "Query type: ".$qtype."n";
            echo "Recursion Desired: ";
            echo($this - > recursion) ? "Yesn" : "Non";
            echo "Domain name: ".$domain_name."n";
            echo "n</pre>n";
        }
        if ($this - > getDNSResponse() == FALSE) return FALSE;

        if ($this - > parseDNSResponse() == FALSE) return FALSE;

        return $this - > getResult();
    }

    /**
     *
     *This function create socket, send data to DNS-server and get answer
     *
     **/
    private
    function getDNSResponse() {
        $this - > constructDNSQuery();

        $dnssock = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
        if (!socket_connect($dnssock, $this - > dnsserver, '53')) {
            $this - > setError("Socket error. Can't connect to DNS server. ".socket_strerror(socket_last_error($dnssock)));
            return FALSE;
        }
        if (!socket_write($dnssock, $this - > query)) {
            $this - > setError("Socket error. ".socket_strerror(socket_last_error($dnssock)));
            return FALSE;
        }
        $DNSresponse = socket_read($dnssock, 512);
        socket_close($dnssock);
        $this - > response = $DNSresponse;
        if (empty($this - > response)) {
            $this - > setError('Something is wrong. Zero length response from server');
            return FALSE;
        }
        return strlen($this - > response);
    }

    /**
     *
     *This function returns string with DNS question according RFC1035 which we can send to name server
     *http://tools.ietf.org/html/rfc1035 
     *
     **/
    private
    function constructDNSQuery() {
        //Message header
        $DNSmsg = chr(rand(0, 255)).chr(rand(1, 255)); //id - first 2 bytes in header
        $DNSmsg. = chr($this - > setOptions($this - > recursion, $this - > opcode)).chr(0); //next 2 bytes in header ( |QR|   Opcode  |AA|TC|RD|RA|   Z    |   RCODE   | )
        $DNSmsg. = chr(0).chr(1); //QDCOUNT = 1
        $DNSmsg. = chr(0).chr(0); //ANCOUNT
        $DNSmsg. = chr(0).chr(0); //NSCOUNT
        $DNSmsg. = chr(0).chr(0); //ARCOUNT

        //Message question section
        foreach(explode('.', $this - > domain_name) as $fqdn_parts) {
            $DNSmsg. = chr(strlen($fqdn_parts)); //quantity of symbols in each part of domain name
            $DNSmsg. = $fqdn_parts; //each part of domain name
        }
        $DNSmsg. = chr(0); //NULL-byte - end of domain name
        $DNSmsg. = chr(0).chr($this - > qtype); //QTYPE. SRV = 33
        $DNSmsg. = chr(0).chr($this - > qclass); //QCLASS IN = 1
        $this - > query = $DNSmsg;
        return TRUE;
    }


    /**
     *
     *This function places parsed data into $RR
     *
     **/
    private
    function parseDNSResponse() {
        $this - > parseResponseHeader();

        if ($this - > response_header['RCODE'] == 0) //If No errors
        {
            if (!$this - > parseResponseBody()) return FALSE;
            $this - > parseRDATA();
        } else {
            switch ($this - > response_header['RCODE']) {
            case '1':
                $this - > setError("Response with RCODE. Format error");
                return FALSE;
                break;
            case '2':
                $this - > setError("Response with RCODE. Server failure");
                return FALSE;
                break;
            case '3':
                $this - > setError("Response with RCODE. Name Error");
                return FALSE;
                break;
            case '4':
                $this - > setError("Response with RCODE. Not Implemented");
                return FALSE;
                break;
            case '5':
                $this - > setError("Response with RCODE. Refused");
                return FALSE;
                break;
            default:
                $this - > setError("Response with RCODE. Unknown error code");
                return FALSE;
                break;
            }
        }
        return TRUE;
    }


    /**
     *
     *Parse DNS response header
     *
     **/
    private
    function parseResponseHeader() {
        for ($i = 0; $i < 4; $i++)
        $bytes[$i] = $this - > getOctetByte($this - > response {
            $i
        });

        $response_header = array('ID' = > $bytes[0].$bytes[1], 'QR' = > (bool) $bytes[2] {
            0
        }, 'OPCODE' = > bindec(substr($bytes[2], 1, 4)), 'AA' = > (bool) $bytes[2] {
            5
        }, 'TC' = > (bool) $bytes[2] {
            6
        }, 'RD' = > (bool) $bytes[2] {
            7
        }, 'RA' = > (bool) $bytes[3] {
            0
        }, 'RCODE' = > bindec(substr($bytes[3], 4, 4)), 'QDCOUNT' = > ord($this - > response {
            5
        }), 'ANCOUNT' = > ord($this - > response {
            7
        }), 'NSCOUNT' = > ord($this - > response {
            9
        }), 'ARCOUNT' = > ord($this - > response {
            11
        }), );
        $this - > response_header = $response_header;

        if ($this - > debug == TRUE) {
            echo "<pre>Response header:n";
            var_dump($this - > response_header);
            echo "nn</pre>";
        }
        return TRUE;
    }

    /**
     *
     *Parse RDATA, TYPE, CLASS, TTL sections from DNS response answer body
     *
     **/
    private
    function parseResponseBody() {#Find response section offset
        $current_offset = $body_offset = 12;
        $qcount = $this - > response_header['QDCOUNT']; //Quantity of questions
        while ($qcount > 0) {
            $qcount--;
            if ($this - > isPointer($this - > response, $current_offset)) $current_offset += 6;
            else $current_offset = ((strpos($this - > response, chr(0), $current_offset)) + 5);

        }

        #Parse information from each subsection in response section {

            $rscount = $this - > response_header['ANCOUNT'] + $this - > response_header['NSCOUNT'] + $this - > response_header['ARCOUNT']; //Quantity of sections with response information
            if ($rscount == 0) {
                $this - > setError("No records available for ".$this - > domain_name);
                return FALSE;
            }
            while ($rscount > 0) {
                $rscount--;

                #Get name
                if ($addr = $this - > isPointer($this - > response, $current_offset)) {
                    $name = $this - > getName($this - > response, $addr);
                    $current_offset += 2;
                } else {
                    $name = $this - > getName($this - > response, $current_offset);
                    $current_offset = ((strpos($this - > response, chr(0), $current_offset)) + 1);
                }

                #Get type
                $type = $this - > getInt($this - > response, $current_offset, 2);

                #Get class
                $class = $this - > getInt($this - > response, $current_offset, 2);

                #Get TTL
                $ttl = $this - > getInt($this - > response, $current_offset, 4);

                #Get rdlength
                $rdlength = $this - > getInt($this - > response, $current_offset, 2);

                #Get rdata
                $rdata = substr($this - > response, $current_offset, $rdlength);

                #dataset
                $this - > response_body[] = array('SECTION' = > '', 'NAME' = > $name, 'TYPE' = > $type, 'CLASS' = > $class, 'TTL' = > $ttl, 'RDATA' = > $rdata);

                #Change offset
                $current_offset += $rdlength;
            }

        }

        #This code correlates from what section each dataset
        $response_sections = array('answer' = > 'ANCOUNT', 'authority' = > 'NSCOUNT', 'additional' = > 'ARCOUNT');
        $i = $j = 0;
        foreach($response_sections as $sname = > $count_name) {
            if ($this - > response_header[$count_name] > 0) {
                for ($j = 0; $j < ($this - > response_header[$count_name]); $i++, $j++) {
                    $this - > response_body[$i]['SECTION'] = $sname;
                }
            }
        }

        if ($this - > debug == TRUE) {
            echo "<pre>nResponse body:n";
            var_dump($this - > response_body);
            echo "nn</pre>";
        }

        return TRUE;
    }


    /**
     *
     *This function represnt information from RDATA in readable view
     *This function very edged because i need only SRV and A records
     *
     **/
    private
    function parseRDATA() {#SRV#http: //www.dnspython.org/docs/1.11.1/dns.rdtypes.IN.SRV-pysrc.html#SRV
        #__slots__ = ['priority', 'weight', 'port', 'target']

        #We work only
        if at least one answer present(or
        if $debug flag is set) if (($this - > response_header['ANCOUNT'] == 0) && ($this - > debug == FALSE)) {
            $this - > setError("Response from DNS server is obtained without errors but no ANSWER data for ".$this - > domain_name);
            return FALSE;
        }
        elseif(($this - > response_header['ANCOUNT'] == 0) && ($this - > debug != FALSE)) {
            echo "n<pre>nNo ANSWER data for ".$this - > domain_name."n</pre>n";
        }

        #Parse and collect information from RDATA
        foreach($this - > response_body as $n = > $response_entity) {
            $current_offset = 0;
            if ($response_entity['SECTION'] == 'answer') {
                switch ($response_entity['TYPE']) {
                case '33':
                    //SRV
                    $this - > RR['SRV'][$n]['name'] = $response_entity['NAME'];
                    $this - > RR['SRV'][$n]['priority'] = $this - > getInt($response_entity['RDATA'], $current_offset, 2);
                    $this - > RR['SRV'][$n]['weight'] = $this - > getInt($response_entity['RDATA'], $current_offset, 2);
                    $this - > RR['SRV'][$n]['port'] = $this - > getInt($response_entity['RDATA'], $current_offset, 2);
                    if ($addr = $this - > isPointer($response_entity['RDATA'], $current_offset)) $this - > RR['SRV'][$n]['target'] = $this - > getName($response_entity['RDATA'], $addr);
                    else $this - > RR['SRV'][$n]['target'] = $this - > getName($response_entity['RDATA'], $current_offset);
                    break;
                case '1':
                    //A
                    $this - > RR['A'][$n]['name'] = $response_entity['NAME'];
                    $this - > RR['A'][$n]['address'] = $this - > getIpAddress($response_entity['RDATA']);
                    break;
                case '28':
                    //AAAA
                    $this - > RR['AAAA'][$n]['name'] = $response_entity['NAME'];
                    //$this->RR['AAAA'][$n]['address'] = $this->getIpv6Address($response_entity['RDATA']);
                    true;
                    break;
                default:
                    //All other
                    $this - > RR['unknown'][$n] = $response_entity['RDATA'];
                    break;
                }
            }

            /*

			IF(DEBUG IS SET)
				SHOW AUTHORITATIVE ANSWERS;

			*/
        }

        if ($this - > debug == TRUE) {
            echo "<pre>Obtained resourse records:n";
            var_dump($this - > RR);
            echo "</pre>n";
        }

        return count($this - > RR);
    }





















    /*
     *
     *This function returns information according client question. Check query type and return string
     *
     **/
    private
    function getResult() {
        $flip = array_flip($this - > qtypes);
        switch ($flip[$this - > qtype]) {
        case 'SRV':
            $serverData = $this - > selectServer();
            $this - > result = $serverData['target'].':'.$serverData['port'];
            break;
        case 'A':
            $this - > result = $this - > RR['A'][0]['address'];
            break;
        case 'AAAA':
            $this - > result = FALSE;
            break;
        default:
            break;
        }

        unset($this - > query);
        unset($this - > response);
        unset($this - > response_header);
        unset($this - > response_body);
        unset($this - > RR);
        return $this - > result;
    }

    private
    function selectServer() {
        foreach($this - > RR['SRV'] as $n = > $server) {
            $pn = $server['priority'];
            if (isset($servers[$pn])) {
                if ($servers[$pn]['weight'] < $server['weight']) $servers[$pn] = $server;
            } else $servers[$pn] = $server;
        }
        ksort($servers);
        return reset($servers);
    }















    /**
     *
     *Just returns decimal integer $count bytes length from $str
     *
     **/
    private
    function getInt($str, & $pointer, $count) {
        $result = '';
        for ($i = 0; $i < $count; $i++)
        $result. = $this - > getOctetByte($str {
            $pointer++
        });
        return bindec($result);
    }

    /**
     *
     *Check symbol at offset. If first two bits is ones then it is pointer and then function return address wich places in next byte ($symbol_offset+1)
     *
     **/
    private
    function isPointer($sourceString, $symbol_offset) {
        return (substr($this - > getOctetByte($sourceString {
            $symbol_offset
        }), 0, 2) == '11') ? ord($sourceString {
            ($symbol_offset + 1)
        }) : FALSE;
    }

    /**
     *
     *This function returns normally formatted name from offset.
     *
     **/
    private
    function getName($sourceStr, $offset) {
        $name = '';
        $string_offset = 0;
        $end = strpos($sourceStr, chr(0), $offset);
        $length = $end - $offset;
        $string = substr($sourceStr, $offset, $length);

        while ($string_offset < $length) {
            $count = ord($string {
                $string_offset++
            });
            $name. = substr($string, $string_offset, $count).'.';
            $string_offset += $count;
        }
        return substr($name, 0, (strlen($name) - 1));
    }

    private
    function getIpAddress($str) {
        return ord($str {
            0
        }).".".ord($str {
            1
        }).".".ord($str {
            2
        }).".".ord($str {
            3
        });
    }

    /**
     *
     *Function returns binary representation of byte/symbol
     *
     **/
    private
    function getOctetByte($byte) {
        return sprintf("%08d", decbin(ord($byte)));
    }

    private
    function setError($text) {
        $this - > error = $text;
    }

    private
    function setOptions($RD = 0, $OPCODE = 0) {
        $optionset = '00000000';
        if ($RD) $optionset = $optionset | '00000001';
        switch ($OPCODE) {
        case 0:
            true;
            break;
        case 1:
            $optionset = $optionset | '00001000';
            break;
        case 2:
            $optionset = $optionset | '00001000';
            break;
        case 3:
            $optionset = $optionset | '00010000';
            break;
        case 4:
            $optionset = $optionset | '00011000';
            break;
        case 5:
            $optionset = $optionset | '00100000';
            break;
        case 6:
            $optionset = $optionset | '00101000';
            break;
        case 7:
            $optionset = $optionset | '00111000';
            break;
        case 8:
            $optionset = $optionset | '01000000';
            break;
        case 9:
            $optionset = $optionset | '01001000';
            break;
        case 10:
            $optionset = $optionset | '01010000';
            break;
        case 11:
            $optionset = $optionset | '01011000';
            break;
        case 12:
            $optionset = $optionset | '01100000';
            break;
        case 13:
            $optionset = $optionset | '01101000';
            break;
        case 14:
            $optionset = $optionset | '01110000';
            break;
        case 15:
            $optionset = $optionset | '01111000';
            break;
        }
        return decbin($optionset);
    }

}

?>
Setting Validate Copy Format