packet.php

来自「视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.」· PHP 代码 · 共 626 行 · 第 1/2 页

     */
    function data()
    {
        $data = $this->header->data();

        for ($ctr = 0; $ctr < $this->header->qdcount; $ctr++) {
            $data .= $this->question[$ctr]->data($this, strlen($data));
        }

        for ($ctr = 0; $ctr < $this->header->ancount; $ctr++) {
            $data .= $this->answer[$ctr]->data($this, strlen($data));
        }

        for ($ctr = 0; $ctr < $this->header->nscount; $ctr++) {
            $data .= $this->authority[$ctr]->data($this, strlen($data));
        }

        for ($ctr = 0; $ctr < $this->header->arcount; $ctr++) {
            $data .= $this->additional[$ctr]->data($this, strlen($data));
        }

        return($data);
    }

    /*}}}*/
    /* Net_DNS_Packet::dn_comp($name, $offset) {{{*/
    /**
     * DNS packet compression method
     *
     * Returns a domain name compressed for a particular packet object, to
     * be stored beginning at the given offset within the packet data.  The
     * name will be added to a running list of compressed domain names for
     * future use.
     * 
     * @param string    $name       The name of the label to compress
     * @param integer   $offset     The location offset in the packet to where
     *                              the label will be stored.
     * @return string   $compname   A binary string containing the compressed
     *                              label.
     * @see Net_DNS_Packet::dn_expand()
     */
    function dn_comp($name, $offset)
    {
        $names = explode('.', $name);
        $compname = '';
        while (count($names)) {
            $dname = join('.', $names);
            if (isset($this->compnames[$dname])) {
                $compname .= pack('n', 0xc000 | $this->compnames[$dname]);
                break;
            }

            $this->compnames[$dname] = $offset;
            $first = array_shift($names);
            $length = strlen($first);
            $compname .= pack('Ca*', $length, $first);
            $offset += $length + 1;
        }
        if (! count($names)) {
            $compname .= pack('C', 0);
        }
        return($compname);
    }

    /*}}}*/
    /* Net_DNS_Packet::dn_expand($packet, $offset) {{{ */
    /**
     * DNS packet decompression method
     *
     * Expands the domain name stored at a particular location in a DNS
     * packet.  The first argument is a variable containing  the packet
     * data.  The second argument is the offset within the  packet where
     * the (possibly) compressed domain name is stored.
     * 
     * @param   string  $packet The packet data
     * @param   integer $offset The location offset in the packet of the
     *                          label to decompress.
     * @return  array   Returns a list of type array($name, $offset) where
     *                  $name is the name of the label which was decompressed
     *                  and $offset is the offset of the next field in the
     *                  packet.  Returns array(NULL, NULL) on error
     */
    function dn_expand($packet, $offset)
    {
        $packetlen = strlen($packet);
        $int16sz = 2;
        $name = '';
        while (1) {
            if ($packetlen < ($offset + 1)) {
                return(array(NULL, NULL));
            }

            $a = unpack("@$offset/Cchar", $packet);
            $len = $a['char'];

            if ($len == 0) {
                $offset++;
                break;
            } else if (($len & 0xc0) == 0xc0) {
                if ($packetlen < ($offset + $int16sz)) {
                    return(array(NULL, NULL));
                }
                $ptr = unpack("@$offset/ni", $packet);
                $ptr = $ptr['i'];
                $ptr = $ptr & 0x3fff;
                $name2 = Net_DNS_Packet::dn_expand($packet, $ptr);

                if (is_null($name2[0])) {
                    return(array(NULL, NULL));
                }
                $name .= $name2[0];
                $offset += $int16sz;
                break;
            } else {
                $offset++;

                if ($packetlen < ($offset + $len)) {
                    return(array(NULL, NULL));
                }

                $elem = substr($packet, $offset, $len);
                $name .= $elem . '.';
                $offset += $len;
            }
        }
        $name = ereg_replace('\.$', '', $name);
        return(array($name, $offset));
    }

    /*}}}*/
    /* Net_DNS_Packet::parse_question($data, $offset) {{{ */
    /**
     * Parses the question section of a packet
     *
     * Examines a DNS packet at the specified offset and parses the data
     * of the QUESTION section.
     *
     * @param   string  $data   The packet data returned from the server
     * @param   integer $offset The location offset of the start of the
     *                          question section.
     * @return  array   An array of type array($q, $offset) where $q
     *                  is a Net_DNS_Question object and $offset is the
     *                  location of the next section of the packet which
     *                  needs to be parsed.
     */
    function parse_question($data, $offset)
    {
        list($qname, $offset) = $this->dn_expand($data, $offset);
        if (is_null($qname)) {
            return(array(NULL, NULL));
        }

        if (strlen($data) < ($offset + 2 * 2)) {
            return(array(NULL, NULL));
        }

        $q = unpack("@$offset/n2int", $data);
        $qtype = $q['int1'];
        $qclass = $q['int2'];
        $offset += 2 * 2;

        $qtype = Net_DNS::typesbyval($qtype);
        $qclass = Net_DNS::classesbyval($qclass);

        $q = new Net_DNS_Question($qname, $qtype, $qclass);
        return(array($q, $offset));
    }

    /*}}}*/
    /* Net_DNS_Packet::parse_rr($data, $offset) {{{ */
    /**
     * Parses a resource record section of a packet
     *
     * Examines a DNS packet at the specified offset and parses the data
     * of a section which contains RRs (ANSWER, AUTHORITY, ADDITIONAL).
     *
     * @param string    $data   The packet data returned from the server
     * @param integer   $offset The location offset of the start of the resource
     *                          record section.
     * @return  array   An array of type array($rr, $offset) where $rr
     *                  is a Net_DNS_RR object and $offset is the
     *                  location of the next section of the packet which
     *                  needs to be parsed.
     */
    function parse_rr($data, $offset)
    {
        list($name, $offset) = $this->dn_expand($data, $offset);
        if (! strlen($name)) {
            return(array(NULL, NULL));
        }

        if (strlen($data) < ($offset + 10)) {
            return(array(NULL, NULL));
        }

        $a = unpack("@$offset/n2tc/Nttl/nrdlength", $data);
        $type = $a['tc1'];
        $class = $a['tc2'];
        $ttl = $a['ttl'];
        $rdlength = $a['rdlength'];

        $type = Net_DNS::typesbyval($type);
        $class = Net_DNS::classesbyval($class);

        $offset += 10;
        if (strlen($data) < ($offset + $rdlength)) {
            return(array(NULL, NULL));
        }

        $rrobj = new Net_DNS_RR(array($name,
                    $type,
                    $class,
                    $ttl,
                    $rdlength,
                    $data,
                    $offset));

        if (is_null($rrobj)) {
            return(array(NULL, NULL));
        }

        $offset += $rdlength;

        return(array($rrobj, $offset));
    }

    /* }}} */
    /* Net_DNS_Packet::display() {{{ */
    /**
     * Prints out the packet in a human readable formatted string
     */
    function display()
    {
        echo $this->string();
    }

    /*}}}*/
    /* Net_DNS_Packet::string() {{{ */
    /**
     * Builds a human readable formatted string representing a packet
     */ 
    function string()
    {
        $retval = '';
        if ($this->answerfrom) {
            $retval .= ';; Answer received from ' . $this->answerfrom . '(' .
                $this->answersize . " bytes)\n;;\n";
        }

        $retval .= ";; HEADER SECTION\n";
        $retval .= $this->header->string();
        $retval .= "\n";

        $section = ($this->header->opcode == 'UPDATE') ? 'ZONE' : 'QUESTION';
        $retval .= ";; $section SECTION (" . $this->header->qdcount     .
            ' record' . ($this->header->qdcount == 1 ? '' : 's') .
            ")\n";

        foreach ($this->question as $qr) {
            $retval .= ';; ' . $qr->string() . "\n";
        }

        $section = ($this->header->opcode == 'UPDATE') ? 'PREREQUISITE' : 'ANSWER';
        $retval .= "\n;; $section SECTION (" . $this->header->ancount     .
            ' record' . ($this->header->ancount == 1 ? '' : 's') .
            ")\n";

        if (is_array($this->answer)) {
            foreach ($this->answer as $ans) {
                $retval .= ';; ' . $ans->string() . "\n";
            }
        }

        $section = ($this->header->opcode == 'UPDATE') ? 'UPDATE' : 'AUTHORITY';
        $retval .= "\n;; $section SECTION (" . $this->header->nscount     .
            ' record' . ($this->header->nscount == 1 ? '' : 's') .
            ")\n";

        if (is_array($this->authority)) {
            foreach ($this->authority as $auth) {
                $retval .= ';; ' . $auth->string() . "\n";
            }
        }

        $retval .= "\n;; ADDITIONAL SECTION (" . $this->header->arcount     .
            ' record' . ($this->header->arcount == 1 ? '' : 's') .
            ")\n";

        if (is_array($this->additional)) {
            foreach ($this->additional as $addl) {
                $retval .= ';; ' . $addl->string() . "\n";
            }
        }

        $retval .= "\n\n";
        return($retval);
    }

    /*}}}*/
}
/* }}} */
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