mysql数据库连接程序

这里提供的数据库连接类程序，后面还提供了一个sql安全检测函数与sql语句完整性检测函数。*/

class db_mysql {
 var $connid;
 var $querynum = 0;
 var $expires;
 var $cursor = 0;
 var $cache_id = '';
 var $cache_file = '';
 var $cache_expires = '';
 var $halt = 0;
 var $result = array();

 function connect($dbhost, $dbuser, $dbpw, $dbname, $pconnect = 0) {
  global $cfg;
  $this->expires = $cfg['db_expires'];
  $func = $pconnect == 1 ? 'mysql_pconnect' : 'mysql_connect';
  if(!$this->connid = $func($dbhost, $dbuser, $dbpw)) {
   $this->halt('can not connect to mysql server');
  }
  if($this->version() > '4.1' && $cfg['db_charset']) {
   mysql_query("set names '".$cfg['db_charset']."'" , $this->connid);
  }
  if($this->version() > '5.0') {
   mysql_query("set sql_mode=''" , $this->connid);
  }
  if($dbname) {
   if(!mysql_select_db($dbname , $this->connid)) {
    $this->halt('cannot use database '.$dbname);
   }
  }
  return $this->connid;
 }

 function select_db($dbname) {
  return mysql_select_db($dbname , $this->connid);
 }

 function query($sql , $type = '', $expires = 0, $save_id = false) {
        $sql=checksql($sql);
  if($type == 'cache' && stristr($sql, 'select')) {
   $this->cursor = 0;
   $this->cache_id = md5($sql);
   $this->result = array();
   $this->cache_expires = $expires ? $expires + mt_rand(-9, 9) : $this->expires;
   return $this->_query($sql);
  }
  if(!$save_id) $this->cache_id = 0;
  $func = $type == 'unbuffered' ? 'mysql_unbuffered_query' : 'mysql_query';
  if(!($query = $func($sql , $this->connid)) && $this->halt) {
   $this->halt('mysql query error', $sql);
  }
  $this->querynum++;
  return $query;
 }

 function get_one($sql, $type = '', $expires = 0) {
  $query = $this->query($sql, $type, $expires);
  $r = $this->fetch_array($query);
  $this->free_result($query);
  return $r ;
 }
 
 function counter($table, $condition = '', $type = '', $expires = 0) {
  global $cfg;
  $table = strpos($table, $cfg['tb_pre']) === false ? $cfg['tb_pre'].$table : $table;
  $sql = "select count(*) as num from {$table}";
  if($condition) $sql .= " where $condition";
  $r = $this->get_one($sql, $type, $expires);
  return $r ? $r['num'] : 0;
 }

 function fetch_array($query, $result_type = mysql_assoc) {
  return $this->cache_id ? $this->_fetch_array($query) : @mysql_fetch_array($query, $result_type);
 }

 function affected_rows() {
  return mysql_affected_rows($this->connid);
 }

 function num_rows($query) {
  return mysql_num_rows($query);
 }

 function num_fields($query) {
  return mysql_num_fields($query);
 }
 function escape_string($str){
  return mysql_escape_string($str);
 }
 function result($query, $row) {
  return @mysql_result($query, $row);
 }

 function free_result($query) {
  return @mysql_free_result($query);
 }

 function insert_id() {
  return mysql_insert_id($this->connid);
 }

 function fetch_row($query) {
  return mysql_fetch_row($query);
 }

 function version() {
  return mysql_get_server_info($this->connid);
 }

 function close() {
  return mysql_close($this->connid);
 }

 function error() {
  return @mysql_error($this->connid);
 }

 function errno() {
  return intval(@mysql_errno($this->connid)) ;
 }

 function halt($message = '', $sql = '') {
  global $cfg;
  if($message) {
   if($cfg['errlog']) {
    $log = "query:$sql|errno:".$this->errno()."|error:".$this->error()."|errmsg:$message";
    log_write($log, 'sql');
   }
  }
        showmsg("mysqlerror:$message",'-1');
        exit();
 }

 function _query($sql) {
  global $fr_time;
  $this->cache_file = cache_root.'/sql/'.substr($this->cache_id, 0, 2).'/'.$this->cache_id.'.php教程';
  if(!is_file($this->cache_file) || ($fr_time - @filemtime($this->cache_file) > $this->cache_expires)) {
   $tmp = array();
   $result = $this->query($sql, '', '', true);
   while($r = mysql_fetch_array($result, mysql_assoc)) {
    $tmp[] = $r;
   }
   $this->result = $tmp;
   $this->free_result($result);
   file_put($this->cache_file, "cache_expires)."*/ return ".var_export($this->result, true).";n?>");
  } else {
      $this->result = include $this->cache_file;
  }
  return $this->result;
 }

 function _fetch_array($query = array()) {
  if($query) $this->result = $query;
  if(isset($this->result[$this->cursor])) {
   return $this->result[$this->cursor++];
  } else {
   $this->cursor = $this->cache_id = 0;
   return array();
  }
 }
}

function checksql($dbstr,$querytype='select'){
 $clean = '';
 $old_pos = 0;
 $pos = -1;
 //普通语句，直接过滤特殊语法
 if($querytype=='select'){
  $nastr = "/[^0-9a-z@._-]{1,}(union|sleep|benchmark|load_file|outfile)[^[email protected]]{1,}/i";
  if(preg_match($nastr,$dbstr)){
            log_write($dbstr,'sql');
            showmsg('safeerror:10001', '网页特效:;');
            exit();
  }
 }
 //完整的sql检查
 while (true){
  $pos = strpos($dbstr, ''', $pos + 1);
  if ($pos === false){
   break;
  }
  $clean .= substr($dbstr, $old_pos, $pos - $old_pos);
  while (true){
   $pos1 = strpos($dbstr, ''', $pos + 1);
   $pos2 = strpos($dbstr, '', $pos + 1);
   if ($pos1 === false){
    break;
   }
   elseif ($pos2 == false || $pos2 > $pos1){
    $pos = $pos1;
    break;
   }
   $pos = $pos2 + 1;
  }
  $clean .= '$s$';
  $old_pos = $pos + 1;
 }
 $clean .= substr($dbstr, $old_pos);
 $clean = trim(strtolower(preg_replace(array('~s+~s' ), array(' '), $clean)));
 if (strpos($clean, 'union') !== false && preg_match('~(^|[^a-z])union($|[^[a-z])~s', $clean) != 0){
  $fail = true;
 }
 elseif (strpos($clean, '/*') > 2 || strpos($clean, '--') !== false || strpos($clean, '#') !== false){
  $fail = true;
 }
 elseif (strpos($clean, 'sleep') !== false && preg_match('~(^|[^a-z])sleep($|[^[a-z])~s', $clean) != 0){
  $fail = true;
 }
 elseif (strpos($clean, 'benchmark') !== false && preg_match('~(^|[^a-z])benchmark($|[^[a-z])~s', $clean) != 0){
  $fail = true;
 }
 elseif (strpos($clean, 'load_file') !== false && preg_match('~(^|[^a-z])load_file($|[^[a-z])~s', $clean) != 0){
  $fail = true;
 }
 elseif (strpos($clean, 'into outfile') !== false && preg_match('~(^|[^a-z])intos+outfile($|[^[a-z])~s', $clean) != 0){
  $fail = true;
 }
 elseif (preg_match('~([^)]*?select~s', $clean) != 0){
  $fail = true;
 }
 if (!empty($fail)){
        log_write($dbstr,'sql');
        showmsg('safeerror:10002', 'javascript:;');exit;
 }
 else
 {
  return $dbstr;
 }
}