📄 16-6.php3
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<HTML>
<HEAD>
<TITLE>Figure 16-6</TITLE>
</HEAD>
<BODY>
<?
/*
** Demonstration of using session identifiers
*/
// generates a session id
function SessionID($length=8)
{
/*
** Set pool of possible characters
*/
$Pool = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
$Pool .= "abcdefghijklmnopqrstuvwxyz";
for($index = 0; $index < $length; $index++)
{
$sid .= substr($Pool,
(rand()%(strlen($Pool))), 1);
}
return($sid);
}
// Seed the generator
srand(time());
//start HTML page
print("<HTML>\n");
print("<HEAD>\n");
print("<TITLE>Figure 16-6</TITLE>\n");
print("</HEAD>\n");
print("<BODY>\n");
//set up connection to database
$mysql_link = mysql_connect("localhost", "httpd", "");
mysql_select_db("test", $mysql_link);
//clear out any old sessions
$Query = "DELETE FROM session ";
$Query .= "WHERE LastAction < '";
$Query .= date("Y-m-d H:i:s", (time()-10800));
$Query .= "'";
mysql_query($Query, $mysql_link);
//check session
if(isset($session))
{
//we have a session, so check it
$Query = "SELECT * ";
$Query .= "FROM session ";
$Query .= "WHERE ID='$session' ";
$mysql_result = mysql_query($Query, $mysql_link);
if(mysql_numrows($mysql_result))
{
//session exists, update last action
$Query = "UPDATE session ";
$Query .= "SET LastAction = now() ";
$Query .= "WHERE ID='$session' ";
mysql_query($Query, $mysql_link);
}
else
{
//session is bad
print("Bad Session ID ($session)!<BR>\n");
$session = "";
}
}
//if session is empty, we need to create it
if($session == "")
{
//no session, so create one
$session = SessionID(8);
//insert session to database
$Query = "INSERT INTO session ";
$Query .= "VALUES ('$session', now()) ";
mysql_query($Query, $mysql_link);
}
print("You session identifier is $session<BR>\n");
print("<A HREF=\"16-6.php3?session=$session\">");
print("Refresh Page");
print("</A><BR>\n");
//close page
print("</BODY>\n");
print("</HTML>\n");
?>
</BODY>
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