Cookie清除后，登录功能无法正常工作

Question

下面的登录系统正常工作。但是，当从Chrome浏览器清除cookie时，在用户首次登录时不起作用，在cookie被清除后第二次起作用。

任何想法为什么从Chrome中清除cookie后第一次登录不起作用？

由于提前，

约翰

<?php 
if (!isLoggedIn()) 
{ 
    if (isset($_POST['cmdlogin'])) 
    { 
     if (checkLogin($_POST['username'], $_POST['password'])) 
     { 
      show_userbox();    
     } else 
     { 
      echo "Incorrect Login information !"; 
      show_loginform(); 
     } 
    } else 
    { 
     show_loginform(); 
    } 


} else 
{ 
    show_userbox();   
} 
?> 

登录表单功能：

function show_loginform($disabled = false) 
{ 
    echo '<form name="login-form" id="login-form" method="post" action="./index.php"> 

    <div class="usernameformtext"><label title="Username">Username: </label></div> 
    <div class="usernameformfield"><input tabindex="1" accesskey="u" name="username" type="text" maxlength="30" id="username" /></div> 

    <div class="passwordformtext"><label title="Password">Password: </label></div> 
    <div class="passwordformfield"><input tabindex="2" accesskey="p" name="password" type="password" maxlength="15" id="password" /></div> 

    <div class="registertext"><a href="http://www...com/.../register.php" title="Register">Register</a></div> 
    <div class="lostpasswordtext"><a href="http://www...com/.../lostpassword.php" title="Lost Password">Lost password?</a></div> 

    <p class="loginbutton"><input tabindex="3" accesskey="l" type="submit" name="cmdlogin" value="Login" '; 
    if ($disabled == true) 
    { 
     echo 'disabled="disabled"'; 
    } 
    echo ' /></p></form>';  
} 

登录功能：

function isLoggedIn() 
{ 

    if (isset($_SESSION['loginid']) && isset($_SESSION['username'])) 
    { 
     return true; // the user is loged in 
    } 
    else 
    { 
     return false; // not logged in 
    } 

    return false; 

} 

function checkLogin($u, $p) 
{ 
global $seed; // global because $seed is declared in the header.php file 

    if (!valid_username($u) || !valid_password($p) || !user_exists($u)) 
    { 
     return false; // the name was not valid, or the password, or the username did not exist 
    } 

    //Now let us look for the user in the database. 
    $query = sprintf(" 
     SELECT loginid 
     FROM login 
     WHERE 
     username = '%s' AND password = '%s' 
     AND disabled = 0 AND activated = 1 
     LIMIT 1;", mysql_real_escape_string($u), mysql_real_escape_string(sha1($p . $seed))); 
    $result = mysql_query($query); 
    // If the database returns a 0 as result we know the login information is incorrect. 
    // If the database returns a 1 as result we know the login was correct and we proceed. 
    // If the database returns a result > 1 there are multple users 
    // with the same username and password, so the login will fail. 
    if (mysql_num_rows($result) != 1) 
    { 
     return false; 
    } else 
    { 
     // Login was successfull 
     $row = mysql_fetch_array($result); 
     // Save the user ID for use later 
     $_SESSION['loginid'] = $row['loginid']; 
     // Save the username for use later 
     $_SESSION['username'] = $u; 
     // Now we show the userbox 
     return true; 
    } 
    return false; 
} 

Answer 1

您的会话数据将丢失我猜。 http://www.allaboutcookies.org/cookies/session-cookies-used-for.html