Emtec

function check_for_symbols($string)
{
$len=strlen($string);
$allowed_chars="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
for($i=0;$i<$len;$i++)if(!strstr($allowed_chars,$string[$i]))
return TRUE;
return FALSE;
}

function check_for_symbols($string)
 
{
    if(preg_replace("([^A-Za-z0-9])", "", $string) != $string)
        return false;
    return true;
}

function sha_password($user,$pass)
{
$user = strtoupper($user);
$pass = strtoupper($pass);
return SHA1($user.':'.$pass);
}

function sha_password($user,$pass)
 
{
    return sha1(strtoupper($user.':'.$pass));
}

if ($host != "" && $user != "" && $pass != "" && $auth != "")

if(!empty($host) AND !empty($user) AND !empty($pass) AND !empty($auth))

<?php
$server_ip = "127.0.0.1"; // Server ip

<?php
 
error_reporting(0);
$server_ip = "127.0.0.1"; // Server ip

    	if ($username == "")
    	{
        	echo "Field username is empty!";
    	}
    	else if ($password == "")
    	{
        	echo "Field password is empty!";
    	}
    	else if ($email == "")
    	{
        	echo "Field email is empty!";
    	}
    	else if (mysql_num_rows($check_email) != NULL)
    	{
        	echo "Email is already used";
    	}
    	else if (check_for_symbols($_POST[password]) == TRUE)
    	{
        	echo "Error with creating account: password has invalid symbols in it.";
    	}
    	else if (check_for_symbols($username) == TRUE)
    	{
        	echo "Error with creating account: username has invalid symbols in it.";
    	}
    	else if (mysql_num_rows($check_username) != NULL)
    	{
        	echo "Error with creating account: name is already in use.";
    	}
    	else if ($password != $password2)
    	{
        	echo "Passwords not matches!";
    	}

       if (empty($username))
        	$err[] = "Field username is empty!";
        if (empty($password) or empty($password2))
        	$err[] = "Field password is empty!";
        if (empty($email))
        	$err[] = "Field email is empty!";
        if (mysql_num_rows($check_email) /* not need 0 = false */ != NULL)
            $err[] = "Email is already used";
    	// Password can have all chars, in db is in sha1
    	//elseif (check_for_symbols($_POST[password]) == TRUE)
    	//{
    	//	echo "Error with creating account: password has invalid symbols in it.";
    	//}
        if (check_for_symbols($username) == TRUE)
        	$err[] = "Error with creating account: username has invalid symbols in it.";
        if (mysql_num_rows($check_username) != NULL)
        	$err[] = "Error with creating account: name is already in use.";
        if ($password != $password2)
        	$err[] = "Passwords not matches!";
    	if(isset($err) and is_array($err))
    	{
        	echo "<ul>";
        	foreach($err as $i => $var)
			{
            	echo "<li>{$var}</li>";
			}
        	echo "</ul>";
        	exit;
    	}

Code written on fast, no tested. Small clean up