Simple PHP Controller, any issues with this code?

Question

I'm trying to build a really simple php controller page for a small site. Here is what I have so far. It seems to work well. Are there any issues I might be missing with doing it this way?

$page = $_GET['p'];

switch ($page)
{
case "":
    ob_start();
    include "inc/home.php";
    $content = ob_get_contents();
    ob_end_clean();
    break;
case $page:
    $page = str_replace("/", "", $page);
    if (file_exists("inc/".$page.".php"))
    {
       ob_start();
       include "inc/".$page.".php";
       $content = ob_get_contents();
       ob_end_clean();
    }
    else
       include "inc/404.php";
    break;
}

include("inc/header.php");

echo $content;

include("inc/footer.php");

UPDATE: Here is the final code based on comments that works well.

<?php

$page = (isset( $_GET['p']) && !empty($_GET['p'])) ? $_GET['p'] : 'home';

if( preg_match( '/[^a-z]/i', $page))
{
    $page = '404';
}

if( !file_exists( "inc/".$page.".php"))
{
    $page = '404';
}

ob_start();
include("inc/header.php");
include("inc/".$page.".php");
include("inc/footer.php");

?>

Answer 1

Your entire script can be rewritten as follows:

$page = ( isset( $_GET['p']) && !empty( $_GET['p'])) ? $_GET['p'] : 'home';

// Only allow alphabetic characters in a user supplied page
if( preg_match( '/[^a-z]/i', $page))
{
    $page = '404';
}

if( !file_exists( "inc/".$page.".php"))
{
    $page = '404';
}

include("inc/header.php");
include("inc/".$page.".php");
include("inc/footer.php");

However, this is also no longer susceptible to Local File Inclusion, as $page is restricted to only alphabetic characters, and the script will show the 404 page if anything else is submitted.

It's also more efficient as its not using output buffering.