External Authority Library Sample
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switchcast_ext_auth_lib.php
Code
<?php
// Decode public-key-encrypted and base64-encoded token into channel_id/clip_id/plain_token
function ext_auth_decode_encrypted_token($encrypted_token_base64) {
$encrypted_token = base64_decode($encrypted_token_base64); // Todo: Handle decryption failure
$private_key = openssl_get_privatekey("file://".EXT_AUTH_PRIVATE_KEY, EXT_AUTH_PASSPHRASE); // Todo: Handle missing/invalid private key
ext_auth_debug("Private key = \n$private_key");
openssl_private_decrypt($encrypted_token, $decrypted_token, $private_key); // Todo: Handle decryption errors
ext_auth_debug("Decrypted token = $decrypted_token");
// Token structure: <channel_id>::<clip_id>::<plain_token>
$parts = explode("::", $decrypted_token); // Todo: Handle non-conforming tokens
if (count($parts) == 3) {
ext_auth_debug("Channel ID: {$parts[0]}, clip ID: {$parts[1]}, plain token: {$parts[2]}");
return array('channel_id' => $parts[0],
'clip_id' => $parts[1],
'plain_token' => $parts[2]);
} else {
ext_auth_debug("Token decryption was unsuccessful");
return NULL;
}
}
/* ------------------------------------------------------------------------- */
// Redirect back to the SWITCHcast VOD URL with plain token
function ext_auth_redirect_to_vod_url($redirect_url, $plain_token) {
if (strpos($redirect_url, 'token=::plain::') > 0) {
// URL format: https://cast.switch.ch/vod/clip.url?token=::plain::
$redirect_url = str_replace('::plain::', urlencode($plain_token), $redirect_url);
} elseif (strpos($redirect_url, '?') === FALSE) {
// URL format: https://cast.switch.ch/vod/clip.url
$redirect_url .= '?token=' . urlencode($plain_token);
} else {
// URL format: https://cast.switch.ch/vod/clip.url?param=value
$redirect_url .= '&token=' . urlencode($plain_token);
}
// Perform HTTP redirect
ext_auth_debug("Redirecting to URL $redirect_url");
header("Location: $redirect_url");
}
/* ------------------------------------------------------------------------- */
// Render HTTP status 403 (Forbidden)
function ext_auth_show_permission_denied_page() {
ext_auth_debug("Rendering HTTP 403 Forbidden page");
header("HTTP/1.1 403 Forbidden");
echo("<html><head><title>403 Forbidden</title></head><body><h1>Access denied</h1>" .
"<h2>You have no permission to access this content.</h2></body></html>");
}
/* ------------------------------------------------------------------------- */
// Simple debug logger into EXT_AUTH_LOGFILE
function ext_auth_debug($message) {
if (!EXT_AUTH_DEBUG) {
return;
}
$fh = fopen(EXT_AUTH_LOGFILE, 'a');
fwrite($fh, date("d/m/y H:i:s:ms ", time()) . $message . "\n");
}
?>
