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<?php
// partials/proxy_helpers.php — small shared helpers for the *-proxy.php endpoints.
//
// - lastfm_api_key(): read LASTFM_API_KEY from env (with legacy fallback).
// - proxy_host_is_safe(): reject hosts that resolve to private/reserved IPs (SSRF guard).
// - proxy_rate_limit(): simple per-IP sliding-window limit, file-backed.
if (!function_exists('lastfm_api_key')) {
function lastfm_api_key(): string {
$env = getenv('LASTFM_API_KEY');
if (is_string($env) && $env !== '') return $env;
throw new RuntimeException('LASTFM_API_KEY is not set in the php-fpm environment');
}
}
if (!function_exists('proxy_host_is_safe')) {
function proxy_host_is_safe(string $host): bool {
if ($host === '') return false;
// Reject anything that looks like a literal IPv6 with brackets stripped earlier.
$records = @dns_get_record($host, DNS_A | DNS_AAAA);
$ips = [];
if (is_array($records)) {
foreach ($records as $r) {
if (!empty($r['ip'])) $ips[] = $r['ip'];
if (!empty($r['ipv6'])) $ips[] = $r['ipv6'];
}
}
// Also check if the host is itself an IP literal.
if (filter_var($host, FILTER_VALIDATE_IP)) {
$ips[] = $host;
}
if (!$ips) return false; // unresolvable -> deny
foreach ($ips as $ip) {
$ok = filter_var(
$ip,
FILTER_VALIDATE_IP,
FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE
);
if ($ok === false) return false;
}
return true;
}
}
if (!function_exists('proxy_rate_limit')) {
/**
* Returns true if the request is allowed. Uses a tiny file per
* (endpoint, client IP) holding recent unix timestamps.
*/
function proxy_rate_limit(string $endpoint, int $max = 30, int $windowSec = 60): bool {
$ip = $_SERVER['REMOTE_ADDR'] ?? '0.0.0.0';
$key = preg_replace('/[^A-Za-z0-9._-]/', '_', $endpoint . '_' . $ip);
$dir = sys_get_temp_dir() . '/sillylaird_ratelimit';
if (!is_dir($dir)) @mkdir($dir, 0700, true);
$file = $dir . '/' . $key;
$now = time();
$cutoff = $now - $windowSec;
$fp = @fopen($file, 'c+');
if (!$fp) return true; // fail-open: don't block legit traffic on disk error
try {
flock($fp, LOCK_EX);
$data = stream_get_contents($fp);
$stamps = $data === '' ? [] : array_map('intval', explode("\n", trim($data)));
$stamps = array_values(array_filter($stamps, fn($t) => $t >= $cutoff));
if (count($stamps) >= $max) {
return false;
}
$stamps[] = $now;
ftruncate($fp, 0);
rewind($fp);
fwrite($fp, implode("\n", $stamps));
return true;
} finally {
flock($fp, LOCK_UN);
fclose($fp);
}
}
}
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