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@@ -130,6 +130,210 @@ function host_matches_suffix($host, $suffix)
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return substr($host, -strlen($needle)) === $needle;
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}
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function parse_allowlist_suffixes($allowlistEnv)
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{
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$suffixes = array();
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if ($allowlistEnv === false || trim((string) $allowlistEnv) === '') {
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return $suffixes;
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}
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$parts = explode(',', (string) $allowlistEnv);
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foreach ($parts as $part) {
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$suffix = strtolower(trim((string) $part));
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if ($suffix !== '') {
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$suffixes[] = $suffix;
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}
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}
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return $suffixes;
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}
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function resolve_host_ips($host)
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{
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$ips = array();
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$ipv4 = @gethostbynamel($host);
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if (is_array($ipv4)) {
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foreach ($ipv4 as $ip) {
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$ip = trim((string) $ip);
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if ($ip !== '') {
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$ips[$ip] = true;
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}
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}
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}
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if (function_exists('dns_get_record')) {
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$aaaa = @dns_get_record($host, DNS_AAAA);
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if (is_array($aaaa)) {
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foreach ($aaaa as $record) {
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if (!isset($record['ipv6'])) {
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continue;
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}
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$ip = trim((string) $record['ipv6']);
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if ($ip !== '') {
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$ips[$ip] = true;
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}
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}
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}
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}
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return array_keys($ips);
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}
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function validate_public_ip($ip)
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{
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return filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE) !== false;
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}
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function validate_target_url($url, $allowlistSuffixes, &$error)
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{
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$error = '';
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$parsed = parse_url($url);
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if ($parsed === false || !isset($parsed['scheme']) || !isset($parsed['host'])) {
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$error = 'invalid url';
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return false;
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}
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$scheme = strtolower((string) $parsed['scheme']);
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if ($scheme !== 'http' && $scheme !== 'https') {
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$error = 'unsupported scheme';
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return false;
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}
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$host = strtolower((string) $parsed['host']);
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if ($host === 'localhost' || $host === '127.0.0.1' || $host === '::1') {
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$error = 'forbidden host';
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return false;
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}
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if (!empty($allowlistSuffixes)) {
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$allowed = false;
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foreach ($allowlistSuffixes as $suffix) {
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if (host_matches_suffix($host, $suffix)) {
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$allowed = true;
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break;
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}
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}
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if (!$allowed) {
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$error = 'host not allowed';
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return false;
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}
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}
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$resolved = array();
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if (filter_var($host, FILTER_VALIDATE_IP)) {
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$resolved[] = $host;
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} else {
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$resolved = resolve_host_ips($host);
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}
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if (count($resolved) === 0) {
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$error = 'dns resolution failed';
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return false;
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}
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foreach ($resolved as $ip) {
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if (!validate_public_ip($ip)) {
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$error = 'resolved ip not allowed';
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return false;
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}
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}
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return true;
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}
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function resolve_redirect_url($baseUrl, $location)
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{
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$location = trim((string) $location);
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if ($location === '') {
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return '';
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}
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$target = parse_url($location);
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if ($target !== false && isset($target['scheme']) && isset($target['host'])) {
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return $location;
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}
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$base = parse_url($baseUrl);
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if ($base === false || !isset($base['scheme']) || !isset($base['host'])) {
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return '';
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}
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$scheme = strtolower((string) $base['scheme']);
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$host = (string) $base['host'];
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$port = isset($base['port']) ? ':' . (int) $base['port'] : '';
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if (strpos($location, '//') === 0) {
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return $scheme . ':' . $location;
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}
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$path = isset($base['path']) ? (string) $base['path'] : '/';
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if ($path === '') {
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$path = '/';
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}
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if ($location[0] === '/') {
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return $scheme . '://' . $host . $port . $location;
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}
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$dir = preg_replace('#/[^/]*$#', '/', $path);
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if ($dir === null || $dir === '') {
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$dir = '/';
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}
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return $scheme . '://' . $host . $port . $dir . $location;
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}
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function resolve_safe_redirect_chain($initialUrl, $allowlistSuffixes, $requestHeaders, $maxRedirects, &$error)
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{
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$error = '';
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$currentUrl = $initialUrl;
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for ($hop = 0; $hop <= $maxRedirects; $hop += 1) {
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if (!validate_target_url($currentUrl, $allowlistSuffixes, $error)) {
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return '';
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}
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$GLOBALS['CHGRID_PROXY_STATUS'] = 200;
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$GLOBALS['CHGRID_PROXY_UP_HEADERS'] = array();
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$GLOBALS['CHGRID_PROXY_HEADERS_SENT'] = false;
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$ch = curl_init();
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if (!$ch) {
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$error = 'proxy init failed';
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return '';
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}
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curl_setopt($ch, CURLOPT_URL, $currentUrl);
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curl_setopt($ch, CURLOPT_FOLLOWLOCATION, false);
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curl_setopt($ch, CURLOPT_MAXREDIRS, 0);
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curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
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curl_setopt($ch, CURLOPT_TIMEOUT, 20);
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curl_setopt($ch, CURLOPT_HEADER, false);
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curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
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curl_setopt($ch, CURLOPT_NOSIGNAL, true);
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curl_setopt($ch, CURLOPT_USERAGENT, 'ChatGridMediaProxy/1.0');
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curl_setopt($ch, CURLOPT_HTTPHEADER, $requestHeaders);
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curl_setopt($ch, CURLOPT_HEADERFUNCTION, 'proxy_header_callback');
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curl_setopt($ch, CURLOPT_NOBODY, true);
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$ok = curl_exec($ch);
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if ($ok === false) {
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$error = 'upstream fetch failed: ' . curl_error($ch);
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curl_close($ch);
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return '';
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}
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curl_close($ch);
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$status = isset($GLOBALS['CHGRID_PROXY_STATUS']) ? (int) $GLOBALS['CHGRID_PROXY_STATUS'] : 200;
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if ($status < 300 || $status >= 400) {
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return $currentUrl;
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}
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if ($hop >= $maxRedirects) {
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$error = 'too many redirects';
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return '';
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}
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$headers = isset($GLOBALS['CHGRID_PROXY_UP_HEADERS']) ? $GLOBALS['CHGRID_PROXY_UP_HEADERS'] : array();
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$location = isset($headers['location']) ? (string) $headers['location'] : '';
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$nextUrl = resolve_redirect_url($currentUrl, $location);
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if ($nextUrl === '') {
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$error = 'redirect location missing or invalid';
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return '';
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}
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$currentUrl = $nextUrl;
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}
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$error = 'too many redirects';
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return '';
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}
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header('Access-Control-Allow-Origin: *');
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header('Access-Control-Allow-Methods: GET, HEAD, OPTIONS');
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header('Access-Control-Allow-Headers: Range');
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@@ -148,52 +352,9 @@ if ($rawUrl === '') {
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send_text(400, 'missing url query param');
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}
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$parsed = parse_url($rawUrl);
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if ($parsed === false || !isset($parsed['scheme']) || !isset($parsed['host'])) {
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send_text(400, 'invalid url');
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}
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$scheme = strtolower((string) $parsed['scheme']);
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if ($scheme !== 'http' && $scheme !== 'https') {
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send_text(400, 'unsupported scheme');
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}
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$host = strtolower((string) $parsed['host']);
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if ($host === 'localhost' || $host === '127.0.0.1' || $host === '::1') {
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send_text(403, 'forbidden host');
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}
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// Optional allowlist env var: CHGRID_MEDIA_PROXY_ALLOWLIST=dropbox.com,example.com
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$allowlistEnv = getenv('CHGRID_MEDIA_PROXY_ALLOWLIST');
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if ($allowlistEnv !== false && trim($allowlistEnv) !== '') {
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$allowed = false;
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$parts = explode(',', (string) $allowlistEnv);
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foreach ($parts as $part) {
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$suffix = strtolower(trim((string) $part));
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if ($suffix === '') {
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continue;
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}
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if (host_matches_suffix($host, $suffix)) {
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$allowed = true;
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break;
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}
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}
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if (!$allowed) {
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send_text(403, 'host not allowed');
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}
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}
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// Basic SSRF guard for IPv4.
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$resolved = @gethostbynamel($host);
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if ($resolved === false || count($resolved) === 0) {
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send_text(502, 'dns resolution failed');
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}
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foreach ($resolved as $ip) {
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$ok = filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE);
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if ($ok === false) {
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send_text(403, 'resolved ip not allowed');
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}
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}
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$allowlistSuffixes = parse_allowlist_suffixes($allowlistEnv);
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if (!function_exists('curl_init')) {
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send_text(500, 'curl extension is required');
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@@ -210,9 +371,28 @@ if ($range !== '') {
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$requestHeaders[] = 'Range: ' . $range;
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}
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curl_setopt($ch, CURLOPT_URL, $rawUrl);
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curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
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curl_setopt($ch, CURLOPT_MAXREDIRS, 5);
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$resolveError = '';
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$finalUrl = resolve_safe_redirect_chain($rawUrl, $allowlistSuffixes, $requestHeaders, 5, $resolveError);
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if ($finalUrl === '') {
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if (strpos($resolveError, 'invalid url') === 0 || strpos($resolveError, 'unsupported scheme') === 0) {
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send_text(400, $resolveError);
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}
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if (
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strpos($resolveError, 'forbidden host') === 0 ||
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strpos($resolveError, 'host not allowed') === 0 ||
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strpos($resolveError, 'resolved ip not allowed') === 0
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) {
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send_text(403, $resolveError);
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}
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if (strpos($resolveError, 'proxy init failed') === 0) {
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send_text(500, $resolveError);
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}
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send_text(502, $resolveError !== '' ? $resolveError : 'redirect resolution failed');
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}
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curl_setopt($ch, CURLOPT_URL, $finalUrl);
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curl_setopt($ch, CURLOPT_FOLLOWLOCATION, false);
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curl_setopt($ch, CURLOPT_MAXREDIRS, 0);
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curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
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curl_setopt($ch, CURLOPT_TIMEOUT, 0);
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curl_setopt($ch, CURLOPT_HEADER, false);
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