Add WOPI discovery service and connection diagnostics

lib/Discovery/ServerAddress.php

@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace KTXM\ServiceWopi\Discovery;
+
+use InvalidArgumentException;
+
+final readonly class ServerAddress
+{
+    public string $url;
+    public string $origin;
+
+    public function __construct(string $url)
+    {
+        $parts = parse_url($url);
+        if ($parts === false || strtolower($parts['scheme'] ?? '') !== 'https'
+            || empty($parts['host']) || isset($parts['user']) || isset($parts['pass'])
+            || isset($parts['query']) || isset($parts['fragment'])
+            || preg_match('/[\x00-\x20\x7f\\\\]/', $url)
+            || filter_var($url, FILTER_VALIDATE_URL) === false) {
+            throw new InvalidArgumentException('Use an HTTPS server URL without credentials, query parameters, or a fragment.');
+        }
+        $this->origin = 'https://' . strtolower($parts['host'])
+            . (isset($parts['port']) && $parts['port'] !== 443 ? ':' . $parts['port'] : '');
+        $this->url = $this->origin . rtrim($parts['path'] ?? '', '/');
+    }
+
+    public function discoveryUrl(): string { return $this->url . '/hosting/discovery'; }
+
+    public function assertTrustedAction(string $url): void
+    {
+        $plain = preg_replace('/<[^<>]*>/', '', $url);
+        $parts = parse_url($plain);
+        if ($parts === false || isset($parts['user']) || isset($parts['pass'])
+            || isset($parts['fragment']) || preg_match('/[\x00-\x20\x7f\\\\<>]/', $plain)
+            || filter_var($plain, FILTER_VALIDATE_URL) === false) {
+            throw new InvalidArgumentException('Discovery contains an invalid action URL.');
+        }
+        $origin = strtolower($parts['scheme'] ?? '') . '://' . strtolower($parts['host'] ?? '')
+            . (isset($parts['port']) && $parts['port'] !== 443 ? ':' . $parts['port'] : '');
+        if ($origin !== $this->origin) {
+            throw new InvalidArgumentException('Discovery action URL is outside the configured HTTPS server origin.');
+        }
+    }
+}