Add DownloadAttachment class to handle file downloads and permissions validation

src/FederationServer/Methods/DownloadAttachment.php

@@ -0,0 +1,101 @@
+<?php
+
+    namespace FederationServer\Methods;
+
+    use FederationServer\Classes\Configuration;
+    use FederationServer\Classes\Managers\EvidenceManager;
+    use FederationServer\Classes\Managers\FileAttachmentManager;
+    use FederationServer\Classes\RequestHandler;
+    use FederationServer\Classes\Validate;
+    use FederationServer\Exceptions\RequestException;
+    use FederationServer\FederationServer;
+    use Throwable;
+
+    class DownloadAttachment extends RequestHandler
+    {
+        /**
+         * @inheritDoc
+         */
+        public static function handleRequest(): void
+        {
+            if(!preg_match('#^/attachment/([a-fA-F0-9\-]{36,})$#', FederationServer::getPath(), $matches))
+            {
+                throw new RequestException('Attachment UUID required', 405);
+            }
+
+            $uuid = $matches[1];
+            if(!$uuid || !Validate::uuid($uuid))
+            {
+                throw new RequestException('Invalid attachment UUID', 400);
+            }
+
+            try
+            {
+                $attachment = FileAttachmentManager::getRecord($uuid);
+                if(!$attachment)
+                {
+                    throw new RequestException('Attachment not found', 404);
+                }
+
+                $evidence = EvidenceManager::getEvidence($attachment->getEvidence());
+                if($evidence && $evidence->isConfidential())
+                {
+                    // Require authentication if confidential
+                    $operator = FederationServer::getAuthenticatedOperator();
+                    if(!$operator->canManageBlacklist())
+                    {
+                        throw new RequestException('Insufficient Permissions to view confidential evidence', 401);
+                    }
+                }
+            }
+            catch(Throwable $e)
+            {
+                throw new RequestException('Error retrieving attachment: ' . $e->getMessage(), 500, $e);
+            }
+
+            $fileLocation = Configuration::getServerConfiguration()->getStoragePath() . DIRECTORY_SEPARATOR . $attachment->getUuid();
+            if(!file_exists($fileLocation))
+            {
+                throw new RequestException('Attachment file not found', 404);
+            }
+
+            // Set headers for file download
+            header('Content-Type: ' . $attachment->getFileMime());
+            header('Content-Disposition: attachment; filename="' . $attachment->getFileName() . '"');
+            header('Content-Length: ' . filesize($fileLocation));
+            header('Cache-Control: no-cache, no-store, must-revalidate'); // HTTP 1.1
+            header('Pragma: no-cache'); // HTTP 1.0
+            header('Expires: 0'); // Proxies
+
+            $chunkSize = 8192; // 8KB per chunk
+            $handle = fopen($fileLocation, 'rb');
+
+            if ($handle === false)
+            {
+                throw new RequestException('Failed to open attachment file for reading', 500);
+            }
+
+            while (!feof($handle))
+            {
+                $buffer = fread($handle, $chunkSize);
+                if ($buffer === false)
+                {
+                    fclose($handle);
+                    throw new RequestException('Error reading attachment file', 500);
+                }
+
+                print($buffer);
+
+                // Flush output buffers to send data immediately
+                if (ob_get_level())
+                {
+                    ob_flush();
+                }
+
+                flush();
+            }
+
+            fclose($handle);
+        }
+    }
+