Range requests: Added basic HTTP range support

Author: ssddanbrown

app/Http/DownloadResponseFactory.php

@@ -2,7 +2,6 @@
 
 namespace BookStack\Http;
 
-use BookStack\Util\WebSafeMimeSniffer;
 use Illuminate\Http\Request;
 use Illuminate\Http\Response;
 use Symfony\Component\HttpFoundation\StreamedResponse;
@@ -19,18 +18,21 @@ public function __construct(
      */
     public function directly(string $content, string $fileName): Response
     {
-        return response()->make($content, 200, $this->getHeaders($fileName));
+        return response()->make($content, 200, $this->getHeaders($fileName, strlen($content)));
     }
 
     /**
      * Create a response that forces a download, from a given stream of content.
      */
     public function streamedDirectly($stream, string $fileName, int $fileSize): StreamedResponse
     {
-        $rangeStream = new RangeSupportedStream($stream, $fileSize, $this->request->headers);
-        return response()->stream(function () use ($rangeStream) {
-            $rangeStream->outputAndClose();
-        }, 200, $this->getHeaders($fileName));
+        $rangeStream = new RangeSupportedStream($stream, $fileSize, $this->request);
+        $headers = array_merge($this->getHeaders($fileName, $fileSize), $rangeStream->getResponseHeaders());
+        return response()->stream(
+            fn() => $rangeStream->outputAndClose(),
+            $rangeStream->getResponseStatus(),
+            $headers,
+        );
     }
 
     /**
@@ -40,24 +42,28 @@ public function streamedDirectly($stream, string $fileName, int $fileSize): Stre
      */
     public function streamedInline($stream, string $fileName, int $fileSize): StreamedResponse
     {
-        $rangeStream = new RangeSupportedStream($stream, $fileSize, $this->request->headers);
+        $rangeStream = new RangeSupportedStream($stream, $fileSize, $this->request);
         $mime = $rangeStream->sniffMime();
+        $headers = array_merge($this->getHeaders($fileName, $fileSize, $mime), $rangeStream->getResponseHeaders());
 
-        return response()->stream(function () use ($rangeStream) {
-            $rangeStream->outputAndClose();
-        }, 200, $this->getHeaders($fileName, $mime));
+        return response()->stream(
+            fn() => $rangeStream->outputAndClose(),
+            $rangeStream->getResponseStatus(),
+            $headers,
+        );
     }
 
     /**
      * Get the common headers to provide for a download response.
      */
-    protected function getHeaders(string $fileName, string $mime = 'application/octet-stream'): array
+    protected function getHeaders(string $fileName, int $fileSize, string $mime = 'application/octet-stream'): array
     {
         $disposition = ($mime === 'application/octet-stream') ? 'attachment' : 'inline';
         $downloadName = str_replace('"', '', $fileName);
 
         return [
             'Content-Type'           => $mime,
+            'Content-Length'         => $fileSize,
             'Content-Disposition'    => "{$disposition}; filename=\"{$downloadName}\"",
             'X-Content-Type-Options' => 'nosniff',
         ];

app/Http/RangeSupportedStream.php

@@ -3,17 +3,30 @@
 namespace BookStack\Http;
 
 use BookStack\Util\WebSafeMimeSniffer;
-use Symfony\Component\HttpFoundation\HeaderBag;
+use Illuminate\Http\Request;
 
+/**
+ * Helper wrapper for range-based stream response handling.
+ * Much of this used symfony/http-foundation as a reference during build.
+ * URL: https://github.com/symfony/http-foundation/blob/v6.0.20/BinaryFileResponse.php
+ * License: MIT license, Copyright (c) Fabien Potencier.
+ */
 class RangeSupportedStream
 {
     protected string $sniffContent;
+    protected array $responseHeaders;
+    protected int $responseStatus = 200;
+
+    protected int $responseLength = 0;
+    protected int $responseOffset = 0;
 
     public function __construct(
         protected $stream,
         protected int $fileSize,
-        protected HeaderBag $requestHeaders,
+        Request $request,
     ) {
+        $this->responseLength = $this->fileSize;
+        $this->parseRequest($request);
     }
 
     /**
@@ -40,18 +53,82 @@ public function outputAndClose(): void
         }
 
         $outStream = fopen('php://output', 'w');
-        $offset = 0;
+        $sniffOffset = strlen($this->sniffContent);
 
-        if (!empty($this->sniffContent)) {
-            fwrite($outStream, $this->sniffContent);
-            $offset = strlen($this->sniffContent);
+        if (!empty($this->sniffContent) && $this->responseOffset < $sniffOffset) {
+            $sniffOutput = substr($this->sniffContent, $this->responseOffset, min($sniffOffset, $this->responseLength));
+            fwrite($outStream, $sniffOutput);
+        } else if ($this->responseOffset !== 0) {
+            fseek($this->stream, $this->responseOffset);
         }
 
-        $toWrite = $this->fileSize - $offset;
-        stream_copy_to_stream($this->stream, $outStream, $toWrite);
-        fpassthru($this->stream);
+        stream_copy_to_stream($this->stream, $outStream, $this->responseLength);
 
         fclose($this->stream);
         fclose($outStream);
     }
+
+    public function getResponseHeaders(): array
+    {
+        return $this->responseHeaders;
+    }
+
+    public function getResponseStatus(): int
+    {
+        return $this->responseStatus;
+    }
+
+    protected function parseRequest(Request $request): void
+    {
+        $this->responseHeaders['Accept-Ranges'] = $request->isMethodSafe() ? 'bytes' : 'none';
+
+        $range = $this->getRangeFromRequest($request);
+        if ($range) {
+            [$start, $end] = $range;
+            if ($start < 0 || $start > $end) {
+                $this->responseStatus = 416;
+                $this->responseHeaders['Content-Range'] = sprintf('bytes */%s', $this->fileSize);
+            } elseif ($end - $start < $this->fileSize - 1) {
+                $this->responseLength = $end < $this->fileSize ? $end - $start + 1 : -1;
+                $this->responseOffset = $start;
+                $this->responseStatus = 206;
+                $this->responseHeaders['Content-Range'] = sprintf('bytes %s-%s/%s', $start, $end, $this->fileSize);
+                $this->responseHeaders['Content-Length'] = $end - $start + 1;
+            }
+        }
+
+        if ($request->isMethod('HEAD')) {
+            $this->responseLength = 0;
+        }
+    }
+
+    protected function getRangeFromRequest(Request $request): ?array
+    {
+        $range = $request->headers->get('Range');
+        if (!$range || !$request->isMethod('GET') || !str_starts_with($range, 'bytes=')) {
+            return null;
+        }
+
+        if ($request->headers->has('If-Range')) {
+            return null;
+        }
+
+        [$start, $end] = explode('-', substr($range, 6), 2) + [0];
+
+        $end = ('' === $end) ? $this->fileSize - 1 : (int) $end;
+
+        if ('' === $start) {
+            $start = $this->fileSize - $end;
+            $end = $this->fileSize - 1;
+        } else {
+            $start = (int) $start;
+        }
+
+        if ($start > $end) {
+            return null;
+        }
+
+        $end = min($end, $this->fileSize - 1);
+        return [$start, $end];
+    }
 }