Fix video streaming: parse total size from S3 Content-Range header

backend/src/services/rustfs.ts

@@ -7,7 +7,6 @@ import {
     CompleteMultipartUploadCommand,
     AbortMultipartUploadCommand,
     GetObjectCommand,
-    HeadObjectCommand,
 } from "@aws-sdk/client-s3";
 import { getSignedUrl } from "@aws-sdk/s3-request-presigner";
 
@@ -169,61 +168,49 @@ export async function getVideoStream(
 ): Promise<VideoStreamResult> {
     const s3 = getRustFsClient();
 
-    // Get object metadata first to know total size
-    const headResult = await s3.send(
-        new HeadObjectCommand({
-            Bucket: RUSTFS_BUCKET,
-            Key: key,
-        }),
-    );
-    const totalSize = headResult.ContentLength ?? 0;
-    const contentType = headResult.ContentType || "video/webm";
-
-    let range: { start: number; end: number } | undefined;
-    let command: GetObjectCommand;
-
-    if (rangeHeader) {
-        // Parse Range header like "bytes=0-1023" or "bytes=1024-"
-        const match = rangeHeader.match(/bytes=(\d*)-(\d*)/);
-        if (match) {
-            const start = match[1] ? parseInt(match[1], 10) : 0;
-            const end = match[2] ? parseInt(match[2], 10) : totalSize - 1;
-            range = { start, end: Math.min(end, totalSize - 1) };
-
-            command = new GetObjectCommand({
-                Bucket: RUSTFS_BUCKET,
-                Key: key,
-                Range: `bytes=${range.start}-${range.end}`,
-            });
-        } else {
-            command = new GetObjectCommand({
-                Bucket: RUSTFS_BUCKET,
-                Key: key,
-            });
-        }
-    } else {
-        command = new GetObjectCommand({
-            Bucket: RUSTFS_BUCKET,
-            Key: key,
-        });
-    }
+    // Build the GetObject command, optionally with a Range
+    const command = new GetObjectCommand({
+        Bucket: RUSTFS_BUCKET,
+        Key: key,
+        ...(rangeHeader ? { Range: rangeHeader } : {}),
+    });
 
     const result = await s3.send(command);
     if (!result.Body) {
         throw new Error("Empty response body from RustFS");
     }
 
+    const contentType = result.ContentType || "video/webm";
+
     // Convert SDK stream to web ReadableStream
     const sdkStream = result.Body as any;
     const webStream: ReadableStream<Uint8Array> = sdkStream.transformToWebStream
         ? sdkStream.transformToWebStream()
         : sdkStream;
 
+    // If we sent a range request, parse the Content-Range header from S3
+    // Format: "bytes start-end/total"
+    if (rangeHeader && result.ContentRange) {
+        const match = result.ContentRange.match(/bytes (\d+)-(\d+)\/(\d+)/);
+        if (match) {
+            const start = parseInt(match[1], 10);
+            const end = parseInt(match[2], 10);
+            const totalSize = parseInt(match[3], 10);
+            return {
+                stream: webStream,
+                contentType,
+                contentLength: totalSize,
+                range: { start, end },
+            };
+        }
+    }
+
+    // No range request (or no Content-Range in response) — full object
     return {
         stream: webStream,
         contentType,
-        contentLength: totalSize,
-        range,
+        contentLength: result.ContentLength ?? 0,
+        range: undefined,
     };
 }