address comments

weed/s3api/s3_sse_s3_multipart_test.go

@@ -64,7 +64,10 @@ func TestSSES3MultipartChunkViewDecryption(t *testing.T) {
 
 			// Verify decryption works with the chunk's IV
 			decryptedData := make([]byte, len(ciphertext))
-			decryptBlock, _ := aes.NewCipher(key)
+			decryptBlock, err := aes.NewCipher(key)
+			if err != nil {
+				t.Fatalf("Failed to create decrypt cipher: %v", err)
+			}
 			decryptStream := cipher.NewCTR(decryptBlock, chunkIV)
 			decryptStream.XORKeyStream(decryptedData, ciphertext)
 

weed/s3api/s3api_object_handlers.go

@@ -732,24 +732,7 @@ func (s3a *S3ApiServer) streamFromVolumeServers(w http.ResponseWriter, r *http.R
 		return err
 	}
 
-	// Set standard HTTP headers from entry metadata
+	// Get chunks and validate BEFORE setting headers
-	// IMPORTANT: Set ALL headers BEFORE calling WriteHeader (headers are ignored after WriteHeader)
-	tHeaderSet := time.Now()
-	s3a.setResponseHeaders(w, entry, totalSize)
-
-	// Override/add range-specific headers if this is a range request
-	if isRangeRequest {
-		w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", offset, offset+size-1, totalSize))
-		w.Header().Set("Content-Length", strconv.FormatInt(size, 10))
-	}
-	headerSetTime = time.Since(tHeaderSet)
-
-	// Now write status code (headers are all set)
-	if isRangeRequest {
-		w.WriteHeader(http.StatusPartialContent)
-	}
-
-	// Get chunks
 	chunks := entry.GetChunks()
 	glog.Infof("streamFromVolumeServers: entry has %d chunks, totalSize=%d, isRange=%v, offset=%d, size=%d",
 		len(chunks), totalSize, isRangeRequest, offset, size)
@@ -759,17 +742,13 @@ func (s3a *S3ApiServer) streamFromVolumeServers(w http.ResponseWriter, r *http.R
 		if totalSize > 0 && len(entry.Content) == 0 {
 			glog.Errorf("streamFromVolumeServers: Data integrity error - entry reports size %d but has no content or chunks", totalSize)
 			// IMPORTANT: Write error status before returning, since headers haven't been written yet
-			// Clear any headers set by setResponseHeaders to avoid misleading Content-Length
-			w.Header().Del("Content-Length")
-			w.Header().Del("Content-Range")
 			w.WriteHeader(http.StatusInternalServerError)
+			fmt.Fprintf(w, "Internal Server Error: data integrity issue (size %d reported but no content available)", totalSize)
 			return fmt.Errorf("data integrity error: size %d reported but no content available", totalSize)
 		}
-		// Empty object - need to set headers before writing status
+		// Empty object - set headers and write status
-		if !isRangeRequest {
+		s3a.setResponseHeaders(w, entry, totalSize)
-			// Headers were already set by setResponseHeaders above
+		w.WriteHeader(http.StatusOK)
-			w.WriteHeader(http.StatusOK)
-		}
 		return nil
 	}
 
@@ -778,7 +757,8 @@ func (s3a *S3ApiServer) streamFromVolumeServers(w http.ResponseWriter, r *http.R
 		glog.Infof("  GET Chunk[%d]: fid=%s, offset=%d, size=%d", i, chunk.GetFileIdString(), chunk.Offset, chunk.Size)
 	}
 
-	// Create lookup function via filer client (reuse shared helper)
+	// CRITICAL: Resolve chunks and prepare stream BEFORE WriteHeader
+	// This ensures we can write proper error responses if these operations fail
 	ctx := r.Context()
 	lookupFileIdFn := s3a.createLookupFileIdFunction()
 
@@ -788,7 +768,8 @@ func (s3a *S3ApiServer) streamFromVolumeServers(w http.ResponseWriter, r *http.R
 	chunkResolveTime = time.Since(tChunkResolve)
 	if err != nil {
 		glog.Errorf("streamFromVolumeServers: failed to resolve chunks: %v", err)
-		// Don't try to write headers if we already wrote them for range request
+		w.WriteHeader(http.StatusInternalServerError)
+		fmt.Fprintf(w, "Internal Server Error: failed to resolve chunks")
 		return fmt.Errorf("failed to resolve chunks: %v", err)
 	}
 
@@ -810,10 +791,29 @@ func (s3a *S3ApiServer) streamFromVolumeServers(w http.ResponseWriter, r *http.R
 	streamPrepTime = time.Since(tStreamPrep)
 	if err != nil {
 		glog.Errorf("streamFromVolumeServers: failed to prepare stream: %v", err)
-		// Don't try to write headers if we already wrote them for range request
+		w.WriteHeader(http.StatusInternalServerError)
+		fmt.Fprintf(w, "Internal Server Error: failed to prepare stream")
 		return fmt.Errorf("failed to prepare stream: %v", err)
 	}
 
+	// All validation and preparation successful - NOW set headers and write status
+	tHeaderSet := time.Now()
+	s3a.setResponseHeaders(w, entry, totalSize)
+
+	// Override/add range-specific headers if this is a range request
+	if isRangeRequest {
+		w.Header().Set("Content-Range", fmt.Sprintf("bytes %d-%d/%d", offset, offset+size-1, totalSize))
+		w.Header().Set("Content-Length", strconv.FormatInt(size, 10))
+	}
+	headerSetTime = time.Since(tHeaderSet)
+
+	// Now write status code (headers are all set, stream is ready)
+	if isRangeRequest {
+		w.WriteHeader(http.StatusPartialContent)
+	} else {
+		w.WriteHeader(http.StatusOK)
+	}
+
 	// Stream directly to response
 	tStreamExec := time.Now()
 	glog.Infof("streamFromVolumeServers: starting streamFn, offset=%d, size=%d", offset, size)
@@ -1458,21 +1458,28 @@ func (s3a *S3ApiServer) decryptSSES3ChunkView(ctx context.Context, fileChunk *fi
 			return nil, fmt.Errorf("failed to fetch full chunk: %w", err)
 		}
 
-		// Use the chunk's IV directly (already adjusted for part offset during encryption)
+		// Use the chunk's IV directly (already adjusted for block offset during encryption)
-		// Note: SSE-S3 stores the offset-adjusted IV in chunk metadata, unlike SSE-C which stores base IV + PartOffset
+		// Note: SSE-S3 encryption flow:
+		// 1. Upload: CreateSSES3EncryptedReaderWithBaseIV(reader, key, baseIV, partOffset)
+		//    calls calculateIVWithOffset(baseIV, partOffset) → (blockAlignedIV, skip)
+		//    The blockAlignedIV is stored in chunk metadata
+		// 2. Download: We decrypt the FULL chunk from offset 0 using that blockAlignedIV
+		//    Then skip to chunkView.OffsetInChunk in the PLAINTEXT (not ciphertext)
+		// This differs from SSE-C which stores base IV + PartOffset and calculates IV during decryption
+		// No ivSkip needed here because we're decrypting from chunk start (offset 0)
 		iv := chunkSSES3Metadata.IV
 
 		glog.V(4).Infof("Decrypting multipart SSE-S3 chunk %s with chunk-specific IV length=%d",
 			chunkView.FileId, len(iv))
 
-		// Decrypt the full chunk
+		// Decrypt the full chunk starting from offset 0
 		decryptedReader, decryptErr := CreateSSES3DecryptedReader(fullChunkReader, chunkSSES3Metadata, iv)
 		if decryptErr != nil {
 			fullChunkReader.Close()
 			return nil, fmt.Errorf("failed to create SSE-S3 decrypted reader: %w", decryptErr)
 		}
 
-		// Skip to position within chunk and limit to ViewSize
+		// Skip to position within the decrypted chunk (plaintext offset, not ciphertext offset)
 		if chunkView.OffsetInChunk > 0 {
 			_, err = io.CopyN(io.Discard, decryptedReader, chunkView.OffsetInChunk)
 			if err != nil {
@@ -2873,8 +2880,16 @@ func (s3a *S3ApiServer) createMultipartSSECDecryptedReaderDirect(ctx context.Con
 			glog.V(4).Infof("Decrypting SSE-C chunk %s with IV=%x, PartOffset=%d",
 				chunk.GetFileIdString(), chunkIV[:8], ssecMetadata.PartOffset)
 
-			// Note: For multipart SSE-C, each part was encrypted with offset=0
+			// Note: SSE-C multipart behavior (differs from SSE-KMS/SSE-S3):
-			// So we don't need to adjust the IV with PartOffset - just use the stored IV directly
+			// - Upload: CreateSSECEncryptedReader generates RANDOM IV per part (no base IV + offset)
+			// - Metadata: PartOffset is stored but not used during encryption
+			// - Decryption: Use stored random IV directly (no offset adjustment needed)
+			//
+			// This differs from:
+			// - SSE-KMS/SSE-S3: Use base IV + calculateIVWithOffset(partOffset) during encryption
+			// - CopyObject: Applies calculateIVWithOffset to SSE-C (which may be incorrect)
+			//
+			// TODO: Investigate CopyObject SSE-C PartOffset handling for consistency
 			decryptedChunkReader, decErr := CreateSSECDecryptedReader(chunkReader, customerKey, chunkIV)
 			if decErr != nil {
 				chunkReader.Close()