chunking

Backend/src/main/java/com/gregor_lohaus/gtransfer/controller/DownloadController.java

@@ -1,6 +1,7 @@
 package com.gregor_lohaus.gtransfer.controller;
 
 import java.time.LocalDateTime;
+import java.util.Map;
 import java.util.Optional;
 
 import org.springframework.beans.factory.annotation.Autowired;
@@ -12,11 +13,13 @@ import org.springframework.stereotype.Controller;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.ResponseBody;
 
 import com.gregor_lohaus.gtransfer.model.File;
 import com.gregor_lohaus.gtransfer.model.FileRepository;
 import com.gregor_lohaus.gtransfer.services.filewriter.AbstractStorageService;
+import com.gregor_lohaus.gtransfer.services.filewriter.StorageKeys;
 
 @Controller
 public class DownloadController {
@@ -32,28 +35,78 @@ public class DownloadController {
         return "download/page";
     }
 
+    @GetMapping("/download/{id}/metadata")
+    @ResponseBody
+    @Transactional
+    public ResponseEntity<Map<String, Object>> metadata(@PathVariable String id) {
+        AvailableFile available = getAvailableFile(id);
+        if (!available.found()) {
+            return ResponseEntity.status(available.status()).build();
+        }
+
+        File file = available.file();
+        return ResponseEntity.ok(Map.of(
+                "name", file.getName(),
+                "chunkCount", file.getChunkCount(),
+                "size", file.getSize() == null ? 0 : file.getSize()));
+    }
+
+    @GetMapping("/download/{id}/chunk/{index}")
+    @ResponseBody
+    @Transactional
+    public ResponseEntity<byte[]> chunk(@PathVariable String id, @PathVariable Integer index) {
+        AvailableFile available = getAvailableFile(id);
+        if (!available.found()) {
+            return ResponseEntity.status(available.status()).build();
+        }
+
+        File file = available.file();
+        if (index == null || index < 0 || index >= file.getChunkCount()) {
+            return ResponseEntity.badRequest().build();
+        }
+
+        Optional<byte[]> data = storageService.get(storageKey(file, index));
+        if (data.isEmpty()) {
+            return ResponseEntity.notFound().build();
+        }
+
+        return ResponseEntity.ok()
+                .contentType(MediaType.APPLICATION_OCTET_STREAM)
+                .body(data.get());
+    }
+
+    @PostMapping("/download/{id}/complete")
+    @ResponseBody
+    @Transactional
+    public ResponseEntity<Void> complete(@PathVariable String id) {
+        AvailableFile available = getAvailableFile(id);
+        if (!available.found()) {
+            return ResponseEntity.status(available.status()).build();
+        }
+
+        File file = available.file();
+        file.setDownloads(file.getDownloads() + 1);
+        fileRepository.save(file);
+
+        if (file.getDownloadLimit() != null && file.getDownloads() >= file.getDownloadLimit()) {
+            deleteStoredFile(file);
+            fileRepository.delete(file);
+        }
+
+        return ResponseEntity.noContent().build();
+    }
+
     @GetMapping("/download/{id}/data")
     @ResponseBody
     @Transactional
     public ResponseEntity<byte[]> data(@PathVariable String id) {
-        Optional<File> fileOpt = fileRepository.findById(id);
+        AvailableFile available = getAvailableFile(id);
-        if (fileOpt.isEmpty()) {
+        if (!available.found()) {
-            return ResponseEntity.notFound().build();
+            return ResponseEntity.status(available.status()).build();
         }
 
-        File file = fileOpt.get();
+        File file = available.file();
-
+        if (file.isChunked()) {
-        // Check expiry
-        if (file.getExpireyDateTime() != null && LocalDateTime.now().isAfter(file.getExpireyDateTime())) {
-            storageService.delete(id);
-            fileRepository.delete(file);
-            return ResponseEntity.status(HttpStatus.GONE).build();
-        }
-
-        // Check download limit before serving
-        if (file.getDownloadLimit() != null && file.getDownloads() >= file.getDownloadLimit()) {
-            storageService.delete(id);
-            fileRepository.delete(file);
             return ResponseEntity.status(HttpStatus.GONE).build();
         }
 
@@ -62,22 +115,80 @@ public class DownloadController {
             return ResponseEntity.notFound().build();
         }
 
-        // Increment counter
         file.setDownloads(file.getDownloads() + 1);
         fileRepository.save(file);
 
-        // Clean up if limit now reached
         if (file.getDownloadLimit() != null && file.getDownloads() >= file.getDownloadLimit()) {
-            storageService.delete(id);
+            deleteStoredFile(file);
             fileRepository.delete(file);
         }
 
-        String disposition = "attachment; filename=\""
-                + file.getName().replace("\\", "\\\\").replace("\"", "\\\"") + "\"";
-
         return ResponseEntity.ok()
-                .header(HttpHeaders.CONTENT_DISPOSITION, disposition)
+                .header(HttpHeaders.CONTENT_DISPOSITION, contentDisposition(file.getName()))
                 .contentType(MediaType.APPLICATION_OCTET_STREAM)
                 .body(data.get());
     }
+
+    private AvailableFile getAvailableFile(String id) {
+        Optional<File> fileOpt = fileRepository.findById(id);
+        if (fileOpt.isEmpty()) {
+            return AvailableFile.notFound();
+        }
+
+        File file = fileOpt.get();
+        if (file.getExpireyDateTime() != null && LocalDateTime.now().isAfter(file.getExpireyDateTime())) {
+            deleteStoredFile(file);
+            fileRepository.delete(file);
+            return AvailableFile.gone();
+        }
+
+        if (file.getDownloadLimit() != null && file.getDownloads() >= file.getDownloadLimit()) {
+            deleteStoredFile(file);
+            fileRepository.delete(file);
+            return AvailableFile.gone();
+        }
+
+        return AvailableFile.ok(file);
+    }
+
+    private void deleteStoredFile(File file) {
+        if (!file.isChunked()) {
+            storageService.delete(file.getId());
+            return;
+        }
+
+        for (int i = 0; i < file.getChunkCount(); i++) {
+            storageService.delete(StorageKeys.chunk(file.getId(), i));
+        }
+    }
+
+    private String storageKey(File file, int index) {
+        if (!file.isChunked()) {
+            return file.getId();
+        }
+        return StorageKeys.chunk(file.getId(), index);
+    }
+
+    private String contentDisposition(String filename) {
+        return "attachment; filename=\""
+                + filename.replace("\\", "\\\\").replace("\"", "\\\"") + "\"";
+    }
+
+    private record AvailableFile(File file, HttpStatus status) {
+        static AvailableFile ok(File file) {
+            return new AvailableFile(file, HttpStatus.OK);
+        }
+
+        static AvailableFile notFound() {
+            return new AvailableFile(null, HttpStatus.NOT_FOUND);
+        }
+
+        static AvailableFile gone() {
+            return new AvailableFile(null, HttpStatus.GONE);
+        }
+
+        boolean found() {
+            return file != null;
+        }
+    }
 }

Backend/src/main/java/com/gregor_lohaus/gtransfer/controller/UploadController.java

@@ -2,11 +2,15 @@ package com.gregor_lohaus.gtransfer.controller;
 
 import java.io.IOException;
 import java.time.LocalDateTime;
+import java.util.OptionalLong;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
+import org.springframework.http.ResponseEntity;
+import org.springframework.http.HttpStatus;
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
+import org.springframework.web.server.ResponseStatusException;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestParam;
@@ -15,6 +19,7 @@ import org.springframework.web.multipart.MultipartFile;
 import com.gregor_lohaus.gtransfer.model.File;
 import com.gregor_lohaus.gtransfer.model.FileRepository;
 import com.gregor_lohaus.gtransfer.services.filewriter.AbstractStorageService;
+import com.gregor_lohaus.gtransfer.services.filewriter.StorageKeys;
 
 @Controller
 public class UploadController {
@@ -41,21 +46,46 @@ public class UploadController {
 
     @PostMapping("/upload")
     public String upload(
-            @RequestParam("file") MultipartFile file,
             @RequestParam("hash") String hash,
             @RequestParam("name") String name,
+            @RequestParam("chunkCount") Integer chunkCount,
+            @RequestParam("size") Long size,
             @RequestParam(required = false) Integer expiryDays,
-            @RequestParam(required = false) Integer downloadLimit) throws IOException {
+            @RequestParam(required = false) Integer downloadLimit) {
-
+        if (!isValidId(hash) || chunkCount == null || chunkCount < 1 || size == null || size < 0) {
-        storageService.put(hash, file.getBytes());
+            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Invalid upload metadata");
+        }
 
         int days = expiryDays != null ? Math.min(expiryDays, maxExpiryDays) : maxExpiryDays;
         Integer limit = downloadLimit != null ? Math.min(downloadLimit, maxDownloadLimit) : null;
 
         File f = new File(hash, hash, name, LocalDateTime.now().plusDays(days));
+        f.setChunkCount(chunkCount);
+        f.setSize(size);
         f.setDownloadLimit(limit);
         fileRepository.save(f);
 
         return "upload/result :: view";
     }
+
+    @PostMapping("/upload/chunk")
+    public ResponseEntity<Void> uploadChunk(
+            @RequestParam("chunk") MultipartFile chunk,
+            @RequestParam("hash") String hash,
+            @RequestParam("index") Integer index) throws IOException {
+        if (!isValidId(hash) || index == null || index < 0) {
+            return ResponseEntity.badRequest().build();
+        }
+
+        OptionalLong written = storageService.put(StorageKeys.chunk(hash, index), chunk.getBytes());
+        if (written.isEmpty()) {
+            return ResponseEntity.internalServerError().build();
+        }
+
+        return ResponseEntity.noContent().build();
+    }
+
+    private boolean isValidId(String id) {
+        return id != null && id.matches("[a-f0-9]{64}");
+    }
 }

Backend/src/main/java/com/gregor_lohaus/gtransfer/model/File.java

@@ -13,6 +13,8 @@ public class File {
   private String id;
   private String path;
   private String name;
+  private Integer chunkCount;
+  private Long size;
   private LocalDateTime expireyDateTime;
   private Integer downloadLimit;
   @Column(columnDefinition = "integer default 0")
@@ -41,6 +43,21 @@ public class File {
   public void setName(String name) {
 	this.name = name;
   }
+  public Integer getChunkCount() {
+    return chunkCount == null ? 1 : chunkCount;
+  }
+  public void setChunkCount(Integer chunkCount) {
+    this.chunkCount = chunkCount;
+  }
+  public boolean isChunked() {
+    return chunkCount != null;
+  }
+  public Long getSize() {
+    return size;
+  }
+  public void setSize(Long size) {
+    this.size = size;
+  }
   public Integer getDownloadLimit() {
     return downloadLimit;
   }

Backend/src/main/java/com/gregor_lohaus/gtransfer/services/filecleanup/FileCleanupService.java

@@ -14,6 +14,7 @@ import org.springframework.transaction.annotation.Transactional;
 import com.gregor_lohaus.gtransfer.model.File;
 import com.gregor_lohaus.gtransfer.model.FileRepository;
 import com.gregor_lohaus.gtransfer.services.filewriter.AbstractStorageService;
+import com.gregor_lohaus.gtransfer.services.filewriter.StorageKeys;
 
 public class FileCleanupService {
     private Boolean enabled;
@@ -43,9 +44,20 @@ public class FileCleanupService {
         };
 
         for (File file : expired) {
-            storageService.delete(file.getId());
+            deleteStoredFile(file);
             fileRepository.delete(file);
         }
         log.info("Cleaned up {} expired file(s)", expired.size());
     }
+
+    private void deleteStoredFile(File file) {
+        if (!file.isChunked()) {
+            storageService.delete(file.getId());
+            return;
+        }
+
+        for (int i = 0; i < file.getChunkCount(); i++) {
+            storageService.delete(StorageKeys.chunk(file.getId(), i));
+        }
+    }
 }

Backend/src/main/java/com/gregor_lohaus/gtransfer/services/filewriter/LocalStorageService.java

@@ -15,8 +15,12 @@ public class LocalStorageService extends AbstractStorageService {
   @Override
   public OptionalLong put(String id, byte[] data) {
     try {
-      Files.createDirectories(root);
+      Path target = root.resolve(id);
-      Files.write(root.resolve(id), data);
+      Path parent = target.getParent();
+      if (parent != null) {
+        Files.createDirectories(parent);
+      }
+      Files.write(target, data);
       return OptionalLong.of(data.length);
     } catch (IOException e) {
       return OptionalLong.empty();

Backend/src/main/java/com/gregor_lohaus/gtransfer/services/filewriter/StorageKeys.java

@@ -0,0 +1,9 @@
+package com.gregor_lohaus.gtransfer.services.filewriter;
+
+public final class StorageKeys {
+  private StorageKeys() {}
+
+  public static String chunk(String id, int index) {
+    return id + "/chunks/" + index;
+  }
+}

Backend/src/main/resources/static/crypto.js

@@ -1,3 +1,33 @@
+var DEFAULT_CHUNK_SIZE = 4 * 1024 * 1024;
+
+async function generateFileKey() {
+    const key = await crypto.subtle.generateKey(
+        { name: 'AES-GCM', length: 256 },
+        true,
+        ['encrypt', 'decrypt']
+    );
+
+    const rawKey = await crypto.subtle.exportKey('raw', key);
+    const hash = await hashKey(rawKey);
+    const base64urlKey = encodeKey(rawKey);
+
+    return { key, rawKey, hash, base64urlKey };
+}
+
+async function encryptFileChunk(file, index, key, chunkSize = DEFAULT_CHUNK_SIZE) {
+    const start = index * chunkSize;
+    const end = Math.min(start + chunkSize, file.size);
+    const plaintext = await file.slice(start, end).arrayBuffer();
+    const iv = crypto.getRandomValues(new Uint8Array(12));
+    const ciphertext = await crypto.subtle.encrypt({ name: 'AES-GCM', iv }, key, plaintext);
+
+    const payload = new Uint8Array(12 + ciphertext.byteLength);
+    payload.set(iv, 0);
+    payload.set(new Uint8Array(ciphertext), 12);
+
+    return payload;
+}
+
 async function encryptFile(arrayBuffer) {
     const key = await crypto.subtle.generateKey(
         { name: 'AES-GCM', length: 256 },
@@ -30,6 +60,10 @@ async function hashKey(rawKey) {
 }
 
 async function decryptFile(payload, key) {
+    return decryptChunk(payload, key);
+}
+
+async function decryptChunk(payload, key) {
     const bytes = new Uint8Array(payload);
     const iv = bytes.slice(0, 12);
     const ciphertext = bytes.slice(12);

Backend/src/main/resources/static/download.js

@@ -11,24 +11,46 @@ if (!fragment) {
         'raw', rawKeyBytes, { name: 'AES-GCM' }, false, ['decrypt']
     );
 
-    setStatus('Downloading\u2026');
+    setProgress('Loading metadata\u2026', 0, 1);
-    const response = await fetch('/download/' + id + '/data');
+    const metadataResponse = await fetch('/download/' + id + '/metadata');
 
-    if (response.status === 410) {
+    if (metadataResponse.status === 410) {
         showError('This file has expired or reached its download limit.');
-    } else if (!response.ok) {
+    } else if (!metadataResponse.ok) {
-        showError(`Download failed (${response.status}).`);
+        showError(`Download failed (${metadataResponse.status}).`);
     } else {
-        const disposition = response.headers.get('Content-Disposition') || '';
+        const metadata = await metadataResponse.json();
-        const filename = disposition.match(/filename="?([^"]+)"?/)?.[1] || 'download';
+        const filename = metadata.name || 'download';
+        const chunkCount = metadata.chunkCount || 1;
+        const chunks = [];
 
-        setStatus('Decrypting\u2026');
+        for (let index = 0; index < chunkCount; index++) {
-        const plaintext = await decryptFile(await response.arrayBuffer(), key);
+            setProgress(`Downloading chunk ${index + 1} of ${chunkCount}\u2026`, index, chunkCount);
+            const chunkResponse = await fetch('/download/' + id + '/chunk/' + index);
+            if (chunkResponse.status === 410) {
+                throw new Error('This file has expired or reached its download limit.');
+            }
+            if (!chunkResponse.ok) {
+                throw new Error(`Chunk download failed (${chunkResponse.status})`);
+            }
 
+            setProgress(`Decrypting chunk ${index + 1} of ${chunkCount}\u2026`, index + 0.5, chunkCount);
+            const plaintextChunk = await decryptChunk(await chunkResponse.arrayBuffer(), key);
+            chunks.push(new Uint8Array(plaintextChunk));
+            setProgress(`Downloaded ${index + 1} of ${chunkCount} chunks`, index + 1, chunkCount);
+        }
+
+        const completeResponse = await fetch('/download/' + id + '/complete', { method: 'POST' });
+        if (!completeResponse.ok && completeResponse.status !== 404 && completeResponse.status !== 410) {
+            throw new Error(`Download completion failed (${completeResponse.status})`);
+        }
+
+        setProgress('Preparing preview\u2026', chunkCount, chunkCount);
+        const plaintext = combineChunks(chunks);
         showPreview(filename, plaintext);
     }
 } catch (err) {
-    showError('Decryption failed: ' + err.message);
+    showError(err.message);
 }
 
 function setStatus(msg) {
@@ -36,6 +58,16 @@ function setStatus(msg) {
     if (el) el.textContent = msg;
 }
 
+function setProgress(msg, completed, total) {
+    setStatus(msg);
+    const percent = Math.round((completed / total) * 100);
+    const bar = htmx.find('#download-progress');
+    if (!bar) return;
+    bar.style.width = `${percent}%`;
+    bar.textContent = `${percent}%`;
+    bar.setAttribute('aria-valuenow', String(percent));
+}
+
 function escapeHtml(str) {
     return str.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;').replace(/"/g, '&quot;');
 }
@@ -58,6 +90,17 @@ function getMimeType(filename) {
     return types[ext] || 'application/octet-stream';
 }
 
+function combineChunks(chunks) {
+    const size = chunks.reduce((sum, chunk) => sum + chunk.byteLength, 0);
+    const combined = new Uint8Array(size);
+    let offset = 0;
+    for (const chunk of chunks) {
+        combined.set(chunk, offset);
+        offset += chunk.byteLength;
+    }
+    return combined.buffer;
+}
+
 function showPreview(filename, plaintext) {
     const mimeType = getMimeType(filename);
     const blob = new Blob([plaintext], { type: mimeType });

Backend/src/main/resources/static/upload.js

@@ -43,22 +43,41 @@ async function startUpload() {
                 <span class="visually-hidden">Loading\u2026</span>
             </div>
         </div>
-        <div class="drop-zone-text" id="upload-status">Encrypting\u2026</div>`,
+        <div class="drop-zone-text mb-3" id="upload-status">Preparing\u2026</div>
+        <div class="progress" role="progressbar" aria-label="Upload progress" aria-valuemin="0" aria-valuemax="100">
+            <div id="upload-progress" class="progress-bar bg-success" style="width: 0%">0%</div>
+        </div>`,
         { swapStyle: 'innerHTML' });
 
     try {
-        const { payload, hash, base64urlKey } = await encryptFile(await selectedFile.arrayBuffer());
+        const { key, hash, base64urlKey } = await generateFileKey();
+        const chunkCount = Math.max(1, Math.ceil(selectedFile.size / DEFAULT_CHUNK_SIZE));
 
-        setStatus('Uploading\u2026');
+        for (let index = 0; index < chunkCount; index++) {
+            setProgress(`Encrypting chunk ${index + 1} of ${chunkCount}\u2026`, index, chunkCount);
+            const payload = await encryptFileChunk(selectedFile, index, key);
 
-        const formData = new FormData();
+            setProgress(`Uploading chunk ${index + 1} of ${chunkCount}\u2026`, index + 0.5, chunkCount);
-        formData.append('file', new Blob([payload]), selectedFile.name);
+            const chunkData = new FormData();
-        formData.append('hash', hash);
+            chunkData.append('chunk', new Blob([payload]), String(index));
-        formData.append('name', selectedFile.name);
+            chunkData.append('hash', hash);
-        if (expiryDays)    formData.append('expiryDays', expiryDays);
+            chunkData.append('index', index);
-        if (downloadLimit) formData.append('downloadLimit', downloadLimit);
 
-        const response = await fetch('/upload', { method: 'POST', body: formData });
+            const chunkResponse = await fetch('/upload/chunk', { method: 'POST', body: chunkData });
+            if (!chunkResponse.ok) throw new Error(`Chunk upload failed (${chunkResponse.status})`);
+            setProgress(`Uploaded chunk ${index + 1} of ${chunkCount}`, index + 1, chunkCount);
+        }
+
+        setProgress('Finalizing\u2026', chunkCount, chunkCount);
+        const metadata = new FormData();
+        metadata.append('hash', hash);
+        metadata.append('name', selectedFile.name);
+        metadata.append('chunkCount', chunkCount);
+        metadata.append('size', selectedFile.size);
+        if (expiryDays)    metadata.append('expiryDays', expiryDays);
+        if (downloadLimit) metadata.append('downloadLimit', downloadLimit);
+
+        const response = await fetch('/upload', { method: 'POST', body: metadata });
         if (!response.ok) throw new Error(`Server error ${response.status}`);
 
         htmx.swap(dropZone, await response.text(), { swapStyle: 'innerHTML' });
@@ -79,6 +98,16 @@ function setStatus(msg) {
     if (el) el.textContent = msg;
 }
 
+function setProgress(msg, completed, total) {
+    setStatus(msg);
+    const percent = Math.round((completed / total) * 100);
+    const bar = htmx.find('#upload-progress');
+    if (!bar) return;
+    bar.style.width = `${percent}%`;
+    bar.textContent = `${percent}%`;
+    bar.setAttribute('aria-valuenow', String(percent));
+}
+
 function resetUpload() {
     selectedFile = null;
     fileInput.value = '';

Backend/src/main/resources/templates/download/page.html

@@ -20,7 +20,10 @@
     <main class="flex-grow-1 d-flex align-items-center justify-content-center py-5 px-3">
         <div id="download-state" class="drop-zone text-center py-5 px-4" style="max-width: 520px; width: 100%;">
             <div class="drop-zone-icon mb-3">&#x1F512;</div>
-<div class="drop-zone-text" id="download-status">Preparing&hellip;</div>
+            <div class="drop-zone-text mb-3" id="download-status">Preparing&hellip;</div>
+            <div class="progress" role="progressbar" aria-label="Download progress" aria-valuemin="0" aria-valuemax="100">
+                <div id="download-progress" class="progress-bar bg-success" style="width: 0%">0%</div>
+            </div>
         </div>
     </main>