feat: file upload, allowlist, and download/preview

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/api/public.py

@@ -1,12 +1,16 @@
-from fastapi import APIRouter, Depends, HTTPException, Query, Request
+from fastapi import APIRouter, Depends, File, Form, HTTPException, Query, Request, UploadFile
+from fastapi.responses import FileResponse
 from sqlalchemy.orm import Session
 
 from app.db import get_db
-from app.schemas import ItemCreate, ItemOut, WallResponse
+from app.schemas import ItemCreate, ItemOut, TTLOption, WallResponse
 from app.services import items as items_service
+from app.services import storage as storage_service
 
 router = APIRouter(prefix="/api/items", tags=["items"])
 
+_INLINE_IMAGE_PREFIXES = ("image/",)
+
 
 def _client_ip(request: Request) -> str:
     forwarded = request.headers.get("x-forwarded-for")
@@ -27,6 +31,32 @@ def create_item(
     return items_service.item_to_dict(item)
 
 
+@router.post("/upload", response_model=ItemOut)
+async def upload_item(
+    request: Request,
+    db: Session = Depends(get_db),
+    file: UploadFile = File(...),
+    is_public: bool = Form(True),
+    burn_after_read: bool = Form(False),
+    ttl: TTLOption = Form("24h"),
+    title: str | None = Form(None),
+):
+    rel_path, size, mime, safe_name = await storage_service.save_upload(file)
+    item = items_service.create_file_item(
+        db,
+        file_name=safe_name,
+        file_path=rel_path,
+        mime=mime,
+        size_bytes=size,
+        is_public=is_public,
+        burn_after_read=burn_after_read,
+        ttl=ttl,
+        created_ip=_client_ip(request),
+        title=title,
+    )
+    return items_service.item_to_dict(item)
+
+
 @router.get("/wall", response_model=WallResponse)
 def wall(
     page: int = Query(1, ge=1),
@@ -42,6 +72,26 @@ def wall(
     )
 
 
+@router.get("/{slug}/file")
+def download_file(slug: str, db: Session = Depends(get_db)):
+    item = items_service.get_file_item(db, slug)
+    if item is None:
+        raise HTTPException(status_code=404, detail="Not found")
+    path = items_service.resolve_file_path(item)
+    if path is None or not path.is_file():
+        raise HTTPException(status_code=404, detail="Not found")
+
+    media_type = item.mime or "application/octet-stream"
+    filename = item.file_name or path.name
+    inline = media_type.startswith(_INLINE_IMAGE_PREFIXES)
+    return FileResponse(
+        path,
+        media_type=media_type,
+        filename=filename,
+        content_disposition_type="inline" if inline else "attachment",
+    )
+
+
 @router.get("/{slug}", response_model=ItemOut)
 def get_item(slug: str, db: Session = Depends(get_db)):
     item = items_service.get_item(db, slug)

backend/app/services/items.py

@@ -7,7 +7,7 @@ from pathlib import Path
 from sqlalchemy import func, select
 from sqlalchemy.orm import Session
 
-from app.config import settings
+from app import config
 from app.models import Item
 from app.schemas import ItemCreate, TTLOption
 
@@ -83,6 +83,57 @@ def create_text_item(db: Session, payload: ItemCreate, created_ip: str) -> Item:
     return item
 
 
+def create_file_item(
+    db: Session,
+    *,
+    file_name: str,
+    file_path: str,
+    mime: str,
+    size_bytes: int,
+    is_public: bool,
+    burn_after_read: bool,
+    ttl: TTLOption,
+    created_ip: str,
+    title: str | None = None,
+) -> Item:
+    now = datetime.utcnow()
+    item = Item(
+        slug=_slug(),
+        kind="file",
+        title=(title or file_name)[:255],
+        body=None,
+        file_name=file_name,
+        file_path=file_path,
+        mime=mime,
+        size_bytes=size_bytes,
+        is_public=is_public,
+        burn_after_read=burn_after_read,
+        expires_at=_expires_at(ttl, now),
+        created_ip=created_ip,
+        created_at=now,
+    )
+    db.add(item)
+    db.commit()
+    db.refresh(item)
+    return item
+
+
+def resolve_file_path(item: Item) -> Path | None:
+    if not item.file_path:
+        return None
+    path = Path(item.file_path)
+    if not path.is_absolute():
+        path = config.settings.data_dir / path
+    return path
+
+
+def get_file_item(db: Session, slug: str) -> Item | None:
+    item = db.scalar(select(Item).where(Item.slug == slug))
+    if item is None or item.kind != "file" or _is_unavailable(item):
+        return None
+    return item
+
+
 def get_item(db: Session, slug: str) -> Item | None:
     item = db.scalar(select(Item).where(Item.slug == slug))
     if item is None or _is_unavailable(item):
@@ -91,10 +142,8 @@ def get_item(db: Session, slug: str) -> Item | None:
     item.view_count += 1
     if item.burn_after_read:
         item.burned = True
-        if item.file_path:
-            path = Path(item.file_path)
-            if not path.is_absolute():
-                path = settings.data_dir / path
+        path = resolve_file_path(item)
+        if path is not None:
             try:
                 path.unlink(missing_ok=True)
             except OSError:

backend/app/services/storage.py

@@ -0,0 +1,82 @@
+from __future__ import annotations
+
+import re
+import uuid
+from pathlib import Path
+
+from fastapi import HTTPException, UploadFile
+
+from app import config
+
+ALLOWED_EXTENSIONS = frozenset(
+    {
+        "png",
+        "jpg",
+        "jpeg",
+        "gif",
+        "webp",
+        "svg",
+        "txt",
+        "md",
+        "pdf",
+        "doc",
+        "docx",
+        "xls",
+        "xlsx",
+        "ppt",
+        "pptx",
+        "csv",
+        "zip",
+        "7z",
+        "tar",
+        "gz",
+        "rar",
+        "json",
+    }
+)
+
+_SAFE_NAME_RE = re.compile(r"[^A-Za-z0-9._-]+")
+
+
+def _safe_original_name(filename: str | None) -> str:
+    name = Path(filename or "file").name
+    name = _SAFE_NAME_RE.sub("_", name).strip("._") or "file"
+    return name[:255]
+
+
+def _extension(filename: str) -> str:
+    return Path(filename).suffix.lstrip(".").lower()
+
+
+async def save_upload(file: UploadFile) -> tuple[str, int, str, str]:
+    original = _safe_original_name(file.filename)
+    ext = _extension(original)
+    if ext not in ALLOWED_EXTENSIONS:
+        raise HTTPException(status_code=400, detail="File type not allowed")
+
+    max_bytes = config.settings.max_upload_mb * 1024 * 1024
+    config.settings.uploads_dir.mkdir(parents=True, exist_ok=True)
+
+    stored_name = f"{uuid.uuid4().hex}.{ext}"
+    dest = config.settings.uploads_dir / stored_name
+    size = 0
+    try:
+        with dest.open("wb") as out:
+            while True:
+                chunk = await file.read(1024 * 1024)
+                if not chunk:
+                    break
+                size += len(chunk)
+                if size > max_bytes:
+                    raise HTTPException(status_code=413, detail="File too large")
+                out.write(chunk)
+    except HTTPException:
+        dest.unlink(missing_ok=True)
+        raise
+    except Exception:
+        dest.unlink(missing_ok=True)
+        raise
+
+    mime = file.content_type or "application/octet-stream"
+    rel_path = f"uploads/{stored_name}"
+    return rel_path, size, mime, original