From 58dc1059f32c698718f7f0ac88c4728519b9ad79 Mon Sep 17 00:00:00 2001
From: Alex Vandiver <alexmv@zulip.com>
Date: Wed, 14 Dec 2022 22:00:43 +0000
Subject: [PATCH] uploads: Move unauth-signed tokens into view.

---
 zerver/lib/upload/local.py | 27 ---------------------------
 zerver/views/upload.py     | 35 +++++++++++++++++++++++++++++------
 2 files changed, 29 insertions(+), 33 deletions(-)

diff --git a/zerver/lib/upload/local.py b/zerver/lib/upload/local.py
index 69ffd7b332..6520e9e490 100644
--- a/zerver/lib/upload/local.py
+++ b/zerver/lib/upload/local.py
@@ -1,16 +1,11 @@
-import base64
-import binascii
 import logging
 import os
 import random
 import secrets
 import shutil
-from datetime import timedelta
 from typing import IO, Any, Callable, Literal, Optional
 
 from django.conf import settings
-from django.core.signing import BadSignature, TimestampSigner
-from django.urls import reverse
 
 from zerver.lib.avatar_hash import user_avatar_path
 from zerver.lib.upload.base import (
@@ -68,28 +63,6 @@ def delete_local_file(type: Literal["avatars", "files"], path: str) -> bool:
     return False
 
 
-LOCAL_FILE_ACCESS_TOKEN_SALT = "local_file_"
-
-
-def generate_unauthed_file_access_url(path_id: str) -> str:
-    signed_data = TimestampSigner(salt=LOCAL_FILE_ACCESS_TOKEN_SALT).sign(path_id)
-    token = base64.b16encode(signed_data.encode()).decode()
-
-    filename = path_id.split("/")[-1]
-    return reverse("local_file_unauthed", args=[token, filename])
-
-
-def get_local_file_path_id_from_token(token: str) -> Optional[str]:
-    signer = TimestampSigner(salt=LOCAL_FILE_ACCESS_TOKEN_SALT)
-    try:
-        signed_data = base64.b16decode(token).decode()
-        path_id = signer.unsign(signed_data, max_age=timedelta(seconds=60))
-    except (BadSignature, binascii.Error):
-        return None
-
-    return path_id
-
-
 class LocalUploadBackend(ZulipUploadBackend):
     def get_public_upload_root_url(self) -> str:
         return "/user_avatars/"
diff --git a/zerver/views/upload.py b/zerver/views/upload.py
index fb45cbad1f..bd7d46ca03 100644
--- a/zerver/views/upload.py
+++ b/zerver/views/upload.py
@@ -1,11 +1,15 @@
+import base64
+import binascii
 import os
+from datetime import timedelta
 from mimetypes import guess_type
-from typing import Union
+from typing import Optional, Union
 from urllib.parse import quote, urlparse
 
 from django.conf import settings
 from django.contrib.auth.models import AnonymousUser
 from django.core.files.uploadedfile import UploadedFile
+from django.core.signing import BadSignature, TimestampSigner
 from django.http import (
     FileResponse,
     HttpRequest,
@@ -15,6 +19,7 @@ from django.http import (
     HttpResponseNotFound,
 )
 from django.shortcuts import redirect
+from django.urls import reverse
 from django.utils.cache import patch_cache_control
 from django.utils.translation import gettext as _
 
@@ -27,11 +32,7 @@ from zerver.lib.upload import (
     upload_message_image_from_request,
 )
 from zerver.lib.upload.base import INLINE_MIME_TYPES
-from zerver.lib.upload.local import (
-    assert_is_local_storage_path,
-    generate_unauthed_file_access_url,
-    get_local_file_path_id_from_token,
-)
+from zerver.lib.upload.local import assert_is_local_storage_path
 from zerver.lib.upload.s3 import get_signed_upload_url
 from zerver.models import UserProfile, validate_attachment_request
 
@@ -175,6 +176,28 @@ def serve_file(
     return serve_s3(request, path_id, url_only, download=download)
 
 
+LOCAL_FILE_ACCESS_TOKEN_SALT = "local_file_"
+
+
+def generate_unauthed_file_access_url(path_id: str) -> str:
+    signed_data = TimestampSigner(salt=LOCAL_FILE_ACCESS_TOKEN_SALT).sign(path_id)
+    token = base64.b16encode(signed_data.encode()).decode()
+
+    filename = path_id.split("/")[-1]
+    return reverse("local_file_unauthed", args=[token, filename])
+
+
+def get_local_file_path_id_from_token(token: str) -> Optional[str]:
+    signer = TimestampSigner(salt=LOCAL_FILE_ACCESS_TOKEN_SALT)
+    try:
+        signed_data = base64.b16decode(token).decode()
+        path_id = signer.unsign(signed_data, max_age=timedelta(seconds=60))
+    except (BadSignature, binascii.Error):
+        return None
+
+    return path_id
+
+
 def serve_local_file_unauthed(request: HttpRequest, token: str, filename: str) -> HttpResponseBase:
     path_id = get_local_file_path_id_from_token(token)
     if path_id is None: