Make filename check more strict (pypi#14027)

* Add a failing test

* Make the test fail all the way to DID NOT RAISE

* Refactor the test a bit

* Add another failing test case

* More test cases

* Ensure filenames only have the project name

No more, no less. Previously this allowed filenames that started with
the project name.

tests/unit/forklift/test_legacy.py

@@ -2310,31 +2310,53 @@ def test_upload_fails_with_diff_filename_same_blake2(
             "400 File already exists. See /the/help/url/ for more information."
         )
 
-    def test_upload_fails_with_wrong_filename(self, pyramid_config, db_request):
+    @pytest.mark.parametrize(
+        "filename, project_name",
+        [
+            # completely different
+            ("nope-{version}.tar.gz", "something_else"),
+            ("nope-{version}-py3-none-any.whl", "something_else"),
+            # starts with same prefix
+            ("nope-{version}.tar.gz", "no"),
+            ("nope-{version}-py3-none-any.whl", "no"),
+            # starts with same prefix with hyphen
+            ("no-way-{version}.tar.gz", "no"),
+            ("no_way-{version}-py3-none-any.whl", "no"),
+        ],
+    )
+    def test_upload_fails_with_wrong_filename(
+        self, pyramid_config, db_request, metrics, filename, project_name
+    ):
         user = UserFactory.create()
         pyramid_config.testing_securitypolicy(identity=user)
         db_request.user = user
+        db_request.user_agent = "warehouse-tests/6.6.6"
         EmailFactory.create(user=user)
-        project = ProjectFactory.create()
+        project = ProjectFactory.create(name=project_name)
         release = ReleaseFactory.create(project=project, version="1.0")
         RoleFactory.create(user=user, project=project)
 
-        filename = f"nope-{release.version}.tar.gz"
+        storage_service = pretend.stub(store=lambda path, filepath, meta: None)
+        db_request.find_service = lambda svc, name=None, context=None: {
+            IFileStorage: storage_service,
+            IMetricsService: metrics,
+        }.get(svc)
 
         db_request.POST = MultiDict(
             {
                 "metadata_version": "1.2",
                 "name": project.name,
                 "version": release.version,
                 "filetype": "sdist",
-                "md5_digest": "nope!",
+                "md5_digest": _TAR_GZ_PKG_MD5,
                 "content": pretend.stub(
-                    filename=filename,
-                    file=io.BytesIO(b"a" * (legacy.MAX_FILESIZE + 1)),
+                    filename=filename.format(version=release.version),
+                    file=io.BytesIO(_TAR_GZ_PKG_TESTDATA),
                     type="application/tar",
                 ),
             }
         )
+        db_request.help_url = lambda **kw: "/the/help/url/"
 
         with pytest.raises(HTTPBadRequest) as excinfo:
             legacy.file_upload(db_request)

warehouse/forklift/legacy.py

@@ -1208,10 +1208,20 @@ def file_upload(request):
     # Ensure the filename doesn't contain any characters that are too 🌶️spicy🥵
     _validate_filename(filename)
 
+    # Extract the project name from the filename and normalize it.
+    filename_prefix = pkg_resources.safe_name(
+        # For wheels, the project name is normalized and won't contain hyphens, so
+        # we can split on the first hyphen.
+        filename.partition("-")[0]
+        if filename.endswith(".whl")
+        # For source releases, we know that the version should not contain any
+        # hypens, so we can split on the last hypen to get the project name.
+        else filename.rpartition("-")[0]
+    ).lower()
+
     # Make sure that our filename matches the project that it is being uploaded
     # to.
-    prefix = pkg_resources.safe_name(project.name).lower()
-    if not pkg_resources.safe_name(filename).lower().startswith(prefix):
+    if (prefix := pkg_resources.safe_name(project.name).lower()) != filename_prefix:
         raise _exc_with_message(
             HTTPBadRequest,
             f"Start filename for {project.name!r} with {prefix!r}.",