1 files changed, 69 insertions, 0 deletions
diff --git a/app/controllers/concerns/sends_blob.rb b/app/controllers/concerns/sends_blob.rb
new file mode 100644
index 00000000000..971390d9118
--- /dev/null
+++ b/app/controllers/concerns/sends_blob.rb
@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+module SendsBlob
+  extend ActiveSupport::Concern
+
+  included do
+    include BlobHelper
+    include SendFileUpload
+  end
+
+  def send_blob(blob, params = {})
+    if blob
+      headers['X-Content-Type-Options'] = 'nosniff'
+
+      return if cached_blob?(blob)
+
+      if blob.stored_externally?
+        send_lfs_object(blob)
+      else
+        send_git_blob(repository, blob, params)
+      end
+    else
+      render_404
+    end
+  end
+
+  private
+
+  def cached_blob?(blob)
+    stale = stale?(etag: blob.id) # The #stale? method sets cache headers.
+
+    # Because we are opinionated we set the cache headers ourselves.
+    response.cache_control[:public] = project.public?
+
+    response.cache_control[:max_age] =
+      if @ref && @commit && @ref == @commit.id # rubocop:disable Gitlab/ModuleWithInstanceVariables
+        # This is a link to a commit by its commit SHA. That means that the blob
+        # is immutable. The only reason to invalidate the cache is if the commit
+        # was deleted or if the user lost access to the repository.
+        Blob::CACHE_TIME_IMMUTABLE
+      else
+        # A branch or tag points at this blob. That means that the expected blob
+        # value may change over time.
+        Blob::CACHE_TIME
+      end
+
+    response.etag = blob.id
+    !stale
+  end
+
+  def send_lfs_object(blob)
+    lfs_object = find_lfs_object(blob)
+
+    if lfs_object && lfs_object.project_allowed_access?(project)
+      send_upload(lfs_object.file, attachment: blob.name)
+    else
+      render_404
+    end
+  end
+
+  def find_lfs_object(blob)
+    lfs_object = LfsObject.find_by_oid(blob.lfs_oid)
+    if lfs_object && lfs_object.file.exists?
+      lfs_object
+    else
+      nil
+    end
+  end
+end