Deny content encoding and length headers when proxying websockets #249
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
augustoccesar
approved these changes
Jun 26, 2025
15d0c8d to
52cce3f
Compare
52cce3f to
80af503
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
When proxying WebSocket connections over two hops via the Cloudflare worker and the linkup local server, we have found that there are cases where content encoding and content length headers exist in the upstream response from the underlying local server.
When those headers exist in a WebSocket handshake, Cloudflare workers completely denies the WebSocket connection.
These headers shouldn't make sense in a WebSocket proxying scenario since they are only valid for HTTP response bodies which shouldn't exist when using WebSockets.