Summary:
This includes two fixes: one to ensure that any exception from websocket
upgrade handlers are handled (by destroying the socket). A test case is
added for this.
The other is to ensure verifyClient returns false instead of failing; this
should lead to a better error to the client (Forbidden, rather than just socket
close). This is only tested manually with a curl request.
Test Plan: Added a test case for the more sensitive half of the fix.
Reviewers: georgegevoian
Reviewed By: georgegevoian
Subscribers: georgegevoian
Differential Revision: https://phab.getgrist.com/D4323
The motivation for supporting an alternative to WebSockets is that while all browsers supported by Grist offer native WebSocket support, some networking environments do not allow WebSocket traffic.
Engine.IO is used as the underlying implementation of HTTP long polling. The Grist client will first attempt a regular WebSocket connection, using the same protocol and endpoints as before, but fall back to long polling using Engine.IO if the WebSocket connection fails.
Include these changes:
- CORS websocket requests are now rejected as a stronger security measure. This shouldn’t affect anything in practice; but previously it could be possible to make unauthenticated websocket requests from another origin.
- GRIST_HOST variable no longer affects CORS responses (also should not affect anything in practice, as it wasn't serving a useful purpose)
