Bump socket.io from 2.2.0 to 2.4.0 in /reveal.js

[dependabot]

Bumps socket.io from 2.2.0 to 2.4.0.

Release notes

Sourced from socket.io's releases.

2.4.0

Related blog post: https://socket.io/blog/socket-io-2-4-0/

Features (from Engine.IO)

• add support for all cookie options (19cc582)
• disable perMessageDeflate by default (5ad2736)

Bug Fixes

• security: do not allow all origins by default (f78a575)
• properly overwrite the query sent in the handshake (d33a619)

⚠️ BREAKING CHANGE ⚠️

Previously, CORS was enabled by default, which meant that a Socket.IO server sent the necessary CORS headers (Access-Control-Allow-xxx) to any domain. This will not be the case anymore, and you now have to explicitly enable it.

Please note that you are not impacted if:

• you are using Socket.IO v2 and the origins option to restrict the list of allowed domains
• you are using Socket.IO v3 (disabled by default)

This commit also removes the support for '*' matchers and protocol-less URL:

io.origins('https://example.com:443'); => io.origins(['https://example.com']);
io.origins('localhost:3000');          => io.origins(['http://localhost:3000']);
io.origins('http://localhost:*');      => io.origins(['http://localhost:3000']);
io.origins('*:3000');                  => io.origins(['http://localhost:3000']);

To restore the previous behavior (please use with caution):

io.origins((_, callback) => {
  callback(null, true);
});

See also:

• https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS
• https://socket.io/docs/v3/handling-cors/
• https://socket.io/docs/v3/migrating-from-2-x-to-3-0/#CORS-handling

Thanks a lot to @ni8walk3r for the security report.

Links:

... (truncated)

Changelog

Sourced from socket.io's changelog.

2.4.0 (2021-01-04)

Bug Fixes

• security: do not allow all origins by default (f78a575)
• properly overwrite the query sent in the handshake (d33a619)

Commits

• 873fdc5 chore(release): 2.4.0
• f78a575 fix(security): do not allow all origins by default
• d33a619 fix: properly overwrite the query sent in the handshake
• 3951a79 chore: bump engine.io version
• 6fa026f ci: migrate to GitHub Actions
• 47161a6 [chore] Release 2.3.0
• cf39362 [chore] Bump socket.io-parser to version 3.4.0
• 4d01b2c test: remove deprecated Buffer usage (#3481)
• 8227192 [docs] Fix the default value of the 'origins' parameter (#3464)
• 1150eb5 [chore] Bump engine.io to version 3.4.0
• Additional commits viewable in compare view

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