fix: add null check for connection.headers

[wood1986]

fix #2199

• This is a bugfix
• This is a feature
• This is a code refactor
• This is a test update
• This is a docs update
• This is a metadata update

For Bugs and Features; did you add new tests?

Motivation / Use-Case

Breaking Changes

Additional Info

[jsf-clabot]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #2200 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #2200   +/-   ##
=======================================
  Coverage   93.91%   93.91%           
=======================================
  Files          34       34           
  Lines        1282     1282           
  Branches      370      371    +1     
=======================================
  Hits         1204     1204           
  Misses         71       71           
  Partials        7        7

Impacted Files	Coverage Δ
lib/servers/SockJSServer.js	93.75% <100%> (ø)	⬆️

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[alexander-akait]

/cc @Loonride

[alexander-akait]

need tests

[knagaitsev]

If the connection object is null, there is no use in passing it along to the callback since we can't do anything with it. I think it is better off being:

if (connection) {
  f(connection, connection.headers);
}

[wood1986]

If the connection object is null, there is no use in passing it along to the callback since we can't do anything with it. I think it is better off being:

if (connection) {
  f(connection, connection.headers);
}

I thought about this. As you have a check in

webpack-dev-server/lib/Server.js

Lines 662 to 672 in a355894

	this.socketServer.onConnection((connection, headers) => {
	if (!connection) {
	return;
	}
	if (!headers) {
	this.log.warn(
	'transportMode.server implementation must pass headers to the callback of onConnection(f) ' +
	'via f(connection, headers) in order for clients to pass a headers security check'
	);
	}

I want to reuse.

[wood1986]

need tests

I added

[wood1986]

Any updates?

[knagaitsev]

I want to reuse.

Understood. I have added some notes on the tests.

[knagaitsev]

Looks good to me /cc @evilebottnawi @hiroppy

[alexander-akait]

/cc @hiroppy

[wood1986]

When will you guys do the npm publish?

[Sleepful]

@wood1986 not yet I guess, you can use the master branch on your package.json for now if you want:

"webpack-dev-server": "git+https://github.com/webpack/webpack-dev-server.git"