NIOTypedHTTPServerUpgradeHandler: propagate error and remove self on invalid HTTP ordering

[shoemoney]

Motivation

NIOTypedHTTPServerUpgradeHandler.channelRead(context:requestPart:) handles the .failUpgradePromise(error) action from the state machine like this:

case .failUpgradePromise(let error):
    self.upgradeResultPromise.fail(error)

That's the only effect. It fails the internal upgradeResultFuture, but nothing else happens: the error is never fired down the pipeline, and the handler never removes itself, so it just sits there in the pipeline having silently absorbed a protocol error.

The untyped sibling, HTTPServerUpgradeHandler, handles the equivalent case (an unexpected HTTP part ordering, firstRequestHeadReceived in HTTPServerUpgradeHandler.swift) differently:

guard case .head(let request) = requestPart else {
    context.fireErrorCaught(HTTPServerUpgradeErrors.invalidHTTPOrdering)
    self.notUpgrading(context: context, data: requestPart)
    return
}

notUpgrading(context:data:) ends with:

// Ok, we've delivered all the parts. We can now remove ourselves, which should happen synchronously.
context.pipeline.syncOperations.removeHandler(context: context, promise: nil)

So the untyped handler both fires the error down the pipeline and removes itself; the typed handler does neither.

Modifications

NIOTypedHTTPServerUpgradeHandler's .failUpgradePromise case now also calls context.fireErrorCaught(error) and context.pipeline.syncOperations.removeHandler(self, promise: nil), in the same order already used by the existing .fireErrorCaughtAndRemoveHandler case a few lines below it in the same file.

Added testTypedUpgradeHandlerBarfsOnUnexpectedOrdering, which drives the typed handler directly on an EmbeddedChannel with an out-of-order HTTPServerRequestPart and asserts both that upgradeResultFuture fails with .invalidHTTPOrdering and that the handler removes itself from the pipeline.

Result

The typed upgrade handler now surfaces invalid-ordering errors to the rest of the pipeline and cleans itself up, matching HTTPServerUpgradeHandler's existing behavior.