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[HTTP2] Tolerate GoAway and Settings frames after connection close #578

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Merged
merged 1 commit into from
Apr 11, 2022
Merged

[HTTP2] Tolerate GoAway and Settings frames after connection close #578

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32 changes: 26 additions & 6 deletions Sources/AsyncHTTPClient/ConnectionPool/HTTP2/HTTP2IdleHandler.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -168,7 +168,7 @@ extension HTTP2IdleHandler {

mutating func settingsReceived(_ settings: HTTP2Settings) -> Action {
switch self.state {
case .initialized, .closed:
case .initialized:
preconditionFailure("Invalid state: \(self.state)")

case .connected:
Expand All @@ -188,12 +188,17 @@ extension HTTP2IdleHandler {

case .closing:
return .nothing

case .closed:
// We may receive a Settings frame after we have called connection close, because of
// packages being delivered from the incoming buffer.
return .nothing
}
}

mutating func goAwayReceived() -> Action {
switch self.state {
case .initialized, .closed:
case .initialized:
preconditionFailure("Invalid state: \(self.state)")

case .connected:
Expand All @@ -206,6 +211,11 @@ extension HTTP2IdleHandler {

case .closing:
return .notifyConnectionGoAwayReceived(close: false)

case .closed:
// We may receive a GoAway frame after we have called connection close, because of
// packages being delivered from the incoming buffer.
return .nothing
}
}

Expand Down Expand Up @@ -234,6 +244,9 @@ extension HTTP2IdleHandler {

mutating func streamCreated() -> Action {
switch self.state {
case .initialized, .connected:
preconditionFailure("Invalid state: \(self.state)")

case .active(var openStreams, let maxStreams):
openStreams += 1
self.state = .active(openStreams: openStreams, maxStreams: maxStreams)
Expand All @@ -246,13 +259,18 @@ extension HTTP2IdleHandler {
self.state = .closing(openStreams: openStreams, maxStreams: maxStreams)
return .nothing

case .initialized, .connected, .closed:
preconditionFailure("Invalid state: \(self.state)")
case .closed:
// We may receive a events after we have called connection close, because of
// internal races. We should just ignore these cases.
return .nothing
Comment on lines +262 to +265
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@Lukasa Is this something that can happen? Should we be defensive here as well?

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This can happen, yes, unless we take action to defend against it. As we don't right now, it's a good idea to do this.

}
}

mutating func streamClosed() -> Action {
switch self.state {
case .initialized, .connected:
preconditionFailure("Invalid state: \(self.state)")

case .active(var openStreams, let maxStreams):
openStreams -= 1
assert(openStreams >= 0)
Expand All @@ -269,8 +287,10 @@ extension HTTP2IdleHandler {
self.state = .closing(openStreams: openStreams, maxStreams: maxStreams)
return .nothing

case .initialized, .connected, .closed:
preconditionFailure("Invalid state: \(self.state)")
case .closed:
// We may receive a events after we have called connection close, because of
// internal races. We should just ignore these cases.
return .nothing
}
}
}
Expand Down
1 change: 1 addition & 0 deletions Tests/AsyncHTTPClientTests/HTTP2IdleHandlerTests+XCTest.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ extension HTTP2IdleHandlerTests {
("testCloseEventWhileNoOpenStreams", testCloseEventWhileNoOpenStreams),
("testCloseEventWhileThereAreOpenStreams", testCloseEventWhileThereAreOpenStreams),
("testGoAwayWhileThereAreOpenStreams", testGoAwayWhileThereAreOpenStreams),
("testReceiveSettingsAndGoAwayAfterClientSideClose", testReceiveSettingsAndGoAwayAfterClientSideClose),
]
}
}
26 changes: 26 additions & 0 deletions Tests/AsyncHTTPClientTests/HTTP2IdleHandlerTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -225,6 +225,32 @@ class HTTP2IdleHandlerTests: XCTestCase {
}
}
}

func testReceiveSettingsAndGoAwayAfterClientSideClose() {
let delegate = MockHTTP2IdleHandlerDelegate()
let idleHandler = HTTP2IdleHandler(delegate: delegate, logger: Logger(label: "test"))
let embedded = EmbeddedChannel(handlers: [idleHandler])
XCTAssertNoThrow(try embedded.connect(to: .makeAddressResolvingHost("localhost", port: 0)).wait())

let settingsFrame = HTTP2Frame(streamID: 0, payload: .settings(.settings([.init(parameter: .maxConcurrentStreams, value: 10)])))
XCTAssertEqual(delegate.maxStreams, nil)
XCTAssertNoThrow(try embedded.writeInbound(settingsFrame))
XCTAssertEqual(delegate.maxStreams, 10)

XCTAssertTrue(embedded.isActive)
embedded.pipeline.triggerUserOutboundEvent(HTTPConnectionEvent.shutdownRequested, promise: nil)
XCTAssertFalse(embedded.isActive)

let newSettingsFrame = HTTP2Frame(streamID: 0, payload: .settings(.settings([.init(parameter: .maxConcurrentStreams, value: 20)])))
XCTAssertEqual(delegate.maxStreams, 10)
XCTAssertNoThrow(try embedded.writeInbound(newSettingsFrame))
XCTAssertEqual(delegate.maxStreams, 10, "Expected message to not be forwarded.")

let goAwayFrame = HTTP2Frame(streamID: HTTP2StreamID(0), payload: .goAway(lastStreamID: 2, errorCode: .http11Required, opaqueData: nil))
XCTAssertEqual(delegate.goAwayReceived, false)
XCTAssertNoThrow(try embedded.writeInbound(goAwayFrame))
XCTAssertEqual(delegate.goAwayReceived, false, "Expected go away to not be forwarded.")
}
}

class MockHTTP2IdleHandlerDelegate: HTTP2IdleHandlerDelegate {
Expand Down