Fix existing behaviour

Author: fabianfett

Diff for: Sources/AsyncHTTPClient/ConnectionPool/HTTPRequestStateMachine.swift

@@ -529,13 +529,7 @@ struct HTTPRequestStateMachine {
             preconditionFailure("How can we receive a response head before sending a request head ourselves. Invalid state: \(self.state)")
 
         case .running(_, .waitingForHead):
-            // If we receive a http response header with a status code of 1xx, we ignore the header
-            // except for 101, which we consume.
-            // If the remote closes the connection after sending a 1xx (not 101) response head, we
-            // will receive a response end from the parser. We need to protect against this case.
-            let error = HTTPClientError.httpEndReceivedAfterHeadWith1xx
-            self.state = .failed(error)
-            return .failRequest(error, .close)
+            preconditionFailure("How can we receive a response end, if we haven't a received a head. Invalid state: \(self.state)")
 
         case .running(.streaming(let expectedBodyLength, let sentBodyBytes, let producerState), .receivingBody(let head, var responseStreamState))
             where head.status.code < 300:

Diff for: Sources/AsyncHTTPClient/HTTPClient.swift

@@ -996,5 +996,6 @@ public struct HTTPClientError: Error, Equatable, CustomStringConvertible {
     ///  - Tasks are not processed fast enough on the existing connections, to process all waiters in time
     public static let getConnectionFromPoolTimeout = HTTPClientError(code: .getConnectionFromPoolTimeout)
 
+    @available(*, deprecated, message: "AsyncHTTPClient now correctly supports informational headers. For this reason `httpEndReceivedAfterHeadWith1xx` will not be thrown anymore.")
     public static let httpEndReceivedAfterHeadWith1xx = HTTPClientError(code: .httpEndReceivedAfterHeadWith1xx)
 }

Diff for: Tests/AsyncHTTPClientTests/HTTP1ConnectionStateMachineTests.swift

@@ -265,7 +265,7 @@ class HTTP1ConnectionStateMachineTests: XCTestCase {
         XCTAssertEqual(newRequestAction, .sendRequestHead(requestHead, startBody: false))
         let responseHead = HTTPResponseHead(version: .http1_1, status: .init(statusCode: 103, reasonPhrase: "Early Hints"))
         XCTAssertEqual(state.channelRead(.head(responseHead)), .wait)
-        XCTAssertEqual(state.channelRead(.end(nil)), .failRequest(HTTPClientError.httpEndReceivedAfterHeadWith1xx, .close))
+        XCTAssertEqual(state.channelInactive(), .failRequest(HTTPClientError.remoteConnectionClosed, .none))
     }
 }
 

Diff for: Tests/AsyncHTTPClientTests/HTTP1ConnectionTests+XCTest.swift

@@ -33,7 +33,7 @@ extension HTTP1ConnectionTests {
             ("testConnectionClosesOnRandomlyAppearingCloseHeader", testConnectionClosesOnRandomlyAppearingCloseHeader),
             ("testConnectionClosesAfterTheRequestWithoutHavingSentAnCloseHeader", testConnectionClosesAfterTheRequestWithoutHavingSentAnCloseHeader),
             ("testConnectionIsClosedAfterSwitchingProtocols", testConnectionIsClosedAfterSwitchingProtocols),
-            ("testConnectionDoesntCrashAfterConnectionCloseAndEarlyHints", testConnectionDoesntCrashAfterConnectionCloseAndEarlyHints),
+            ("testConnectionDropAfterEarlyHints", testConnectionDropAfterEarlyHints),
             ("testConnectionIsClosedIfResponseIsReceivedBeforeRequest", testConnectionIsClosedIfResponseIsReceivedBeforeRequest),
             ("testDoubleHTTPResponseLine", testDoubleHTTPResponseLine),
             ("testDownloadStreamingBackpressure", testDownloadStreamingBackpressure),

Diff for: Tests/AsyncHTTPClientTests/HTTP1ConnectionTests.swift

@@ -430,7 +430,7 @@ class HTTP1ConnectionTests: XCTestCase {
         XCTAssertEqual(response?.body, nil)
     }
 
-    func testConnectionDoesntCrashAfterConnectionCloseAndEarlyHints() {
+    func testConnectionDropAfterEarlyHints() {
         let embedded = EmbeddedChannel()
         let logger = Logger(label: "test.http1.connection")
 
@@ -481,25 +481,15 @@ class HTTP1ConnectionTests: XCTestCase {
         XCTAssertEqual(connectionDelegate.hitConnectionReleased, 0)
         XCTAssertNoThrow(try embedded.writeInbound(ByteBuffer(string: responseString)))
 
-        if !embedded.isActive {
-            // behavior before https://github.com/apple/swift-nio/pull/1984
-            embedded.embeddedEventLoop.run() // tick once to run futures.
-            XCTAssertEqual(connectionDelegate.hitConnectionClosed, 1)
-            XCTAssertEqual(connectionDelegate.hitConnectionReleased, 0)
+        XCTAssertTrue(embedded.isActive, "The connection remains active after the informational response head")
+        XCTAssertNoThrow(try embedded.close().wait(), "the connection was closed")
 
-            XCTAssertThrowsError(try requestBag.task.futureResult.wait()) {
-                XCTAssertEqual($0 as? HTTPClientError, .httpEndReceivedAfterHeadWith1xx)
-            }
-        } else {
-            // behavior after https://github.com/apple/swift-nio/pull/1984
-            XCTAssertNoThrow(try embedded.close().wait())
-            embedded.embeddedEventLoop.run() // tick once to run futures.
-            XCTAssertEqual(connectionDelegate.hitConnectionClosed, 1)
-            XCTAssertEqual(connectionDelegate.hitConnectionReleased, 0)
-
-            XCTAssertThrowsError(try requestBag.task.futureResult.wait()) {
-                XCTAssertEqual($0 as? HTTPClientError, .remoteConnectionClosed)
-            }
+        embedded.embeddedEventLoop.run() // tick once to run futures.
+        XCTAssertEqual(connectionDelegate.hitConnectionClosed, 1)
+        XCTAssertEqual(connectionDelegate.hitConnectionReleased, 0)
+
+        XCTAssertThrowsError(try requestBag.task.futureResult.wait()) {
+            XCTAssertEqual($0 as? HTTPClientError, .remoteConnectionClosed)
         }
     }