Fix HTTP/1.0 support (#431)

Use `HTTPResponseHead.isKeepAlive` instead of relying on our own keep-alive test.

Author: fabianfett

Diff for: Sources/AsyncHTTPClient/ConnectionPool/HTTP1.1/HTTP1ConnectionStateMachine.swift

@@ -256,7 +256,7 @@ struct HTTP1ConnectionStateMachine {
                 let action = requestStateMachine.channelRead(part)
 
                 if case .head(let head) = part, close == false {
-                    close = head.headers[canonicalForm: "connection"].contains(where: { $0.lowercased() == "close" })
+                    close = !head.isKeepAlive
                 }
                 state = .inRequest(requestStateMachine, close: close)
                 return state.modify(with: action)

Diff for: Tests/AsyncHTTPClientTests/HTTP1ConnectionStateMachineTests+XCTest.swift

@@ -28,6 +28,8 @@ extension HTTP1ConnectionStateMachineTests {
             ("testPOSTRequestWithWriteAndReadBackpressure", testPOSTRequestWithWriteAndReadBackpressure),
             ("testResponseReadingWithBackpressure", testResponseReadingWithBackpressure),
             ("testAConnectionCloseHeaderInTheRequestLeadsToConnectionCloseAfterRequest", testAConnectionCloseHeaderInTheRequestLeadsToConnectionCloseAfterRequest),
+            ("testAHTTP1_0ResponseWithoutKeepAliveHeaderLeadsToConnectionCloseAfterRequest", testAHTTP1_0ResponseWithoutKeepAliveHeaderLeadsToConnectionCloseAfterRequest),
+            ("testAHTTP1_0ResponseWithKeepAliveHeaderLeadsToConnectionBeingKeptAlive", testAHTTP1_0ResponseWithKeepAliveHeaderLeadsToConnectionBeingKeptAlive),
             ("testAConnectionCloseHeaderInTheResponseLeadsToConnectionCloseAfterRequest", testAConnectionCloseHeaderInTheResponseLeadsToConnectionCloseAfterRequest),
             ("testNIOTriggersChannelActiveTwice", testNIOTriggersChannelActiveTwice),
             ("testIdleConnectionBecomesInactive", testIdleConnectionBecomesInactive),

Diff for: Tests/AsyncHTTPClientTests/HTTP1ConnectionStateMachineTests.swift

@@ -97,6 +97,37 @@ class HTTP1ConnectionStateMachineTests: XCTestCase {
         let responseBody = ByteBuffer(bytes: [1, 2, 3, 4])
         XCTAssertEqual(state.channelRead(.body(responseBody)), .wait)
         XCTAssertEqual(state.channelRead(.end(nil)), .succeedRequest(.close, .init([responseBody])))
+        XCTAssertEqual(state.channelInactive(), .fireChannelInactive)
+    }
+
+    func testAHTTP1_0ResponseWithoutKeepAliveHeaderLeadsToConnectionCloseAfterRequest() {
+        var state = HTTP1ConnectionStateMachine()
+        XCTAssertEqual(state.channelActive(isWritable: true), .fireChannelActive)
+        let requestHead = HTTPRequestHead(version: .http1_1, method: .GET, uri: "/")
+        let metadata = RequestFramingMetadata(connectionClose: false, body: .none)
+        XCTAssertEqual(state.runNewRequest(head: requestHead, metadata: metadata), .sendRequestHead(requestHead, startBody: false))
+
+        let responseHead = HTTPResponseHead(version: .http1_0, status: .ok, headers: ["content-length": "4"])
+        XCTAssertEqual(state.channelRead(.head(responseHead)), .forwardResponseHead(responseHead, pauseRequestBodyStream: false))
+        let responseBody = ByteBuffer(bytes: [1, 2, 3, 4])
+        XCTAssertEqual(state.channelRead(.body(responseBody)), .wait)
+        XCTAssertEqual(state.channelRead(.end(nil)), .succeedRequest(.close, .init([responseBody])))
+        XCTAssertEqual(state.channelInactive(), .fireChannelInactive)
+    }
+
+    func testAHTTP1_0ResponseWithKeepAliveHeaderLeadsToConnectionBeingKeptAlive() {
+        var state = HTTP1ConnectionStateMachine()
+        XCTAssertEqual(state.channelActive(isWritable: true), .fireChannelActive)
+        let requestHead = HTTPRequestHead(version: .http1_1, method: .GET, uri: "/")
+        let metadata = RequestFramingMetadata(connectionClose: false, body: .none)
+        XCTAssertEqual(state.runNewRequest(head: requestHead, metadata: metadata), .sendRequestHead(requestHead, startBody: false))
+
+        let responseHead = HTTPResponseHead(version: .http1_0, status: .ok, headers: ["content-length": "4", "connection": "keep-alive"])
+        XCTAssertEqual(state.channelRead(.head(responseHead)), .forwardResponseHead(responseHead, pauseRequestBodyStream: false))
+        let responseBody = ByteBuffer(bytes: [1, 2, 3, 4])
+        XCTAssertEqual(state.channelRead(.body(responseBody)), .wait)
+        XCTAssertEqual(state.channelRead(.end(nil)), .succeedRequest(.informConnectionIsIdle, .init([responseBody])))
+        XCTAssertEqual(state.channelInactive(), .fireChannelInactive)
     }
 
     func testAConnectionCloseHeaderInTheResponseLeadsToConnectionCloseAfterRequest() {