Fix body-writer exception causes hang

XCode/Sources/HttpServerIO.swift

@@ -130,6 +130,16 @@ open class HttpServerIO {
                 }
             } catch {
                 print("Failed to send response: \(error)")
+                /*
+                    The bodyWriter threw an exception, this could be because the socket is closed, in
+                    which case we fail when we attempt to read from the socket again, or it could be
+                    because the bodyWriter was unable to finish writing the body, session will be out
+                    of sync. If we kept the connection alive, then the client will be waiting for the
+                    remainder of the body until it gives up, and we'll never get the next request.
+
+                    Ideal action is to possibly abruptly close the connection.
+                 */
+                break
             }
             if let session = response.socketSession() {
                 delegate?.socketConnectionReceived(socket)

XCode/Swifter.xcodeproj/project.pbxproj

@@ -110,6 +110,9 @@
 		7CDAB8131BE2A1D400C8A977 /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 7CDAB80D1BE2A1D400C8A977 /* Main.storyboard */; };
 		7CDAB8141BE2A1D400C8A977 /* Images.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 7CDAB80F1BE2A1D400C8A977 /* Images.xcassets */; };
 		7CDAB8161BE2A1D400C8A977 /* ViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7CDAB8111BE2A1D400C8A977 /* ViewController.swift */; };
+		AB83D32D2919F84500D4D434 /* ServerRawResponseTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = AB83D32C2919F84500D4D434 /* ServerRawResponseTests.swift */; };
+		AB83D32E2919F84500D4D434 /* ServerRawResponseTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = AB83D32C2919F84500D4D434 /* ServerRawResponseTests.swift */; };
+		AB83D32F2919F84500D4D434 /* ServerRawResponseTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = AB83D32C2919F84500D4D434 /* ServerRawResponseTests.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -222,6 +225,7 @@
 		7CDAB80F1BE2A1D400C8A977 /* Images.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Images.xcassets; sourceTree = "<group>"; };
 		7CDAB8101BE2A1D400C8A977 /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		7CDAB8111BE2A1D400C8A977 /* ViewController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ViewController.swift; sourceTree = "<group>"; };
+		AB83D32C2919F84500D4D434 /* ServerRawResponseTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ServerRawResponseTests.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -429,6 +433,7 @@
 				0858E7F31D68BB2600491CD1 /* IOSafetyTests.swift */,
 				6A0D4511204E9988000A0726 /* MimeTypesTests.swift */,
 				0C1F3CAC2265FC470076B6F5 /* SwifterTestsHttpResponseBody.swift */,
+				AB83D32C2919F84500D4D434 /* ServerRawResponseTests.swift */,
 				7B55EC94226E0E4F00042D23 /* ServerThreadingTests.swift */,
 			);
 			path = Tests;
@@ -781,6 +786,7 @@
 				043660CD21FED35200497989 /* SwifterTestsHttpRouter.swift in Sources */,
 				047F1F02226AB9AD00909B95 /* XCTestManifests.swift in Sources */,
 				043660CE21FED35500497989 /* SwifterTestsHttpParser.swift in Sources */,
+				AB83D32E2919F84500D4D434 /* ServerRawResponseTests.swift in Sources */,
 				043660D521FED36C00497989 /* MimeTypesTests.swift in Sources */,
 				0C1F3CAE2265FC470076B6F5 /* SwifterTestsHttpResponseBody.swift in Sources */,
 				7B55EC96226E0E4F00042D23 /* ServerThreadingTests.swift in Sources */,
@@ -793,6 +799,7 @@
 			files = (
 				043660E721FED51600497989 /* PingServer.swift in Sources */,
 				043660E921FED51B00497989 /* SwifterTestsWebSocketSession.swift in Sources */,
+				AB83D32F2919F84500D4D434 /* ServerRawResponseTests.swift in Sources */,
 				043660EA21FED51E00497989 /* IOSafetyTests.swift in Sources */,
 				043660E821FED51900497989 /* SwifterTestsStringExtensions.swift in Sources */,
 				043660E521FED51100497989 /* SwifterTestsHttpRouter.swift in Sources */,
@@ -912,6 +919,7 @@
 				7C4785E91C71D15600A9FE73 /* SwifterTestsWebSocketSession.swift in Sources */,
 				043660D421FED36900497989 /* IOSafetyTests.swift in Sources */,
 				7CCD87721C660B250068099B /* SwifterTestsStringExtensions.swift in Sources */,
+				AB83D32D2919F84500D4D434 /* ServerRawResponseTests.swift in Sources */,
 				7B11AD4B21C9A8A6002F8820 /* SwifterTestsHttpRouter.swift in Sources */,
 				0C1F3CAD2265FC470076B6F5 /* SwifterTestsHttpResponseBody.swift in Sources */,
 				7B55EC95226E0E4F00042D23 /* ServerThreadingTests.swift in Sources */,

Xcode/Tests/ServerRawResponseTests.swift

@@ -0,0 +1,134 @@
+//
+//  ServerRawResponseTests.swift
+//  Swifter
+//
+//  Created by Stuart Espey on 11/08/22.
+
+import XCTest
+#if os(Linux)
+import FoundationNetworking
+#endif
+@testable import Swifter
+
+class ServerRawResponseTests: XCTestCase {
+
+    public enum TestError: Error {
+        case aborted
+    }
+
+    var server: HttpServer!
+
+    override func setUp() {
+        super.setUp()
+        server = HttpServer()
+    }
+
+    override func tearDown() {
+        if server.operating {
+            server.stop()
+        }
+        server = nil
+        super.tearDown()
+    }
+
+    /**
+        Adds the handler, at the teststring path, then expects that XXX-CustomHeader is equal to testString, and the
+        body. Test should pass instantly-ish.
+
+        If expectError is true, then an error is expected, and response and body should be nil
+     */
+    func doHandlerTest( handler: @escaping (HttpRequest) -> HttpResponse, testString: String, expectError: Bool = false) {
+        let path = "/\(testString)"
+        server.GET[path] = handler
+
+        var requestExpectation: XCTestExpectation? = expectation(description: "Should handle the request quickly")
+
+        do {
+            try server.start()
+
+            DispatchQueue.global().async {
+
+                let task = URLSession.shared.executeAsyncTask(path: path) { (body, response, error ) in
+
+                    if expectError {
+                        XCTAssertNil(body)
+                        XCTAssertNil(response)
+                        XCTAssertNotNil(error)
+                    } else {
+                        XCTAssertNil(error)
+                        let response = response as? HTTPURLResponse
+                        XCTAssertNotNil(response)
+
+                        let statusCode = response?.statusCode
+                        XCTAssertNotNil(statusCode)
+                        XCTAssertEqual(statusCode, 200)
+                    #if !os(Linux)
+                        if #available(iOS 13.0, macOS 10.15, tvOS 13.0, *) {
+                            let header = response?.value(forHTTPHeaderField: "XXX-Custom-Header") ?? ""
+                            XCTAssertEqual(header, testString)
+                        }
+                    #endif
+
+                        XCTAssertEqual(body, testString.data(using: .utf8))
+                    }
+
+                    requestExpectation?.fulfill()
+                    requestExpectation = nil
+                }
+
+                task.resume()
+            }
+
+        } catch let error {
+            XCTFail("\(error)")
+        }
+
+        waitForExpectations(timeout: 5, handler: nil)
+    }
+
+    func testRawResponseWithBodyWriter() {
+
+        let testString = "normal"
+
+        let handler: ((HttpRequest) -> HttpResponse)  = { _ in
+            return HttpResponse.raw(200, "OK", ["XXX-Custom-Header": testString], {
+                try $0.write([UInt8]((testString) .utf8))
+            })
+        }
+
+        doHandlerTest(handler: handler, testString: testString)
+    }
+
+    func testFailedUnboundedResponseShouldNotHang() {
+
+        let testString = "unbounded"
+        let handler: ((HttpRequest) -> HttpResponse)  = { _ in
+            return HttpResponse.raw(200, "OK", ["XXX-Custom-Header": testString], {
+                try $0.write([UInt8]((testString) .utf8))
+
+                // simulates the body writer not being able to finish the body.
+                throw TestError.aborted
+            })
+        }
+
+        doHandlerTest(handler: handler, testString: testString)
+    }
+
+    func testFailedBoundedResponseShouldNotHang() {
+
+        let testString = "bounded"   // content-length: 7
+        let handler: ((HttpRequest) -> HttpResponse)  = { _ in
+            return HttpResponse.raw(200, "OK", [
+                "XXX-Custom-Header": testString,
+                "Content-Length": "\(testString.utf8.count+1)"  // we'll be missing one byte
+            ], {
+                try $0.write([UInt8]((testString) .utf8))
+
+                throw TestError.aborted
+            })
+        }
+
+        // because the length is known, we should trigger a network failure
+        doHandlerTest(handler: handler, testString: testString, expectError: true)
+    }
+}