workaround ab (ApacheBench) in keep-alive mode (#260)

Motivation:

`ab -k` behaves weirdly: it'll send an HTTP/1.0 request with keep-alive set
but stops doing anything at all if the server doesn't also set Connection: keep-alive
which our example HTTP1Server didn't do.

Modifications:

In the HTTP1Server example if we receive an HTTP/1.0 request with
Connection: keep-alive, we'll now set keep-alive too.

Result:

ab -k doesn't get stuck anymore.

IntegrationTests/tests_01_http/test_18_close_with_no_keepalive.sh

@@ -28,6 +28,7 @@ echo -e 'GET /dynamic/count-to-ten HTTP/1.1\r\nConnection: close\r\n\r\n' | \
 backslash_r=$(echo -ne '\r')
 cat > "$tmp/expected" <<EOF
 HTTP/1.1 200 OK$backslash_r
+Connection: close$backslash_r
 transfer-encoding: chunked$backslash_r
 $backslash_r
 1$backslash_r

IntegrationTests/tests_01_http/test_22_http_1.0_keep_alive.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+##===----------------------------------------------------------------------===##
+##
+## This source file is part of the SwiftNIO open source project
+##
+## Copyright (c) 2017-2018 Apple Inc. and the SwiftNIO project authors
+## Licensed under Apache License v2.0
+##
+## See LICENSE.txt for license information
+## See CONTRIBUTORS.txt for the list of SwiftNIO project authors
+##
+## SPDX-License-Identifier: Apache-2.0
+##
+##===----------------------------------------------------------------------===##
+
+source defines.sh
+
+token=$(create_token)
+start_server "$token"
+do_curl "$token" -H 'connection: keep-alive' -v --http1.0 \
+    "http://foobar.com/dynamic/info" > "$tmp/out_actual" 2>&1
+grep -qi '< Connection: keep-alive' "$tmp/out_actual"
+grep -qi '< HTTP/1.0 200 OK' "$tmp/out_actual"
+stop_server "$token"

Sources/NIOHTTP1Server/main.swift

@@ -33,6 +33,28 @@ extension String {
     }
 }
 
+private func httpResponseHead(request: HTTPRequestHead, status: HTTPResponseStatus, headers: HTTPHeaders = HTTPHeaders()) -> HTTPResponseHead {
+    var head = HTTPResponseHead(version: request.version, status: status, headers: headers)
+    let connectionHeaders: [String] = head.headers[canonicalForm: "connection"].map { $0.lowercased() }
+
+    if !connectionHeaders.contains("keep-alive") && !connectionHeaders.contains("close") {
+        // the user hasn't pre-set either 'keep-alive' or 'close', so we might need to add headers
+
+        switch (request.isKeepAlive, request.version.major, request.version.minor) {
+        case (true, 1, 0):
+            // HTTP/1.0 and the request has 'Connection: keep-alive', we should mirror that
+            head.headers.add(name: "Connection", value: "keep-alive")
+        case (false, 1, let n) where n >= 1:
+            // HTTP/1.1 (or treated as such) and the request has 'Connection: close', we should mirror that
+            head.headers.add(name: "Connection", value: "close")
+        default:
+            // we should match the default or are dealing with some HTTP that we don't support, let's leave as is
+            ()
+        }
+    }
+    return head
+}
+
 private final class HTTPHandler: ChannelInboundHandler {
     private enum FileIOMethod {
         case sendfile
@@ -104,7 +126,7 @@ private final class HTTPHandler: ChannelInboundHandler {
             self.buffer.write(string: response)
             var headers = HTTPHeaders()
             headers.add(name: "Content-Length", value: "\(response.utf8.count)")
-            ctx.write(self.wrapOutboundOut(.head(HTTPResponseHead(version: self.infoSavedRequestHead!.version, status: .ok, headers: headers))), promise: nil)
+            ctx.write(self.wrapOutboundOut(.head(httpResponseHead(request: self.infoSavedRequestHead!, status: .ok, headers: headers))), promise: nil)
             ctx.write(self.wrapOutboundOut(.body(.byteBuffer(self.buffer))), promise: nil)
             self.completeResponse(ctx, trailers: nil, promise: nil)
         }
@@ -118,6 +140,7 @@ private final class HTTPHandler: ChannelInboundHandler {
         switch request {
         case .head(let request):
             self.keepAlive = request.isKeepAlive
+            self.infoSavedRequestHead = request
             self.state.requestReceived()
             if balloonInMemory {
                 self.buffer.clear()
@@ -135,7 +158,7 @@ private final class HTTPHandler: ChannelInboundHandler {
             if balloonInMemory {
                 var headers = HTTPHeaders()
                 headers.add(name: "Content-Length", value: "\(self.buffer.readableBytes)")
-                ctx.write(self.wrapOutboundOut(.head(HTTPResponseHead(version: HTTPVersion(major: 1, minor: 0), status: .ok, headers: headers))), promise: nil)
+                ctx.write(self.wrapOutboundOut(.head(httpResponseHead(request: self.infoSavedRequestHead!, status: .ok, headers: headers))), promise: nil)
                 ctx.write(self.wrapOutboundOut(.body(.byteBuffer(self.buffer))), promise: nil)
                 self.completeResponse(ctx, trailers: nil, promise: nil)
             } else {
@@ -185,7 +208,7 @@ private final class HTTPHandler: ChannelInboundHandler {
                     self.completeResponse(ctx, trailers: nil, promise: nil)
                 }
             }
-            ctx.writeAndFlush(self.wrapOutboundOut(.head(HTTPResponseHead(version: request.version, status: .ok))), promise: nil)
+            ctx.writeAndFlush(self.wrapOutboundOut(.head(httpResponseHead(request: request, status: .ok))), promise: nil)
             doNext()
         case .end:
             self.state.requestComplete()
@@ -212,7 +235,7 @@ private final class HTTPHandler: ChannelInboundHandler {
                     }
                 }
             }
-            ctx.writeAndFlush(self.wrapOutboundOut(.head(HTTPResponseHead(version: request.version, status: .ok))), promise: nil)
+            ctx.writeAndFlush(self.wrapOutboundOut(.head(httpResponseHead(request: request, status: .ok))), promise: nil)
             doNext()
         case .end:
             self.state.requestComplete()
@@ -254,7 +277,7 @@ private final class HTTPHandler: ChannelInboundHandler {
             self.keepAlive = request.isKeepAlive
             self.state.requestReceived()
             guard !request.uri.containsDotDot() else {
-                let response = HTTPResponseHead(version: request.version, status: .forbidden)
+                let response = httpResponseHead(request: request, status: .forbidden)
                 ctx.write(self.wrapOutboundOut(.head(response)), promise: nil)
                 self.completeResponse(ctx, trailers: nil, promise: nil)
                 return
@@ -263,7 +286,7 @@ private final class HTTPHandler: ChannelInboundHandler {
             do {
                 let file = try FileHandle(path: path)
                 let region = try FileRegion(fileHandle: file)
-                var response = HTTPResponseHead(version: request.version, status: .ok)
+                var response = httpResponseHead(request: request, status: .ok)
 
                 response.headers.add(name: "Content-Length", value: "\(region.endIndex)")
                 response.headers.add(name: "Content-Type", value: "text/plain; charset=utf-8")
@@ -287,7 +310,7 @@ private final class HTTPHandler: ChannelInboundHandler {
                         return p.futureResult
                     }.thenIfError { error in
                         if !responseStarted {
-                            let response = HTTPResponseHead(version: request.version, status: .ok)
+                            let response = httpResponseHead(request: request, status: .ok)
                             ctx.write(self.wrapOutboundOut(.head(response)), promise: nil)
                             var buffer = ctx.channel.allocator.buffer(capacity: 100)
                             buffer.write(string: "fail: \(error)")
@@ -319,15 +342,15 @@ private final class HTTPHandler: ChannelInboundHandler {
                     switch error {
                     case let e as IOError where e.errnoCode == ENOENT:
                         body.write(staticString: "IOError (not found)\r\n")
-                        return HTTPResponseHead(version: request.version, status: .notFound)
+                        return httpResponseHead(request: request, status: .notFound)
                     case let e as IOError:
                         body.write(staticString: "IOError (other)\r\n")
                         body.write(string: e.description)
                         body.write(staticString: "\r\n")
-                        return HTTPResponseHead(version: request.version, status: .notFound)
+                        return httpResponseHead(request: request, status: .notFound)
                     default:
                         body.write(string: "\(type(of: error)) error\r\n")
-                        return HTTPResponseHead(version: request.version, status: .internalServerError)
+                        return httpResponseHead(request: request, status: .internalServerError)
                     }
                 }()
                 body.write(string: "\(error)")
@@ -381,7 +404,7 @@ private final class HTTPHandler: ChannelInboundHandler {
             self.keepAlive = request.isKeepAlive
             self.state.requestReceived()
 
-            var responseHead = HTTPResponseHead(version: request.version, status: HTTPResponseStatus.ok)
+            var responseHead = httpResponseHead(request: request, status: HTTPResponseStatus.ok)
             responseHead.headers.add(name: "content-length", value: "12")
             let response = HTTPServerResponsePart.head(responseHead)
             ctx.write(self.wrapOutboundOut(response), promise: nil)