Added heap-allocation to allow long-lived websocket connections.

.gitea/workflows/ci.yaml

@@ -0,0 +1,32 @@
+name: Build and Test Module
+on:
+  push:
+    paths:
+      - 'source/**'
+      - '.gitea/workflows/ci.yaml'
+  pull_request:
+    types: [opened, reopened, synchronize]
+jobs:
+  build-and-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup DLang
+        uses: dlang-community/setup-dlang@v2
+        with:
+          compiler: ldc-latest
+      - name: Build and Test
+        run: dub -q test
+
+  integration-tests:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup DLang
+        uses: dlang-community/setup-dlang@v2
+        with:
+          compiler: ldc-latest
+
+      - name: http1-test
+        working-directory: integration-tests/http1-basic
+        run: dub run --single http1-test.d

README.md

@@ -10,7 +10,7 @@ implemented so far.
 
 ## HTTP/1.1
 
-Use the `Http1Transport` implementation of `HttpTransport` to serve content
+Use the `TaskPoolHttp1Transport` implementation of `HttpTransport` to serve content
 using the HTTP/1.1 protocol. See the example below:
 
 ```d
@@ -26,7 +26,7 @@ class MyHandler : HttpRequestHandler {
 }
 
 void main() {
-    HttpTransport tp = new Http1Transport(new MyHandler(), 8080);
+    HttpTransport tp = new TaskPoolHttp1Transport(new MyHandler(), 8080);
     tp.start();
 }
 ```

dub.json

@@ -4,9 +4,10 @@
 	],
 	"copyright": "Copyright © 2024, Andrew Lalis",
 	"dependencies": {
-		"handy-http-primitives": "~>1.0.0",
-		"photon": "~>0.10.2",
-		"streams": "~>3.5.0"
+		"handy-http-primitives": "~>1.6",
+		"photon": "~>0.11",
+		"streams": "~>3.6",
+		"slf4d": "~>4.0"
 	},
 	"description": "Implementations of HTTP transport protocols.",
 	"license": "CC0",

dub.selections.json

@@ -1,9 +1,10 @@
 {
 	"fileVersion": 1,
 	"versions": {
-		"handy-http-primitives": "1.0.0",
-		"photon": "0.10.2",
+		"handy-http-primitives": "1.7.0",
+		"photon": "0.11.0",
 		"sharded-map": "2.7.0",
-		"streams": "3.5.0"
+		"slf4d": "4.1.1",
+		"streams": "3.6.0"
 	}
 }

integration-tests/http1-basic/.gitignore

@@ -0,0 +1 @@
+http1-test

integration-tests/http1-basic/http1-test.d

@@ -0,0 +1,53 @@
+/+ dub.sdl:
+    dependency "handy-http-transport" path="../../"
+    dependency "requests" version="~>2.1"
++/
+
+/**
+ * This tests the basic HTTP functionality of the Http1Transport implementation
+ * by starting a server, sending a request, and checking the response.
+ */
+module integration_tests.http1_test;
+
+import handy_http_primitives;
+import handy_http_transport;
+import slf4d;
+import slf4d.default_provider;
+import requests;
+
+import core.thread;
+
+int main() {
+    auto loggingProvider = DefaultProvider.builder()
+        .withRootLoggingLevel(Levels.INFO)
+        .withConsoleSerializer(true, 48)
+        .build();
+    configureLoggingProvider(loggingProvider);
+
+    HttpTransport transport = new TaskPoolHttp1Transport(HttpRequestHandler.of(&handleRequest));
+    Thread thread = transport.startInNewThread();
+    scope(exit) {
+        transport.stop();
+        thread.join();
+    }
+    info("Started server in another thread.");
+    Thread.sleep(msecs(100)); // Wait for the server to start.
+
+    // Send a simple GET request to the server.
+    info("Sending GET request to http://localhost:8080");
+    auto content = getContent("http://localhost:8080");
+    ubyte[] data = content.data;
+    if (data.length != 13 || (cast(string) data) != "Hello, world!") {
+        error("Received unexpected content: " ~ cast(string) data);
+        return 1;
+    }
+
+    info("Test completed successfully.");
+    return 0;
+}
+
+void handleRequest(ref ServerHttpRequest request, ref ServerHttpResponse response) {
+    response.headers.add("Content-Type", "text/plain");
+    response.headers.add("Content-Length", "13");
+    response.outputStream.writeToStream(cast(ubyte[]) "Hello, world!");
+}

integration-tests/http1-speed-test/.gitignore

@@ -0,0 +1 @@
+http1-speed-test

integration-tests/http1-speed-test/http1-speed-test.d

@@ -0,0 +1,28 @@
+/+ dub.sdl:
+    dependency "handy-http-transport" path="../../"
++/
+module integration_tests.http1_speed_test;
+
+import handy_http_primitives;
+import handy_http_transport;
+import slf4d;
+import slf4d.default_provider;
+
+void main() {
+    auto loggingProvider = DefaultProvider.builder()
+        .withRootLoggingLevel(Levels.ERROR)
+        .withConsoleSerializer(true, 48)
+        .build();
+    configureLoggingProvider(loggingProvider);
+    HttpTransport transport;
+    transport = new TaskPoolHttp1Transport(HttpRequestHandler.of(
+        (ref ServerHttpRequest request, ref ServerHttpResponse response) {
+            if (request.method == HttpMethod.DELETE) {
+                transport.stop();
+            }
+            response.headers.add("Content-Type", "text/plain");
+            response.headers.add("Content-Length", "13");
+            response.outputStream.writeToStream(cast(ubyte[]) "Hello, world!");
+        }));
+    transport.start();
+}

integration-tests/run_all.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+# This script runs all integration tests.
+
+set -e -o pipefail
+
+cd http1-basic
+dub build --single http1-test.d
+./http1-test
+cd ..
+
+# cd http1-speed-test
+# dub build --single --build=release http1-speed-test.d
+

source/handy_http_transport/helpers.d

@@ -20,15 +20,14 @@ Either!(string, "value", StreamError, "error") consumeUntil(S)(
         auto result = inputStream.readFromStream(buffer[idx .. idx + 1]);
         if (result.hasError) return Either!(string, "value", StreamError, "error")(result.error);
         if (result.count != 1) return Either!(string, "value", StreamError, "error")(
-            StreamError("Failed to read a single element", 1)
+            StreamError("Failed to read a single element", 0)
         );
         idx++;
         if (idx >= target.length && buffer[idx - target.length .. idx] == target) {
             return Either!(string, "value", StreamError, "error")(
                 cast(string) buffer[0 .. idx - target.length].idup
             );
-        }
-        if (idx >= buffer.length) {
+        } else if (idx >= buffer.length) {
             return Either!(string, "value", StreamError, "error")(
                 StreamError("Couldn't find target \"" ~ target ~ "\" after reading 1024 bytes.", 1)
             );
@@ -61,13 +60,22 @@ ptrdiff_t indexOf(string s, char c, size_t offset = 0) {
 string stripSpaces(string s) {
     if (s.length == 0) return s;
     ptrdiff_t startIdx = 0;
-    while (s[startIdx] == ' ' && startIdx < s.length) startIdx++;
+    while (startIdx < s.length && s[startIdx] == ' ') startIdx++;
     s = s[startIdx .. $];
-    ptrdiff_t endIdx = s.length - 1;
+    if (s.length == 0) return "";
+    ptrdiff_t endIdx = cast(ptrdiff_t) s.length - 1;
     while (s[endIdx] == ' ' && endIdx >= 0) endIdx--;
     return s[0 .. endIdx + 1];
 }
 
+unittest {
+    assert(stripSpaces("") == "");
+    assert(stripSpaces("    ") == "");
+    assert(stripSpaces("test") == "test");
+    assert(stripSpaces("  test") == "test");
+    assert(stripSpaces("  test string   ") == "test string");
+}
+
 /**
  * Helper function to append an unsigned integer value to a char buffer. It is
  * assumed that there's enough space to write the value.

source/handy_http_transport/http1/epoll.d

@@ -0,0 +1,122 @@
+module handy_http_transport.http1.epoll;
+
+import core.sys.posix.sys.socket;
+import core.sys.linux.epoll;
+import core.sys.posix.netinet.in_;
+import core.sys.posix.fcntl;
+import core.sys.posix.unistd;
+
+import core.stdc.errno;
+
+extern(C) {
+    int accept4(int sockfd, sockaddr *addr, socklen_t *addrlen, int flags);
+}
+
+import handy_http_transport.interfaces;
+import handy_http_transport.http1;
+import handy_http_primitives;
+import slf4d;
+
+class Http1EpollTransport : Http1Transport {
+
+    this(HttpRequestHandler requestHandler, ushort port) {
+        super(requestHandler, port);
+    }
+
+    override void start() {
+        super.start();
+        // Create the server socket.
+        enum SOCK_NONBLOCK = 0x4000;
+        int listenFd = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, 0);
+        sockaddr_in serverAddress;
+        serverAddress.sin_family = AF_INET;
+        serverAddress.sin_port = htons(port);
+        serverAddress.sin_addr.s_addr = INADDR_ANY;
+
+        if (bind(listenFd, cast(sockaddr*) &serverAddress, serverAddress.sizeof) == -1) {
+            errorF!"Failed to bind socket: %d"(errno);
+            close(listenFd);
+            return;
+        }
+
+        if (listen(listenFd, SOMAXCONN) == -1) {
+            errorF!"Failed to listen on socket: %d"(errno);
+            close(listenFd);
+            return;
+        }
+
+
+        int epollFd = epoll_create1(0);
+        if (epollFd == -1) {
+            errorF!"Failed to create epoll instance: %d"(errno);
+            return;
+        }
+
+        epoll_event event;
+        epoll_event[64] events;
+        event.events = EPOLLIN | EPOLLET;
+        event.data.fd = listenFd;
+        if (epoll_ctl(epollFd, EPOLL_CTL_ADD, listenFd, &event) == -1) {
+            errorF!"Failed to add listen socket to epoll: %d"(errno);
+            close(listenFd);
+            close(epollFd);
+            return;
+        }
+
+        infoF!"Server listening on port %d."(port);
+
+        while (true) {
+            int eventCount = epoll_wait(epollFd, &event, 64, 5000);
+            if (eventCount == -1) {
+                errorF!"Epoll wait failed: %d"(errno);
+                break;
+            }
+
+            for (int i = 0; i < eventCount; i++) {
+                if (events[i].data.fd == listenFd) {
+                    // New incoming connection.
+                    while (true) {
+                        sockaddr_in clientAddress;
+                        socklen_t clientAddressLength = clientAddress.sizeof;
+                        int clientFd = accept4(
+                            listenFd,
+                            cast(sockaddr*) &clientAddress,
+                            &clientAddressLength,
+                            SOCK_NONBLOCK
+                        );
+                        if (clientFd == -1) {
+                            if (errno == EAGAIN || errno == EWOULDBLOCK) {
+                                // No more connections to accept.
+                                break;
+                            } else {
+                                errorF!"Failed to accept connection: %d"(errno);
+                                break;
+                            }
+                        }
+
+                        // Add the client socket to epoll's listening list.
+                        event.events = EPOLLIN | EPOLLET;
+                        event.data.fd = clientFd;
+                        if (epoll_ctl(epollFd, EPOLL_CTL_ADD, clientFd, &event) == -1) {
+                            errorF!"Failed to add client socket to epoll: %d"(errno);
+                            close(clientFd);
+                        }
+
+                        infoF!"Accepted new connection from %s:%d."(
+                            inet_ntoa(clientAddress.sin_addr),
+                            ntohs(clientAddress.sin_port)
+                        );
+                    }
+                } else {
+                    // Event on an existing client socket.
+
+                    int clientFd = events[i].data.fd;
+
+                    if (events[i].events & EPOLLIN) {
+                        
+                    }
+                }
+            }
+        }
+    }
+}

source/handy_http_transport/http1/package.d

@@ -3,3 +3,5 @@
  */
 module handy_http_transport.http1;
 
+public import handy_http_transport.http1.transport;
+public import handy_http_transport.http1.task_pool;

source/handy_http_transport/http1/task_pool.d

@@ -0,0 +1,62 @@
+module handy_http_transport.http1.task_pool;
+
+import std.socket;
+import std.parallelism;
+
+import handy_http_transport.http1.transport;
+import handy_http_primitives;
+import slf4d;
+
+/**
+ * An implementation of Http1Transport which uses D's standard library
+ * parallelization, where each incoming client request is turned into a task
+ * and submitted to the standard task pool.
+ */
+class TaskPoolHttp1Transport : Http1Transport {
+    this(HttpRequestHandler requestHandler, ushort port = 8080) {
+        super(requestHandler, port);
+    }
+
+    override void runServer() {
+        Socket serverSocket = new TcpSocket();
+        serverSocket.setOption(SocketOptionLevel.SOCKET, SocketOption.REUSEADDR, 1);
+        serverSocket.bind(new InternetAddress("127.0.0.1", port));
+        serverSocket.listen(1024);
+
+        while (super.isRunning) {
+            try {
+                Socket clientSocket = serverSocket.accept();
+                auto t = task!handleClient(clientSocket, requestHandler);
+                taskPool().put(t);
+            } catch (SocketAcceptException e) {
+                warn("Failed to accept socket connection.", e);
+            }
+        }
+        serverSocket.close();
+    }
+
+    override void stop() {
+        super.stop();
+        // Send a dummy request to cause the server's blocking accept() call to end.
+        try {
+            Socket dummySocket = new TcpSocket(new InternetAddress("127.0.0.1", port));
+            dummySocket.shutdown(SocketShutdown.BOTH);
+            dummySocket.close();
+        } catch (SocketOSException e) {
+            warn("Failed to send empty request to stop server.", e);
+        }
+    }
+}
+
+unittest {
+    import slf4d.default_provider;
+    auto logProvider = DefaultProvider.builder().withRootLoggingLevel(Levels.DEBUG).build();
+    configureLoggingProvider(logProvider);
+
+    HttpRequestHandler handler = HttpRequestHandler.of(
+        (ref ServerHttpRequest request, ref ServerHttpResponse response) {
+            response.status = HttpStatus.OK;
+            response.writeBodyString("Testing");
+        });
+    testHttp1Transport(new TaskPoolHttp1Transport(handler));
+}

source/handy_http_transport/http1/transport.d

@@ -1,6 +1,7 @@
 module handy_http_transport.http1.transport;
 
 import std.socket;
+import core.atomic : atomicStore, atomicLoad;
 
 import handy_http_transport.interfaces;
 import handy_http_transport.helpers;
@@ -10,51 +11,94 @@ import handy_http_primitives;
 import handy_http_primitives.address;
 
 import streams;
-import photon;
+import slf4d;
 
 /**
- * The HTTP/1.1 transport protocol implementation, using Dimitry Olshansky's
- * Photon fiber scheduling library for concurrency.
+ * Base class for HTTP/1.1 transport, where different subclasses can define
+ * how the actual socket communication works (threadpool / epoll/ etc).
  */
-class Http1Transport : HttpTransport {
-    private Socket serverSocket;
-    private HttpRequestHandler requestHandler;
-    private const ushort port;
+abstract class Http1Transport : HttpTransport {
+    protected HttpRequestHandler requestHandler;
+    protected immutable ushort port;
     private bool running = false;
 
     this(HttpRequestHandler requestHandler, ushort port = 8080) {
         assert(requestHandler !is null);
-        this.serverSocket = new TcpSocket();
         this.requestHandler = requestHandler;
         this.port = port;
     }
 
-    void start() {
-        startloop();
-        go(() => runServer());
-        runFibers();
+    bool isRunning() {
+        return atomicLoad(running);
     }
 
+    void start() {
+        infoF!"Starting Http1Transport server on port %d."(port);
+        atomicStore(running, true);
+        runServer();
+    }
+
+    protected abstract void runServer();
+
     void stop() {
-        this.running = false;
-        this.serverSocket.shutdown(SocketShutdown.BOTH);
-        this.serverSocket.close();
+        infoF!"Stopping Http1Transport server on port %d."(port);
+        atomicStore(running, false);
     }
+}
 
-    private void runServer() {
-        this.running = true;
-        serverSocket.setOption(SocketOptionLevel.SOCKET, SocketOption.REUSEADDR, 1);
-        serverSocket.bind(new InternetAddress("127.0.0.1", port));
-        serverSocket.listen(100);
-        while (running) {
-            try {
-                Socket clientSocket = serverSocket.accept();
-                go(() => handleClient(clientSocket, requestHandler));
-            } catch (SocketAcceptException e) {
-                import std.stdio;
-                stderr.writefln!"Failed to accept socket connection: %s"(e);
+version(unittest) {
+    /**
+     * A generic test to ensure that any Http1Transport implementation behaves
+     * properly to start & stop, and process requests when running.
+     *
+     * It's assumed that the given transport is configured to run on localhost,
+     * port 8080, and return a standard 200 OK empty response to all requests.
+     * Params:
+     *   transport = The transport implementation to test.
+     */
+    void testHttp1Transport(Http1Transport transport) {
+        import core.thread;
+        import std.string;
+        infoF!"Testing Http1Transport implementation: %s"(transport);
+
+        Thread thread = transport.startInNewThread();
+        Thread.sleep(msecs(100));
+
+        Socket clientSocket1 = new TcpSocket(new InternetAddress(8080));
+        const requestBody = "POST /users HTTP/1.1\r\n" ~
+            "Host: example.com\r\n" ~
+            "Content-Type: text/plain\r\n" ~
+            "Content-Length: 13\r\n" ~
+            "\r\n" ~
+            "Hello, world!";
+        ptrdiff_t bytesSent = clientSocket1.send(requestBody);
+        assert(bytesSent == requestBody.length, "Couldn't send the full request body to the server.");
+
+        ubyte[8192] buffer;
+        size_t totalBytesReceived = 0;
+        ptrdiff_t bytesReceived;
+        do {
+            bytesReceived = clientSocket1.receive(buffer[totalBytesReceived .. $]);
+            if (bytesReceived == Socket.ERROR) {
+                assert(false, "Socket error when attempting to receive a response from the HttpTransport server.");
             }
-        }
+            totalBytesReceived += bytesReceived;
+        } while (bytesReceived > 0);
+         
+        string httpResponseContent = cast(string) buffer[0 .. totalBytesReceived];
+        string[] parts = httpResponseContent.split("\r\n\r\n");
+        assert(parts.length > 0, "HTTP 1.1 response is missing required status and headers section.");
+        string[] headerLines = parts[0].split("\r\n");
+        assert(headerLines.length > 0, "HTTP 1.1 response is missing required status line.");
+        string statusLine = headerLines[0];
+        string[] statusLineParts = statusLine.split(" ");
+        assert(statusLineParts[0] == "HTTP/1.1");
+        assert(statusLineParts[1] == "200");
+        assert(statusLineParts[2] == "OK");
+
+        info("Testing is complete. Stopping the server.");
+        transport.stop();
+        thread.join();
     }
 }
 
@@ -68,32 +112,73 @@ class Http1Transport : HttpTransport {
  *   requestHandler = The request handler that will handle the received HTTP request.
  */
 void handleClient(Socket clientSocket, HttpRequestHandler requestHandler) {
-    auto inputStream = SocketInputStream(clientSocket);
-    auto bufferedInput = bufferedInputStreamFor!(8192)(inputStream);
+    SocketInputStream* inputStream = new SocketInputStream(clientSocket);
+    BufferedInputStream!(SocketInputStream*, 8192)* bufferedInput
+        = new BufferedInputStream!(SocketInputStream*, 8192)(inputStream);
     // Get remote address from the socket.
     import handy_http_primitives.address;
     ClientAddress addr = getAddress(clientSocket);
-    auto result = readHttpRequest(&bufferedInput, addr);
+    traceF!"Got request from client: %s"(addr.toString());
+    auto result = readHttpRequest(bufferedInput, addr);
     if (result.hasError) {
-        import std.stdio;
-        stderr.writeln("Failed to read HTTP request: " ~ result.error.message);
+        if (result.error.code != -1) {
+            // Only warn if we didn't read an empty request.
+            warnF!"Failed to read request: %s"(result.error.message);
+        }
         inputStream.closeStream();
         return;
     }
     scope ServerHttpRequest request = result.request;
     scope ServerHttpResponse response;
-    SocketOutputStream outputStream = SocketOutputStream(clientSocket);
+    SocketOutputStream* outputStream = new SocketOutputStream(clientSocket);
     response.outputStream = outputStreamObjectFor(HttpResponseOutputStream!(SocketOutputStream*)(
-        &outputStream,
+        outputStream,
         &response
     ));
     try {
         requestHandler.handle(request, response);
+        debugF!"%s %s -> %d %s"(request.method, request.url, response.status.code, response.status.text);
     } catch (Exception e) {
-        import std.stdio;
-        stderr.writeln("Exception thrown while handling request: " ~ e.msg);
+        error("Exception thrown while handling request.", e);
+    } catch (Throwable t) {
+        errorF!"Throwable error while handling request: %s"(t.msg);
+        throw t;
     }
-    inputStream.closeStream();
+    
+    if (response.status != HttpStatus.SWITCHING_PROTOCOLS) {
+        inputStream.closeStream();
+    }
+}
+
+// Test case where we use a local socket pair to test the full handleClient
+// workflow from the HttpRequestHandler's point of view.
+unittest {
+    Socket[2] sockets = socketPair();
+    Socket clientSocket = sockets[0];
+    Socket serverSocket = sockets[1];
+    const requestContent =
+        "POST /data HTTP/1.1\r\n" ~
+        "Content-Type: application/json\r\n" ~
+        "Content-Length: 22\r\n" ~
+        "\r\n" ~
+        "{\"x\": 5, \"flag\": true}";
+    clientSocket.send(cast(ubyte[]) requestContent);
+    
+    class TestHandler : HttpRequestHandler {
+        import std.conv;
+
+        void handle(ref ServerHttpRequest request, ref ServerHttpResponse response) {
+            assert(request.headers["Content-Type"] == ["application/json"]);
+            assert("Content-Length" in request.headers && request.headers["Content-Length"].length > 0);
+            ulong contentLength = request.headers["Content-Length"][0].to!ulong;
+            assert(contentLength == 22);
+            ubyte[22] bodyBuffer;
+            auto readResult = request.inputStream.readFromStream(bodyBuffer);
+            assert(readResult.hasCount && readResult.count == 22);
+            assert(cast(string) bodyBuffer == "{\"x\": 5, \"flag\": true}");
+        }
+    }
+    handleClient(serverSocket, new TestHandler());
 }
 
 /**
@@ -143,9 +228,17 @@ alias HttpRequestParseResult = Either!(ServerHttpRequest, "request", StreamError
  */
 HttpRequestParseResult readHttpRequest(S)(S inputStream, in ClientAddress addr) if (isByteInputStream!S) {
     auto methodStr = consumeUntil(inputStream, " ");
-    if (methodStr.hasError) return HttpRequestParseResult(methodStr.error);
+    if (methodStr.hasError) {
+        if (methodStr.error.code == 0) {
+            // Set a custom code to indicate an empty request.
+            return HttpRequestParseResult(StreamError(methodStr.error.message, -1));
+        }
+        return HttpRequestParseResult(methodStr.error);
+    }
+
     auto urlStr = consumeUntil(inputStream, " ");
     if (urlStr.hasError) return HttpRequestParseResult(urlStr.error);
+
     auto versionStr = consumeUntil(inputStream, "\r\n");
     if (versionStr.hasError) return HttpRequestParseResult(versionStr.error);
     
@@ -159,6 +252,8 @@ HttpRequestParseResult readHttpRequest(S)(S inputStream, in ClientAddress addr)
     auto headersResult = parseHeaders(inputStream);
     if (headersResult.hasError) return HttpRequestParseResult(headersResult.error);
 
+    auto queryParams = parseQueryParameters(urlStr.value);
+
     import std.uri : decode; // TODO: Remove dependency on phobos for this?
 
     return HttpRequestParseResult(ServerHttpRequest(
@@ -167,15 +262,57 @@ HttpRequestParseResult readHttpRequest(S)(S inputStream, in ClientAddress addr)
         methodStr.value,
         decode(urlStr.value),
         headersResult.headers,
+        queryParams,
         inputStreamObjectFor(inputStream)
     ));
 }
 
+unittest {
+    import streams;
+
+    auto makeStream(string text) {
+        return arrayInputStreamFor(cast(ubyte[]) text);
+    }
+
+    // Basic HTTP request.
+    ArrayInputStream!ubyte s1 = makeStream(
+        "GET /test?x=5 HTTP/1.1\r\n" ~
+        "Accept: text/plain\r\n" ~
+        "\r\n"
+    );
+    auto r1 = readHttpRequest(&s1, ClientAddress.unknown());
+    assert(r1.hasRequest);
+    assert(r1.request.httpVersion == HttpVersion.V1);
+    assert(r1.request.method == HttpMethod.GET);
+    assert(r1.request.url == "/test?x=5");
+    const r1ExpectedHeaders = ["Accept": ["text/plain"]];
+    assert(r1.request.headers == r1ExpectedHeaders);
+    assert(r1.request.clientAddress == ClientAddress.unknown());
+
+    // POST request with body. Test that the body is read correctly.
+    ArrayInputStream!ubyte s2 = makeStream(
+        "POST /data HTTP/1.1\r\n" ~
+        "Content-Type: text/plain\r\n" ~
+        "Content-Length: 12\r\n" ~
+        "\r\n" ~
+        "Hello world!"
+    );
+    auto r2 = readHttpRequest(&s2, ClientAddress.unknown());
+    assert(r2.hasRequest);
+    assert(r2.request.method == HttpMethod.POST);
+    ubyte[12] r2BodyBuffer;
+    StreamResult r2BodyReadResult = s2.readFromStream(r2BodyBuffer);
+    assert(r2BodyReadResult.count == 12);
+    assert(cast(string) r2BodyBuffer == "Hello world!");
+}
+
 /**
  * Parses HTTP headers from an input stream, and returns them as an associative
  * array mapping header names to their list of values.
  * Params:
- *   inputStream = The byte input stream to read from.
+ *   inputStream = The byte input stream to read from. Note that this stream
+ *                 should be passed as a pointer / reference, values will be
+ *                 consumed from the stream.
  * Returns: Either the headers, or a stream error.
  */
 Either!(string[][string], "headers", StreamError, "error") parseHeaders(S)(S inputStream) if (isByteInputStream!S) {
@@ -202,14 +339,40 @@ Either!(string[][string], "headers", StreamError, "error") parseHeaders(S)(S inp
 }
 
 unittest {
-    class TestHandler : HttpRequestHandler {
-        void handle(ref ServerHttpRequest request, ref ServerHttpResponse response) {
-            response.status = HttpStatus.OK;
-            response.headers.add("Content-Type", "application/json");
-            response.outputStream.writeToStream(cast(ubyte[]) "{\"a\": 1}");
-        }
+    import streams;
+
+    auto makeStream(string text) {
+        return arrayInputStreamFor(cast(ubyte[]) text);
     }
 
-    HttpTransport tp = new Http1Transport(new TestHandler(), 8080);
-    tp.start();
+    // Basic valid headers.
+    auto s1 = makeStream("Content-Type: application/json\r\n\r\n");
+    auto r1 = parseHeaders(&s1);
+    assert(r1.hasHeaders);
+    assert("Content-Type" in r1.headers);
+    assert(r1.headers["Content-Type"] == ["application/json"]);
+
+    // Multiple headers.
+    auto s2 = makeStream("Accept: text, json, image\r\nContent-Length: 1234\r\n\r\n");
+    auto r2 = parseHeaders(&s2);
+    assert(r2.hasHeaders);
+    assert("Accept" in r2.headers);
+    assert(r2.headers["Accept"] == ["text, json, image"]);
+    assert(r2.headers["Content-Length"] == ["1234"]);
+
+    // Basic invalid header string.
+    auto s3 = makeStream("Invalid headers");
+    auto r3 = parseHeaders(&s3);
+    assert(r3.hasError);
+    
+    // No trailing \r\n
+    auto s4 = makeStream("Content-Type: application/json");
+    auto r4 = parseHeaders(&s4);
+    assert(r4.hasError);
+
+    // Empty headers.
+    auto s5 = makeStream("\r\n");
+    auto r5 = parseHeaders(&s5);
+    assert(r5.hasHeaders);
+    assert(r5.headers.length == 0);
 }

source/handy_http_transport/interfaces.d

@@ -4,3 +4,21 @@ interface HttpTransport {
     void start();
     void stop();
 }
+
+import core.thread;
+
+/**
+ * Starts a new thread to run an HTTP transport implementation in, separate
+ * from the calling thread. This is useful for running a server in the
+ * background, like for integration tests.
+ * Params:
+ *   transport = The transport implementation to start.
+ * Returns: The thread that was started.
+ */
+Thread startInNewThread(HttpTransport transport) {
+    Thread t = new Thread(() {
+        transport.start();
+    });
+    t.start();
+    return t;
+}

source/handy_http_transport/package.d

@@ -2,3 +2,6 @@ module handy_http_transport;
 
 public import handy_http_transport.http1;
 public import handy_http_transport.http2;
+
+public import handy_http_transport.interfaces;
+public import handy_http_transport.response_output_stream;

source/handy_http_transport/response_output_stream.d

@@ -50,28 +50,75 @@ struct HttpResponseOutputStream(S) if (isByteOutputStream!S) {
      * Returns: The stream result of writing.
      */
     StreamResult writeHeaders() {
-        // TODO: Come up with a better way of writing headers than string concatenation.
         size_t idx = 0;
         char[6] statusCodeBuffer; // Normal HTTP codes are 3 digits, but this leaves room for extensions.
         writeUIntToBuffer(response.status.code, statusCodeBuffer, idx);
-
-        string statusAndHeaders = "HTTP/1.1 "
-            ~ cast(string) statusCodeBuffer[0..idx]
-            ~ " " ~ response.status.text
-            ~ "\r\n";
+        // Write the status line.
+        StreamResult r = outputStream.writeToStream(cast(ubyte[]) "HTTP/1.1 ");
+        if (r.hasError) return r;
+        size_t writeCount = r.count;
+        r = outputStream.writeToStream(cast(ubyte[]) statusCodeBuffer[0..idx]);
+        if (r.hasError) return r;
+        writeCount += r.count;
+        r = outputStream.writeToStream([' ']);
+        if (r.hasError) return r;
+        writeCount += r.count;
+        r = outputStream.writeToStream(cast(ubyte[]) response.status.text);
+        if (r.hasError) return r;
+        writeCount += r.count;
+        r = outputStream.writeToStream(['\r', '\n']);
+        if (r.hasError) return r;
+        writeCount += r.count;
+        
         foreach (headerName; response.headers.keys) {
-            string headerLine = headerName ~ ": ";
+            // Write the header name.
+            r = outputStream.writeToStream(cast(ubyte[]) headerName);
+            if (r.hasError) return r;
+            writeCount += r.count;
+            r = outputStream.writeToStream([':', ' ']);
+            if (r.hasError) return r;
+            writeCount += r.count;
+            // Write the comma-separated list of values.
             string[] headerValues = response.headers.getAll(headerName);
             for (size_t i = 0; i < headerValues.length; i++) {
-                headerLine ~= headerValues[i];
+                r = outputStream.writeToStream(cast(ubyte[]) headerValues[i]);
+                if (r.hasError) return r;
+                writeCount += r.count;
                 if (i + 1 < headerValues.length) {
-                    headerLine ~= ", ";
+                    r = outputStream.writeToStream([',', ' ']);
+                    if (r.hasError) return r;
+                    writeCount += r.count;
                 }
             }
-            headerLine ~= "\r\n";
-            statusAndHeaders ~= headerLine;
+            r = outputStream.writeToStream(['\r', '\n']);
+            if (r.hasError) return r;
+            writeCount += r.count;
         }
-        statusAndHeaders ~= "\r\n"; // Trailing CLRF before the body.
-        return outputStream.writeToStream(cast(ubyte[]) statusAndHeaders);
+        r = outputStream.writeToStream(['\r', '\n']); // Trailing CLRF before the body.
+        if (r.hasError) return r;
+        writeCount += r.count;
+        return StreamResult(cast(uint) writeCount);
     }
 }
+
+// Test basic functionality for writing a standard response with headers and a
+// body.
+unittest {
+    import handy_http_primitives.response;
+
+    ArrayOutputStream!ubyte os;
+    ServerHttpResponse resp;
+    resp.status = HttpStatus.OK;
+    resp.headers.add("Content-Type", "text/plain");
+    auto httpOut = HttpResponseOutputStream!(ArrayOutputStream!ubyte*)(&os, &resp);
+    resp.outputStream = outputStreamObjectFor(httpOut);
+    StreamResult r = resp.outputStream.writeToStream(cast(ubyte[]) "Hello world!");
+    const expectedOutput =
+        "HTTP/1.1 200 OK\r\n" ~
+        "Content-Type: text/plain\r\n" ~
+        "\r\n" ~
+        "Hello world!";
+    assert(os.toArray() == expectedOutput);
+    assert(r.hasCount);
+    assert(r.count == os.toArray().length);
+}