8278353: Provide Duke as default favicon in Simple Web Server

Reviewed-by: dfuchs

make/modules/jdk.httpserver/Java.gmk

@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2020, 2024, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # This code is free software; you can redistribute it and/or modify it
@@ -24,3 +24,5 @@
 #
 
 DISABLED_WARNINGS_java += missing-explicit-ctor this-escape
+
+COPY += .ico

src/jdk.httpserver/share/classes/sun/net/httpserver/simpleserver/FileServerHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -57,6 +57,9 @@ public final class FileServerHandler implements HttpHandler {
     private static final List<String> SUPPORTED_METHODS = List.of("HEAD", "GET");
     private static final List<String> UNSUPPORTED_METHODS =
             List.of("CONNECT", "DELETE", "OPTIONS", "PATCH", "POST", "PUT", "TRACE");
+    private static final String FAVICON_RESOURCE_PATH =
+            "/sun/net/httpserver/simpleserver/resources/favicon.ico";
+    private static final String FAVICON_LAST_MODIFIED = "Mon, 23 May 1995 11:11:11 GMT";
 
     private final Path root;
     private final UnaryOperator<String> mimeTable;
@@ -250,6 +253,31 @@ private static Path indexFile(Path path) {
         return Files.exists(html) ? html : Files.exists(htm) ? htm : null;
     }
 
+    private static boolean isFavIconRequest(HttpExchange exchange) {
+        return "/favicon.ico".equals(exchange.getRequestURI().getPath());
+    }
+
+    private void serveDefaultFavIcon(HttpExchange exchange, boolean writeBody)
+            throws IOException
+    {
+        var respHdrs = exchange.getResponseHeaders();
+        try (var stream = getClass().getModule().getResourceAsStream(FAVICON_RESOURCE_PATH)) {
+            var bytes = stream.readAllBytes();
+            respHdrs.set("Content-Type", "image/x-icon");
+            respHdrs.set("Last-Modified", FAVICON_LAST_MODIFIED);
+            if (writeBody) {
+                exchange.sendResponseHeaders(200, bytes.length);
+                try (OutputStream os = exchange.getResponseBody()) {
+                    os.write(bytes);
+                }
+            } else {
+                respHdrs.set("Content-Length", Integer.toString(bytes.length));
+                exchange.sendResponseHeaders(200, -1);
+            }
+        }
+    }
+
+
     private void serveFile(HttpExchange exchange, Path path, boolean writeBody)
         throws IOException
     {
@@ -371,17 +399,26 @@ public void handle(HttpExchange exchange) throws IOException {
         assert List.of("GET", "HEAD").contains(exchange.getRequestMethod());
         try (exchange) {
             discardRequestBody(exchange);
+            boolean isHeadRequest = exchange.getRequestMethod().equals("HEAD");
             Path path = mapToPath(exchange, root);
             if (path != null) {
                 exchange.setAttribute("request-path", path.toString());  // store for OutputFilter
                 if (!Files.exists(path) || !Files.isReadable(path) || isHiddenOrSymLink(path)) {
                     handleNotFound(exchange);
-                } else if (exchange.getRequestMethod().equals("HEAD")) {
+                } else if (isHeadRequest) {
                     handleHEAD(exchange, path);
                 } else {
                     handleGET(exchange, path);
                 }
             } else {
+                if (isFavIconRequest(exchange)) {
+                    try {
+                        serveDefaultFavIcon(exchange, !isHeadRequest);
+                        return;
+                    } catch (IOException ignore) {
+                        // fall through to send the not-found response
+                    }
+                }
                 exchange.setAttribute("request-path", "could not resolve request URI path");
                 handleNotFound(exchange);
             }

test/jdk/com/sun/net/httpserver/simpleserver/SimpleFileServerTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -76,6 +76,8 @@ public class SimpleFileServerTest {
     static final boolean ENABLE_LOGGING = true;
     static final Logger LOGGER = Logger.getLogger("com.sun.net.httpserver");
 
+    static final String EXPECTED_LAST_MODIFIED_OF_FAVICON = "Mon, 23 May 1995 11:11:11 GMT";
+
     @BeforeTest
     public void setup() throws IOException {
         if (ENABLE_LOGGING) {
@@ -142,6 +144,65 @@ public void testDirectoryGET() throws Exception {
         }
     }
 
+    @Test
+    public void testFavIconGET() throws Exception {
+        var root = Files.createDirectory(TEST_DIR.resolve("testFavIconGET"));
+
+        var server = SimpleFileServer.createFileServer(LOOPBACK_ADDR, root, OutputLevel.VERBOSE);
+        server.start();
+        try {
+            // expect built-in icon
+            var client = HttpClient.newBuilder().proxy(NO_PROXY).build();
+            var request = HttpRequest.newBuilder(uri(server, "favicon.ico")).build();
+            var response = client.send(request, BodyHandlers.ofString());
+            assertEquals(response.statusCode(), 200);
+            assertEquals(response.headers().firstValue("content-type").get(), "image/x-icon");
+            assertEquals(response.headers().firstValue("last-modified").get(), EXPECTED_LAST_MODIFIED_OF_FAVICON);
+
+            // expect custom (and broken) icon
+            var file = Files.writeString(root.resolve("favicon.ico"), "broken icon", CREATE);
+            try {
+                var lastModified = getLastModified(file);
+                var expectedLength = Long.toString(Files.size(file));
+                response = client.send(request, BodyHandlers.ofString());
+                assertEquals(response.statusCode(), 200);
+                assertEquals(response.headers().firstValue("content-type").get(), "application/octet-stream");
+                assertEquals(response.headers().firstValue("content-length").get(), expectedLength);
+                assertEquals(response.headers().firstValue("last-modified").get(), lastModified);
+            } finally {
+                Files.delete(file);
+            }
+
+            // expect built-in icon
+            response = client.send(request, BodyHandlers.ofString());
+            assertEquals(response.statusCode(), 200);
+            assertEquals(response.headers().firstValue("content-type").get(), "image/x-icon");
+            assertEquals(response.headers().firstValue("last-modified").get(), EXPECTED_LAST_MODIFIED_OF_FAVICON);
+        } finally {
+            server.stop(0);
+        }
+    }
+
+    @Test
+    public void testFavIconHEAD() throws Exception {
+        var root = Files.createDirectory(TEST_DIR.resolve("testFavIconHEAD"));
+
+        var server = SimpleFileServer.createFileServer(LOOPBACK_ADDR, root, OutputLevel.VERBOSE);
+        server.start();
+        try {
+            var client = HttpClient.newBuilder().proxy(NO_PROXY).build();
+            var request = HttpRequest.newBuilder(uri(server, "favicon.ico"))
+                    .method("HEAD", BodyPublishers.noBody()).build();
+            var response = client.send(request, BodyHandlers.ofString());
+            assertEquals(response.statusCode(), 200);
+            assertEquals(response.headers().firstValue("content-type").get(), "image/x-icon");
+            assertEquals(response.headers().firstValue("last-modified").get(), EXPECTED_LAST_MODIFIED_OF_FAVICON);
+            assertEquals(response.body(), "");
+        } finally {
+            server.stop(0);
+        }
+    }
+
     @Test
     public void testFileHEAD() throws Exception {
         var root = Files.createDirectory(TEST_DIR.resolve("testFileHEAD"));