websockets: final polish before release. Tested on IE, Chrome and Firefox

1 files changed, 121 insertions, 0 deletions

diff --git a/websocket/src/main/java/fi/iki/elonen/NanoWebSocketServer.java b/websocket/src/main/java/fi/iki/elonen/NanoWebSocketServer.java
new file mode 100644
index 0000000..7a5e588
--- /dev/null
+++ b/websocket/src/main/java/fi/iki/elonen/NanoWebSocketServer.java
@@ -0,0 +1,121 @@
+package fi.iki.elonen;
+
+import fi.iki.elonen.NanoHTTPD;
+
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Map;
+
+public abstract class NanoWebSocketServer extends NanoHTTPD {
+    public static final String HEADER_UPGRADE = "upgrade";
+    public static final String HEADER_UPGRADE_VALUE = "websocket";
+    public static final String HEADER_CONNECTION = "connection";
+    public static final String HEADER_CONNECTION_VALUE = "Upgrade";
+    public static final String HEADER_WEBSOCKET_VERSION = "sec-websocket-version";
+    public static final String HEADER_WEBSOCKET_VERSION_VALUE = "13";
+    public static final String HEADER_WEBSOCKET_KEY = "sec-websocket-key";
+    public static final String HEADER_WEBSOCKET_ACCEPT = "sec-websocket-accept";
+    public static final String HEADER_WEBSOCKET_PROTOCOL = "sec-websocket-protocol";
+
+    public final static String WEBSOCKET_KEY_MAGIC = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
+
+    public NanoWebSocketServer(int port) {
+        super(port);
+    }
+
+    public NanoWebSocketServer(String hostname, int port) {
+        super(hostname, port);
+    }
+
+    @Override
+    public Response serve(final IHTTPSession session) {
+        Map<String, String> headers = session.getHeaders();
+        if (isWebsocketRequested(session)) {
+            if (!HEADER_UPGRADE_VALUE.equalsIgnoreCase(headers.get(HEADER_UPGRADE))
+                    || !isWebSocketConnectionHeader(session.getHeaders())) {
+                return new Response(Response.Status.BAD_REQUEST, NanoHTTPD.MIME_PLAINTEXT, "Invalid Websocket handshake");
+            }
+            if (!HEADER_WEBSOCKET_VERSION_VALUE.equalsIgnoreCase(headers.get(HEADER_WEBSOCKET_VERSION))) {
+                return new Response(Response.Status.BAD_REQUEST, NanoHTTPD.MIME_PLAINTEXT, "Invalid Websocket-Version " + headers.get(HEADER_WEBSOCKET_VERSION));
+            }
+            if (!headers.containsKey(HEADER_WEBSOCKET_KEY)) {
+                return new Response(Response.Status.BAD_REQUEST, NanoHTTPD.MIME_PLAINTEXT, "Missing Websocket-Key");
+            }
+
+            WebSocket webSocket = openWebSocket(session);
+            try {
+                webSocket.getHandshakeResponse().addHeader(HEADER_WEBSOCKET_ACCEPT, makeAcceptKey(headers.get(HEADER_WEBSOCKET_KEY)));
+            } catch (NoSuchAlgorithmException e) {
+                return new Response(Response.Status.INTERNAL_ERROR, NanoHTTPD.MIME_PLAINTEXT, "The SHA-1 Algorithm required for websockets is not available on the server.");
+            }
+            if (headers.containsKey(HEADER_WEBSOCKET_PROTOCOL)) {
+                webSocket.getHandshakeResponse().addHeader(HEADER_WEBSOCKET_PROTOCOL, headers.get(HEADER_WEBSOCKET_PROTOCOL).split(",")[0]);
+            }
+            return webSocket.getHandshakeResponse();
+        } else {
+            return super.serve(session);
+        }
+    }
+
+    protected abstract WebSocket openWebSocket(IHTTPSession handshake);
+
+    protected boolean isWebsocketRequested(IHTTPSession session) {
+        Map<String, String> headers = session.getHeaders();
+        String upgrade = headers.get(HEADER_UPGRADE);
+        boolean isCorrectConnection = isWebSocketConnectionHeader(headers);
+        boolean isUpgrade = HEADER_UPGRADE_VALUE.equalsIgnoreCase(upgrade);
+        return (isUpgrade && isCorrectConnection);
+    }
+
+    private boolean isWebSocketConnectionHeader(Map<String, String> headers) {
+        String connection = headers.get(HEADER_CONNECTION);
+        return (connection != null && connection.toLowerCase().contains(HEADER_CONNECTION_VALUE.toLowerCase()));
+    }
+
+    public static String makeAcceptKey(String key) throws NoSuchAlgorithmException {
+        MessageDigest md = MessageDigest.getInstance("SHA-1");
+        String text = key + WEBSOCKET_KEY_MAGIC;
+        md.update(text.getBytes(), 0, text.length());
+        byte[] sha1hash = md.digest();
+        return encodeBase64(sha1hash);
+    }
+
+
+    private final static char[] ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
+
+    /**
+     * Translates the specified byte array into Base64 string.
+     * <p>
+     * Android has android.util.Base64, sun has sun.misc.Base64Encoder, Java 8 hast java.util.Base64,
+     * I have this from stackoverflow: http://stackoverflow.com/a/4265472
+     * </p>
+     *
+     * @param buf the byte array (not null)
+     * @return the translated Base64 string (not null)
+     */
+    private static String encodeBase64(byte[] buf) {
+        int size = buf.length;
+        char[] ar = new char[((size + 2) / 3) * 4];
+        int a = 0;
+        int i = 0;
+        while (i < size) {
+            byte b0 = buf[i++];
+            byte b1 = (i < size) ? buf[i++] : 0;
+            byte b2 = (i < size) ? buf[i++] : 0;
+
+            int mask = 0x3F;
+            ar[a++] = ALPHABET[(b0 >> 2) & mask];
+            ar[a++] = ALPHABET[((b0 << 4) | ((b1 & 0xFF) >> 4)) & mask];
+            ar[a++] = ALPHABET[((b1 << 2) | ((b2 & 0xFF) >> 6)) & mask];
+            ar[a++] = ALPHABET[b2 & mask];
+        }
+        switch (size % 3) {
+            case 1:
+                ar[--a] = '=';
+            case 2:
+                ar[--a] = '=';
+        }
+        return new String(ar);
+    }
+}
+