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package fi.iki.elonen;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Map;
import fi.iki.elonen.NanoHTTPD.IHTTPSession;
import fi.iki.elonen.NanoHTTPD.Response;
public class WebSocketResponseHandler {
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";
private final IWebSocketFactory webSocketFactory;
public WebSocketResponseHandler(IWebSocketFactory webSocketFactory) {
this.webSocketFactory = webSocketFactory;
}
public Response serve(final IHTTPSession session) {
Map<String, String> headers = session.getHeaders();
if (isWebsocketRequested(session)) {
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 = webSocketFactory.openWebSocket(session);
Response handshakeResponse = webSocket.getHandshakeResponse();
try {
handshakeResponse.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)) {
handshakeResponse.addHeader(HEADER_WEBSOCKET_PROTOCOL, headers.get(HEADER_WEBSOCKET_PROTOCOL).split(",")[0]);
}
return handshakeResponse;
} else {
return null;
}
}
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);
}
}
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