Safari 5 / iOS，WebSocket握手仅在有时起作用

Question

我在java中创建了一个类，它允许我用WebSocket协议包装现有的套接字。我为RFC6445协议工作，一切都在 chrome 和 FF 中工作。然而，Safari和iOS使用的是hixie76/HyBi00协议（根据维基百科）。

我一切正常，Safari 和 iOS 正确握手并开始发送/接收消息......好吧，至少大多数时候是这样。

大约 20-30% 的时间，握手失败，Safari 会关闭连接。（Java 在尝试读取第一帧时读取 -1 字节）。Safari 不会在控制台中报告任何错误，而只是调用 onclose 事件处理程序。

为什么握手只在部分时间内起作用？

这是我的握手代码：

注意：不会引发异常，并且"握手完成"将写入控制台。但是，在尝试读取第一帧时，连接将关闭。（Java 在 inst.read（）上返回 -1）

// Headers are read in a previous method which wraps the socket using RFC6445
// protocol. If it detects 2 keys it will call this and pass in the headers.
public static MessagingWebSocket wrapOldProtocol(HashMap<String, String> headers, PushbackInputStream pin, Socket sock) throws IOException, NoSuchAlgorithmException {
    // SPEC
    // https://datatracker.ietf.org/doc/html/draft-hixie-thewebsocketprotocol-76#page-32
    
    // Read the "key3" value. This is 8 random bytes after the headers.
    byte[] key3 = new byte[8];
    for ( int i=0; i<key3.length; i++ ) {
        key3[i] = (byte)pin.read();
    }
    
    // Grab the two keys we need to use for the handshake
    String key1 = headers.get("Sec-WebSocket-Key1");
    String key2 = headers.get("Sec-WebSocket-Key2");
    
    // Count the spaces in both keys
    // Abort the connection is either key has 0 spaces
    int spaces1 = StringUtils.countMatches(key1, " ");
    int spaces2 = StringUtils.countMatches(key2, " ");
    if ( spaces1 == 0 || spaces2 == 0 ) {
        throw new IOException("Bad Handshake Request, Possible Cross-protocol attack");
    }
    
    // Strip all non-digit characters from each key
    // Use the remaining value as a base-10 integer.
    // Abort if either number is not a multiple of it's #spaces counterpart
    // Need to use long because the values are unsigned
    long num1 = Long.parseLong( key1.replaceAll("\D", "") );
    long num2 = Long.parseLong( key2.replaceAll("\D", "") );
    if ( !(num1 % spaces1 == 0) || !(num2 % spaces2 == 0) ) {
        throw new IOException("Bad Handshake Request. Possible non-conforming client");
    }
    // Part1/2 is key num divided by the # of spaces
    int part1 = (int)(num1 / spaces1);
    int part2 = (int)(num2 / spaces2);
    
    // Now calculate the challenge response
    // MD5( num1 + num2 + key3 )  ... concat, not add
    MessageDigest md = MessageDigest.getInstance("MD5");
    md.update(ByteBuffer.allocate(4).putInt(part1));
    md.update(ByteBuffer.allocate(4).putInt(part2));
    md.update(key3);
    byte[] response = md.digest();
    
    // Now build the server handshake response
    // Ignore Sec-WebSocket-Protocol (we don't use this)
    String origin = headers.get("Origin");
    String location = "ws://" + headers.get("Host") + "/";
    
    StringBuilder sb = new StringBuilder();
    sb.append("HTTP/1.1 101 WebSocket Protocol Handshake").append("rn");
    sb.append("Upgrade: websocket").append("rn");
    sb.append("Connection: Upgrade").append("rn");
    sb.append("Sec-WebSocket-Origin: ").append(origin).append("rn");
    sb.append("Sec-WebSocket-Location: ").append(location).append("rn");
    sb.append("rn");
    
    // Anything left in the buffer?
    if ( pin.available() > 0 ) {
        throw new IOException("Unexpected bytes after handshake!");
    }
    
    // Send the handshake & challenge response
    OutputStream out = sock.getOutputStream();
    out.write(sb.toString().getBytes());
    out.write(response);
    out.flush();
    
    System.out.println("[MessagingWebSocket] Handshake Complete.");
    
    // Return the wrapper socket class.
    MessagingWebSocket ws = new MessagingWebSocket(sock);
    ws.oldProtocol = true;
    return ws;
}

谢谢！

注意：我不是在为WebSockets寻找第三方替代品，例如jWebSocket，Jetty和 Socket.IO。我已经知道其中的许多。

Answer 1

您的 MD5 摘要方法有一个错误：协议描述如下： https://datatracker.ietf.org/doc/html/draft-hixie-thewebsocketprotocol-76#section-5.2

byte[] bytes = new byte[16];    
BytesUtil.fillBytesWithArray(bytes, 0, 3, BytesUtil.intTobyteArray(part1));
BytesUtil.fillBytesWithArray(bytes, 4, 7, BytesUtil.intTobyteArray(part2));
BytesUtil.fillBytesWithArray(bytes, 8, 15, key3);

我认为你的问题是小端和大端引起的。