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。我的一切都适用于RFC6445协议，一切都适用于 chrome 和 FF。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……嗯，至少大部分时间是这样。
大约 20-30% 的时间，握手失败并且 Safari 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起作用？
这是我的握手代码：
注意：没有异常被抛出，并且“握手完成”被写入控制台。但是在尝试读取第一帧时，连接被关闭。（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("\r\n");
sb.append("Upgrade: websocket").append("\r\n");
sb.append("Connection: Upgrade").append("\r\n");
sb.append("Sec-WebSocket-Origin: ").append(origin).append("\r\n");
sb.append("Sec-WebSocket-Location: ").append(location).append("\r\n");
sb.append("\r\n");
// 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：我不是在寻找 WebSockets 的第三方替代品，例如 jWebSocket、Jetty 和 Socket.IO。我已经知道其中的许多。