Question

我尝试实现WebSocket协议并将JavaScript WebSocket与Java WebSocket服务器连接。

JavaScript部分非常直接并且按预期工作。我自己编写了Java服务器，并阅读rfc 6455 page 7以获得正确的握手响应。因此服务器生成正确的响应并发送它。我写了一个Java客户端虚拟来确保它被发送。

但问题是JavaScript /浏览器似乎没有收到握手响应并在几秒后杀死请求（但没有关闭tcp套接字）。

这是握手：

客户端

GET / HTTP/1.1
Host: 127.0.0.1:4455
User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:52.0) Gecko/20100101 Firefox/52.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: de,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate
Sec-WebSocket-Version: 13
Origin: http://localhost
Sec-WebSocket-Extensions: permessage-deflate
Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
Connection: keep-alive, Upgrade
Pragma: no-cache
Cache-Control: no-cache
Upgrade: websocket

服务器

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=
Sec-WebSocket-Protocol: chat

HTML JavaScript

<!DOCTYPE HTML>
<html>
    <head>
        <meta charset="utf-8">
        <title>Socket testing - Client</title>
    </head>
    <body>
        <div id="container"></div>
        <script type="text/javascript">

            var socket = new WebSocket('ws://127.0.0.1:4455');

            socket.addEventListener("error",function(e){
                console.log("an error ocurred: ",e)
            })
            socket.addEventListener("close",function(e){
                console.log("the connection was closed: ",e)
            })
            socket.addEventListener("open",function(e){
                console.log("the connection was opened: ",e)
            })
            socket.addEventListener("message",function(e){
                console.log("recieved a message: ",e)
            })

        </script>
    </body>
</html>

Java（摘录）

public class SocketHandlerWebSocketLevel extends SocketHandler {

    private HashMap<String, String> connectionHeaders;
    private InputStreamReader stringReader;
    private OutputStreamWriter stringWriter;

    public SocketHandlerWebSocketLevel(Socket socket) {
        super(socket);
        connectionHeaders = new HashMap<String, String>();

        try {
            stringReader = new InputStreamReader(s.getInputStream());
        } catch (IOException e) {
            e.printStackTrace();
            close();
            print("could not get the input stream");
            return;
        }

        try {
            stringWriter = new OutputStreamWriter(s.getOutputStream());
        } catch (IOException e) {
            e.printStackTrace();
            close();
            print("could not get the output stream");
            return;
        }
    }

    @Override
    public void run() {

        print("Started handler");
        char b;
        String buffer = "";
        try {
            mainLoop: while (true) {
                while (stringReader.ready() || buffer.length() == 0) {
                    if ((b = (char) stringReader.read()) != -1) {
                        buffer += b;
                    } else {
                        break mainLoop;
                    }

                }
                gotMessage(buffer);
                buffer = "";
            }
        } catch (IOException e) {
            close();
            print("connection was killed remotly, could not read the next byte");
            return;
        }

        close();
        print("connection was closed remotely, stopped Handler, closed socked");
    }

    private void gotMessage(String message) {
        if (connectionHeaders.size() == 0) {
            connectionHeaders = parseHttpHeader(message);
            handshakeResponse();
        } else {
            print(message);
        }
    }

    private void handshakeResponse() {
        /* 
           taken from: https://tools.ietf.org/html/rfc6455#page-7
           For this header field, the server has to take the value (as present
           in the header field, e.g., the base64-encoded [RFC4648] version minus
           any leading and trailing whitespace) and concatenate this with the
           Globally Unique Identifier (GUID, [RFC4122]) "258EAFA5-E914-47DA-
           95CA-C5AB0DC85B11" in string form, which is unlikely to be used by
           network endpoints that do not understand the WebSocket Protocol.  A
           SHA-1 hash (160 bits) [FIPS.180-3], base64-encoded (see Section 4 of
           [RFC4648]), of this concatenation is then returned in the server's
           handshake.

           Concretely, if as in the example above, the |Sec-WebSocket-Key|
           header field had the value "dGhlIHNhbXBsZSBub25jZQ==", the server
           would concatenate the string "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
           to form the string "dGhlIHNhbXBsZSBub25jZQ==258EAFA5-E914-47DA-95CA-
           C5AB0DC85B11".  The server would then take the SHA-1 hash of this,
           giving the value 0xb3 0x7a 0x4f 0x2c 0xc0 0x62 0x4f 0x16 0x90 0xf6
           0x46 0x06 0xcf 0x38 0x59 0x45 0xb2 0xbe 0xc4 0xea.  This value is
           then base64-encoded (see Section 4 of [RFC4648]), to give the value
           "s3pPLMBiTxaQ9kYGzzhZRbK+xOo=".  This value would then be echoed in
           the |Sec-WebSocket-Accept| header field.
        */

        String secWebSocketKey, secWebSocketAccept, GUID, template, merged, toSend;
        secWebSocketKey = connectionHeaders.get("Sec-WebSocket-Key");
        GUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
        template = "HTTP/1.1 101 Switching Protocols\nUpgrade: websocket\nConnection: Upgrade\nSec-WebSocket-Accept: %s\nSec-WebSocket-Protocol: chat\n";

        // combine secWebSocketKey and the GUID
        merged = secWebSocketKey + GUID;
        print("merged: " + merged);

        // convert to byte[]
        byte[] asBytes = merged.getBytes();
        print("asBytes: " + Arrays.toString(asBytes));

        // SHA-1 hash
        byte[] sha1 = SHA1Hash(asBytes);
        print("sha1: " + Arrays.toString(sha1));

        // base64 encode
        byte[] base64 = base64Encode(sha1);
        print("base64: " + Arrays.toString(base64));

        // reconvert to string to put it into the template
        secWebSocketAccept = new String(base64);

        toSend = String.format(template, secWebSocketAccept);
        print(toSend);

        try {
            stringWriter.write(toSend, 0, toSend.length());
            stringWriter.flush();
        } catch (IOException e) {
            print("hanshake sending failed!");
        }

    }

    private HashMap<String, String> parseHttpHeader(String h) {
        HashMap<String, String> fields = new HashMap<String, String>();

        String[] rows = h.split("\n");
        if (rows.length > 1) {
            fields.put("Prototcol", rows[0]);
            Pattern pattern = Pattern.compile("^([^:]+): (.+)$");
            for (int i = 1; i < rows.length; i++) {
                Matcher matcher = pattern.matcher(rows[i]);
                while (matcher.find()) {
                    if (matcher.groupCount() == 2) {
                        fields.put(matcher.group(1), matcher.group(2));
                    }
                }
            }
        }
        return fields;
    }

    private byte[] SHA1Hash(byte[] bytes) {
        MessageDigest md;

        try {
            md = MessageDigest.getInstance("SHA-1");
        } catch (NoSuchAlgorithmException e) {
            return null;
        }

        md.update(bytes);
        return md.digest();
    }

    private byte[] base64Encode(byte[] bytes) {
        byte[] encodedBytes = Base64.getEncoder().encode(bytes);
        return encodedBytes;
    }

哪里可能是我的错误？可能缺少什么，也许是“消息结束”符号？

请注意，我不想使用框架。

Answer 1

解决方案很简单。我刚刚使用Wireshark来调试这一切：我只是忘了回车了。

Java类中的正确字符串是：

template = "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: %s\r\nSec-WebSocket-Protocol: chat\r\n\r\n";

在此修改之前，浏览器无法将其解释为TCP包中的HTTP数据。

JS WebSocket和Java之间的握手

1 个答案: