如何在 Socket.Stream 中向客户端发送消息？

Question

在 C# 中有一个应用程序，我需要附加一个具有最短响应时间的 Web 界面（显示几个计时器），所以我想通过套接字连接 mozilla has a great example just for me. It already shows the connection, handshake and reading a message from the client. Bonus, the JS side is shown. It just doesn't show how to compose a response to the client. The following page 显示消息的字节数是从，但我还是不能把它弄好。每当您尝试向客户端发送内容时，连接都会立即终止，即使您发送的是相同的字节数组。请帮我实现发送消息的功能，我自己不会((

Answer 1

我找到了方法。如果有人需要它，我会把我的代码留在这里。它与 mozila 相同，但我添加了 SendEcho 函数

C# 上的代码服务器

 using System;
 using System.Collections.Generic;
 using System.Net;
 using System.Net.Sockets;
 using System.Text;
 using System.Text.RegularExpressions;

 namespace TestSocket
 {
class Program
{
   
    public static void Main()
    {

        string ip = "127.0.0.1";
        int port = 80;
        var server = new TcpListener(IPAddress.Parse(ip), port);

        string swkaSha1Base64 = "";
        byte[] response = new byte[1];
        server.Start();
        Console.WriteLine("Server has started on {0}:{1}, Waiting for a connection...", ip, port);


        TcpClient client = server.AcceptTcpClient();
        Console.WriteLine("A client connected.");

        NetworkStream stream = client.GetStream();

        // enter to an infinite cycle to be able to handle every change in stream
        while (true)
        {
            while (!stream.DataAvailable) ;
            while (client.Available < 3) ; // match against "get"

            byte[] bytes = new byte[client.Available];
            stream.Read(bytes, 0, client.Available);
            string s = Encoding.UTF8.GetString(bytes);

            if (Regex.IsMatch(s, "^GET", RegexOptions.IgnoreCase))
            {
                Console.WriteLine("=====Handshaking from client=====\n{0}", s);

                // 1. Obtain the value of the "Sec-WebSocket-Key" request header without any leading or trailing whitespace
                // 2. Concatenate it with "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" (a special GUID specified by RFC 6455)
                // 3. Compute SHA-1 and Base64 hash of the new value
                // 4. Write the hash back as the value of "Sec-WebSocket-Accept" response header in an HTTP response
                string swk = Regex.Match(s, "Sec-WebSocket-Key: (.*)").Groups[1].Value.Trim();
                string swka = swk + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
                byte[] swkaSha1 = System.Security.Cryptography.SHA1.Create().ComputeHash(Encoding.UTF8.GetBytes(swka));
                swkaSha1Base64 = Convert.ToBase64String(swkaSha1);

                // HTTP/1.1 defines the sequence CR LF as the end-of-line marker
                response = Encoding.UTF8.GetBytes(
                    "HTTP/1.1 101 Switching Protocols\r\n" +
                    "Connection: Upgrade\r\n" +
                    "Upgrade: websocket\r\n" +
                    "Sec-WebSocket-Accept: " + swkaSha1Base64 + "\r\n\r\n");

                string x = Encoding.UTF8.GetString(response);
                Console.WriteLine(x);

                stream.Write(response, 0, response.Length);
            }
            else
            {
                bool fin = (bytes[0] & 0b10000000) != 0,
                    mask = (bytes[1] & 0b10000000) != 0; // must be true, "All messages from the client to the server have this bit set"

                if (bytes[0] == 0x88)
                {
                    Console.WriteLine("соединение закрыто");
                }

                int opcode = bytes[0] & 0b00001111, // expecting 1 - text message
                    msglen = bytes[1] - 128, // & 0111 1111
                    offset = 2;

                if (msglen == 126)
                {
                    // was ToUInt16(bytes, offset) but the result is incorrect
                    msglen = BitConverter.ToUInt16(new byte[] { bytes[3], bytes[2] }, 0);
                    offset = 4;
                }
                else if (msglen == 127)
                {
                    Console.WriteLine("TODO: msglen == 127, needs qword to store msglen");
                    // i don't really know the byte order, please edit this
                    // msglen = BitConverter.ToUInt64(new byte[] { bytes[5], bytes[4], bytes[3], bytes[2], bytes[9], bytes[8], bytes[7], bytes[6] }, 0);
                    // offset = 10;
                }

                if (msglen == 0)
                    Console.WriteLine("msglen == 0");
                else if (mask)
                {
                    byte[] decoded = new byte[msglen];
                    byte[] masks = new byte[4] { bytes[offset], bytes[offset + 1], bytes[offset + 2], bytes[offset + 3] };
                    offset += 4;


                    for (int i = 0; i < msglen; ++i)
                        decoded[i] = (byte)(bytes[offset + i] ^ masks[i % 4]);

                    string text = Encoding.UTF8.GetString(decoded);
                    

                    SendEcho(stream, text); //my update
                    
                    Console.WriteLine("{0}", text);
                }
                else
                    Console.WriteLine("mask bit not set");

                Console.WriteLine();
            }
        }
    }
    private static void SendEcho(NetworkStream stream, string inputText)
    {
        
        byte[] sendBytes = Encoding.UTF8.GetBytes(inputText);
        byte lengthHeader = 0;
        byte[] lengthCount = new byte[] { };

        if (sendBytes.Length <= 125)
            lengthHeader = (byte)sendBytes.Length;

        if (125 < sendBytes.Length && sendBytes.Length < 65535) //System.UInt16
        {
            lengthHeader = 126;

               lengthCount = new byte[] {
                (byte)(sendBytes.Length >> 8),
                (byte)(sendBytes.Length)
            };
        }

        if (sendBytes.Length > 65535)//max 2_147_483_647 but .Length -> System.Int32
        { lengthHeader = 127;
            lengthCount = new byte[] {
                (byte)(sendBytes.Length >> 56),
                (byte)(sendBytes.Length >> 48),
                (byte)(sendBytes.Length >> 40),
                (byte)(sendBytes.Length >> 32),
                (byte)(sendBytes.Length >> 24),
                (byte)(sendBytes.Length >> 16),
                (byte)(sendBytes.Length >> 8),
                (byte)sendBytes.Length,
            };
        }
       
        List<byte> responseArray = new List<byte>() { 0b10000001 };

        responseArray.Add(lengthHeader);
        responseArray.AddRange(lengthCount);
        responseArray.AddRange(sendBytes);

        stream.Write(responseArray.ToArray(), 0, responseArray.Count);
    }

}
}

HTML 和浏览器上的JS代码（我用chrome 98）

<!doctype html>
<style>
textarea { vertical-align: bottom; }
#output { overflow: auto; }
#output > p { overflow-wrap: break-word; }
#output span { color: blue; }
#output span.error { color: red; }
</style>
<h2>WebSocket Test</h2>
<textarea cols=60 rows=6></textarea>
<button>send</button>
<div id=output></div>
<script>
// http://www.websocket.org/echo.html

var button = document.querySelector("button"),
    output = document.querySelector("#output"),
    textarea = document.querySelector("textarea"),
    // wsUri = "ws://echo.websocket.org/",
    wsUri = "ws://127.0.0.1/",
    websocket = new WebSocket(wsUri);

button.addEventListener("click", onClickButton);

websocket.onopen = function (e) {
    writeToScreen("CONNECTED");
    doSend("WebSocket rocks");
};

websocket.onclose = function (e) {
    writeToScreen("DISCONNECTED");
};

websocket.onmessage = function (e) {
    writeToScreen("<span>RESPONSE: " + e.data + "</span>");
};

websocket.onerror = function (e) {
    writeToScreen("<span class=error>ERROR:</span> " + e.data);
};

function doSend(message) {
    writeToScreen("SENT: " + message);
    websocket.send(message);
}

function writeToScreen(message) {
    output.insertAdjacentHTML("afterbegin", "<p>" + message + "</p>");
}

function onClickButton() {
    var text = textarea.value;

    text && doSend(text);
    textarea.value = "";
    textarea.focus();
}
</script>

如何在 Socket.Stream 中向客户端发送消息？

How to send message to client in Socket.Stream?

c#

websocket