Really simple probably non-standard websocket server in nodejs using tcp server

ws.js

import net from 'net';
import crypto from 'crypto';
const port = 5000;
const sha1 = function(str) {
    const shasum = crypto.createHash('sha1')
    shasum.update(str)
    return shasum.digest().toString("base64") 
}
const STATUS = {
    WAITING: 0,
    CONNECTED: 1,
}
const readHeaderListIncludes = (value, str) => {
    let elements = value.split(",");
    for(let i = 0; i < elements.length; i++) {
        let element = elements[i];
        if(element[0] == " ") {
            element = element.substring(1)
        }
        if(element[element.length-1] == " ") {
            element = element.substring(0, element.length-1)
        }
        if(element == str) {
            return true;
        }
    }
}
const server = net.createServer((socket) => {
    console.log("Client connected");
    let status = STATUS.WAITING;

    const writeHTTP = (response) => {
        socket.write(response.split("\r\n").join("\n").split("\n").join("\r\n"));
    }

    const endHTTP = (err) => {
        writeHTTP(
`HTTP/1.1 400 Bad Request
Connection: Close
Access-Control-Allow-Origin: *
Cross-Origin-Opener-Policy: same-origin
Cross-Origin-Embedder-Policy: require-corp
Cache-Control: max-age=15
Sec-Websocket-Version: 13
Awawa: ${err ?? "Bad Request"}
`)
        socket.end();
    }

    const sendWS = (op, payload) => {
        let fin = 0b1;
        let rsv1 = 0b0;
        let rsv2 = 0b0;
        let rsv3 = 0b0;
        let first = ((fin << 7) | (rsv1 << 6) | (rsv2 << 5) | (rsv3 << 4) | (op))
        if(payload.length > 125) {
            console.log(`Unimplemented payload length ${payload.length}`);
            return;
        }
        socket.write(
            Buffer.concat(
                [
                    Buffer.from([first, payload.length]),
                    payload
                ]
            )
        );
    }
    const textWS = (text) => {
        sendWS(0x1, Buffer.from(text));
    }

    const upgradeConnection = (data) => {
        const strData = data.toString();
        console.log(`Received: ${strData}`);

        const request = strData.split("\r\n");
        const [method, path, protocol] = request[0].split(" ");
        if(method !== "GET" || path !== "/ws" || protocol !== "HTTP/1.1") return endHTTP("Invalid route or method");
        const headers = {}
        for(let i = 1; i < request.length; i++) {
            let header = request[i].split(": ");
            headers[header[0]] = header[1];
        }
        console.log(headers);
        if(headers["Upgrade"] === undefined || headers["Upgrade"] !== "websocket") {
            return endHTTP("bad upgrade");
        }
        if(headers["Connection"] === undefined || !readHeaderListIncludes(headers["Connection"], "Upgrade")) {
            return endHTTP("bad connection");
        }
        if(headers["Sec-WebSocket-Version"] === undefined || headers["Sec-WebSocket-Version"] !== "13") {
            return endHTTP("bad version");
        }
        if(headers["Sec-WebSocket-Key"] === undefined) {
            return endHTTP("no key");
        }
        const accept = sha1(headers["Sec-WebSocket-Key"]+"258EAFA5-E914-47DA-95CA-C5AB0DC85B11");
        writeHTTP(
`HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: ${accept}\r\n\r\n`);
        status = STATUS.CONNECTED;
    }

    socket.on("data", (data) => {
        if(status === STATUS.WAITING) return upgradeConnection(data);
        let first  = data[0]
        let fin    = first & 0b10000000;
        let rsv1   = first & 0b01000000;
        let rsv2   = first & 0b00100000;
        let rsv3   = first & 0b00010000;
        let opcode = first & 0b00001111;

        let second = data[1];
        let masked = second & 0b10000000;
        let len    = second & 0b01111111;
        if(len > 125) {
            console.log(`Unimplemented client payload length ${len}`)
            return;
        }

        let payload = data.subarray(2);
        if(masked != 0) {
            let mask = data.subarray(2, 6);
            payload = data.subarray(6);
            let decoded = [];
            for(let i = 0; i < payload.length; i++) {
                decoded[i] = payload[i] ^ mask[i % mask.length];
            } 
            payload = decoded;
        } else {
            socket.end();
            return;
        }
        console.log(`FIN: ${fin != 0}, RSV: ${rsv1 != 0},${rsv2 != 0},${rsv3 != 0}, OP: ${opcode}, MASKED: ${masked != 0}, LEN: ${len}, PAYLOAD: `, payload)
        if(opcode == 0x1) {
            const decoded = String.fromCharCode(...payload);
            console.log(`Decoded: ${decoded}`)
            if(decoded == "hi") textWS("Hi bro!");
        }
        

    });

    socket.on("end", () => {
        console.log("Client disconnected");
    });

    socket.on("error", (error) => {
        console.log(`Socket Error: ${error.message}`);
    });
});

server.on("error", (error) => {
    console.log(`Server Error: ${error.message}`);
});

server.listen(port, () => {
    console.log(`TCP socket server is running on port: ${port}`);
});