ms/packages/websocket/src/engine.io-client/transports/websocket.ts

import { Transport } from "../transport"
import { encode } from "../contrib/parseqs"
import { yeast } from "../contrib/yeast"
import { pick } from "../util"
import {
    defaultBinaryType,
    nextTick,
    usingBrowserWebSocket,
    WebSocket
} from "./websocket-constructor"
// import debugModule from "debug" // debug()
import { encodePacket } from "../../engine.io-parser"

// const debug = debugModule("engine.io-client:websocket") // debug()
const debug = (...args: any) => console.debug('engine.io-client:websocket', ...args)

// detect ReactNative environment
const isReactNative =
    typeof navigator !== "undefined" &&
    typeof navigator.product === "string" &&
    navigator.product.toLowerCase() === "reactnative"

export class WS extends Transport {
    private ws: any

    /**
     * WebSocket transport constructor.
     *
     * @param {Object} opts - connection options
     * @protected
     */
    constructor(opts) {
        super(opts)

        this.supportsBinary = !opts.forceBase64
    }

    override get name() {
        return "websocket"
    }

    override doOpen() {
        if (!this.check()) {
            // let probe timeout
            return
        }

        const uri = this.uri()
        const protocols = this.opts.protocols

        // React Native only supports the 'headers' option, and will print a warning if anything else is passed
        const opts = isReactNative
            ? {}
            : pick(
                this.opts,
                "agent",
                "perMessageDeflate",
                "pfx",
                "key",
                "passphrase",
                "cert",
                "ca",
                "ciphers",
                "rejectUnauthorized",
                "localAddress",
                "protocolVersion",
                "origin",
                "maxPayload",
                "family",
                "checkServerIdentity"
            )

        if (this.opts.extraHeaders) {
            opts.headers = this.opts.extraHeaders
        }

        try {
            this.ws =
                usingBrowserWebSocket && !isReactNative
                    ? protocols
                        ? new WebSocket(uri, protocols)
                        : new WebSocket(uri)
                    : new WebSocket(uri, protocols, opts)
        } catch (err: any) {
            return this.emitReserved("error", err)
        }

        this.ws.binaryType = this.socket.binaryType || defaultBinaryType

        this.addEventListeners()
    }

    /**
     * Adds event listeners to the socket
     *
     * @private
     */
    private addEventListeners() {
        this.ws.onopen = () => {
            if (this.opts.autoUnref) {
                this.ws._socket.unref()
            }
            this.onOpen()
        }
        this.ws.onclose = (closeEvent) =>
            this.onClose({
                description: "websocket connection closed",
                context: closeEvent,
            })
        this.ws.onmessage = (ev) => this.onData(ev.data)
        this.ws.onerror = (e) => this.onError("websocket error", e)
    }

    override write(packets) {
        this.writable = false

        // encodePacket efficient as it uses WS framing
        // no need for encodePayload
        for (let i = 0; i < packets.length; i++) {
            const packet = packets[i]
            const lastPacket = i === packets.length - 1

            encodePacket(packet, this.supportsBinary, (data) => {
                // always create a new object (GH-437)
                const opts: { compress?: boolean } = {}
                if (!usingBrowserWebSocket) {
                    if (packet.options) {
                        opts.compress = packet.options.compress
                    }

                    if (this.opts.perMessageDeflate) {
                        const len =
                            // @ts-ignore
                            "string" === typeof data ? Buffer.byteLength(data) : data.length
                        if (len < this.opts.perMessageDeflate.threshold) {
                            opts.compress = false
                        }
                    }
                }

                // Sometimes the websocket has already been closed but the browser didn't
                // have a chance of informing us about it yet, in that case send will
                // throw an error
                try {
                    if (usingBrowserWebSocket) {
                        // TypeError is thrown when passing the second argument on Safari
                        this.ws.send(data)
                    } else {
                        this.ws.send(data, opts)
                    }
                } catch (e) {
                    debug("websocket closed before onclose event")
                }

                if (lastPacket) {
                    // fake drain
                    // defer to next tick to allow Socket to clear writeBuffer
                    nextTick(() => {
                        this.writable = true
                        this.emitReserved("drain")
                    }, this.setTimeoutFn)
                }
            })
        }
    }

    override doClose() {
        if (typeof this.ws !== "undefined") {
            this.ws.close()
            this.ws = null
        }
    }

    /**
     * Generates uri for connection.
     *
     * @private
     */
    uri() {
        let query: { b64?: number } = this.query || {}
        const schema = this.opts.secure ? "wss" : "ws"
        let port = ""

        // avoid port if default for schema
        if (
            this.opts.port &&
            (("wss" === schema && Number(this.opts.port) !== 443) ||
                ("ws" === schema && Number(this.opts.port) !== 80))
        ) {
            port = ":" + this.opts.port
        }

        // append timestamp to URI
        if (this.opts.timestampRequests) {
            query[this.opts.timestampParam] = yeast()
        }

        // communicate binary support capabilities
        if (!this.supportsBinary) {
            query.b64 = 1
        }

        const encodedQuery = encode(query)
        const ipv6 = this.opts.hostname.indexOf(":") !== -1

        return (
            schema +
            "://" +
            (ipv6 ? "[" + this.opts.hostname + "]" : this.opts.hostname) +
            port +
            this.opts.path +
            (encodedQuery.length ? "?" + encodedQuery : "")
        )
    }

    /**
     * Feature detection for WebSocket.
     *
     * @return {Boolean} whether this transport is available.
     * @private
     */
    private check() {
        return !!WebSocket
    }
}