Get IPv4 and IPv6 WAN IP from FritzBox

FritzBoxIP.ts

import { parse as xmlParser } from 'fsp-xml-parser';

export default class FritzBoxIP {
    private _fritzBox: string;

    constructor(fritzBox: string) {
        this._fritzBox = fritzBox;
    }

    async IPv4(): Promise<string> {
        const xml = await fetch(`${this._fritzBox}/igdupnp/control/WANIPConn1`, {
            headers: {
                "Content-Type": "text/xml; charset=utf-8",
                "SoapAction": "urn:schemas-upnp-org:service:WANIPConnection:1#GetExternalIPAddress"
            },
            method: "POST",
            body: "<?xml version='1.0' encoding='utf-8'?> <s:Envelope s:encodingStyle='http://schemas.xmlsoap.org/soap/encoding/' xmlns:s='http://schemas.xmlsoap.org/soap/envelope/'> <s:Body> <u:GetExternalIPAddress xmlns:u='urn:schemas-upnp-org:service:WANIPConnection:1' /> </s:Body> </s:Envelope>"
        });

        const IP4 = xmlParser(await xml.text());

        return IP4.root!.children![0].children![0].children![0].content!;
    }

    async IPv6(): Promise<string> {
        const xml = await fetch(`${this._fritzBox}/igdupnp/control/WANIPConn1`, {
            headers: {
                "Content-Type": "text/xml; charset=utf-8",
                "SoapAction": "urn:schemas-upnp-org:service:WANIPConnection:1#X_AVM_DE_GetExternalIPv6Address"
            },
            method: "POST",
            body: "<?xml version='1.0' encoding='utf-8'?> <s:Envelope s:encodingStyle='http://schemas.xmlsoap.org/soap/encoding/' xmlns:s='http://schemas.xmlsoap.org/soap/envelope/'> <s:Body> <u:GetExternalIPAddress xmlns:u='urn:schemas-upnp-org:service:WANIPConnection:1' /> </s:Body> </s:Envelope>"
        });

        const IP6 = xmlParser(await xml.text());
        
        return IP6.root!.children![0].children![0].children![0].content!;
    }
}

USAGE.ts

import FritzBoxIP from "./FritzBoxIP";
const fritzBoxIP = new FritzBoxIP({ "FritzBox": "http://fritz.box:49000" });

let IPv4: string;
let IPv6: string;

try {
    IPv4 = await fritzBoxIP.IPv4();
    IPv6 = await fritzBoxIP.IPv6();
} catch(e) {
    console.log("ERROR", "Can't get WAN IP", e);
}