Get server side page full URL for Next.js

next-url.ts

import { IncomingMessage } from "http";

const basePath = process.env.NEXT_PUBLIC_BASE_PATH ?? "";

export type RequestURL = URL & {
  basePath: string;
};

const getFromMeta = (req: IncomingMessage) => {
  const meta = Object.getOwnPropertySymbols(req).find(
    ({ description }) => description === "NextRequestMeta"
  );

  return meta ? (req as any)[meta]?.__NEXT_INIT_URL ?? null : null;
};

export const getRequestURL = (req: IncomingMessage) => {
  const referer = req.headers.referer ?? getFromMeta(req);

  if (referer) {
    const url = new URL(referer);
    const matchBasePathPrefix =
      basePath.length && url.pathname.startsWith(basePath);
    const pathname = matchBasePathPrefix
      ? url.pathname.substring(0, basePath.length)
      : url.pathname;
    const href = req.url
      ? url.href.substring(0, url.href.lastIndexOf(pathname)) + req.url
      : url.href;

    return {
      href: href,
      origin: url.origin,
      protocol: url.protocol,
      username: url.username,
      password: url.password,
      host: url.host,
      basePath: matchBasePathPrefix ? basePath : "",
      hostname: url.hostname,
      port: url.port,
      pathname: req?.url ?? pathname,
      search: url.search,
      searchParams: url.searchParams,
      hash: url.hash,
    };
  } else {
    return null;
  }
};

the value of the __NEXT_INIT_URL property can be obtained like this:

import { getRequestMeta } from 'next/dist/server/request-meta';
// ...
const initUrl = getRequestMeta(req, '__NEXT_INIT_URL')!;