server list builder

build-params.js

import { readFile, writeFile } from "node:fs/promises";

const INPUT = "servers.json";
const OUTPUT = "params.txt";

function extractRelays(data) {
  for (const item of data) {
    if (
      item &&
      item.type === "data" &&
      item.data &&
      Array.isArray(item.data.relays)
    ) {
      return item.data.relays;
    }
  }
  throw new Error("Could not find relays array in servers.json");
}

async function main() {
  const raw = await readFile(INPUT, "utf8");
  const json = JSON.parse(raw);

  const relays = extractRelays(json);

  const params = relays
    .filter(r => r.active)
    .map(r => `-r socks5://${r.socks_name}:${r.socks_port}`)
    .join(" ");

  await writeFile(OUTPUT, params + "\n", "utf8");

  console.log(`Wrote ${OUTPUT} with ${relays.length} relays (${params.split(" -r ").length - 1} active)`);
}

main().catch(err => {
  console.error(err);
  process.exit(1);
});

fetch-servers.js

import { writeFile } from "node:fs/promises";

const URL = "https://mullvad.net/en/servers?type=wireguard&status=true";
const OUTPUT_FILE = "servers.json";

function extractDataArray(source) {
  const marker = "data:";
  const markerIndex = source.indexOf(marker);

  if (markerIndex === -1) {
    throw new Error(`Could not find "${marker}" in response`);
  }

  const arrayStart = source.indexOf("[", markerIndex);
  if (arrayStart === -1) {
    throw new Error("Could not find array start after data:");
  }

  let depth = 0;
  let inString = false;
  let stringQuote = "";
  let escaped = false;

  for (let i = arrayStart; i < source.length; i++) {
    const ch = source[i];

    if (inString) {
      if (escaped) {
        escaped = false;
        continue;
      }

      if (ch === "\\") {
        escaped = true;
        continue;
      }

      if (ch === stringQuote) {
        inString = false;
        stringQuote = "";
      }

      continue;
    }

    if (ch === '"' || ch === "'" || ch === "`") {
      inString = true;
      stringQuote = ch;
      continue;
    }

    if (ch === "[") {
      depth++;
    } else if (ch === "]") {
      depth--;
      if (depth === 0) {
        return source.slice(arrayStart, i + 1);
      }
    }
  }

  throw new Error("Could not find matching closing bracket for data array");
}

async function main() {
  const res = await fetch(URL, {
    headers: {
      "user-agent": "bun fetch script",
    },
  });

  if (!res.ok) {
    throw new Error(`Fetch failed: ${res.status} ${res.statusText}`);
  }

  const html = await res.text();

  if (!html.includes('data: [null,{type:"data"')) {
    console.warn('Warning: expected prefix `data: [null,{type:"data"` was not found exactly.');
  }

  const arraySource = extractDataArray(html);

  const data = Function(`"use strict"; return (${arraySource});`)();

  await writeFile(OUTPUT_FILE, JSON.stringify(data, null, 2), "utf8");

  console.log(`Saved ${OUTPUT_FILE}`);
}

main().catch((err) => {
  console.error(err);
  process.exit(1);
});