Refactor README for clarity and add Node.js server implementation

2026-03-27 12:04:23 +01:00
parent 83fd45bebd
commit aa2d51a0dd
2 changed files with 339 additions and 3 deletions
--- a/README.md
+++ b/README.md
@@ -1,12 +1,14 @@
 # Connectivity Test Server

-A simple HTTP server for connectivity testing. It can be run from the command line or in a container. It relies only on Python's standard library, so it should work in any environment with Python installed.
+A simple HTTP server for connectivity testing. It can be run from the command line or in a container.
+
+The Python version relies only on Python's standard library, so it should work in any environment with Python installed. The Node.js version also relies only on the standard library, so it should work in any environment with Node.js installed.

 It displays a simple HTML or plain-text page with the client's IP address and any detected `X-*` headers.

 ## Disclaimer

-The `ok-server.py` file was generated using AI under human supervision. The owner of the repository is not responsible for any issues that may arise from using the AI-generated code.
+The **ok-server** scripts were generated using AI under human supervision. The owner of the repository is not responsible for any issues that may arise from using the AI-generated code.

 ## Usage

@@ -23,8 +25,18 @@ python3 ok-server.py --bind 127.0.0.1 --port 8080 --look bootstrap
 `--look` accepts `basic`, `nice`, or `bootstrap`.
 You can override the look per request with the `look` query parameter, for example:

+or
+
 ```bash
-curl -i "http://localhost:8000/?look=basic"
+node ok-server.js
+node ok-server.js --look basic
+node ok-server.js --bind 127.0.0.1 --port 8080 --look bootstrap
+```
+
+Connect to the server using a web browser or a tool like `curl`:
+
+```bash
+curl -si "http://localhost:8000"
 ```

 ### Docker
--- a/ok-server.mjs
+++ b/ok-server.mjs
@@ -0,0 +1,324 @@
+#!/usr/bin/env node
+/**
+ * Simple HTTP server that responds 200 with a test message including client IP.
+ *
+ * Behavior:
+ *   - GET returns HTTP/1.1 200 with a message including the requester IP
+ *   - HEAD returns the same headers as GET but no body
+ *   - Displays incoming X-* headers when present
+ *   - If User-Agent contains "curl" or "wget" (case-insensitive), the server
+ *     responds with Content-Type: text/plain; otherwise Content-Type: text/html.
+ *   - --look controls which HTML variant is returned for non-CLI agents:
+ *       * basic     - plain HTML with no external references
+ *       * nice      - includes Google Font "Noto Sans" (default)
+ *       * bootstrap - Bootstrap 5 layout
+ *   - The URL query parameter "look" (e.g. /?look=nice) overrides --look for
+ *     that request only. Values are case-insensitive and must be basic,nice,bootstrap.
+ */
+
+import http from "node:http";
+import { URL } from "node:url";
+
+const VALID_LOOKS = new Set(["basic", "nice", "bootstrap"]);
+
+const PLAIN_TEMPLATE =
+  "Hello, This is a test HTTP server.\n\n" +
+  "Your request came from {ip}.\n\n" +
+  "{proxy_headers_block}" +
+  "Have a nice day!\n";
+
+const HTML_BASIC = `<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8">
+    <title>Test HTTP server</title>
+  </head>
+  <body>
+    <h1>Hello,</h1>
+    <p>This is a test HTTP server.</p>
+    <p>Your request came from <strong>{ip}</strong>.</p>
+    {proxy_headers_html}
+    <p>Have a nice day!</p>
+  </body>
+</html>
+`;
+
+const HTML_NICE = `<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <title>Test HTTP server</title>
+    <!-- Google Font: Noto Sans -->
+    <link href="https://fonts.googleapis.com/css2?family=Noto+Sans:wght@400;700&display=swap" rel="stylesheet">
+    <style>
+      body { font-family: "Noto Sans", system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif; padding: 2rem; background: #f6f7fb; }
+      .card { background: white; padding: 1.5rem; border-radius: 8px; box-shadow: 0 2px 8px rgba(0,0,0,0.06); max-width: 800px; margin: 2rem auto; }
+      h1 { margin-top: 0; }
+    </style>
+  </head>
+  <body>
+    <div class="card">
+      <h1>Hello,</h1>
+      <p>This is a test HTTP server.</p>
+      <p>Your request came from <strong>{ip}</strong>.</p>
+      {proxy_headers_html}
+      <p>Have a nice day!</p>
+    </div>
+  </body>
+</html>
+`;
+
+const HTML_BOOTSTRAP = `<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <title>Test HTTP server</title>
+    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/css/bootstrap.min.css" rel="stylesheet" crossorigin="anonymous">
+  </head>
+  <body class="bg-light">
+    <nav class="navbar navbar-expand-lg navbar-dark bg-primary mb-4">
+      <div class="container">
+        <a class="navbar-brand" href="#">Test HTTP server</a>
+      </div>
+    </nav>
+
+    <main class="container">
+      <div class="row justify-content-center">
+        <div class="col-md-8">
+          <div class="card shadow-sm">
+            <div class="card-body">
+              <h1 class="card-title">Hello,</h1>
+              <p class="card-text">This is a test HTTP server.</p>
+              <p class="card-text">Your request came from <strong>{ip}</strong>.</p>
+              {proxy_headers_html}
+              <hr>
+              <p class="mb-0">Have a nice day!</p>
+            </div>
+          </div>
+        </div>
+      </div>
+    </main>
+
+    <footer class="text-center mt-4 mb-4">
+      <small class="text-muted">Simple status page for firewall/testing</small>
+    </footer>
+  </body>
+</html>
+`;
+
+function escapeHtml(value) {
+  return String(value)
+    .replace(/&/g, "&amp;")
+    .replace(/</g, "&lt;")
+    .replace(/>/g, "&gt;")
+    .replace(/\"/g, "&quot;")
+    .replace(/'/g, "&#x27;");
+}
+
+function isCliAgent(userAgent) {
+  if (!userAgent) {
+    return false;
+  }
+  const ua = userAgent.toLowerCase();
+  return ua.includes("curl") || ua.includes("wget");
+}
+
+function getRequestLook(req) {
+  const url = new URL(req.url || "/", "http://localhost");
+  const look = (url.searchParams.get("look") || "").trim().toLowerCase();
+  if (VALID_LOOKS.has(look)) {
+    return look;
+  }
+  return null;
+}
+
+function collectXHeaders(req) {
+  const xHeaders = [];
+  for (const [name, value] of Object.entries(req.headers)) {
+    if (!name.toLowerCase().startsWith("x-")) {
+      continue;
+    }
+    if (Array.isArray(value)) {
+      xHeaders.push([name, value.join(", ")]);
+    } else if (value !== undefined) {
+      xHeaders.push([name, value]);
+    }
+  }
+  xHeaders.sort((a, b) => a[0].localeCompare(b[0], "en", { sensitivity: "base" }));
+  return xHeaders;
+}
+
+function proxyMarkup(xHeaders) {
+  if (xHeaders.length === 0) {
+    return { proxyHeadersBlock: "", proxyHeadersHtml: "" };
+  }
+
+  const plainLines = xHeaders.map(([name, value]) => `  - ${name}: ${value}`);
+  const proxyHeadersBlock =
+    "Reverse proxy condition: detected via X-* headers.\n" +
+    "X-* headers:\n" +
+    plainLines.join("\n") +
+    "\n\n";
+
+  const htmlItems = xHeaders
+    .map(([name, value]) => `<li><code>${escapeHtml(name)}</code>: ${escapeHtml(value)}</li>`)
+    .join("");
+  const proxyHeadersHtml =
+    "<p>Reverse proxy condition: <strong>detected via X-* headers</strong>.</p>" +
+    `<p>X-* headers:</p><ul>${htmlItems}</ul>`;
+
+  return { proxyHeadersBlock, proxyHeadersHtml };
+}
+
+function htmlForLook(look, ip, proxyHeadersHtml) {
+  const template =
+    look === "basic" ? HTML_BASIC : look === "nice" ? HTML_NICE : HTML_BOOTSTRAP;
+
+  return template
+    .replaceAll("{ip}", ip)
+    .replace("{proxy_headers_html}", proxyHeadersHtml);
+}
+
+function makeBodyAndType(req, clientIp, defaultLook) {
+  const userAgent = req.headers["user-agent"] || "";
+  const xHeaders = collectXHeaders(req);
+  const { proxyHeadersBlock, proxyHeadersHtml } = proxyMarkup(xHeaders);
+
+  if (isCliAgent(userAgent)) {
+    const body = PLAIN_TEMPLATE
+      .replace("{ip}", clientIp)
+      .replace("{proxy_headers_block}", proxyHeadersBlock);
+    return { body: Buffer.from(body, "utf8"), contentType: "text/plain; charset=utf-8" };
+  }
+
+  const requestLook = getRequestLook(req);
+  const look = requestLook || defaultLook;
+  const html = htmlForLook(look, clientIp, proxyHeadersHtml);
+  return { body: Buffer.from(html, "utf8"), contentType: "text/html; charset=utf-8" };
+}
+
+function getClientIp(req) {
+  return req.socket?.remoteAddress || "unknown";
+}
+
+function parseArgs(argv) {
+  let bind = "0.0.0.0";
+  let port = 8000;
+  let look = "nice";
+
+  for (let i = 0; i < argv.length; i += 1) {
+    const arg = argv[i];
+
+    if (arg === "-b" || arg === "--bind") {
+      i += 1;
+      if (i >= argv.length) {
+        throw new Error(`${arg} requires a value`);
+      }
+      bind = argv[i];
+      continue;
+    }
+
+    if (arg === "-p" || arg === "--port") {
+      i += 1;
+      if (i >= argv.length) {
+        throw new Error(`${arg} requires a value`);
+      }
+      const parsedPort = Number.parseInt(argv[i], 10);
+      if (!Number.isInteger(parsedPort) || parsedPort < 1 || parsedPort > 65535) {
+        throw new Error(`Invalid port: ${argv[i]}`);
+      }
+      port = parsedPort;
+      continue;
+    }
+
+    if (arg === "--look") {
+      i += 1;
+      if (i >= argv.length) {
+        throw new Error(`${arg} requires a value`);
+      }
+      const value = String(argv[i]).trim().toLowerCase();
+      if (!VALID_LOOKS.has(value)) {
+        throw new Error(`Invalid look: ${argv[i]} (expected one of: basic, nice, bootstrap)`);
+      }
+      look = value;
+      continue;
+    }
+
+    if (arg === "-h" || arg === "--help") {
+      const help = [
+        "Usage:",
+        "  node ok-server.mjs [-b|--bind ADDRESS] [-p|--port PORT] [--look basic|nice|bootstrap]",
+        "",
+        "Defaults:",
+        "  --bind 0.0.0.0",
+        "  --port 8000",
+        "  --look nice",
+      ].join("\n");
+      console.log(help);
+      process.exit(0);
+    }
+
+    throw new Error(`Unknown argument: ${arg}`);
+  }
+
+  return { bind, port, look };
+}
+
+function run(bind, port, look) {
+  const server = http.createServer((req, res) => {
+    const method = req.method || "GET";
+
+    if (method !== "GET" && method !== "HEAD") {
+      res.writeHead(405, { "Content-Length": "0" });
+      res.end();
+      return;
+    }
+
+    const clientIp = getClientIp(req);
+    const { body, contentType } = makeBodyAndType(req, clientIp, look);
+
+    res.writeHead(200, {
+      "Content-Type": contentType,
+      "Content-Length": String(body.length),
+    });
+
+    if (method === "HEAD") {
+      res.end();
+      return;
+    }
+
+    res.end(body);
+  });
+
+  server.on("request", (req) => {
+    const clientIp = getClientIp(req);
+    const now = new Date().toUTCString();
+    const method = req.method || "GET";
+    const path = req.url || "/";
+    process.stderr.write(`${clientIp} - - [${now}] "${method} ${path}"\n`);
+  });
+
+  server.on("error", (err) => {
+    process.stderr.write(`Server error: ${err.message}\n`);
+    process.exitCode = 1;
+  });
+
+  server.listen(port, bind, () => {
+    console.log(`Serving on ${bind}:${port} (default look=${look}) (Ctrl-C to stop)`);
+  });
+
+  process.on("SIGINT", () => {
+    console.log("\nShutting down server");
+    server.close(() => process.exit(0));
+  });
+}
+
+try {
+  const { bind, port, look } = parseArgs(process.argv.slice(2));
+  run(bind, port, look);
+} catch (err) {
+  process.stderr.write(`${err.message}\n`);
+  process.exit(2);
+}