426 - Upgrade Required

1// Client-side: Handle 426 by upgrading protocol
2async function fetchWithProtocolUpgrade(url) {
3  let response = await fetch(url);
4  
5  if (response.status === 426) {
6    // Check Upgrade header for required protocol
7    const upgradeHeader = response.headers.get('Upgrade');
8    console.warn(`Protocol upgrade required: ${upgradeHeader}`);
9    
10    // Upgrade to HTTPS if HTTP was used
11    if (url.startsWith('http://')) {
12      const httpsUrl = url.replace('http://', 'https://');
13      console.log(`Upgrading to HTTPS: ${httpsUrl}`);
14      response = await fetch(httpsUrl);
15    }
16    
17    // Or check Upgrade header for specific protocol
18    if (upgradeHeader && upgradeHeader.includes('TLS')) {
19      // Upgrade to HTTPS
20      const urlObj = new URL(url);
21      urlObj.protocol = 'https:';
22      response = await fetch(urlObj.toString());
23    }
24  }
25  
26  return response;
27}
28
29// Usage
30fetchWithProtocolUpgrade('http://api.example.com/endpoint')
31  .then(response => response.json())
32  .catch(error => console.error('Protocol upgrade failed:', error));

1// Server-side: Return 426 for protocol upgrades
2const express = require('express');
3const app = express();
4
5// Middleware to require HTTP/1.1 or higher
6app.use((req, res, next) => {
7  const httpVersion = req.httpVersion;
8  
9  if (httpVersion === '1.0') {
10    return res.status(426)
11      .set('Upgrade', 'HTTP/1.1')
12      .set('Connection', 'Upgrade')
13      .json({
14        error: 'Upgrade Required',
15        message: 'Server requires HTTP/1.1 or higher',
16        upgrade: 'HTTP/1.1',
17      });
18  }
19  
20  next();
21});
22
23// Require HTTPS
24app.use((req, res, next) => {
25  if (req.protocol !== 'https' && process.env.NODE_ENV === 'production') {
26    return res.status(426)
27      .set('Upgrade', 'TLS/1.2')
28      .set('Connection', 'Upgrade')
29      .json({
30        error: 'Upgrade Required',
31        message: 'Server requires HTTPS',
32        upgrade: 'TLS/1.2',
33      });
34  }
35  next();
36});
37
38// Redirect HTTP to HTTPS
39app.use((req, res, next) => {
40  if (req.protocol === 'http' && process.env.NODE_ENV === 'production') {
41    return res.redirect(301, `https://${req.get('host')}${req.originalUrl}`);
42  }
43  next();
44});

1# Nginx: Configure protocol upgrade requirements
2server {
3    listen 80;
4    server_name api.example.com;
5    
6    # Redirect HTTP to HTTPS (upgrade required)
7    return 301 https://$server_name$request_uri;
8}
9
10# HTTPS server
11server {
12    listen 443 ssl http2;
13    server_name api.example.com;
14    
15    # SSL/TLS configuration
16    ssl_certificate /etc/ssl/certs/api.example.com.crt;
17    ssl_certificate_key /etc/ssl/private/api.example.com.key;
18    
19    # Require HTTP/1.1 minimum
20    # Nginx automatically handles this, but you can add custom logic
21    
22    location /api/ {
23        proxy_pass http://backend;
24        proxy_set_header Host $host;
25        proxy_set_header X-Real-IP $remote_addr;
26        proxy_set_header X-Forwarded-Proto $scheme;
27        
28        # Pass protocol version to backend
29        proxy_set_header X-Protocol-Version $server_protocol;
30    }
31    
32    # Custom 426 response if needed
33    # error_page 426 @upgrade_required;
34    # location @upgrade_required {
35    #     return 426 '{"error":"Upgrade Required","upgrade":"HTTP/1.1"}';
36    #     add_header Upgrade "HTTP/1.1" always;
37    #     add_header Connection "Upgrade" always;
38    # }
39}