telegram-api-proxy-worker.js

// Cloudflare Worker script to proxy Telegram API requests
// This script intercepts requests to the Telegram Bot API and forwards them
// allowing your bot to work even when direct access to api.telegram.org is blocked

export default {
  async fetch(request, env, ctx) {
    // Get the original request URL
    const originalUrl = new URL(request.url);
    
    // Handle CORS preflight requests
    if (request.method === 'OPTIONS') {
      return new Response(null, {
        headers: {
          'Access-Control-Allow-Origin': '*',
          'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
          'Access-Control-Allow-Headers': 'Content-Type, Authorization',
        },
      });
    }

    // Check if this is a request to our worker
    // If the path starts with /telegram-api, forward to Telegram API
    if (originalUrl.pathname.startsWith('/telegram-api')) {
      // Extract the path after /telegram-api
      // The full path should be like /telegram-api/bot{TOKEN}/{METHOD}
      const telegramApiPath = originalUrl.pathname.replace('/telegram-api', '');
      
      // Construct the target URL for Telegram API
      const telegramApiUrl = `https://api.telegram.org${telegramApiPath}`;
      
      // Clone the original request to modify it
      // Remove the Cloudflare-specific headers that might cause issues
      const newHeaders = new Headers(request.headers);
      newHeaders.delete('cf-ray');
      newHeaders.delete('cf-connecting-ip');
      newHeaders.delete('x-forwarded-for');
      
      const modifiedRequest = new Request(telegramApiUrl, {
        method: request.method,
        headers: newHeaders,
        body: request.body,
        redirect: 'follow'
      });
      
      try {
        // Send request to Telegram API
        const response = await fetch(modifiedRequest);
        
        // Return the response from Telegram API with CORS headers
        const modifiedResponse = new Response(response.body, {
          status: response.status,
          statusText: response.statusText,
          headers: {
            ...response.headers,
            'Access-Control-Allow-Origin': '*',
            'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
            'Access-Control-Allow-Headers': 'Content-Type, Authorization',
          }
        });
        
        return modifiedResponse;
      } catch (error) {
        console.error('Proxy error:', error);
        return new Response(JSON.stringify({ 
          error: 'Proxy error', 
          details: error.message,
          message: 'Failed to connect to Telegram API'
        }), {
          status: 502, // Bad Gateway
          headers: { 
            'Content-Type': 'application/json',
            'Access-Control-Allow-Origin': '*',
          }
        });
      }
    }
    
    // If not a Telegram API request, return info about the proxy
    return new Response('Telegram API Proxy Worker - Ready to forward requests to Telegram API', {
      status: 200,
      headers: { 
        'Content-Type': 'text/plain',
        'Access-Control-Allow-Origin': '*',
      }
    });
  }
};