btn-mdw-ace-server-local/ace_proxy.js

const http = require('http');

const targetPorts = [4534, 4474, 4454, 4494];

targetPorts.forEach((targetPort) => {
  const proxyPort = parseInt(`${targetPort}5`);

  const server = http.createServer(async (req, res) => {
    // Construct the full URL using the host header
    const host = req.headers.host || 'localhost';
    const url = new URL(req.url, `http://${host}`);
    const target = `http://localhost:${targetPort}${url.pathname}${url.search}`;
    
    console.log(`\n[INCOMING] ${req.method} ${url.pathname}`);
    
    // 1. ECLIPSE TO ACE: Intercept headers and rewrite (e.g., 44545 -> 4454)
    const aceHeaders = new Headers();
    for (const [key, value] of Object.entries(req.headers)) {
      const strValue = String(value);
      const modifiedValue = strValue.replaceAll(`${targetPort}5`, targetPort.toString());
      aceHeaders.set(key, modifiedValue);
      
      if (strValue !== modifiedValue) {
        console.log(`  -> [TO ACE] Modified Header '${key}': sent as ${modifiedValue}`);
      }
    }

    // Node.js streams the request body, so we need to buffer it manually if it exists
    let reqBody;
    if (req.method !== "GET" && req.method !== "HEAD") {
      const chunks = [];
      for await (const chunk of req) {
        chunks.push(chunk);
      }
      reqBody = Buffer.concat(chunks);
    }

    const init = {
      method: req.method,
      headers: aceHeaders,
      ...(reqBody && { body: reqBody })
    };

    try {
      const response = await fetch(target, init);
      console.log(`[ACE RESPONDED] Status: ${response.status}`);
      
      // Transfer headers to the Node response
      response.headers.forEach((value, key) => {
        // Drop content-length as our payload modification will change the size
        if (key.toLowerCase() !== "content-length") {
          res.setHeader(key, value);
        }
      });
      res.statusCode = response.status;
      res.statusMessage = response.statusText;

      // 2. ACE TO ECLIPSE: Intercept JSON payload and rewrite (e.g., 4454 -> 44545)
      const contentType = response.headers.get("content-type") || "";
      
      if (contentType.includes("application/json") || contentType.includes("text/")) {
        let bodyText = await response.text();
        
        // THE PROOF: Log exactly what ACE sends back BEFORE we touch it
        console.log(`  -> [RAW ACE RESPONSE]: ${bodyText.substring(0, 250)}...`);
        
        if (bodyText.includes(targetPort.toString())) {
          console.log(`  -> [INTERCEPT] Found port ${targetPort}. Rewriting to ${targetPort}5...`);
          
          bodyText = bodyText.replaceAll(`localhost:${targetPort}`, `localhost:${targetPort}5`);
          bodyText = bodyText.replaceAll(`127.0.0.1:${targetPort}`, `127.0.0.1:${targetPort}5`);
          
          // Log the payload AFTER the rewrite to confirm the change
          console.log(`  -> [MODIFIED PAYLOAD]: ${bodyText.substring(0, 250)}...`);
        }
        
        res.end(bodyText);
      } else {
        // If it's an image, binary file, or other non-text format, handle it gracefully
        const arrayBuffer = await response.arrayBuffer();
        res.end(Buffer.from(arrayBuffer));
      }

    } catch (err) {
      console.error(`[ERROR]`, err);
      res.writeHead(502);
      res.end("Proxy Error");
    }
  });

  server.listen(proxyPort, () => {
    console.log(`Listening on ${proxyPort} -> Forwarding to ${targetPort}`);
  });
});

console.log(`2-Way Proxy Running. Check the terminal for RAW payload logs...`);