From 99a616717b898271cc075c83e0db976574795079 Mon Sep 17 00:00:00 2001
From: Karol Czeryna <karol.czeryna@gmail.com>
Date: Sun, 30 Mar 2025 15:29:14 +0200
Subject: [PATCH] add gzip and brotli support to FetchMode.PROXY mode

---
 proxy.ts | 73 ++++++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 61 insertions(+), 12 deletions(-)

diff --git a/proxy.ts b/proxy.ts
index 4a25bc633..eea5e979e 100644
--- a/proxy.ts
+++ b/proxy.ts
@@ -2,6 +2,7 @@ import { FetchMode, ServerSetting } from './src/types/types';
 import { Connect } from 'vite';
 import httpProxy from 'http-proxy';
 import { exec } from 'child_process';
+import { brotliDecompressSync, gunzipSync } from 'zlib';
 
 const proxy = httpProxy.createProxyServer({});
 
@@ -211,19 +212,67 @@ proxy.on('proxyRes', function (proxyRes, req, res) {
     proxyRequest(req, res);
     return false;
   }
-  for (const _header in proxyRes.headers) {
-    if (!settings.disAllowResponseHeaders.includes(_header)) {
-      res.setHeader(_header, proxyRes.headers[_header] as string);
+
+  const contentEncoding = proxyRes.headers['content-encoding'];
+  const isBrotli =
+    contentEncoding &&
+    (Array.isArray(contentEncoding)
+      ? contentEncoding.some(enc => enc.includes('br'))
+      : contentEncoding.includes('br'));
+
+  const isGzip =
+    contentEncoding &&
+    (Array.isArray(contentEncoding)
+      ? contentEncoding.some(enc => enc.includes('gzip'))
+      : contentEncoding.includes('gzip'));
+
+  if (isBrotli || isGzip) {
+    delete proxyRes.headers['content-encoding'];
+    delete proxyRes.headers['content-length'];
+
+    for (const _header in proxyRes.headers) {
+      if (!settings.disAllowResponseHeaders.includes(_header)) {
+        res.setHeader(_header, proxyRes.headers[_header] as string);
+      }
     }
+
+    const chunks: Buffer[] = [];
+    proxyRes.on('data', chunk => chunks.push(Buffer.from(chunk)));
+    proxyRes.on('end', async function () {
+      try {
+        const buffer = Buffer.concat(chunks);
+        let decompressed;
+
+        if (isBrotli) {
+          decompressed = brotliDecompressSync(buffer);
+        } else {
+          decompressed = gunzipSync(buffer);
+        }
+
+        res.write(Buffer.from(decompressed));
+        res.end();
+      } catch (err) {
+        console.error(err);
+        res.statusCode = 500;
+        res.end(`Error decompressing ${isBrotli ? 'Brotli' : 'GZIP'} content`);
+      }
+    });
+  } else {
+    for (const _header in proxyRes.headers) {
+      if (!settings.disAllowResponseHeaders.includes(_header)) {
+        res.setHeader(_header, proxyRes.headers[_header] as string);
+      }
+    }
+    for (const _header in settings.disAllowedRequestHeaders) {
+      delete proxyRes.headers[_header];
+    }
+    proxyRes.on('data', function (chunk) {
+      res.write(chunk);
+    });
+    proxyRes.on('end', function () {
+      res.end();
+    });
   }
-  for (const _header in settings.disAllowedRequestHeaders) {
-    delete proxyRes.headers[_header];
-  }
-  proxyRes.on('data', function (chunk) {
-    res.write(chunk);
-  });
-  proxyRes.on('end', function () {
-    res.end();
-  });
 });
+
 export { proxyHandlerMiddle, proxySettingMiddleware };