fix(dev): don't overwrite proxy headers if already set (#896)

* fix: don't overwrite proxy headers if already set

* perf: only call `getHeaders()` once

---------

Co-authored-by: Mike Bellika <mike@altinget.dk>

src/dev/server.ts

@@ -158,14 +158,14 @@ export function createDevServer(nitro: Nitro): NitroDevServer {
   // Main worker proxy
   const proxy = createProxy();
   proxy.proxy.on("proxyReq", (proxyReq, req) => {
-    // TODO: Avoid overwriting headers if already set
-    if (req.socket.remoteAddress) {
+    const proxyRequestHeaders = proxyReq.getHeaders();
+    if (req.socket.remoteAddress && !proxyRequestHeaders["x-forwarded-for"]) {
       proxyReq.setHeader("X-Forwarded-For", req.socket.remoteAddress);
     }
-    if (req.socket.remotePort) {
+    if (req.socket.remotePort && !proxyRequestHeaders["x-forwarded-port"]) {
       proxyReq.setHeader("X-Forwarded-Port", req.socket.remotePort);
     }
-    if (req.socket.remoteFamily) {
+    if (req.socket.remoteFamily && !proxyRequestHeaders["x-forwarded-proto"]) {
       proxyReq.setHeader("X-Forwarded-Proto", req.socket.remoteFamily);
     }
   });