remove spoof-able request header (#7103)

* remove spoof-able request header

https://github.com/seaweedfs/seaweedfs/issues/7094#issuecomment-3158320497

* Update weed/security/guard.go

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

weed/security/guard.go

@@ -77,34 +77,8 @@ func (g *Guard) WhiteList(f http.HandlerFunc) http.HandlerFunc {
 }
 
 func GetActualRemoteHost(r *http.Request) string {
-	// Check X-Forwarded-For headers first (may contain comma-separated IPs)
-	// HTTP_X_FORWARDED_FOR is used for SeaweedFS internal communication when master proxies to leader
-	host := r.Header.Get("HTTP_X_FORWARDED_FOR")
-	if host == "" {
-		host = r.Header.Get("X-FORWARDED-FOR")
-	}
-	if host != "" {
-		for _, ipStr := range strings.Split(host, ",") {
-			host = strings.TrimSpace(ipStr)
-			if host != "" {
-				break
-			}
-		}
-	}
-
-	// If no valid IP from X-Forwarded-For, try X-Real-IP (single IP)
-	if host == "" {
-		host = r.Header.Get("X-Real-IP")
-	}
-
-	// If we got a host from headers, use it (can be IP or hostname)
-	if host != "" {
-		if host = strings.TrimSpace(host); host != "" {
-			return host
-		}
-	}
-
-	// If no host from headers, extract from RemoteAddr
+	// For security reasons, only use RemoteAddr to determine the client's IP address.
+	// Do not trust headers like X-Forwarded-For, as they can be easily spoofed by clients.
 	host, _, err := net.SplitHostPort(r.RemoteAddr)
 	if err == nil {
 		return host

weed/server/master_server.go

@@ -257,12 +257,6 @@ func (ms *MasterServer) proxyToLeader(f http.HandlerFunc) http.HandlerFunc {
 		// proxy to leader
 		glog.V(4).Infoln("proxying to leader", raftServerLeader)
 		proxy := httputil.NewSingleHostReverseProxy(targetUrl)
-		director := proxy.Director
-		proxy.Director = func(req *http.Request) {
-			actualHost := security.GetActualRemoteHost(req)
-			req.Header.Set("HTTP_X_FORWARDED_FOR", actualHost)
-			director(req)
-		}
 		proxy.Transport = util_http.GetGlobalHttpClient().GetClientTransport()
 		proxy.ServeHTTP(w, r)
 	}