fix: null-safe IP extraction in RequestLoggingFilter

gateway-service/src/main/java/com/posthub/gateway/filter/RequestLoggingFilter.java

@@ -9,6 +9,8 @@ import org.springframework.stereotype.Component;
 import org.springframework.web.server.ServerWebExchange;
 import reactor.core.publisher.Mono;
 
+import java.net.InetSocketAddress;
+
 @Slf4j
 @Component
 public class RequestLoggingFilter implements GlobalFilter, Ordered {
@@ -18,9 +20,7 @@ public class RequestLoggingFilter implements GlobalFilter, Ordered {
         ServerHttpRequest request = exchange.getRequest();
         String method = request.getMethod().name();
         String path = request.getURI().getPath();
-        String clientIp = request.getRemoteAddress() != null
-                ? request.getRemoteAddress().getAddress().getHostAddress()
-                : "unknown";
+        String clientIp = extractClientIp(request);
 
         log.info(">>> {} {} from {}", method, path, clientIp);
 
@@ -35,8 +35,23 @@ public class RequestLoggingFilter implements GlobalFilter, Ordered {
         }));
     }
 
+    private String extractClientIp(ServerHttpRequest request) {
+        // Prefer X-Forwarded-For header set by Nginx
+        String xForwardedFor = request.getHeaders().getFirst("X-Forwarded-For");
+        if (xForwardedFor != null && !xForwardedFor.isBlank()) {
+            return xForwardedFor.split(",")[0].trim();
+        }
+
+        InetSocketAddress remoteAddress = request.getRemoteAddress();
+        if (remoteAddress != null && remoteAddress.getAddress() != null) {
+            return remoteAddress.getAddress().getHostAddress();
+        }
+
+        return "unknown";
+    }
+
     @Override
     public int getOrder() {
         return Ordered.HIGHEST_PRECEDENCE;
     }
-}
+}