From 9a62ec61c96516ee39f21c32ee737275316c297a Mon Sep 17 00:00:00 2001
From: Gent Semaj <me@ycc.dev>
Date: Thu, 19 Mar 2026 22:00:29 -0700
Subject: [PATCH] Set TCP_NODELAY on clients

---
 src/core/CNProtocol.cpp | 23 ++++++++++++++++-------
 src/core/CNProtocol.hpp |  2 ++
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/src/core/CNProtocol.cpp b/src/core/CNProtocol.cpp
index c96916d..0d7b22f 100644
--- a/src/core/CNProtocol.cpp
+++ b/src/core/CNProtocol.cpp
@@ -365,14 +365,8 @@ void CNServer::init() {
     }
 
     // attach socket to the port
-    int opt = 1;
-#ifdef _WIN32
-    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (const char*)&opt, sizeof(opt)) != 0) {
-#else
-    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) != 0) {
-#endif
+    if (!setSocketOption(sock, SOL_SOCKET, SO_REUSEADDR, 1)) {
         std::cerr << "[FATAL] OpenFusion: setsockopt failed" << std::endl;
-        printSocketError("setsockopt");
         exit(EXIT_FAILURE);
     }
     address.sin_family = AF_INET;
@@ -414,6 +408,18 @@ void CNServer::init() {
 CNServer::CNServer() {};
 CNServer::CNServer(uint16_t p): port(p) {}
 
+bool CNServer::setSocketOption(SOCKET s, int level, int option, int value) {
+#ifdef _WIN32
+    if (setsockopt(s, level, option, (const char*)&value, sizeof(value)) != 0) {
+#else
+    if (setsockopt(s, level, option, &value, sizeof(value)) != 0) {
+#endif
+        printSocketError("setsockopt");
+        return false;
+    }
+    return true;
+}
+
 void CNServer::addPollFD(SOCKET s) {
     fds.push_back({s, POLLIN});
 }
@@ -462,6 +468,9 @@ void CNServer::start() {
                     continue;
                 }
 
+                if (!setSocketOption(newConnectionSocket, IPPROTO_TCP, TCP_NODELAY, 1))
+                    std::cout << "[WARN] OpenFusion: failed to set TCP_NODELAY on new connection" << std::endl;
+
                 if (!setSockNonblocking(sock, newConnectionSocket))
                     continue;
 
diff --git a/src/core/CNProtocol.hpp b/src/core/CNProtocol.hpp
index 1bf5dbc..ffedd7a 100644
--- a/src/core/CNProtocol.hpp
+++ b/src/core/CNProtocol.hpp
@@ -28,6 +28,7 @@
 // posix platform
     #include <sys/socket.h>
     #include <netinet/in.h>
+    #include <netinet/tcp.h>
     #include <arpa/inet.h>
     #include <poll.h>
     #include <unistd.h>
@@ -239,6 +240,7 @@ protected:
 
     bool active = true;
 
+    bool setSocketOption(SOCKET s, int level, int option, int value);
     void addPollFD(SOCKET s);
     void removePollFD(int i);