From 637cd52e967b04859c68cbe5089486d431819cbe Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Sun, 29 Mar 2020 15:44:14 -0700
Subject: [PATCH] Enable QoS prioritization on Linux

---
 unix.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/unix.c b/unix.c
index 7a17d50..4694149 100644
--- a/unix.c
+++ b/unix.c
@@ -320,11 +320,27 @@ enet_socket_set_option (ENetSocket socket, ENetSocketOption option, int value)
             break;
 
         case ENET_SOCKOPT_QOS:
-#if defined(SO_NET_SERVICE_TYPE)
+#ifdef SO_NET_SERVICE_TYPE
             // iOS/macOS
             value = value ? NET_SERVICE_TYPE_VO : NET_SERVICE_TYPE_BE;
             result = setsockopt (socket, SOL_SOCKET, SO_NET_SERVICE_TYPE, (char *) & value, sizeof (int));
+#else
+#ifdef IP_TOS
+            // UNIX - IPv4
+            value = 0xE0; // DSCP: CS7
+            result = setsockopt (socket, IPPROTO_IP, IP_TOS, (char *) & value, sizeof (int));
 #endif
+#ifdef IPV6_TCLASS
+            // UNIX - IPv6
+            value = 0xE0; // DSCP: CS7
+            result = setsockopt (socket, IPPROTO_IPV6, IPV6_TCLASS, (char *) & value, sizeof (int));
+#endif
+#ifdef SO_PRIORITY
+            // Linux
+            value = 6; // Max priority without NET_CAP_ADMIN
+            result = setsockopt (socket, SOL_SOCKET, SO_PRIORITY, (char *) & value, sizeof (int));
+#endif
+#endif /* SO_NET_SERVICE_TYPE */
             break;
 
         default: