From: Guus Sliepen <guus@tinc-vpn.org>
Date: Sat, 24 Oct 2009 20:32:35 +0000 (+0200)
Subject: Use IP_DONTFRAGMENT instead of IP_MTU_DISCOVER on Windows.
X-Git-Tag: import-tinc-1.1~584^2~6
X-Git-Url: https://git.meshlink.io/?a=commitdiff_plain;h=c3acae034c4da2d1c70f31b852b14ca098c0eeb9;p=meshlink

Use IP_DONTFRAGMENT instead of IP_MTU_DISCOVER on Windows.

This ensures the DF bit on outgoing UDP packets gets set on Windows when path
MTU discovery is enabled, reducing fragmentation.
---

diff --git a/src/net_socket.c b/src/net_socket.c
index baf0227a..f5a569b2 100644
--- a/src/net_socket.c
+++ b/src/net_socket.c
@@ -279,6 +279,11 @@ int setup_vpn_in_socket(const sockaddr_t *sa) {
 		option = IP_PMTUDISC_DO;
 		setsockopt(nfd, SOL_IP, IP_MTU_DISCOVER, &option, sizeof(option));
 	}
+#elif defined(IPPROTO_IP) && defined(IP_DONTFRAGMENT)
+	if(myself->options & OPTION_PMTU_DISCOVERY) {
+		option = 1;
+		setsockopt(nfd, IPPROTO_IP, IP_DONTFRAGMENT, &option, sizeof(option));
+	}
 #endif
 
 #if defined(SOL_IPV6) && defined(IPV6_MTU_DISCOVER) && defined(IPV6_PMTUDISC_DO)