From 6bb1598fa386982720d7d6cdc6fbbd3f57cb7a7e Mon Sep 17 00:00:00 2001
From: Adam Ierymenko <adam.ierymenko@zerotier.com>
Date: Wed, 15 Sep 2021 11:50:54 -0400
Subject: [PATCH] Another fix for routing and interface issues on MacOS

---
 osdep/ManagedRoute.cpp | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/osdep/ManagedRoute.cpp b/osdep/ManagedRoute.cpp
index abe768930..fd06f9cfe 100644
--- a/osdep/ManagedRoute.cpp
+++ b/osdep/ManagedRoute.cpp
@@ -437,6 +437,24 @@ bool ManagedRoute::sync()
 
 #ifdef __BSD__ // ------------------------------------------------------------
 
+	if (_device[0]) {
+		bool haveDevice = false;
+		struct ifaddrs *ifa = (struct ifaddrs *)0;
+		if (!getifaddrs(&ifa)) {
+			struct ifaddrs *p = ifa;
+			while (p) {
+				if ((p->ifa_name)&&(!strcmp(_device, p->ifa_name))) {
+					haveDevice = true;
+					break;
+				}
+				p = p->ifa_next;
+			}
+			freeifaddrs(ifa);
+		}
+		if (!haveDevice)
+			return false;
+	}
+
 	// Find lowest metric system route that this route should override (if any)
 	InetAddress newSystemVia;
 	char newSystemDevice[128];