From: Jan-Benedict Glaw <jbglaw@lug-owl.de>
Date: Sun, 22 Sep 2024 16:52:51 +0200
Subject: Fix tap device support on Linux

---
 src/net/net_tap.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/src/net/net_tap.c b/src/net/net_tap.c
index 188276e..d920695 100644
--- a/src/net/net_tap.c
+++ b/src/net/net_tap.c
@@ -48,6 +48,11 @@
 #include "misc.h"
 #include "net.h"
 
+#ifdef __linux__
+#  include <linux/if.h>
+#  include <linux/if_tun.h>
+#endif
+
 /*
  *  net_tap_rx_for_nic():
  *
@@ -166,7 +171,11 @@ bool net_tap_init(struct net *net, const char *tapdev)
 	int fd;
 	int one = 1;
 
+#ifdef __linux__
+	fd = open("/dev/net/tun", O_RDWR);
+#else
 	fd = open(tapdev, O_RDWR);
+#endif
 	if (fd < 0) {
 		debugmsg(SUBSYS_NET, "tap", VERBOSITY_ERROR,
 		    "unable to open tap device '%s': %s",
@@ -174,6 +183,22 @@ bool net_tap_init(struct net *net, const char *tapdev)
 		return false;
 	}
 
+#ifdef __linux__
+	struct ifreq ifr;
+
+	memset(&ifr, 0, sizeof(ifr));
+	ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+	strncpy(ifr.ifr_name, tapdev, IFNAMSIZ);
+
+	if (ioctl(fd, TUNSETIFF, &ifr) < 0) {
+		debugmsg(SUBSYS_NET, "tap", VERBOSITY_ERROR,
+		    "unable to attach to "
+		    "tap device '%s': %s", tapdev, strerror(errno));
+		close(fd);
+		return false;
+	}
+#endif
+
 	if (ioctl(fd, FIONBIO, &one) < 0) {
 		debugmsg(SUBSYS_NET, "tap", VERBOSITY_ERROR,
 		    "unable to set non-blocking mode on "