now i remember why i had to open /dev/tun twice on solaris

that _should_ fully close the TUN interface on Solaris

include/tuntap.h

@@ -151,6 +151,7 @@ extern "C"
 #endif
 #if defined(__sun)
     int ip_fd;
+    int reserved;
     char internal_name[IF_NAMESIZE];
 #endif
   };

vendor/libtuntap-master/tuntap-unix-sunos.c

@@ -52,7 +52,7 @@
 static int
 tuntap_sys_create_dev(struct device *dev, int tun)
 {
-	int if_fd, ip_muxid, ppa = -1;
+	int if_fd, fd, ip_muxid, ppa = -1;
 	struct lifreq lifr;
 	struct ifreq ifr;
 	const char *ptr = NULL;
@@ -74,7 +74,7 @@ tuntap_sys_create_dev(struct device *dev, int tun)
 		return -1;
 	}
 
-	if ((dev->tun_fd = open("/dev/tun", O_RDWR, 0)) < 0)
+	if ((if_fd = open("/dev/tun", O_RDWR, 0)) < 0)
 	{
 		tuntap_log(TUNTAP_LOG_ERR, "Can't open /dev/tun");
 		return -1;
@@ -102,7 +102,7 @@ tuntap_sys_create_dev(struct device *dev, int tun)
 		bool found_one = false;
 		while (!found_one && ppa < 64)
 		{
-			int new_ppa = ioctl(dev->tun_fd, I_STR, &strioc_ppa);
+			int new_ppa = ioctl(if_fd, I_STR, &strioc_ppa);
 			if (new_ppa >= 0)
 			{
 				char* msg = alloca(512);
@@ -127,7 +127,7 @@ tuntap_sys_create_dev(struct device *dev, int tun)
 	}
 	else                        /* try this particular one */
 	{
-		if ((ppa = ioctl(dev->tun_fd, I_STR, &strioc_ppa)) < 0)
+		if ((ppa = ioctl(if_fd, I_STR, &strioc_ppa)) < 0)
 		{
 			char *msg = alloca(512);
 			sprintf(msg, "Can't assign PPA for new interface (tun%i)", ppa);
@@ -136,20 +136,20 @@ tuntap_sys_create_dev(struct device *dev, int tun)
 		}
 	}
 
-	if ((if_fd = open("/dev/tun", O_RDWR, 0)) < 0)
+	if ((fd = open("/dev/tun", O_RDWR, 0)) < 0)
 	{
 		tuntap_log(TUNTAP_LOG_ERR, "Can't open /dev/tun (2)");
 		return -1;
 	}
 
-	if (ioctl(if_fd, I_PUSH, "ip") < 0)
+	if (ioctl(fd, I_PUSH, "ip") < 0)
 	{
 		tuntap_log(TUNTAP_LOG_ERR, "Can't push IP module");
 		return -1;
 	}
 
 	/* Assign ppa according to the unit number returned by tun device */
-	if (ioctl(if_fd, IF_UNITSEL, (char *) &ppa) < 0)
+	if (ioctl(fd, IF_UNITSEL, (char *) &ppa) < 0)
 	{
 		char *msg = alloca(512);
 		sprintf(msg, "Can't set PPA %i", ppa);
@@ -159,7 +159,7 @@ tuntap_sys_create_dev(struct device *dev, int tun)
 
 	snprintf(dev->internal_name, IF_NAMESIZE, "%s%d", "tun", ppa);
 
-	if ((ip_muxid = ioctl(dev->ip_fd, I_PLINK, if_fd)) < 0)
+	if ((ip_muxid = ioctl(dev->ip_fd, I_PLINK, fd)) < 0)
 	{
 		tuntap_log(TUNTAP_LOG_ERR, "Can't link tun device to IP");
 		return -1;
@@ -177,8 +177,10 @@ tuntap_sys_create_dev(struct device *dev, int tun)
 		return -1;
 	}
 
-	fcntl(dev->tun_fd, F_SETFL, O_NONBLOCK);
-	fcntl(dev->tun_fd, F_SETFD, FD_CLOEXEC);
+	fcntl(if_fd, F_SETFL, O_NONBLOCK);
+	fcntl(if_fd, F_SETFD, FD_CLOEXEC);
+	fcntl(fd, F_SETFL, O_NONBLOCK);
+	fcntl(fd, F_SETFD, FD_CLOEXEC);
 	fcntl(dev->ip_fd, F_SETFD, FD_CLOEXEC);
 	char *msg = alloca(512);
 	sprintf(msg, "TUN device %s opened as %s", dev->if_name, dev->internal_name);
@@ -194,7 +196,8 @@ tuntap_sys_create_dev(struct device *dev, int tun)
 	}
 	/* Save flags for tuntap_{up, down} */
 	dev->flags = ifr.ifr_flags;
-	return 0;
+	dev->reserved = fd;
+	return if_fd;
 }
 
 int
@@ -245,6 +248,8 @@ tuntap_sys_destroy(struct device *dev)
 	}
 
 	close(dev->ip_fd);
+	close(dev->reserved);
+	dev->reserved = -1;
 	dev->ip_fd = -1;
 }