Prepare for choosing device name

iodine.c

@@ -247,7 +247,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	if ((tun_fd = open_tun()) == -1)
+	if ((tun_fd = open_tun(NULL)) == -1)
 		goto cleanup1;
 	if ((dns_fd = open_dns(argv[1], 0)) == -1)
 		goto cleanup2;

iodined.c

@@ -263,7 +263,7 @@ main(int argc, char **argv)
 		usage();
 	}
 
-	if ((tun_fd = open_tun()) == -1)
+	if ((tun_fd = open_tun(NULL)) == -1)
 		goto cleanup0;
 	if (tun_setip(argv[0]) != 0 || tun_setmtu(mtu) != 0)
 		goto cleanup1;

tun.c

@@ -31,7 +31,6 @@
 
 #define TUN_MAX_TRY 50
 
-char *tun_device = NULL;
 char if_name[50];
 
 #ifdef LINUX
@@ -41,17 +40,15 @@ char if_name[50];
 #include <linux/if_tun.h>
 
 int 
-open_tun() 
+open_tun(const char *tun_device) 
 {
 	int i;
 	int tun_fd;
 	struct ifreq ifreq;
+	char *tunnel = "/dev/net/tun";
 
-	if (tun_device == NULL)
+	if ((tun_fd = open(tunnel, O_RDWR)) < 0) {
-		tun_device = "/dev/net/tun";
+		warn("open_tun: %s: %s", tunnel, strerror(errno));
-
-	if ((tun_fd = open(tun_device, O_RDWR)) < 0) {
-		warn("open_tun: %s: %s", tun_device, strerror(errno));
 		return -1;
 	}
 
@@ -59,6 +56,20 @@ open_tun()
 
 	ifreq.ifr_flags = IFF_TUN; 
 
+	if (tun_device != NULL) {
+			strncpy(ifreq.ifr_name, tun_device, IFNAMSIZ);
+
+			if (ioctl(tun_fd, TUNSETIFF, (void *) &ifreq) != -1) {
+				printf("Opened %s\n", ifreq.ifr_name);
+				snprintf(if_name, sizeof(if_name), "dns%d", i);
+				return tun_fd;
+			}
+
+			if (errno != EBUSY) {
+				warn("open_tun: ioctl[TUNSETIFF]: %s", strerror(errno));
+				return -1;
+			}
+	} else {
 		for (i = 0; i < TUN_MAX_TRY; i++) {
 			snprintf(ifreq.ifr_name, IFNAMSIZ, "dns%d", i);
 
@@ -75,14 +86,14 @@ open_tun()
 		}
 
 		warn("open_tun: Couldn't set interface name.\n");
-	
+	}
 	return -1;
 }
 
 #else /* BSD */
 
 int 
-open_tun() 
+open_tun(const char *tun_device) 
 {
 	int i;
 	int tun_fd;

tun.h

@@ -19,7 +19,7 @@
 #ifndef _TUN_H_
 #define _TUN_H_
 
-int open_tun();
+int open_tun(const char *);
 void close_tun(int);
 int write_tun(int, char *, int);
 int read_tun(int, char *, int);