tun-device: Avoid opening /dev/tunX multiple times (e.g. on FreeBSD)

diff --git a/src/libstrongswan/networking/tun_device.c b/src/libstrongswan/networking/tun_device.c
index 2191198e2927d69ad6fa1833cf689311af0f5fe2..00de2eddf5342a76c6fcfb60a355dbb999625f28 100644 (file)
--- a/src/libstrongswan/networking/tun_device.c
+++ b/src/libstrongswan/networking/tun_device.c
@@ -390,14 +390,18 @@ static bool init_tun(private_tun_device_t *this, const char *name_tmpl)
        /* this works on FreeBSD and might also work on Linux with older TUN
         * driver versions (no IFF_TUN) */
        char devname[IFNAMSIZ];
-       int i;
+       /* the same process is allowed to open a device again, but that's not what
+        * we want (unless we previously closed a device, which we don't know at
+        * this point).  therefore, this counter is static so we don't accidentally
+        * open a device twice */
+       static int i = -1;
 
        if (name_tmpl)
        {
                DBG1(DBG_LIB, "arbitrary naming of TUN devices is not supported");
        }
 
-       for (i = 0; i < 256; i++)
+       for (; ++i < 256; )
        {
                snprintf(devname, IFNAMSIZ, "/dev/tun%d", i);
                this->tunfd = open(devname, O_RDWR);