[Openvpn-devel,2/3] tun: always pass a valid tt pointer

Message ID 20180613081218.1834-4-a@unstable.cc
State Changes Requested
Headers show
Series
  • Untitled series #248
Related show

Commit Message

Antonio Quartulli June 13, 2018, 8:12 a.m.
From: Antonio Quartulli <antonio@openvpn.net>

This patch is a small "logic restyle" which basically moves the
check for "tt != NULL" outside of the various close_tun()
implementations and replaces it with an ASSERT.

This way the check is done only once and the function can rely
on the assumption that "tt" is always valid.

This change is mainly to improve the code style inside close_tun()
implementations by removing one level of indentation.

No functional change is present.

Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
---
 src/openvpn/init.c |   7 +-
 src/openvpn/tun.c  | 434 ++++++++++++++++++++++-----------------------
 2 files changed, 220 insertions(+), 221 deletions(-)

Comments

Gert Doering June 13, 2018, 11:28 a.m. | #1
Hi,

On Wed, Jun 13, 2018 at 04:12:17PM +0800, Antonio Quartulli wrote:
> From: Antonio Quartulli <antonio@openvpn.net>
> 
> This patch is a small "logic restyle" which basically moves the
> check for "tt != NULL" outside of the various close_tun()
> implementations and replaces it with an ASSERT.
> 
> This way the check is done only once and the function can rely
> on the assumption that "tt" is always valid.
> 
> This change is mainly to improve the code style inside close_tun()
> implementations by removing one level of indentation.
> 
> No functional change is present.

Mostly-ACK-but :-)

The changes look good.  It won't apply after the gc_arena-fixed 1/3 of
this series, so we need a new one.

I've applied the patch and checked with "git diff -w", and it does what
it says on the lid...

Not sure the ASSERT(tt) is needed in solaris_error_close() - tt can
never be NULL there (because all the caller functions are working with
an active tt).  So I'd tend to leave that out, it's not doing something 
useful.


In those close_tun() instances where you removed the

else if (tt)
{

}

part - some of them had a comment ("/* close and destroy */").  Maybe
keep the comment?

As in

     if (tt->persistent_if)        /* keep pre-existing if around */
     {
         close_tun_generic(tt);
         free(tt);
         return;
     }

     /* close and destroy */            <<<<< this one
     struct argv argv = argv_new();

gert
Antonio Quartulli June 13, 2018, 11:38 a.m. | #2
Hi,

On 13/06/18 19:28, Gert Doering wrote:
> Hi,
> 
> On Wed, Jun 13, 2018 at 04:12:17PM +0800, Antonio Quartulli wrote:
>> From: Antonio Quartulli <antonio@openvpn.net>
>>
>> This patch is a small "logic restyle" which basically moves the
>> check for "tt != NULL" outside of the various close_tun()
>> implementations and replaces it with an ASSERT.
>>
>> This way the check is done only once and the function can rely
>> on the assumption that "tt" is always valid.
>>
>> This change is mainly to improve the code style inside close_tun()
>> implementations by removing one level of indentation.
>>
>> No functional change is present.
> 
> Mostly-ACK-but :-)
> 
> The changes look good.  It won't apply after the gc_arena-fixed 1/3 of
> this series, so we need a new one.
> 
> I've applied the patch and checked with "git diff -w", and it does what
> it says on the lid...
> 
> Not sure the ASSERT(tt) is needed in solaris_error_close() - tt can
> never be NULL there (because all the caller functions are working with
> an active tt).  So I'd tend to leave that out, it's not doing something 
> useful.

It's implicitly assumed, so I thought it would be helpful to make it
explicit (mostly to warn other devs to forget about that).

But I'll remove it if you think it's superfluous.


> 
> 
> In those close_tun() instances where you removed the
> 
> else if (tt)
> {
> 
> }
> 
> part - some of them had a comment ("/* close and destroy */").  Maybe
> keep the comment?
> 
> As in
> 
>      if (tt->persistent_if)        /* keep pre-existing if around */
>      {
>          close_tun_generic(tt);
>          free(tt);
>          return;
>      }
> 
>      /* close and destroy */            <<<<< this one
>      struct argv argv = argv_new();
> 
> gert
> 


ACK for the rest of the comments.


Cheers,

Patch

diff --git a/src/openvpn/init.c b/src/openvpn/init.c
index 36c1a4c4..b748357d 100644
--- a/src/openvpn/init.c
+++ b/src/openvpn/init.c
@@ -1847,8 +1847,11 @@  static void
 do_close_tun_simple(struct context *c)
 {
     msg(D_CLOSE, "Closing TUN/TAP interface");
-    close_tun(c->c1.tuntap);
-    c->c1.tuntap = NULL;
+    if (c->c1.tuntap)
+    {
+        close_tun(c->c1.tuntap);
+        c->c1.tuntap = NULL;
+    }
     c->c1.tuntap_owned = false;
 #if P2MP
     CLEAR(c->c1.pulled_options_digest_save);
diff --git a/src/openvpn/tun.c b/src/openvpn/tun.c
index 466d4d42..932c9d2d 100644
--- a/src/openvpn/tun.c
+++ b/src/openvpn/tun.c
@@ -1900,11 +1900,10 @@  open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tun
 void
 close_tun(struct tuntap *tt)
 {
-    if (tt)
-    {
-        close_tun_generic(tt);
-        free(tt);
-    }
+    ASSERT(tt);
+
+    close_tun_generic(tt);
+    free(tt);
 }
 
 int
@@ -2103,77 +2102,76 @@  tuncfg(const char *dev, const char *dev_type, const char *dev_node, int persist_
 void
 close_tun(struct tuntap *tt)
 {
-    if (tt)
+    ASSERT(tt);
+
+    if (tt->type != DEV_TYPE_NULL && tt->did_ifconfig)
     {
-        if (tt->type != DEV_TYPE_NULL && tt->did_ifconfig)
-        {
-            struct argv argv = argv_new();
-            struct gc_arena gc = gc_new();
+        struct argv argv = argv_new();
+        struct gc_arena gc = gc_new();
 
 #ifdef ENABLE_IPROUTE
-            if (is_tun_p2p(tt))
-            {
-                argv_printf(&argv,
-                            "%s addr del dev %s local %s peer %s",
-                            iproute_path,
-                            tt->actual_name,
-                            print_in_addr_t(tt->local, 0, &gc),
-                            print_in_addr_t(tt->remote_netmask, 0, &gc)
-                            );
-            }
-            else
-            {
-                argv_printf(&argv,
-                            "%s addr del dev %s %s/%d",
-                            iproute_path,
-                            tt->actual_name,
-                            print_in_addr_t(tt->local, 0, &gc),
-                            netmask_to_netbits2(tt->remote_netmask)
-                            );
-            }
-#else  /* ifdef ENABLE_IPROUTE */
+        if (is_tun_p2p(tt))
+        {
             argv_printf(&argv,
-                        "%s %s 0.0.0.0",
-                        IFCONFIG_PATH,
-                        tt->actual_name
-                        );
+                        "%s addr del dev %s local %s peer %s",
+                        iproute_path,
+                        tt->actual_name,
+                        print_in_addr_t(tt->local, 0, &gc),
+                        print_in_addr_t(tt->remote_netmask, 0, &gc)
+                       );
+        }
+        else
+        {
+            argv_printf(&argv,
+                        "%s addr del dev %s %s/%d",
+                        iproute_path,
+                        tt->actual_name,
+                        print_in_addr_t(tt->local, 0, &gc),
+                        netmask_to_netbits2(tt->remote_netmask)
+                       );
+        }
+#else  /* ifdef ENABLE_IPROUTE */
+        argv_printf(&argv,
+                    "%s %s 0.0.0.0",
+                    IFCONFIG_PATH,
+                    tt->actual_name
+                   );
 #endif /* ifdef ENABLE_IPROUTE */
 
-            argv_msg(M_INFO, &argv);
-            openvpn_execve_check(&argv, NULL, 0, "Linux ip addr del failed");
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, NULL, 0, "Linux ip addr del failed");
 
-            if (tt->did_ifconfig_ipv6_setup)
-            {
-                const char *ifconfig_ipv6_local = print_in6_addr(tt->local_ipv6, 0, &gc);
+        if (tt->did_ifconfig_ipv6_setup)
+        {
+            const char *ifconfig_ipv6_local = print_in6_addr(tt->local_ipv6, 0, &gc);
 
 #ifdef ENABLE_IPROUTE
-                argv_printf(&argv, "%s -6 addr del %s/%d dev %s",
-                            iproute_path,
-                            ifconfig_ipv6_local,
-                            tt->netbits_ipv6,
-                            tt->actual_name
-                            );
-                argv_msg(M_INFO, &argv);
-                openvpn_execve_check(&argv, NULL, 0, "Linux ip -6 addr del failed");
+            argv_printf(&argv, "%s -6 addr del %s/%d dev %s",
+                        iproute_path,
+                        ifconfig_ipv6_local,
+                        tt->netbits_ipv6,
+                        tt->actual_name
+                       );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, NULL, 0, "Linux ip -6 addr del failed");
 #else  /* ifdef ENABLE_IPROUTE */
-                argv_printf(&argv,
-                            "%s %s del %s/%d",
-                            IFCONFIG_PATH,
-                            tt->actual_name,
-                            ifconfig_ipv6_local,
-                            tt->netbits_ipv6
-                            );
-                argv_msg(M_INFO, &argv);
-                openvpn_execve_check(&argv, NULL, 0, "Linux ifconfig inet6 del failed");
+            argv_printf(&argv,
+                        "%s %s del %s/%d",
+                        IFCONFIG_PATH,
+                        tt->actual_name,
+                        ifconfig_ipv6_local,
+                        tt->netbits_ipv6
+                       );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, NULL, 0, "Linux ifconfig inet6 del failed");
 #endif
-            }
-
-            argv_reset(&argv);
-            gc_free(&gc);
         }
-        close_tun_generic(tt);
-        free(tt);
+
+        argv_reset(&argv);
+        gc_free(&gc);
     }
+    close_tun_generic(tt);
+    free(tt);
 }
 
 int
@@ -2491,18 +2489,17 @@  solaris_close_tun(struct tuntap *tt)
 void
 close_tun(struct tuntap *tt)
 {
-    if (tt)
-    {
-        solaris_close_tun(tt);
+    ASSERT(tt);
 
-        if (tt->actual_name)
-        {
-            free(tt->actual_name);
-        }
+    solaris_close_tun(tt);
 
-        clear_tuntap(tt);
-        free(tt);
+    if (tt->actual_name)
+    {
+        free(tt->actual_name);
     }
+
+    clear_tuntap(tt);
+    free(tt);
 }
 
 static void
@@ -2511,6 +2508,8 @@  solaris_error_close(struct tuntap *tt, const struct env_set *es,
 {
     struct argv argv = argv_new();
 
+    ASSERT(tt);
+
     if (unplumb_inet6)
     {
         argv_printf( &argv, "%s %s inet6 unplumb",
@@ -2591,33 +2590,34 @@  open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tun
 void
 close_tun(struct tuntap *tt)
 {
+    ASSERT(tt);
+
     /* only *TAP* devices need destroying, tun devices auto-self-destruct
      */
-    if (tt && (tt->type == DEV_TYPE_TUN || tt->persistent_if ) )
+    if (tt->type == DEV_TYPE_TUN || tt->persistent_if)
     {
         close_tun_generic(tt);
         free(tt);
+        return;
     }
-    else if (tt)
-    {
-        struct gc_arena gc = gc_new();
-        struct argv argv = argv_new();
 
-        /* setup command, close tun dev (clears tt->actual_name!), run command
-         */
+    struct gc_arena gc = gc_new();
+    struct argv argv = argv_new();
 
-        argv_printf(&argv, "%s %s destroy",
-                    IFCONFIG_PATH, tt->actual_name);
+    /* setup command, close tun dev (clears tt->actual_name!), run command
+    */
 
-        close_tun_generic(tt);
+    argv_printf(&argv, "%s %s destroy",
+                IFCONFIG_PATH, tt->actual_name);
 
-        argv_msg(M_INFO, &argv);
-        openvpn_execve_check(&argv, NULL, 0, "OpenBSD 'destroy tun interface' failed (non-critical)");
+    close_tun_generic(tt);
 
-        free(tt);
-        argv_reset(&argv);
-        gc_free(&gc);
-    }
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, NULL, 0, "OpenBSD 'destroy tun interface' failed (non-critical)");
+
+    free(tt);
+    argv_reset(&argv);
+    gc_free(&gc);
 }
 
 int
@@ -2678,33 +2678,34 @@  open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tun
 void
 close_tun(struct tuntap *tt)
 {
+    ASSERT(tt);
+
     /* only tun devices need destroying, tap devices auto-self-destruct
      */
-    if (tt && ( tt->type != DEV_TYPE_TUN || tt->persistent_if ) )
+    if (tt->type != DEV_TYPE_TUN || tt->persistent_if)
     {
         close_tun_generic(tt);
         free(tt);
+        return;
     }
-    else if (tt)
-    {
-        struct gc_arena gc = gc_new();
-        struct argv argv = argv_new();
 
-        /* setup command, close tun dev (clears tt->actual_name!), run command
-         */
+    struct gc_arena gc = gc_new();
+    struct argv argv = argv_new();
 
-        argv_printf(&argv, "%s %s destroy",
-                    IFCONFIG_PATH, tt->actual_name);
+    /* setup command, close tun dev (clears tt->actual_name!), run command
+    */
 
-        close_tun_generic(tt);
+    argv_printf(&argv, "%s %s destroy",
+                IFCONFIG_PATH, tt->actual_name);
 
-        argv_msg(M_INFO, &argv);
-        openvpn_execve_check(&argv, NULL, 0, "NetBSD 'destroy tun interface' failed (non-critical)");
+    close_tun_generic(tt);
 
-        free(tt);
-        argv_reset(&argv);
-        gc_free(&gc);
-    }
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, NULL, 0, "NetBSD 'destroy tun interface' failed (non-critical)");
+
+    free(tt);
+    argv_reset(&argv);
+    gc_free(&gc);
 }
 
 static inline int
@@ -2820,29 +2821,31 @@  open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tun
 void
 close_tun(struct tuntap *tt)
 {
-    if (tt && tt->persistent_if)        /* keep pre-existing if around */
+    ASSERT(tt);
+
+    if (tt->persistent_if)        /* keep pre-existing if around */
     {
         close_tun_generic(tt);
         free(tt);
+        return;
     }
-    else if (tt)                        /* close and destroy */
-    {
-        struct argv argv = argv_new();
 
-        /* setup command, close tun dev (clears tt->actual_name!), run command
-         */
+    struct argv argv = argv_new();
 
-        argv_printf(&argv, "%s %s destroy",
-                    IFCONFIG_PATH, tt->actual_name);
+    /* setup command, close tun dev (clears tt->actual_name!), run command
+    */
 
-        close_tun_generic(tt);
+    argv_printf(&argv, "%s %s destroy",
+                IFCONFIG_PATH, tt->actual_name);
 
-        argv_msg(M_INFO, &argv);
-        openvpn_execve_check(&argv, NULL, 0, "FreeBSD 'destroy tun interface' failed (non-critical)");
+    close_tun_generic(tt);
 
-        free(tt);
-        argv_reset(&argv);
-    }
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, NULL, 0,
+                         "FreeBSD 'destroy tun interface' failed (non-critical)");
+
+    free(tt);
+    argv_reset(&argv);
 }
 
 int
@@ -2933,11 +2936,10 @@  open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tun
 void
 close_tun(struct tuntap *tt)
 {
-    if (tt)
-    {
-        close_tun_generic(tt);
-        free(tt);
-    }
+    ASSERT(tt);
+
+    close_tun_generic(tt);
+    free(tt);
 }
 
 int
@@ -3190,27 +3192,26 @@  open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tun
 void
 close_tun(struct tuntap *tt)
 {
-    if (tt)
-    {
-        struct gc_arena gc = gc_new();
-        struct argv argv = argv_new();
+    ASSERT(tt);
 
-        if (tt->did_ifconfig_ipv6_setup)
-        {
-            const char *ifconfig_ipv6_local =
-                print_in6_addr(tt->local_ipv6, 0, &gc);
+    struct gc_arena gc = gc_new();
+    struct argv argv = argv_new();
 
-            argv_printf(&argv, "%s delete -inet6 %s",
-                        ROUTE_PATH, ifconfig_ipv6_local );
-            argv_msg(M_INFO, &argv);
-            openvpn_execve_check(&argv, NULL, 0, "MacOS X 'remove inet6 route' failed (non-critical)");
-        }
+    if (tt->did_ifconfig_ipv6_setup)
+    {
+        const char *ifconfig_ipv6_local =
+            print_in6_addr(tt->local_ipv6, 0, &gc);
 
-        close_tun_generic(tt);
-        free(tt);
-        argv_reset(&argv);
-        gc_free(&gc);
+        argv_printf(&argv, "%s delete -inet6 %s",
+                    ROUTE_PATH, ifconfig_ipv6_local );
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, NULL, 0, "MacOS X 'remove inet6 route' failed (non-critical)");
     }
+
+    close_tun_generic(tt);
+    free(tt);
+    argv_reset(&argv);
+    gc_free(&gc);
 }
 
 int
@@ -3339,15 +3340,12 @@  open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tun
 void
 close_tun(struct tuntap *tt)
 {
+    ASSERT(tt);
+
     struct gc_arena gc = gc_new();
     struct argv argv = argv_new();
     struct env_set *es = env_set_create(NULL);
 
-    if (!tt)
-    {
-        return;
-    }
-
     /* persistent devices need IP address unconfig, others need destroyal
      */
     if (tt->persistent_if)
@@ -6187,104 +6185,103 @@  tun_show_debug(struct tuntap *tt)
 void
 close_tun(struct tuntap *tt)
 {
+    ASSERT(tt);
+
     struct gc_arena gc = gc_new();
 
-    if (tt)
+    if (tt->did_ifconfig_ipv6_setup)
     {
-        if (tt->did_ifconfig_ipv6_setup)
-        {
-            /* remove route pointing to interface */
-            delete_route_connected_v6_net(tt, NULL);
+        /* remove route pointing to interface */
+        delete_route_connected_v6_net(tt, NULL);
 
-            if (tt->options.msg_channel)
+        if (tt->options.msg_channel)
+        {
+            do_address_service(false, AF_INET6, tt);
+            if (tt->options.dns6_len > 0)
             {
-                do_address_service(false, AF_INET6, tt);
-                if (tt->options.dns6_len > 0)
-                {
-                    do_dns6_service(false, tt);
-                }
+                do_dns6_service(false, tt);
             }
-            else
-            {
-                const char *ifconfig_ipv6_local;
-                struct argv argv = argv_new();
+        }
+        else
+        {
+            const char *ifconfig_ipv6_local;
+            struct argv argv = argv_new();
 
-                /* "store=active" is needed in Windows 8(.1) to delete the
-                 * address we added (pointed out by Cedric Tabary).
-                 */
+            /* "store=active" is needed in Windows 8(.1) to delete the
+             * address we added (pointed out by Cedric Tabary).
+             */
 
-                /* netsh interface ipv6 delete address \"%s\" %s */
-                ifconfig_ipv6_local = print_in6_addr(tt->local_ipv6, 0,  &gc);
+            /* netsh interface ipv6 delete address \"%s\" %s */
+            ifconfig_ipv6_local = print_in6_addr(tt->local_ipv6, 0,  &gc);
+            argv_printf(&argv,
+                        "%s%sc interface ipv6 delete address %s %s store=active",
+                        get_win_sys_path(),
+                        NETSH_PATH_SUFFIX,
+                        tt->actual_name,
+                        ifconfig_ipv6_local);
+
+            netsh_command(&argv, 1, M_WARN);
+
+            /* delete ipv6 dns servers if any were set */
+            if (tt->options.dns6_len > 0)
+            {
                 argv_printf(&argv,
-                            "%s%sc interface ipv6 delete address %s %s store=active",
+                            "%s%sc interface ipv6 delete dns %s all",
                             get_win_sys_path(),
                             NETSH_PATH_SUFFIX,
-                            tt->actual_name,
-                            ifconfig_ipv6_local);
-
+                            tt->actual_name);
                 netsh_command(&argv, 1, M_WARN);
-
-                /* delete ipv6 dns servers if any were set */
-                if (tt->options.dns6_len > 0)
-                {
-                    argv_printf(&argv,
-                                "%s%sc interface ipv6 delete dns %s all",
-                                get_win_sys_path(),
-                                NETSH_PATH_SUFFIX,
-                                tt->actual_name);
-                    netsh_command(&argv, 1, M_WARN);
-                }
-                argv_reset(&argv);
             }
+            argv_reset(&argv);
         }
+    }
 #if 1
-        if (tt->ipapi_context_defined)
+    if (tt->ipapi_context_defined)
+    {
+        DWORD status;
+        if ((status = DeleteIPAddress(tt->ipapi_context)) != NO_ERROR)
         {
-            DWORD status;
-            if ((status = DeleteIPAddress(tt->ipapi_context)) != NO_ERROR)
-            {
-                msg(M_WARN, "Warning: DeleteIPAddress[%u] failed on TAP-Windows adapter, status=%u : %s",
-                    (unsigned int)tt->ipapi_context,
-                    (unsigned int)status,
-                    strerror_win32(status, &gc));
-            }
+            msg(M_WARN, "Warning: DeleteIPAddress[%u] failed on TAP-Windows adapter, status=%u : %s",
+                (unsigned int)tt->ipapi_context,
+                (unsigned int)status,
+                strerror_win32(status, &gc));
         }
+    }
 #endif
 
-        dhcp_release(tt);
+    dhcp_release(tt);
 
-        if (tt->hand != NULL)
+    if (tt->hand != NULL)
+    {
+        dmsg(D_WIN32_IO_LOW, "Attempting CancelIO on TAP-Windows adapter");
+        if (!CancelIo(tt->hand))
         {
-            dmsg(D_WIN32_IO_LOW, "Attempting CancelIO on TAP-Windows adapter");
-            if (!CancelIo(tt->hand))
-            {
-                msg(M_WARN | M_ERRNO, "Warning: CancelIO failed on TAP-Windows adapter");
-            }
+            msg(M_WARN | M_ERRNO, "Warning: CancelIO failed on TAP-Windows adapter");
         }
+    }
 
-        dmsg(D_WIN32_IO_LOW, "Attempting close of overlapped read event on TAP-Windows adapter");
-        overlapped_io_close(&tt->reads);
-
-        dmsg(D_WIN32_IO_LOW, "Attempting close of overlapped write event on TAP-Windows adapter");
-        overlapped_io_close(&tt->writes);
+    dmsg(D_WIN32_IO_LOW, "Attempting close of overlapped read event on TAP-Windows adapter");
+    overlapped_io_close(&tt->reads);
 
-        if (tt->hand != NULL)
-        {
-            dmsg(D_WIN32_IO_LOW, "Attempting CloseHandle on TAP-Windows adapter");
-            if (!CloseHandle(tt->hand))
-            {
-                msg(M_WARN | M_ERRNO, "Warning: CloseHandle failed on TAP-Windows adapter");
-            }
-        }
+    dmsg(D_WIN32_IO_LOW, "Attempting close of overlapped write event on TAP-Windows adapter");
+    overlapped_io_close(&tt->writes);
 
-        if (tt->actual_name)
+    if (tt->hand != NULL)
+    {
+        dmsg(D_WIN32_IO_LOW, "Attempting CloseHandle on TAP-Windows adapter");
+        if (!CloseHandle(tt->hand))
         {
-            free(tt->actual_name);
+            msg(M_WARN | M_ERRNO, "Warning: CloseHandle failed on TAP-Windows adapter");
         }
+    }
 
-        clear_tuntap(tt);
-        free(tt);
+    if (tt->actual_name)
+    {
+        free(tt->actual_name);
     }
+
+    clear_tuntap(tt);
+    free(tt);
     gc_free(&gc);
 }
 
@@ -6363,11 +6360,10 @@  open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tun
 void
 close_tun(struct tuntap *tt)
 {
-    if (tt)
-    {
-        close_tun_generic(tt);
-        free(tt);
-    }
+    ASSERT(tt);
+
+    close_tun_generic(tt);
+    free(tt);
 }
 
 int