Don't destroy tun on SIGHUP

src/main.c

@@ -28,6 +28,7 @@
 
 static struct {
     volatile sig_atomic_t quit;
+    volatile sig_atomic_t reload;
     char *dev;
     char *keyfile;
     char *host;
@@ -87,6 +88,7 @@ fd_set_nonblock(int fd)
 static void
 gt_quit_handler(int sig)
 {
+    gt.reload = (sig == SIGHUP);
     gt.quit = 1;
 }
 
@@ -103,9 +105,9 @@ gt_set_signal(void)
     sigaction(SIGINT, &sa, NULL);
     sigaction(SIGQUIT, &sa, NULL);
     sigaction(SIGTERM, &sa, NULL);
+    sigaction(SIGHUP, &sa, NULL);
 
     sa.sa_handler = SIG_IGN;
-    sigaction(SIGHUP, &sa, NULL);
     sigaction(SIGPIPE, &sa, NULL);
     sigaction(SIGUSR1, &sa, NULL);
     sigaction(SIGUSR2, &sa, NULL);
@@ -292,6 +294,9 @@ main(int argc, char **argv)
         return 1;
     }
 
+    if (tun_set_persist(tun_fd, 0) == -1)
+        perror("tun_set_persist");
+
     struct mud *mud = mud_create(gt.bind.port, gt.ipv4, gt.ipv6,
                                  !gt.chacha20, GT_MTU(gt.mtu));
 
@@ -482,5 +487,10 @@ main(int argc, char **argv)
         }
     }
 
+    if (gt.reload && tun_fd >= 0) {
+        if (tun_set_persist(tun_fd, 1) == -1)
+            perror("tun_set_persist");
+    }
+
     return 0;
 }

src/tun.c

@@ -17,6 +17,7 @@
 #define IFF_TUN 0x0001
 #define IFF_NO_PI 0x1000
 #define TUNSETIFF _IOW('T', 202, int)
+#define TUNSETPERSIST _IOW('T', 203, int)
 #endif
 
 #ifdef __APPLE__
@@ -260,3 +261,9 @@ tun_set_mtu(char *dev_name, int mtu)
 
     return ret;
 }
+
+int
+tun_set_persist(int fd, int on)
+{
+    return ioctl(fd, TUNSETPERSIST, on);
+}

src/tun.h

@@ -4,3 +4,4 @@ int tun_create  (char *, char **);
 int tun_read        (int, void *, size_t);
 int tun_write       (int, const void *, size_t);
 int tun_set_mtu     (char *, int);
+int tun_set_persist (int, int);