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;
@@ -45,6 +46,10 @@ static struct {
     int mtu_auto;
     int chacha20;
     int version;
+    struct {
+        unsigned char *data;
+        long size;
+    } buf;
 } gt = {
     .port = 5000,
     .bind = {
@@ -56,6 +61,9 @@ static struct {
 #ifdef __linux__
     .ipv6 = 1,
 #endif
+    .buf = {
+        .size = 64 * 1024,
+    },
 };
 
 static void
@@ -80,6 +88,7 @@ fd_set_nonblock(int fd)
 static void
 gt_quit_handler(int sig)
 {
+    gt.reload = (sig == SIGHUP);
     gt.quit = 1;
 }
 
@@ -96,9 +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);
@@ -186,6 +195,7 @@ gt_setup_option(int argc, char **argv)
         { "v4only",         NULL,               option_option },
         { "v6only",         NULL,               option_option },
         { "chacha20",       NULL,               option_option },
+        { "buf-size",       &gt.buf.size,       option_long   },
         { "version",        NULL,               option_option },
         {  NULL                                               },
     };
@@ -213,6 +223,11 @@ gt_setup_option(int argc, char **argv)
         return 1;
     }
 
+    if (gt.buf.size <= 0) {
+        gt_log("bad buf-size\n");
+        return 1;
+    }
+
     if (v4only) {
         gt.ipv4 = 1;
         gt.ipv6 = 0;
@@ -227,6 +242,8 @@ gt_setup_option(int argc, char **argv)
     gt.chacha20 = option_is_set(opts, "chacha20");
     gt.version = option_is_set(opts, "version");
 
+    gt.buf.data = malloc(gt.buf.size);
+
     return 0;
 }
 
@@ -277,6 +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));
 
@@ -345,8 +365,6 @@ main(int argc, char **argv)
     fd_set rfds;
     FD_ZERO(&rfds);
 
-    unsigned char buf[8 * 1024];
-
     int last_fd = 1 + MAX(tun_fd, MAX(mud_fd, icmp_fd));
 
     while (!gt.quit) {
@@ -366,12 +384,12 @@ main(int argc, char **argv)
         if (icmp_fd != -1 && FD_ISSET(icmp_fd, &rfds)) {
             struct sockaddr_storage ss;
             socklen_t sl = sizeof(ss);
-            ssize_t r = recvfrom(icmp_fd, buf, sizeof(buf), 0,
+            ssize_t r = recvfrom(icmp_fd, gt.buf.data, gt.buf.size, 0,
                                  (struct sockaddr *)&ss, &sl);
             if (r >= 8) {
                 struct ip_common ic;
-                if (!ip_get_common(&ic, buf, r) && ic.proto == 1) {
-                    unsigned char *data = &buf[ic.hdr_size];
+                if (!ip_get_common(&ic, gt.buf.data, r) && ic.proto == 1) {
+                    unsigned char *data = &gt.buf.data[ic.hdr_size];
                     if (data[0] == 3) {
                         int mtu = (data[6] << 8) | data[7];
                         if (mtu) {
@@ -386,15 +404,15 @@ main(int argc, char **argv)
         if (FD_ISSET(tun_fd, &rfds)) {
             size_t size = 0;
 
-            while (sizeof(buf) - size >= gt.mtu) {
-                const int r = tun_read(tun_fd, &buf[size], sizeof(buf) - size);
+            while (gt.buf.size - size >= gt.mtu) {
+                const int r = tun_read(tun_fd, &gt.buf.data[size], gt.buf.size - size);
 
                 if (r <= 0 || r > gt.mtu)
                     break;
 
                 struct ip_common ic;
 
-                if (ip_get_common(&ic, &buf[size], r) || ic.size != r)
+                if (ip_get_common(&ic, &gt.buf.data[size], r) || ic.size != r)
                     break;
 
                 size += r;
@@ -409,7 +427,7 @@ main(int argc, char **argv)
                 while (q < size) {
                     struct ip_common ic;
 
-                    if ((ip_get_common(&ic, &buf[q], size - q)) ||
+                    if ((ip_get_common(&ic, &gt.buf.data[q], size - q)) ||
                         (ic.size > size - q))
                         break;
 
@@ -425,7 +443,7 @@ main(int argc, char **argv)
                 if (p >= q)
                     break;
 
-                int r = mud_send(mud, &buf[p], q - p, tc);
+                int r = mud_send(mud, &gt.buf.data[p], q - p, tc);
 
                 if (r == -1 && errno == EMSGSIZE) {
                     gt_setup_mtu(mud, tun_name);
@@ -439,31 +457,40 @@ main(int argc, char **argv)
         }
 
         if (FD_ISSET(mud_fd, &rfds)) {
-            while (1) {
-                const int size = mud_recv(mud, buf, sizeof(buf));
+            size_t size = 0;
 
-                if (size <= 0) {
-                    if (size == -1 && errno != EAGAIN)
+            while (gt.buf.size - size >= gt.mtu) {
+                const int r = mud_recv(mud, &gt.buf.data[size], gt.buf.size - size);
+
+                if (r <= 0) {
+                    if (r == -1 && errno != EAGAIN)
                         perror("mud_recv");
                     break;
                 }
 
-                int p = 0;
+                size += r;
+            }
 
-                while (p < size) {
-                    struct ip_common ic;
+            int p = 0;
 
-                    if ((ip_get_common(&ic, &buf[p], size - p)) ||
-                        (ic.size > size - p))
-                        break;
+            while (p < size) {
+                struct ip_common ic;
 
-                    tun_write(tun_fd, &buf[p], ic.size);
+                if ((ip_get_common(&ic, &gt.buf.data[p], size - p)) ||
+                    (ic.size > size - p))
+                    break;
 
-                    p += ic.size;
-                }
+                tun_write(tun_fd, &gt.buf.data[p], ic.size);
+
+                p += ic.size;
             }
         }
     }
 
+    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

@@ -1,6 +1,7 @@
 #pragma once
 
-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_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);