fix

main.cpp

@@ -49,8 +49,17 @@ int main(int argc, char *argv[]) {
     ifr.ifr_flags = IFF_TUN | IFF_NO_PI;
 
     auto raw = socket(AF_INET, SOCK_RAW, IPPROTO_IPIP);
+    if(raw < 0){
+        perror("socket init error");
+    }
     auto tun = open("/dev/net/tun", O_RDWR);
-    ioctl(tun, TUNSETIFF, &ifr);
+    if(tun < 0){
+        perror("tun init error");
+    }
+    
+    if(ioctl(tun, TUNSETIFF, &ifr) < 0){
+        perror("ioctl error");
+    }
 
     remote = inet_addr(argv[1]);