Allow a CIDR mask (/24) instead of subnetmask in config

parser.c

@@ -403,18 +403,34 @@ int HIDDENSYM make_netent(char *value, struct netent **ent)
         free(*ent);
         return (2);
     }
+
+    // Check if there's a dot in the subnet string.
+    if (strstr(subnet, ".") != NULL) {
+        // There's a dot, so it's a netmask like 255.255.255.0
 #ifdef HAVE_INET_ADDR
-    else if (((*ent)->localnet.s_addr = inet_addr(subnet)) == -1)
-    {
+        if (((*ent)->localnet.s_addr = inet_addr(subnet)) == -1)
+        {
 #elif defined(HAVE_INET_ATON)
-    else if (!(inet_aton(subnet, &((*ent)->localnet))))
-    {
+        if (!(inet_aton(subnet, &((*ent)->localnet))))
+        {
 #endif
-        /* Badly constructed subnet */
-        free(*ent);
-        return (3);
+            /* Badly constructed subnet */
+            free(*ent);
+            return (3);
+        }
     }
-    else if (((*ent)->localip.s_addr & (*ent)->localnet.s_addr) != (*ent)->localip.s_addr)
+    else {
+        // No dot, probably a mask like /24
+        int mask_size = atoi(subnet);
+        if (mask_size < 0 || mask_size > 32) {
+            /* Bad mask */
+            free (*ent);
+            return (3);
+        }
+        (*ent)->localnet.s_addr = htonl((0xFFFFFFFFUL << (32-mask_size)) & 0xFFFFFFFFUL);
+    }
+
+    if (((*ent)->localip.s_addr & (*ent)->localnet.s_addr) != (*ent)->localip.s_addr)
     {
         /* Subnet and Ip != Ip */
         free(*ent);

tnat64.conf.complex.example

@@ -12,10 +12,10 @@
 # the man pages, tnat64(8) and tnat64.conf(8)
 
 # Local networks
-# For this example this machine can directly access 192.168.0.0/255.255.255.0 
+# For this example this machine can directly access 192.168.0.0/24 
 # (192.168.0.*) and 10.0.0.0/255.0.0.0 (10.*)
 
-local = 192.168.0.0/255.255.255.0
+local = 192.168.0.0/24
 local = 10.0.0.0/255.0.0.0
 
 # Paths