Fix buffer overflow

When compiling, the following warning message is generated:
"warning: ‘strncpy’ writing 1040 bytes into a region of size
1024 overflows the destination"
This is because calloc allocates NLMSG_SPACE(MAX_PAYLOAD)
space for nlh, which includes the space for the header,
so the actual space available for the message is only
MAX_PAYLOAD.

Author: jychen0611

vwifi-tool.c

@@ -92,7 +92,7 @@ bool denylist_send(char *denylist)
     nlh->nlmsg_pid = getpid();
     nlh->nlmsg_flags = 0;
 
-    strncpy(NLMSG_DATA(nlh), denylist, NLMSG_SPACE(MAX_PAYLOAD));
+    strncpy(NLMSG_DATA(nlh), denylist, MAX_PAYLOAD);
 
     struct iovec iov = {
         .iov_base = (void *) nlh,