make writenet take const void * and size_t, abort if size it too large

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@15844 ec53bebd-3082-4978-b11e-865c3cabbd6b

appl/telnet/telnetd/utility.c

@@ -323,13 +323,15 @@ netflush(void)
  *    len - How many bytes to write
  */
 void
-writenet(unsigned char *ptr, int len)
+writenet(const void *ptr, size_t len)
 {
     /* flush buffer if no room for new data) */
     while ((&netobuf[BUFSIZ] - nfrontp) < len) {
 	/* if this fails, don't worry, buffer is a little big */
 	netflush();
     }
+    if ((&netobuf[BUFSIZ] - nfrontp) < len)
+	abort();
 
     memmove(nfrontp, ptr, len);
     nfrontp += len;