message: Error generate if packets is empty for winpcap
diff: @@ -19,7 +19,7 @@ use ipnetwork::{ip_mask_to_prefix, IpNetwork};
  use std::cmp;
  use std::collections::VecDeque;
  use std::ffi::{CStr, CString};
  -use std::io;
  +use std::io::{self, Error, ErrorKind};
  use std::mem;
  use std::slice;
  use std::str::from_utf8_unchecked;
  @@ -253,7 +253,12 @@ impl DataLinkReceiver for DataLinkReceiverImpl {
  }
  }
  }
  - let (start, len) = self.packets.pop_front().unwrap();
  + let (start, len) = match self.packets.pop_front(){
  + Some(p) => (p),
  + None => {
  + return Err(Error::new(ErrorKind::Interrupted,"packets is empty"));
  + }
  + };
  let slice = unsafe {
  let data = (*self.packet.packet).Buffer as usize + start;
  slice::from_raw_parts(data as *const u8, len)
  