net: refactor vnet_hdr methods

We're going to use it from different modules, so move them upper in the
crate.

Signed-off-by: Sergio Lopez <[email protected]>

Author: slp

src/devices/src/virtio/net/mod.rs

@@ -1,7 +1,9 @@
 // Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-use std::{io, result};
+use std::{io, mem, result};
+use virtio_bindings::virtio_net::virtio_net_hdr_v1;
+
 pub const MAX_BUFFER_SIZE: usize = 65562;
 pub const QUEUE_SIZE: u16 = 1024;
 pub const NUM_QUEUES: usize = 2;
@@ -17,6 +19,18 @@ mod unixgram;
 mod unixstream;
 mod worker;
 
+fn vnet_hdr_len() -> usize {
+    mem::size_of::<virtio_net_hdr_v1>()
+}
+
+// This initializes to all 0 the virtio_net_hdr part of a buf and return the length of the header
+// https://docs.oasis-open.org/virtio/virtio/v1.1/csprd01/virtio-v1.1-csprd01.html#x1-2050006
+fn write_virtio_net_hdr(buf: &mut [u8]) -> usize {
+    let len = vnet_hdr_len();
+    buf[0..len].fill(0);
+    len
+}
+
 pub use self::device::Net;
 #[derive(Debug)]
 pub enum Error {

src/devices/src/virtio/net/worker.rs

@@ -5,27 +5,15 @@ use crate::virtio::{InterruptTransport, Queue};
 
 use super::backend::{NetBackend, ReadError, WriteError};
 use super::device::{FrontendError, RxError, TxError, VirtioNetBackend};
+use super::{vnet_hdr_len, write_virtio_net_hdr};
 
 use std::os::fd::AsRawFd;
 use std::thread;
-use std::{cmp, mem, result};
+use std::{cmp, result};
 use utils::epoll::{ControlOperation, Epoll, EpollEvent, EventSet};
 use utils::eventfd::EventFd;
-use virtio_bindings::virtio_net::virtio_net_hdr_v1;
 use vm_memory::{Bytes, GuestAddress, GuestMemoryMmap};
 
-fn vnet_hdr_len() -> usize {
-    mem::size_of::<virtio_net_hdr_v1>()
-}
-
-// This initializes to all 0 the virtio_net_hdr part of a buf and return the length of the header
-// https://docs.oasis-open.org/virtio/virtio/v1.1/csprd01/virtio-v1.1-csprd01.html#x1-2050006
-fn write_virtio_net_hdr(buf: &mut [u8]) -> usize {
-    let len = vnet_hdr_len();
-    buf[0..len].fill(0);
-    len
-}
-
 pub struct NetWorker {
     queues: Vec<Queue>,
     queue_evts: Vec<EventFd>,