mirror of https://github.com/dswd/vpncloud.git
97 lines
3.1 KiB
Rust
97 lines
3.1 KiB
Rust
use std::{mem, ptr, fmt};
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use super::ethcloud::{Mac, Error};
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use super::util::{as_bytes, as_obj};
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pub type VlanId = u16;
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#[derive(PartialEq)]
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pub struct Frame<'a> {
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pub vlan: VlanId,
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pub src: &'a Mac,
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pub dst: &'a Mac,
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pub payload: &'a [u8]
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}
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impl<'a> fmt::Debug for Frame<'a> {
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fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
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write!(formatter, "src: {:?}, dst: {:?}, vlan: {}, payload: {} bytes",
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self.src, self.dst, self.vlan, self.payload.len())
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}
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}
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pub fn decode(data: &[u8]) -> Result<Frame, Error> {
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if data.len() < 14 {
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return Err(Error::ParseError("Frame is too short"));
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}
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let mut pos = 0;
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let dst = unsafe { as_obj::<Mac>(&data[pos..]) };
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pos += mem::size_of::<Mac>();
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let src = unsafe { as_obj::<Mac>(&data[pos..]) };
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pos += mem::size_of::<Mac>();
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let mut vlan = 0;
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let mut payload = &data[pos..];
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if data[pos] == 0x81 && data[pos+1] == 0x00 {
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pos += 2;
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if data.len() < pos + 2 {
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return Err(Error::ParseError("Vlan frame is too short"));
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}
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vlan = u16::from_be(* unsafe { as_obj::<u16>(&data[pos..]) });
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pos += 2;
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payload = &data[pos..];
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}
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Ok(Frame{vlan: vlan, src: src, dst: dst, payload: payload})
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}
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pub fn encode(frame: &Frame, buf: &mut [u8]) -> usize {
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assert!(buf.len() >= 16 + frame.payload.len());
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let mut pos = 0;
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unsafe {
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let dst_dat = as_bytes::<Mac>(frame.dst);
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ptr::copy_nonoverlapping(dst_dat.as_ptr(), buf[pos..].as_mut_ptr(), dst_dat.len());
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pos += dst_dat.len();
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let src_dat = as_bytes::<Mac>(frame.src);
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ptr::copy_nonoverlapping(src_dat.as_ptr(), buf[pos..].as_mut_ptr(), src_dat.len());
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pos += src_dat.len();
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if frame.vlan != 0 {
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buf[pos] = 0x81; buf[pos+1] = 0x00;
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pos += 2;
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let vlan_dat = mem::transmute::<u16, [u8; 2]>(frame.vlan.to_be());
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ptr::copy_nonoverlapping(vlan_dat.as_ptr(), buf[pos..].as_mut_ptr(), vlan_dat.len());
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pos += vlan_dat.len();
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}
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ptr::copy_nonoverlapping(frame.payload.as_ptr(), buf[pos..].as_mut_ptr(), frame.payload.len());
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}
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pos += frame.payload.len();
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pos
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}
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#[test]
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fn without_vlan() {
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let src = Mac([1,2,3,4,5,6]);
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let dst = Mac([6,5,4,3,2,1]);
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let payload = [1,2,3,4,5,6,7,8];
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let mut buf = [0u8; 1024];
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let frame = Frame{src: &src, dst: &dst, vlan: 0, payload: &payload};
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let size = encode(&frame, &mut buf);
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assert_eq!(size, 20);
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assert_eq!(&buf[..size], &[6,5,4,3,2,1,1,2,3,4,5,6,1,2,3,4,5,6,7,8]);
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let frame2 = decode(&buf[..size]).unwrap();
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assert_eq!(frame, frame2);
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}
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#[test]
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fn with_vlan() {
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let src = Mac([1,2,3,4,5,6]);
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let dst = Mac([6,5,4,3,2,1]);
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let payload = [1,2,3,4,5,6,7,8];
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let mut buf = [0u8; 1024];
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let frame = Frame{src: &src, dst: &dst, vlan: 1234, payload: &payload};
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let size = encode(&frame, &mut buf);
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assert_eq!(size, 24);
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assert_eq!(&buf[..size], &[6,5,4,3,2,1,1,2,3,4,5,6,0x81,0,4,210,1,2,3,4,5,6,7,8]);
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let frame2 = decode(&buf[..size]).unwrap();
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assert_eq!(frame, frame2);
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}
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