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use std::fmt;
use std::io::Cursor;
use byteorder::{ReadBytesExt, WriteBytesExt, BigEndian};
use crate::error::*;
use crate::packet::{Packet as P, PacketMut as PM, AsPacket, AsPacketMut};
use crate::icmp::Kind;
use crate::icmp::checksum;
pub struct Packet<B> {
buffer: B,
}
sized!(Packet,
header {
min: 4,
max: 4,
size: 4,
}
payload {
min: 0,
size: p => p.buffer.as_ref().len() - 4,
});
impl<B: AsRef<[u8]>> fmt::Debug for Packet<B> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct(if self.is_valid() { "icmp::Packet" } else { "icmp::Packet!" })
.field("kind", &self.kind())
.field("code", &self.code())
.field("checksum", &self.checksum())
.field("payload", &self.payload())
.finish()
}
}
impl<B: AsRef<[u8]>> Packet<B> {
pub fn unchecked(buffer: B) -> Packet<B> {
Packet { buffer }
}
pub fn new(buffer: B) -> Result<Packet<B>> {
use crate::size::header::Min;
let packet = Packet::unchecked(buffer);
if packet.buffer.as_ref().len() < Self::min() {
Err(Error::SmallBuffer)?
}
Ok(packet)
}
}
impl<B: AsRef<[u8]>> Packet<B> {
pub fn to_owned(&self) -> Packet<Vec<u8>> {
Packet::unchecked(self.buffer.as_ref().to_vec())
}
}
impl<B: AsRef<[u8]>> AsRef<[u8]> for Packet<B> {
fn as_ref(&self) -> &[u8] {
use crate::size::Size;
&self.buffer.as_ref()[.. self.size()]
}
}
impl<B: AsRef<[u8]> + AsMut<[u8]>> AsMut<[u8]> for Packet<B> {
fn as_mut(&mut self) -> &mut [u8] {
use crate::size::Size;
let size = self.size();
&mut self.buffer.as_mut()[.. size]
}
}
impl<'a, B: AsRef<[u8]>> AsPacket<'a, Packet<&'a [u8]>> for B {
fn as_packet(&self) -> Result<Packet<&[u8]>> {
Packet::new(self.as_ref())
}
}
impl<'a, B: AsRef<[u8]> + AsMut<[u8]>> AsPacketMut<'a, Packet<&'a mut [u8]>> for B {
fn as_packet_mut(&mut self) -> Result<Packet<&mut [u8]>> {
Packet::new(self.as_mut())
}
}
impl<B: AsRef<[u8]>> P for Packet<B> {
fn split(&self) -> (&[u8], &[u8]) {
self.buffer.as_ref().split_at(4)
}
}
impl<B: AsRef<[u8]> + AsMut<[u8]>> PM for Packet<B> {
fn split_mut(&mut self) -> (&mut [u8], &mut [u8]) {
self.buffer.as_mut().split_at_mut(4)
}
}
macro_rules! kind {
($(#[$attr:meta])* fn $module:ident[$mutable:ident]) => (
$(#[$attr])*
pub fn $module(&self) -> Result<crate::icmp::$module::Packet<&B>> {
crate::icmp::$module::Packet::new(&self.buffer)
}
$(#[$attr])*
pub fn $mutable(&mut self) -> Result<crate::icmp::$module::Packet<&mut B>> {
crate::icmp::$module::Packet::new(&mut self.buffer)
}
)
}
impl<B: AsRef<[u8]>> Packet<B> {
pub fn kind(&self) -> Kind {
Kind::from(self.buffer.as_ref()[0])
}
pub fn code(&self) -> u8 {
self.buffer.as_ref()[1]
}
pub fn checksum(&self) -> u16 {
(&self.buffer.as_ref()[2 ..]).read_u16::<BigEndian>().unwrap()
}
pub fn is_valid(&self) -> bool {
checksum(self.buffer.as_ref()) == self.checksum()
}
kind!(
fn echo[echo_mut]);
kind!(
fn timestamp[timestamp_mut]);
kind!(
fn information[information_mut]);
kind!(
fn parameter_problem[parameter_problem_mut]);
kind!(
fn redirect_message[redirect_message_mut]);
kind!(
fn previous[previous_mut]);
}
pub struct Checked<'a, P: PM + AsRef<[u8]> + AsMut<[u8]>> {
pub(in crate::icmp) packet: &'a mut P,
}
impl<'a, P: PM + AsRef<[u8]> + AsMut<[u8]> + 'a> Drop for Checked<'a, P> {
fn drop(&mut self) {
let checksum = checksum(self.packet.as_ref());
Cursor::new(&mut self.packet.as_mut()[2 ..])
.write_u16::<BigEndian>(checksum).unwrap();
}
}