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use std::cell::Cell;
use std::net::{IpAddr, Ipv4Addr, SocketAddr, UdpSocket};
use crate::options;
use crate::options::{DhcpOption, MessageType};
use crate::packet::*;
pub struct Server {
out_buf: Cell<[u8; 1500]>,
socket: UdpSocket,
src: SocketAddr,
server_ip: Ipv4Addr,
}
pub trait Handler {
fn handle_request(&mut self, server: &Server, in_packet: Packet);
}
pub fn filter_options_by_req(opts: &mut Vec<DhcpOption>, req_params: &[u8]) {
let mut pos = 0;
let h = &[
options::DHCP_MESSAGE_TYPE as u8,
options::SERVER_IDENTIFIER as u8,
options::IP_ADDRESS_LEASE_TIME as u8,
] as &[u8];
for z in [h, req_params].iter() {
for r in z.iter() {
let mut found = false;
let mut at = 0;
for (i, o) in opts[pos..].iter().enumerate() {
if o.code() == *r {
found = true;
at = i + pos;
break;
}
}
if found {
opts.swap(pos, at);
pos += 1;
}
}
}
opts.truncate(pos);
}
impl Server {
pub fn serve<H: Handler>(
udp_soc: UdpSocket,
server_ip: Ipv4Addr,
mut handler: H,
) -> std::io::Error {
let mut in_buf: [u8; 1500] = [0; 1500];
let mut s = Server {
out_buf: Cell::new([0; 1500]),
socket: udp_soc,
server_ip,
src: SocketAddr::new(IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)), 0),
};
loop {
match s.socket.recv_from(&mut in_buf) {
Err(e) => return e,
Ok((l, src)) => {
if let Ok(p) = Packet::from(&in_buf[..l]) {
s.src = src;
handler.handle_request(&s, p);
}
}
}
}
}
pub fn reply(
&self,
msg_type: MessageType,
additional_options: Vec<DhcpOption>,
offer_ip: Ipv4Addr,
req_packet: Packet,
) -> std::io::Result<usize> {
let ciaddr = match msg_type {
MessageType::Nak => Ipv4Addr::new(0, 0, 0, 0),
_ => req_packet.ciaddr,
};
let mut opts: Vec<DhcpOption> = Vec::with_capacity(additional_options.len() + 2);
opts.push(DhcpOption::DhcpMessageType(msg_type));
opts.push(DhcpOption::ServerIdentifier(self.server_ip));
opts.extend(additional_options);
if let Some(DhcpOption::ParameterRequestList(prl)) =
req_packet.option(options::PARAMETER_REQUEST_LIST)
{
filter_options_by_req(&mut opts, &prl);
}
self.send(Packet {
reply: true,
hops: 0,
xid: req_packet.xid,
secs: 0,
broadcast: req_packet.broadcast,
ciaddr,
yiaddr: offer_ip,
siaddr: Ipv4Addr::new(0, 0, 0, 0),
giaddr: req_packet.giaddr,
chaddr: req_packet.chaddr,
options: opts,
})
}
pub fn for_this_server(&self, packet: &Packet) -> bool {
match packet.option(options::SERVER_IDENTIFIER) {
Some(DhcpOption::ServerIdentifier(x)) => (x == &self.server_ip),
_ => false,
}
}
pub fn send(&self, p: Packet) -> std::io::Result<usize> {
let mut addr = self.src;
if p.broadcast || addr.ip() == IpAddr::V4(Ipv4Addr::new(0, 0, 0, 0)) {
addr.set_ip(IpAddr::V4(Ipv4Addr::new(255, 255, 255, 255)));
}
self.socket.send_to(p.encode(&mut self.out_buf.get()), addr)
}
}