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#![feature(generators, generator_trait)]
use std::ops::Generator;
use std::time::Instant;
extern crate log;
extern crate osaka;
use std::time::Duration;
use osaka::mio;
use osaka::mio::net::UdpSocket;
use osaka::{osaka, Again, Poll};
use std::mem;
use std::net::SocketAddr;
use std::fs::File;
use std::io::{BufReader, BufRead};
#[derive(Debug)]
pub enum Error {
NameTooLong,
OutOfOptions,
Io(std::io::Error),
}
#[repr(C)]
pub struct DnsPacket {
id: u16,
flags: u16,
queries: u16,
answers: u16,
authorities: u16,
additionals: u16,
}
fn send_query(name: &str, sock: &UdpSocket, to: &SocketAddr) -> Result<(), Error> {
let mut pkt: DnsPacket = unsafe { mem::zeroed() };
pkt.id = 0x1337u16.to_be();
pkt.flags = 0x100u16.to_be();
pkt.queries = 1u16.to_be();
pkt.answers = 0;
pkt.authorities = 0;
pkt.additionals = 1u16.to_be();
if name.as_bytes().len() > 512 {
return Err(Error::NameTooLong);
}
let mut payload = unsafe {
std::slice::from_raw_parts(
(&pkt as *const DnsPacket) as *const u8,
mem::size_of::<DnsPacket>(),
)
}
.to_vec();
for label in name.split('.') {
payload.push(label.as_bytes().len() as u8);
payload.extend(label.as_bytes());
}
payload.extend(&[
0,
0,
0x10,
0,
1,
]);
payload.extend(&[
0,
0, 0x29,
0x03, 0xe8,
0,
0,
0, 0,
0, 0,
]);
log::debug!("attemping to resolve via {}", to);
sock.send_to(&payload, &to).unwrap();
Ok(())
}
fn get_system_dns_servers() -> Result<Vec<SocketAddr>, Error> {
let mut rr = Vec::new();
let f = File::open("/etc/resolv.conf").map_err(|e|Error::Io(e))?;
let f = BufReader::new(f);
for line in f.lines() {
let line = line.map_err(|e|Error::Io(e))?;
let mut line = line.split_whitespace();
if line.next() == Some("nameserver") {
if let Some(v) = line.next() {
if let Ok(v) = v.parse() {
rr.push(v);
}
let v = format!("{}:53", v);
if let Ok(v) = v.parse() {
rr.push(v);
}
}
}
}
Ok(rr)
}
#[osaka]
pub fn resolve(poll: Poll, names: Vec<String>) -> Result<Vec<String>, Error> {
let mut dns_servers = vec![
"1.1.1.1:53".parse().unwrap(),
"8.8.8.8:53".parse().unwrap(),
"9.9.9.9:53".parse().unwrap(),
"78.35.40.149:53".parse().unwrap(),
];
match get_system_dns_servers() {
Ok(mut v) => dns_servers.append(&mut v),
Err(e) => (),
};
for to in dns_servers {
for name in names.clone() {
let now = Instant::now();
let sock = UdpSocket::bind(&"0.0.0.0:0".parse().unwrap()).map_err(|e| Error::Io(e))?;
let token = poll
.register(&sock, mio::Ready::readable(), mio::PollOpt::level())
.unwrap();
send_query(&name, &sock, &to)?;
let pkt = match loop {
yield poll.again(token.clone(), Some(Duration::from_secs(2)));
if now.elapsed() >= Duration::from_secs(5) {
break None;
}
let mut buf = vec![0; 1024];
let (len, from) = match sock.recv_from(&mut buf) {
Ok(v) => v,
Err(e) => {
if e.kind() == std::io::ErrorKind::WouldBlock {
continue;
}
return Err(Error::Io(e));
}
};
if from == to && len >= mem::size_of::<DnsPacket>() {
buf.truncate(len);
break Some(buf);
}
} {
Some(v) => v,
None => continue,
};
let header: &DnsPacket = unsafe { mem::transmute(pkt.as_ptr() as *const DnsPacket) };
let answers = u16::from_be(header.answers);
if answers < 1 {
continue;
}
let mut at = mem::size_of::<DnsPacket>();
for _ in 0..u16::from_be(header.queries) {
while at < pkt.len() - 1 {
if pkt[at] == 0 {
at += 5;
break;
}
at += 1;
}
}
let mut answers = Vec::new();
for _ in 0..u16::from_be(header.answers) {
while at < pkt.len() - 1 {
if pkt[at] == 0 {
break;
}
if pkt[at] == 0xc0 {
at += 1;
break;
}
at += 1;
}
at += 1;
if at >= pkt.len() {
break;
}
let record_type: *const u16 =
unsafe { mem::transmute(pkt[at..].as_ptr() as *const u16) };
let record_type = u16::from_be(unsafe { *record_type });
at += 2;
if at >= pkt.len() {
break;
}
let record_class: *const u16 =
unsafe { mem::transmute(pkt[at..].as_ptr() as *const u16) };
let record_class = u16::from_be(unsafe { *record_class });
at += 6;
if at >= pkt.len() {
break;
}
let record_len: *const u16 =
unsafe { mem::transmute(pkt[at..].as_ptr() as *const u16) };
let record_len = u16::from_be(unsafe { *record_len }) as usize;
at += 2;
if at + record_len > pkt.len() {
break;
}
if record_type == 0x10 && record_class == 0x01 {
answers
.push(String::from_utf8_lossy(&pkt[at + 1..at + record_len]).to_string());
}
at += record_len;
}
if answers.len() > 0 {
return Ok(answers);
}
}
}
Err(Error::OutOfOptions)
}
#[cfg(test)]
extern crate tinylogger;
#[osaka]
#[cfg(test)]
pub fn r(poll: Poll) -> Result<(), Error> {
let mut a = resolve(
poll.clone(),
vec![
"4.carrier.devguard.io".into(),
"x.carrier.devguard.io".into(),
],
);
let y = osaka::sync!(a);
println!("{:?}", y);
Ok(())
}
#[test]
pub fn main() {
tinylogger::init().ok();
let poll = osaka::Poll::new();
r(poll).run().unwrap();
}