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use async_trait::async_trait;
use libp2prs_core::transport::{IListener, ITransport};
use libp2prs_core::{
multiaddr::{protocol, protocol::Protocol, Multiaddr},
transport::TransportError,
Transport,
};
use libp2prs_runtime::net;
use log::{error, trace};
use std::{error, fmt, io};
#[derive(Clone)]
pub struct DnsConfig<T> {
inner: T,
}
impl<T> DnsConfig<T> {
pub fn new(inner: T) -> Self {
DnsConfig { inner }
}
}
impl<T> fmt::Debug for DnsConfig<T>
where
T: fmt::Debug,
{
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt.debug_tuple("DnsConfig").field(&self.inner).finish()
}
}
#[async_trait]
impl<T> Transport for DnsConfig<T>
where
T: Transport + Clone + 'static,
{
type Output = T::Output;
fn listen_on(&mut self, addr: Multiaddr) -> Result<IListener<Self::Output>, TransportError> {
self.inner.listen_on(addr)
}
async fn dial(&mut self, addr: Multiaddr) -> Result<Self::Output, TransportError> {
let mut iter = addr.iter();
let proto = iter.find_map(|x| match x {
Protocol::Dns(name) => Some((name, true, true)),
Protocol::Dns4(name) => Some((name, true, false)),
Protocol::Dns6(name) => Some((name, false, true)),
_ => None,
});
let index = addr.iter().count() - iter.count() - 1;
let (name, dns4, dns6) = match proto {
Some((name, dns4, dns6)) => (name, dns4, dns6),
None => {
trace!("Pass-through address without DNS: {}", addr);
return self.inner.dial(addr).await;
}
};
let name = name.to_string();
let to_resolve = format!("{}:0", name);
let list = net::resolve_host(to_resolve).await.map_err(|_| {
error!("DNS resolver crashed");
TransportError::ResolveFail(name.clone())
})?;
let list = list.map(|s| s.ip()).collect::<Vec<_>>();
let outcome = list
.into_iter()
.filter_map(|addr| {
if (dns4 && addr.is_ipv4()) || (dns6 && addr.is_ipv6()) {
Some(Protocol::from(addr))
} else {
None
}
})
.next()
.ok_or_else(|| TransportError::ResolveFail(name.clone()))?;
if let Some(addr) = addr.replace(index, |_| Some(outcome.clone())) {
return self.inner.dial(addr).await;
}
Err(TransportError::ResolveFail(name))
}
fn box_clone(&self) -> ITransport<Self::Output> {
Box::new(self.clone())
}
fn protocols(&self) -> Vec<u32> {
let mut p = self.inner.protocols();
p.push(protocol::DNS);
p
}
}
#[derive(Debug)]
pub enum DnsErr {
ResolveFail(String),
ResolveError { domain_name: String, error: io::Error },
MultiaddrNotSupported,
}
impl fmt::Display for DnsErr {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
DnsErr::ResolveFail(addr) => write!(f, "Failed to resolve DNS address: {:?}", addr),
DnsErr::ResolveError { domain_name, error } => write!(f, "Failed to resolve DNS address: {:?}; {:?}", domain_name, error),
DnsErr::MultiaddrNotSupported => write!(f, "Resolve multiaddr not supported"),
}
}
}
impl error::Error for DnsErr {
fn source(&self) -> Option<&(dyn error::Error + 'static)> {
match self {
DnsErr::ResolveFail(_) => None,
DnsErr::ResolveError { error, .. } => Some(error),
DnsErr::MultiaddrNotSupported => None,
}
}
}
#[cfg(test)]
mod tests {
use super::DnsConfig;
use futures::{AsyncReadExt, AsyncWriteExt};
use libp2prs_core::transport::ListenerEvent;
use libp2prs_core::Transport;
use libp2prs_multiaddr::Multiaddr;
use libp2prs_runtime::task;
use libp2prs_tcp::TcpConfig;
#[test]
fn basic_resolve_v4() {
task::block_on(async move {
let listen_addr: Multiaddr = "/ip4/127.0.0.1/tcp/8384".parse().unwrap();
let addr: Multiaddr = "/dns4/localhost/tcp/8384".parse().unwrap();
let mut transport = DnsConfig::new(TcpConfig::default());
let mut client = transport.clone();
let msg = b"Hello World";
let mut listener = transport.listen_on(listen_addr).unwrap();
let handle = task::spawn(async move {
let mut conn = match listener.accept().await.unwrap() {
ListenerEvent::Accepted(s) => s,
_ => panic!("unreachable"),
};
let mut buf = vec![0; msg.len()];
conn.read_exact(&mut buf).await.expect("server read exact");
assert_eq!(&msg[..], &buf[..]);
conn.close().await.expect("server close connection");
});
let mut conn = client.dial(addr).await.expect("client dial");
conn.write_all(&msg[..]).await.expect("client write all");
conn.close().await.expect("client close connection");
handle.await;
});
}
#[test]
fn basic_resolve_v6() {
task::block_on(async move {
let listen_addr: Multiaddr = "/ip6/::1/tcp/8384".parse().unwrap();
let addr: Multiaddr = "/dns6/localhost/tcp/8384".parse().unwrap();
let mut transport = DnsConfig::new(TcpConfig::default());
let mut client = transport.clone();
let msg = b"Hello World";
let mut listener = transport.listen_on(listen_addr).expect("S listen");
let handle = task::spawn(async move {
let mut conn = match listener.accept().await.unwrap() {
ListenerEvent::Accepted(s) => s,
_ => panic!("unreachable"),
};
let mut buf = vec![0; msg.len()];
conn.read_exact(&mut buf).await.expect("S read exact");
assert_eq!(&msg[..], &buf[..]);
conn.close().await.expect("S close connection");
});
let mut conn = client.dial(addr).await.expect("C dial");
conn.write_all(&msg[..]).await.expect("C write all");
conn.close().await.expect("C close connection");
handle.await;
});
}
}