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//! # Common network utilities.
use std::net::{IpAddr, SocketAddr};
use std::net::{Ipv4Addr, Ipv6Addr};
use std::pin::Pin;
use std::str::FromStr;
use std::time::Duration;
use anyhow::{format_err, Context as _, Result};
use tokio::net::{lookup_host, TcpStream};
use tokio::time::timeout;
use tokio_io_timeout::TimeoutStream;
use crate::context::Context;
use crate::tools::time;
pub(crate) mod http;
pub(crate) mod session;
pub(crate) mod tls;
pub use http::{read_url, read_url_blob, Response as HttpResponse};
async fn connect_tcp_inner(addr: SocketAddr, timeout_val: Duration) -> Result<TcpStream> {
let tcp_stream = timeout(timeout_val, TcpStream::connect(addr))
.await
.context("connection timeout")?
.context("connection failure")?;
Ok(tcp_stream)
}
async fn lookup_host_with_timeout(
hostname: &str,
port: u16,
timeout_val: Duration,
) -> Result<Vec<SocketAddr>> {
let res = timeout(timeout_val, lookup_host((hostname, port)))
.await
.context("DNS lookup timeout")?
.context("DNS lookup failure")?;
Ok(res.collect())
}
/// Looks up hostname and port using DNS and updates the address resolution cache.
///
/// If `load_cache` is true, appends cached results not older than 30 days to the end
/// or entries from fallback cache if there are no cached addresses.
async fn lookup_host_with_cache(
context: &Context,
hostname: &str,
port: u16,
timeout_val: Duration,
load_cache: bool,
) -> Result<Vec<SocketAddr>> {
let now = time();
let mut resolved_addrs = match lookup_host_with_timeout(hostname, port, timeout_val).await {
Ok(res) => res,
Err(err) => {
warn!(
context,
"DNS resolution for {}:{} failed: {:#}.", hostname, port, err
);
Vec::new()
}
};
for addr in &resolved_addrs {
let ip_string = addr.ip().to_string();
if ip_string == hostname {
// IP address resolved into itself, not interesting to cache.
continue;
}
info!(context, "Resolved {}:{} into {}.", hostname, port, &addr);
// Update the cache.
context
.sql
.execute(
"INSERT INTO dns_cache
(hostname, address, timestamp)
VALUES (?, ?, ?)
ON CONFLICT (hostname, address)
DO UPDATE SET timestamp=excluded.timestamp",
(hostname, ip_string, now),
)
.await?;
}
if load_cache {
for cached_address in context
.sql
.query_map(
"SELECT address
FROM dns_cache
WHERE hostname = ?
AND ? < timestamp + 30 * 24 * 3600
ORDER BY timestamp DESC",
(hostname, now),
|row| {
let address: String = row.get(0)?;
Ok(address)
},
|rows| {
rows.collect::<std::result::Result<Vec<_>, _>>()
.map_err(Into::into)
},
)
.await?
{
match IpAddr::from_str(&cached_address) {
Ok(ip_addr) => {
let addr = SocketAddr::new(ip_addr, port);
if !resolved_addrs.contains(&addr) {
resolved_addrs.push(addr);
}
}
Err(err) => {
warn!(
context,
"Failed to parse cached address {:?}: {:#}.", cached_address, err
);
}
}
}
if resolved_addrs.is_empty() {
// Load hardcoded cache if everything else fails.
//
// See <https://support.delta.chat/t/no-dns-resolution-result/2778> and
// <https://github.com/deltachat/deltachat-core-rust/issues/4920> for reasons.
//
// In the future we may pre-resolve all provider database addresses
// and build them in.
match hostname {
"mail.sangham.net" => {
resolved_addrs.push(SocketAddr::new(
IpAddr::V6(Ipv6Addr::new(0x2a01, 0x4f8, 0xc17, 0x798c, 0, 0, 0, 1)),
port,
));
resolved_addrs.push(SocketAddr::new(
IpAddr::V4(Ipv4Addr::new(159, 69, 186, 85)),
port,
));
}
"nine.testrun.org" => {
resolved_addrs.push(SocketAddr::new(
IpAddr::V6(Ipv6Addr::new(0x2a01, 0x4f8, 0x241, 0x4ce8, 0, 0, 0, 2)),
port,
));
resolved_addrs.push(SocketAddr::new(
IpAddr::V4(Ipv4Addr::new(116, 202, 233, 236)),
port,
));
}
"disroot.org" => {
resolved_addrs.push(SocketAddr::new(
IpAddr::V4(Ipv4Addr::new(178, 21, 23, 139)),
port,
));
}
"mail.riseup.net" => {
resolved_addrs.push(SocketAddr::new(
IpAddr::V4(Ipv4Addr::new(198, 252, 153, 70)),
port,
));
resolved_addrs.push(SocketAddr::new(
IpAddr::V4(Ipv4Addr::new(198, 252, 153, 71)),
port,
));
}
"imap.gmail.com" => {
resolved_addrs.push(SocketAddr::new(
IpAddr::V6(Ipv6Addr::new(0x2a00, 0x1450, 0x400c, 0xc1f, 0, 0, 0, 0x6c)),
port,
));
resolved_addrs.push(SocketAddr::new(
IpAddr::V6(Ipv6Addr::new(0x2a00, 0x1450, 0x400c, 0xc1f, 0, 0, 0, 0x6d)),
port,
));
resolved_addrs.push(SocketAddr::new(
IpAddr::V4(Ipv4Addr::new(142, 250, 110, 109)),
port,
));
resolved_addrs.push(SocketAddr::new(
IpAddr::V4(Ipv4Addr::new(142, 250, 110, 108)),
port,
));
}
"smtp.gmail.com" => {
resolved_addrs.push(SocketAddr::new(
IpAddr::V6(Ipv6Addr::new(0x2a00, 0x1450, 0x4013, 0xc04, 0, 0, 0, 0x6c)),
port,
));
resolved_addrs.push(SocketAddr::new(
IpAddr::V4(Ipv4Addr::new(142, 250, 110, 109)),
port,
));
}
_ => {}
}
}
}
Ok(resolved_addrs)
}
/// Returns a TCP connection stream with read/write timeouts set
/// and Nagle's algorithm disabled with `TCP_NODELAY`.
///
/// `TCP_NODELAY` ensures writing to the stream always results in immediate sending of the packet
/// to the network, which is important to reduce the latency of interactive protocols such as IMAP.
///
/// If `load_cache` is true, may use cached DNS results.
/// Because the cache may be poisoned with incorrect results by networks hijacking DNS requests,
/// this option should only be used when connection is authenticated,
/// for example using TLS.
/// If TLS is not used or invalid TLS certificates are allowed,
/// this option should be disabled.
pub(crate) async fn connect_tcp(
context: &Context,
host: &str,
port: u16,
timeout_val: Duration,
load_cache: bool,
) -> Result<Pin<Box<TimeoutStream<TcpStream>>>> {
let mut tcp_stream = None;
let mut last_error = None;
for resolved_addr in
lookup_host_with_cache(context, host, port, timeout_val, load_cache).await?
{
match connect_tcp_inner(resolved_addr, timeout_val).await {
Ok(stream) => {
tcp_stream = Some(stream);
// Maximize priority of this cached entry.
context
.sql
.execute(
"UPDATE dns_cache
SET timestamp = ?
WHERE address = ?",
(time(), resolved_addr.ip().to_string()),
)
.await?;
break;
}
Err(err) => {
warn!(
context,
"Failed to connect to {}: {:#}.", resolved_addr, err
);
last_error = Some(err);
}
}
}
let tcp_stream = match tcp_stream {
Some(tcp_stream) => tcp_stream,
None => {
return Err(
last_error.unwrap_or_else(|| format_err!("no DNS resolution results for {host}"))
);
}
};
// Disable Nagle's algorithm.
tcp_stream.set_nodelay(true)?;
let mut timeout_stream = TimeoutStream::new(tcp_stream);
timeout_stream.set_write_timeout(Some(timeout_val));
timeout_stream.set_read_timeout(Some(timeout_val));
let pinned_stream = Box::pin(timeout_stream);
Ok(pinned_stream)
}