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500 lines
17 KiB
Rust
500 lines
17 KiB
Rust
#![allow(clippy::assertions_on_constants)]
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#![allow(unused_imports)]
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#![allow(unused_variables)]
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#![allow(dead_code)]
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#[global_allocator]
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static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
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#[macro_use]
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extern crate clap;
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#[macro_use]
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extern crate derivative;
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#[macro_use]
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extern crate failure;
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#[macro_use]
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extern crate log;
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#[macro_use]
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extern crate serde_derive;
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#[macro_use]
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extern crate serde_big_array;
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mod config;
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mod crypto;
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mod dns;
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mod dnscrypt;
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mod dnscrypt_certs;
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mod errors;
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mod globals;
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use config::*;
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use crypto::*;
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use dns::*;
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use dnscrypt::*;
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use dnscrypt_certs::*;
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use errors::*;
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use globals::*;
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use byteorder::{BigEndian, ByteOrder};
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use clap::Arg;
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use dnsstamps::{InformalProperty, WithInformalProperty};
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use failure::{bail, ensure};
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use futures::join;
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use futures::prelude::*;
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use parking_lot::Mutex;
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use parking_lot::RwLock;
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use privdrop::PrivDrop;
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use rand::prelude::*;
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use std::collections::vec_deque::VecDeque;
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use std::convert::TryFrom;
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use std::fs::{File, OpenOptions};
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use std::io::prelude::*;
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use std::mem;
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use std::net::{IpAddr, SocketAddr};
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use std::path::PathBuf;
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use std::sync::atomic::{AtomicU32, Ordering};
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use std::sync::Arc;
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use std::time::Duration;
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use tokio::io::{AsyncReadExt, AsyncWriteExt};
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use tokio::net::{TcpListener, TcpStream, UdpSocket};
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use tokio::prelude::*;
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use tokio::runtime::Runtime;
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use tokio::sync::oneshot;
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use tokio_net::driver::Handle;
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#[cfg(unix)]
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use std::os::unix::fs::OpenOptionsExt;
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#[derive(Debug)]
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struct UdpClientCtx {
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net_udp_socket: std::net::UdpSocket,
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client_addr: SocketAddr,
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}
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#[derive(Debug)]
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struct TcpClientCtx {
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client_connection: TcpStream,
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}
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#[derive(Debug)]
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enum ClientCtx {
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Udp(UdpClientCtx),
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Tcp(TcpClientCtx),
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}
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fn maybe_truncate_response(
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client_ctx: &ClientCtx,
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packet: Vec<u8>,
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response: Vec<u8>,
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original_packet_size: usize,
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) -> Result<Vec<u8>, Error> {
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if let ClientCtx::Udp(_) = client_ctx {
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let encrypted_response_min_len = response.len() + DNSCRYPT_RESPONSE_MIN_OVERHEAD;
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if encrypted_response_min_len > original_packet_size
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|| encrypted_response_min_len > DNSCRYPT_UDP_RESPONSE_MAX_SIZE
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{
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return Ok(dns::serve_truncated(packet)?);
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}
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}
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Ok(response)
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}
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async fn respond_to_query(
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client_ctx: ClientCtx,
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packet: Vec<u8>,
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response: Vec<u8>,
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original_packet_size: usize,
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shared_key: Option<SharedKey>,
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nonce: Option<[u8; DNSCRYPT_FULL_NONCE_SIZE]>,
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) -> Result<(), Error> {
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ensure!(dns::is_response(&response), "Packet is not a response");
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let max_response_size = match client_ctx {
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ClientCtx::Udp(_) => original_packet_size,
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ClientCtx::Tcp(_) => DNSCRYPT_TCP_RESPONSE_MAX_SIZE,
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};
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let response = match &shared_key {
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None => response,
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Some(shared_key) => dnscrypt::encrypt(
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maybe_truncate_response(&client_ctx, packet, response, original_packet_size)?,
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shared_key,
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nonce.as_ref().unwrap(),
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max_response_size,
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)?,
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};
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match client_ctx {
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ClientCtx::Udp(client_ctx) => {
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let net_udp_socket = client_ctx.net_udp_socket;
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net_udp_socket.send_to(&response, client_ctx.client_addr)?;
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}
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ClientCtx::Tcp(client_ctx) => {
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let response_len = response.len();
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ensure!(
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response_len <= DNSCRYPT_TCP_RESPONSE_MAX_SIZE,
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"Packet too large"
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);
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let mut client_connection = client_ctx.client_connection;
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let mut binlen = [0u8, 0];
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BigEndian::write_u16(&mut binlen[..], response_len as u16);
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client_connection.write_all(&binlen).await?;
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client_connection.write_all(&response).await?;
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client_connection.flush();
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}
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}
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Ok(())
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}
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async fn handle_client_query(
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globals: Arc<Globals>,
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client_ctx: ClientCtx,
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encrypted_packet: Vec<u8>,
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) -> Result<(), Error> {
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let original_packet_size = encrypted_packet.len();
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let mut dnscrypt_encryption_params_set = vec![];
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for params in &**globals.dnscrypt_encryption_params_set.read() {
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dnscrypt_encryption_params_set.push((*params).clone())
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}
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let (shared_key, nonce, mut packet) =
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match dnscrypt::decrypt(&encrypted_packet, &dnscrypt_encryption_params_set) {
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Ok(x) => x,
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Err(_) => {
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let packet = encrypted_packet;
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if let Some(synth_packet) = serve_certificates(
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&packet,
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&globals.provider_name,
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&dnscrypt_encryption_params_set,
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)? {
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return respond_to_query(
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client_ctx,
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packet,
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synth_packet,
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original_packet_size,
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None,
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None,
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)
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.await;
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}
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bail!("Unencrypted query");
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}
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};
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ensure!(packet.len() >= DNS_HEADER_SIZE, "Short packet");
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ensure!(qdcount(&packet) == 1, "No question");
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ensure!(
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!dns::is_response(&packet),
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"Question expected, but got a response instead"
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);
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let original_tid = dns::tid(&packet);
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let tid = random();
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dns::set_tid(&mut packet, tid);
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let mut ext_socket = UdpSocket::bind(&globals.external_addr).await?;
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ext_socket.connect(&globals.upstream_addr).await?;
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set_edns_max_payload_size(&mut packet, DNS_MAX_PACKET_SIZE as u16)?;
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ext_socket.send(&packet).await?;
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let mut response;
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loop {
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response = vec![0u8; DNS_MAX_PACKET_SIZE];
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let (response_len, response_addr) = ext_socket.recv_from(&mut response[..]).await?;
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response.truncate(response_len);
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if response_addr == globals.upstream_addr
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&& response_len >= DNS_HEADER_SIZE
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&& dns::tid(&response) == tid
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&& dns::qname(&packet)? == dns::qname(&response)?
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{
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break;
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}
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dbg!("Response collision");
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}
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if dns::is_truncated(&response) {
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let std_socket = match globals.external_addr {
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SocketAddr::V4(_) => net2::TcpBuilder::new_v4(),
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SocketAddr::V6(_) => net2::TcpBuilder::new_v6(),
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}?
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.bind(&globals.external_addr)?
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.to_tcp_stream()?;
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let mut ext_socket =
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TcpStream::connect_std(std_socket, &globals.upstream_addr, &Handle::default()).await?;
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ext_socket.set_nodelay(true)?;
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let mut binlen = [0u8, 0];
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BigEndian::write_u16(&mut binlen[..], packet.len() as u16);
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ext_socket.write_all(&binlen).await?;
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ext_socket.write_all(&packet).await?;
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ext_socket.flush();
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ext_socket.read_exact(&mut binlen).await?;
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let response_len = BigEndian::read_u16(&binlen) as usize;
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ensure!(
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(DNS_HEADER_SIZE..=DNS_MAX_PACKET_SIZE).contains(&response_len),
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"Unexpected response size"
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);
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response = vec![0u8; response_len];
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ext_socket.read_exact(&mut response).await?;
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ensure!(dns::tid(&response) == tid, "Unexpected transaction ID");
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ensure!(
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dns::qname(&packet)? == dns::qname(&response)?,
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"Unexpected query name in the response"
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);
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}
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dns::set_tid(&mut response, original_tid);
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respond_to_query(
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client_ctx,
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packet,
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response,
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original_packet_size,
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Some(shared_key),
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Some(nonce),
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)
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.await
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}
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async fn tls_proxy(
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globals: Arc<Globals>,
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binlen: [u8; 2],
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client_connection: TcpStream,
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) -> Result<(), Error> {
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let tls_upstream_addr = match &globals.tls_upstream_addr {
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None => return Ok(()),
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Some(tls_upstream_addr) => tls_upstream_addr,
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};
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let std_socket = match globals.external_addr {
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SocketAddr::V4(_) => net2::TcpBuilder::new_v4(),
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SocketAddr::V6(_) => net2::TcpBuilder::new_v6(),
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}?
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.bind(&globals.external_addr)?
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.to_tcp_stream()?;
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let ext_socket =
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TcpStream::connect_std(std_socket, tls_upstream_addr, &Handle::default()).await?;
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let (mut erh, mut ewh) = ext_socket.split();
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let (mut rh, mut wh) = client_connection.split();
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ewh.write_all(&binlen).await?;
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let fut_proxy_1 = rh.copy(&mut ewh);
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let fut_proxy_2 = erh.copy(&mut wh);
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match join!(fut_proxy_1, fut_proxy_2) {
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(Ok(_), Ok(_)) => Ok(()),
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_ => Err(format_err!("TLS proxy error")),
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}
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}
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async fn tcp_acceptor(globals: Arc<Globals>, tcp_listener: TcpListener) -> Result<(), Error> {
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let runtime = globals.runtime.clone();
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let mut tcp_listener = tcp_listener.incoming();
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let timeout = globals.tcp_timeout;
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let concurrent_connections = globals.tcp_concurrent_connections.clone();
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let active_connections = globals.tcp_active_connections.clone();
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while let Some(client) = tcp_listener.next().await {
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let mut client_connection: TcpStream = match client {
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Ok(client_connection) => client_connection,
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Err(e) => bail!(e),
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};
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let (tx, rx) = oneshot::channel::<()>();
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{
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let mut active_connections = active_connections.lock();
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if active_connections.len() >= globals.tcp_max_active_connections as _ {
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let tx_oldest = active_connections.pop_back().unwrap();
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let _ = tx_oldest.send(());
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}
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active_connections.push_front(tx);
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}
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concurrent_connections.fetch_add(1, Ordering::Relaxed);
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client_connection.set_nodelay(true)?;
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let globals = globals.clone();
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let concurrent_connections = concurrent_connections.clone();
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let fut = async {
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let mut binlen = [0u8, 0];
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client_connection.read_exact(&mut binlen).await?;
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let packet_len = BigEndian::read_u16(&binlen) as usize;
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if packet_len == 0x1603 {
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return tls_proxy(globals, binlen, client_connection).await;
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}
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ensure!(
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(DNS_HEADER_SIZE..=DNSCRYPT_TCP_QUERY_MAX_SIZE).contains(&packet_len),
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"Unexpected query size"
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);
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let mut packet = vec![0u8; packet_len];
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client_connection.read_exact(&mut packet).await?;
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let client_ctx = ClientCtx::Tcp(TcpClientCtx { client_connection });
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let _ = handle_client_query(globals, client_ctx, packet).await;
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Ok(())
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};
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let fut_abort = rx;
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let fut_all = future::select(fut.boxed(), fut_abort).timeout(timeout);
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runtime.spawn(fut_all.map(move |_| {
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concurrent_connections.fetch_sub(1, Ordering::Relaxed);
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}));
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}
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Ok(())
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}
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async fn udp_acceptor(
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globals: Arc<Globals>,
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net_udp_socket: std::net::UdpSocket,
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) -> Result<(), Error> {
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let runtime = globals.runtime.clone();
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let mut tokio_udp_socket = UdpSocket::try_from(net_udp_socket.try_clone()?)?;
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let timeout = globals.udp_timeout;
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let concurrent_connections = globals.udp_concurrent_connections.clone();
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let active_connections = globals.udp_active_connections.clone();
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loop {
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let mut packet = vec![0u8; DNSCRYPT_UDP_QUERY_MAX_SIZE];
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let (packet_len, client_addr) = tokio_udp_socket.recv_from(&mut packet).await?;
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if packet_len < DNS_HEADER_SIZE {
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continue;
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}
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let net_udp_socket = net_udp_socket.try_clone()?;
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packet.truncate(packet_len);
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let client_ctx = ClientCtx::Udp(UdpClientCtx {
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net_udp_socket,
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client_addr,
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});
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let (tx, rx) = oneshot::channel::<()>();
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{
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let mut active_connections = active_connections.lock();
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if active_connections.len() >= globals.tcp_max_active_connections as _ {
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let tx_oldest = active_connections.pop_back().unwrap();
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let _ = tx_oldest.send(());
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}
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active_connections.push_front(tx);
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}
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concurrent_connections.fetch_add(1, Ordering::Relaxed);
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let globals = globals.clone();
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let concurrent_connections = concurrent_connections.clone();
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let fut = handle_client_query(globals, client_ctx, packet);
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let fut_abort = rx;
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let fut_all = future::select(fut.boxed(), fut_abort).timeout(timeout);
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runtime.spawn(fut_all.map(move |_| {
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concurrent_connections.fetch_sub(1, Ordering::Relaxed);
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}));
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}
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}
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async fn start(globals: Arc<Globals>, runtime: Arc<Runtime>) -> Result<(), Error> {
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for listen_addr in &globals.listen_addrs {
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let tcp_listener = TcpListener::bind(&listen_addr).await?;
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let udp_socket = std::net::UdpSocket::bind(&listen_addr)?;
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runtime.spawn(tcp_acceptor(globals.clone(), tcp_listener).map(|_| {}));
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runtime.spawn(udp_acceptor(globals.clone(), udp_socket).map(|_| {}));
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}
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Ok(())
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}
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fn main() -> Result<(), Error> {
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env_logger::init();
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crypto::init()?;
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let updater = coarsetime::Updater::new(1000).start()?;
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mem::forget(updater);
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let matches = app_from_crate!()
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.arg(
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Arg::with_name("config")
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.long("config")
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.short("c")
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.value_name("FILE")
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.takes_value(true)
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.default_value("encrypted-dns.toml")
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.help("Path to the configuration file"),
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)
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.get_matches();
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let config_path = matches.value_of("config").unwrap();
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let config = Config::from_path(config_path)?;
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let provider_name = match config.dnscrypt.provider_name {
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provider_name if provider_name.starts_with("2.dnscrypt.") => provider_name.to_string(),
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provider_name => format!("2.dnscrypt.{}", provider_name),
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};
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let external_addr = SocketAddr::new(config.external_addr, 0);
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let state_file = &config.state_file;
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let state = match File::open(state_file) {
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Err(_) => {
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println!("No state file found... creating a new provider key");
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let state = State::new();
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let mut fpb = OpenOptions::new();
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let mut fpb = fpb.create(true).write(true);
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#[cfg(unix)]
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{
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fpb = fpb.mode(0o600);
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}
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let mut fp = fpb.open(state_file)?;
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let state_bin = toml::to_vec(&state)?;
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fp.write_all(&state_bin)?;
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state
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}
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Ok(mut fp) => {
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println!(
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"State file [{}] found; using existing provider key",
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state_file.as_os_str().to_string_lossy()
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);
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let mut state_bin = vec![];
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fp.read_to_end(&mut state_bin)?;
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toml::from_slice(&state_bin)?
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}
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};
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let provider_kp = state.provider_kp;
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for listen_addr_s in &config.listen_addrs {
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info!("Server address: {}", listen_addr_s);
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info!("Provider public key: {}", provider_kp.pk.as_string());
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info!("Provider name: {}", provider_name);
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let stamp = dnsstamps::DNSCryptBuilder::new(dnsstamps::DNSCryptProvider::new(
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provider_name.clone(),
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provider_kp.pk.as_bytes().to_vec(),
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))
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.with_addr(listen_addr_s.to_string())
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.with_informal_property(InformalProperty::DNSSEC)
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.with_informal_property(InformalProperty::NoFilters)
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.with_informal_property(InformalProperty::NoLogs)
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.serialize()
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.unwrap();
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println!("DNS Stamp: {}", stamp);
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}
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let dnscrypt_encryption_params = DNSCryptEncryptionParams::new(&provider_kp);
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let mut runtime_builder = tokio::runtime::Builder::new();
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runtime_builder.name_prefix("encrypted-dns-");
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let runtime = Arc::new(runtime_builder.build()?);
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|
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let mut pd = PrivDrop::default();
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if let Some(user) = &config.user {
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pd = pd.user(user);
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}
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if let Some(group) = &config.group {
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pd = pd.group(group);
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}
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if let Some(chroot) = &config.chroot {
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pd = pd.chroot(chroot);
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}
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|
if config.user.is_some() || config.group.is_some() || config.chroot.is_some() {
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info!("Dropping privileges");
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pd.apply()?;
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}
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|
let globals = Arc::new(Globals {
|
|
runtime: runtime.clone(),
|
|
dnscrypt_encryption_params_set: Arc::new(RwLock::new(Arc::new(vec![Arc::new(
|
|
dnscrypt_encryption_params,
|
|
)]))),
|
|
provider_name,
|
|
provider_kp,
|
|
listen_addrs: config.listen_addrs,
|
|
upstream_addr: config.upstream_addr,
|
|
tls_upstream_addr: config.tls.upstream_addr,
|
|
external_addr,
|
|
tcp_timeout: Duration::from_secs(u64::from(config.tcp_timeout)),
|
|
udp_timeout: Duration::from_secs(u64::from(config.udp_timeout)),
|
|
udp_concurrent_connections: Arc::new(AtomicU32::new(0)),
|
|
tcp_concurrent_connections: Arc::new(AtomicU32::new(0)),
|
|
udp_max_active_connections: config.udp_max_active_connections,
|
|
tcp_max_active_connections: config.tcp_max_active_connections,
|
|
udp_active_connections: Arc::new(Mutex::new(VecDeque::with_capacity(
|
|
config.udp_max_active_connections as _,
|
|
))),
|
|
tcp_active_connections: Arc::new(Mutex::new(VecDeque::with_capacity(
|
|
config.tcp_max_active_connections as _,
|
|
))),
|
|
});
|
|
let updater = DNSCryptEncryptionParamsUpdater::new(globals.clone());
|
|
runtime.spawn(updater.run());
|
|
runtime.spawn(start(globals, runtime.clone()).map(|_| ()));
|
|
runtime.block_on(future::pending::<()>());
|
|
|
|
Ok(())
|
|
}
|