Merge changes I9cbba1b8,I77f8697c,I6d4c296f am: 09a42197b7 am: f76c9616d0 (6276d530) · Commits · e / os / android_packages_modules_DnsResolver

doh/config.rs

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		/*
		* Copyright (C) 2021 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		//! Quiche Config support
		//!
		//! Quiche config objects are needed mutably for constructing a Quiche
		//! connection object, but not when they are actually being used. As these
		//! objects include a `SSL_CTX` which can be somewhat expensive and large when
		//! using a certificate path, it can be beneficial to cache them.
		//!
		//! This module provides a caching layer for loading and constructing
		//! these configurations.

		use quiche::{h3, Result};
		use std::collections::HashMap;
		use std::ops::DerefMut;
		use std::sync::{Arc, Mutex, RwLock, Weak};

		type WeakConfig = Weak<Mutex<quiche::Config>>;

		/// A cheaply clonable `quiche::Config`
		#[derive(Clone)]
		pub struct Config(Arc<Mutex<quiche::Config>>);

		const MAX_INCOMING_BUFFER_SIZE_WHOLE: u64 = 10000000;
		const MAX_INCOMING_BUFFER_SIZE_EACH: u64 = 1000000;
		const MAX_CONCURRENT_STREAM_SIZE: u64 = 100;
		/// Maximum datagram size we will accept.
		pub const MAX_DATAGRAM_SIZE: usize = 1350;
		/// How long with no packets before we assume a connection is dead, in milliseconds.
		pub const QUICHE_IDLE_TIMEOUT_MS: u64 = 180000;

		impl Config {
		fn from_weak(weak: &WeakConfig) -> Option<Self> {
		weak.upgrade().map(Self)
		}

		fn to_weak(&self) -> WeakConfig {
		Arc::downgrade(&self.0)
		}

		/// Construct a `Config` object from certificate path. If no path
		/// is provided, peers will not be verified.
		pub fn from_cert_path(cert_path: Option<&str>) -> Result<Self> {
		let mut config = quiche::Config::new(quiche::PROTOCOL_VERSION)?;
		config.set_application_protos(h3::APPLICATION_PROTOCOL)?;
		match cert_path {
		Some(path) => {
		config.verify_peer(true);
		config.load_verify_locations_from_directory(path)?;
		}
		None => config.verify_peer(false),
		}

		// Some of these configs are necessary, or the server can't respond the HTTP/3 request.
		config.set_max_idle_timeout(QUICHE_IDLE_TIMEOUT_MS);
		config.set_max_recv_udp_payload_size(MAX_DATAGRAM_SIZE);
		config.set_initial_max_data(MAX_INCOMING_BUFFER_SIZE_WHOLE);
		config.set_initial_max_stream_data_bidi_local(MAX_INCOMING_BUFFER_SIZE_EACH);
		config.set_initial_max_stream_data_bidi_remote(MAX_INCOMING_BUFFER_SIZE_EACH);
		config.set_initial_max_stream_data_uni(MAX_INCOMING_BUFFER_SIZE_EACH);
		config.set_initial_max_streams_bidi(MAX_CONCURRENT_STREAM_SIZE);
		config.set_initial_max_streams_uni(MAX_CONCURRENT_STREAM_SIZE);
		config.set_disable_active_migration(true);
		Ok(Self(Arc::new(Mutex::new(config))))
		}

		/// Take the underlying config, usable as `&mut quiche::Config` for use
		/// with `quiche::connect`.
		pub fn take(&mut self) -> impl DerefMut<Target = quiche::Config> + '_ {
		self.0.lock().unwrap()
		}
		}

		#[derive(Clone, Default)]
		struct State {
		// Mapping from cert_path to configs
		path_to_config: HashMap<Option<String>, WeakConfig>,
		// Keep latest config alive to minimize reparsing when flapping
		// If more keep-alive is needed, replace with a LRU LinkedList
		latest: Option<Config>,
		}

		impl State {
		fn get_config(&self, cert_path: &Option<String>) -> Option<Config> {
		self.path_to_config.get(cert_path).and_then(Config::from_weak)
		}

		fn keep_alive(&mut self, config: Config) {
		self.latest = Some(config);
		}

		fn garbage_collect(&mut self) {
		self.path_to_config.retain(\|_, config\| config.strong_count() != 0)
		}
		}

		/// Cache of Quiche Config objects
		///
		/// Cloning this cache will create another handle to the same cache.
		///
		/// Loading a config object through this caching layer will only keep the
		/// latest config loaded alive directly, but will still act as a cache
		/// for any configurations still in use - if the returned `Config` is still
		/// live, queries to `Cache` will not reconstruct it.
		#[derive(Clone, Default)]
		pub struct Cache {
		// Shared state amongst cache handles
		state: Arc<RwLock<State>>,
		}

		impl Cache {
		/// Creates a fresh empty cache
		pub fn new() -> Self {
		Default::default()
		}

		/// Behaves as `Config::from_cert_path`, but with a cache.
		/// If any object previously given out by this cache is still live,
		/// a duplicate will not be made.
		pub fn from_cert_path(&self, cert_path: &Option<String>) -> Result<Config> {
		// Fast path - read-only access to state retrieves config
		if let Some(config) = self.state.read().unwrap().get_config(cert_path) {
		return Ok(config);
		}

		// Unlocked, calculate config. If we have two racing attempts to load
		// the cert path, we'll arbitrate that in the next step, but this
		// makes sure loading a new cert path doesn't block other loads to
		// refresh connections.
		let config = Config::from_cert_path(cert_path.as_deref())?;

		let mut state = self.state.write().unwrap();
		// We now have exclusive access to the state.
		// If someone else calculated a config at the same time as us, we
		// want to discard ours and use theirs, since it will result in
		// less total memory used.
		if let Some(config) = state.get_config(cert_path) {
		return Ok(config);
		}

		// We have exclusive access and a fresh config. Install it into
		// the cache.
		state.keep_alive(config.clone());
		state.path_to_config.insert(cert_path.to_owned(), config.to_weak());
		Ok(config)
		}

		/// Purges any config paths which no longer point to a config entry.
		pub fn garbage_collect(&self) {
		self.state.write().unwrap().garbage_collect();
		}
		}

		#[test]
		fn create_quiche_config() {
		assert!(Config::from_cert_path(None).is_ok(), "quiche config without cert creating failed");
		assert!(
		Config::from_cert_path(Some("data/local/tmp/")).is_ok(),
		"quiche config with cert creating failed"
		);
		}

		#[test]
		fn shared_cache() {
		let cache_a = Cache::new();
		let cache_b = cache_a.clone();
		let config_a = cache_a.from_cert_path(&None).unwrap();
		assert_eq!(Arc::strong_count(&config_a.0), 2);
		let _config_b = cache_b.from_cert_path(&None).unwrap();
		assert_eq!(Arc::strong_count(&config_a.0), 3);
		}

		#[test]
		fn lifetimes() {
		let cache = Cache::new();
		let config_none = cache.from_cert_path(&None).unwrap();
		let config_a = cache.from_cert_path(&Some("a".to_string())).unwrap();
		let config_b = cache.from_cert_path(&Some("b".to_string())).unwrap();
		// The first two we created should have a strong count of one - those handles are the only
		// thing keeping them alive.
		assert_eq!(Arc::strong_count(&config_none.0), 1);
		assert_eq!(Arc::strong_count(&config_a.0), 1);

		// If we try to get another handle we already have, it should be the same one.
		let _config_a2 = cache.from_cert_path(&Some("a".to_string())).unwrap();
		assert_eq!(Arc::strong_count(&config_a.0), 2);

		// config_b was most recently created, so it should have a keep-alive
		// inside the cache.
		assert_eq!(Arc::strong_count(&config_b.0), 2);

		// If we weaken one of the first handles, then drop it, the weak handle should break
		let config_none_weak = Config::to_weak(&config_none);
		assert_eq!(config_none_weak.strong_count(), 1);
		drop(config_none);
		assert_eq!(config_none_weak.strong_count(), 0);
		assert!(Config::from_weak(&config_none_weak).is_none());

		// If we weaken the most recent handle, it should keep working
		let config_b_weak = Config::to_weak(&config_b);
		assert_eq!(config_b_weak.strong_count(), 2);
		drop(config_b);
		assert_eq!(config_b_weak.strong_count(), 1);
		assert!(Config::from_weak(&config_b_weak).is_some());
		assert_eq!(config_b_weak.strong_count(), 1);

		// If we try to get a config which is still kept alive by the cache, we should get the same
		// one.
		let _config_b2 = cache.from_cert_path(&Some("b".to_string())).unwrap();
		assert_eq!(config_b_weak.strong_count(), 2);

		// We broke None, but "a" and "b" should still both be alive. Check that
		// this is still the case in the mapping after garbage collection.
		cache.garbage_collect();
		assert_eq!(cache.state.read().unwrap().path_to_config.len(), 2);
		}

		#[test]
		fn quiche_connect() {
		use std::net::{Ipv4Addr, SocketAddr, SocketAddrV4};
		let mut config = Config::from_cert_path(None).unwrap();
		let socket_addr = SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 42));
		let conn_id = quiche::ConnectionId::from_ref(&[]);
		quiche::connect(None, &conn_id, socket_addr, &mut config.take()).unwrap();
		}

doh/doh.rs

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doh/encoding.rs

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		/*
		* Copyright (C) 2021 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		//! Format DoH requests

		use anyhow::{anyhow, Context, Result};
		use quiche::h3;
		use ring::rand::SecureRandom;
		use url::Url;

		pub type DnsRequest = Vec<quiche::h3::Header>;

		const NS_T_AAAA: u8 = 28;
		const NS_C_IN: u8 = 1;
		// Used to randomly generate query prefix and query id.
		const CHARSET: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ\
		abcdefghijklmnopqrstuvwxyz\
		0123456789";

		/// Produces a DNS query with randomized query ID and random 6-byte charset-legal prefix to produce
		/// a request for a domain of the form:
		/// ??????-dnsohttps-ds.metric.gstatic.com
		#[rustfmt::skip]
		pub fn probe_query() -> Result<String> {
		let mut rnd = [0; 8];
		ring::rand::SystemRandom::new().fill(&mut rnd).context("failed to generate probe rnd")?;
		let c = \|byte\| CHARSET[(byte as usize) % CHARSET.len()];
		let query = vec![
		rnd[6], rnd[7], // [0-1] query ID
		1, 0, // [2-3] flags; query[2] = 1 for recursion desired (RD).
		0, 1, // [4-5] QDCOUNT (number of queries)
		0, 0, // [6-7] ANCOUNT (number of answers)
		0, 0, // [8-9] NSCOUNT (number of name server records)
		0, 0, // [10-11] ARCOUNT (number of additional records)
		19, c(rnd[0]), c(rnd[1]), c(rnd[2]), c(rnd[3]), c(rnd[4]), c(rnd[5]), b'-', b'd', b'n',
		b's', b'o', b'h', b't', b't', b'p', b's', b'-', b'd', b's',
		6, b'm', b'e', b't', b'r', b'i', b'c', 7, b'g', b's',
		b't', b'a', b't', b'i', b'c', 3, b'c', b'o', b'm',
		0, // null terminator of FQDN (root TLD)
		0, NS_T_AAAA, // QTYPE
		0, NS_C_IN // QCLASS
		];
		Ok(base64::encode_config(query, base64::URL_SAFE_NO_PAD))
		}

		/// Takes in a base64-encoded copy of a traditional DNS request and a
		/// URL at which the DoH server is running and produces a set of HTTP/3 headers
		/// corresponding to a DoH request for it.
		pub fn dns_request(base64_query: &str, url: &Url) -> Result<DnsRequest> {
		let mut path = String::from(url.path());
		path.push_str("?dns=");
		path.push_str(base64_query);
		let req = vec![
		h3::Header::new(b":method", b"GET"),
		h3::Header::new(b":scheme", b"https"),
		h3::Header::new(
		b":authority",
		url.host_str().ok_or_else(\|\| anyhow!("failed to get host"))?.as_bytes(),
		),
		h3::Header::new(b":path", path.as_bytes()),
		h3::Header::new(b"user-agent", b"quiche"),
		h3::Header::new(b"accept", b"application/dns-message"),
		];

		Ok(req)
		}

		#[cfg(test)]
		mod tests {
		use quiche::h3::NameValue;
		use url::Url;

		const PROBE_QUERY_SIZE: usize = 56;
		const H3_DNS_REQUEST_HEADER_SIZE: usize = 6;
		const LOCALHOST_URL: &str = "https://mylocal.com/dns-query";

		#[test]
		fn make_probe_query_and_request() {
		let probe_query = super::probe_query().unwrap();
		let url = Url::parse(LOCALHOST_URL).unwrap();
		let request = super::dns_request(&probe_query, &url).unwrap();
		// Verify H3 DNS request.
		assert_eq!(request.len(), H3_DNS_REQUEST_HEADER_SIZE);
		assert_eq!(request[0].name(), b":method");
		assert_eq!(request[0].value(), b"GET");
		assert_eq!(request[1].name(), b":scheme");
		assert_eq!(request[1].value(), b"https");
		assert_eq!(request[2].name(), b":authority");
		assert_eq!(request[2].value(), url.host_str().unwrap().as_bytes());
		assert_eq!(request[3].name(), b":path");
		let mut path = String::from(url.path());
		path.push_str("?dns=");
		path.push_str(&probe_query);
		assert_eq!(request[3].value(), path.as_bytes());
		assert_eq!(request[5].name(), b"accept");
		assert_eq!(request[5].value(), b"application/dns-message");

		// Verify DNS probe packet.
		let bytes = base64::decode_config(probe_query, base64::URL_SAFE_NO_PAD).unwrap();
		assert_eq!(bytes.len(), PROBE_QUERY_SIZE);
		}
		}

doh/ffi.rs

+128 −4

Original line number	Diff line number	Diff line
		@@ -17,19 +17,67 @@
		//! C API for the DoH backend for the Android DnsResolver module.

		use crate::boot_time::{timeout, BootTime, Duration};
		use futures::FutureExt;
		use libc::{c_char, int32_t, size_t, ssize_t, uint32_t, uint64_t};
		use log::error;
		use log::{error, warn};
		use std::ffi::CString;
		use std::net::{IpAddr, SocketAddr};
		use std::ops::DerefMut;
		use std::os::unix::io::RawFd;
		use std::str::FromStr;
		use std::sync::Mutex;
		use std::{ptr, slice};
		use tokio::runtime::Runtime;
		use tokio::sync::oneshot;
		use tokio::task;
		use url::Url;

		use super::DohDispatcher as Dispatcher;
		use super::{DohCommand, Response, ServerInfo, TagSocketCallback, ValidationCallback, DOH_PORT};
		use super::{DohCommand, Response, ServerInfo, SocketTagger, ValidationReporter, DOH_PORT};

		pub type ValidationCallback =
		extern "C" fn(net_id: uint32_t, success: bool, ip_addr: const c_char, host: const c_char);
		pub type TagSocketCallback = extern "C" fn(sock: RawFd);

		fn wrap_validation_callback(validation_fn: ValidationCallback) -> ValidationReporter {
		Box::new(move \|info: &ServerInfo, success: bool\| {
		async move {
		let (ip_addr, domain) = match (
		CString::new(info.peer_addr.ip().to_string()),
		CString::new(info.domain.clone().unwrap_or_default()),
		) {
		(Ok(ip_addr), Ok(domain)) => (ip_addr, domain),
		_ => {
		error!("validation_callback bad input");
		return;
		}
		};
		let netd_id = info.net_id;
		task::spawn_blocking(move \|\| {
		validation_fn(netd_id, success, ip_addr.as_ptr(), domain.as_ptr())
		})
		.await
		.unwrap_or_else(\|e\| warn!("Validation function task failed: {}", e))
		}
		.boxed()
		})
		}

		fn wrap_tag_socket_callback(tag_socket_fn: TagSocketCallback) -> SocketTagger {
		use std::os::unix::io::AsRawFd;
		use std::sync::Arc;
		Arc::new(move \|udp_socket: &std::net::UdpSocket\| {
		let fd = udp_socket.as_raw_fd();
		async move {
		task::spawn_blocking(move \|\| {
		tag_socket_fn(fd);
		})
		.await
		.unwrap_or_else(\|e\| warn!("Socket tag function task failed: {}", e))
		}
		.boxed()
		})
		}

		pub struct DohDispatcher(Mutex<Dispatcher>);

		@@ -97,7 +145,10 @@ pub extern "C" fn doh_dispatcher_new(
		validation_fn: ValidationCallback,
		tag_socket_fn: TagSocketCallback,
		) -> *mut DohDispatcher {
		match Dispatcher::new(validation_fn, tag_socket_fn) {
		match Dispatcher::new(
		wrap_validation_callback(validation_fn),
		wrap_tag_socket_callback(tag_socket_fn),
		) {
		Ok(c) => Box::into_raw(Box::new(DohDispatcher(Mutex::new(c)))),
		Err(e) => {
		error!("doh_dispatcher_new: failed: {:?}", e);
		@@ -158,7 +209,7 @@ pub unsafe extern "C" fn doh_net_new(
		}
		};

		let (url, ip_addr) = match (url::Url::parse(url), IpAddr::from_str(&ip_addr)) {
		let (url, ip_addr) = match (Url::parse(url), IpAddr::from_str(&ip_addr)) {
		(Ok(url), Ok(ip_addr)) => (url, ip_addr),
		_ => {
		error!("bad ip or url"); // Should not happen
		@@ -262,3 +313,76 @@ pub extern "C" fn doh_net_delete(doh: &DohDispatcher, net_id: uint32_t) {
		error!("Failed to send the query: {:?}", e);
		}
		}

		#[cfg(test)]
		mod tests {
		use super::*;

		const TEST_NET_ID: u32 = 50;
		const LOOPBACK_ADDR: &str = "127.0.0.1:443";
		const LOCALHOST_URL: &str = "https://mylocal.com/dns-query";

		extern "C" fn success_cb(
		net_id: uint32_t,
		success: bool,
		ip_addr: *const c_char,
		host: *const c_char,
		) {
		assert!(success);
		unsafe {
		assert_validation_info(net_id, ip_addr, host);
		}
		}

		extern "C" fn fail_cb(
		net_id: uint32_t,
		success: bool,
		ip_addr: *const c_char,
		host: *const c_char,
		) {
		assert!(!success);
		unsafe {
		assert_validation_info(net_id, ip_addr, host);
		}
		}

		// # Safety
		// `ip_addr`, `host` are null terminated strings
		unsafe fn assert_validation_info(
		net_id: uint32_t,
		ip_addr: *const c_char,
		host: *const c_char,
		) {
		assert_eq!(net_id, TEST_NET_ID);
		let ip_addr = std::ffi::CStr::from_ptr(ip_addr).to_str().unwrap();
		let expected_addr: SocketAddr = LOOPBACK_ADDR.parse().unwrap();
		assert_eq!(ip_addr, expected_addr.ip().to_string());
		let host = std::ffi::CStr::from_ptr(host).to_str().unwrap();
		assert_eq!(host, "");
		}

		#[tokio::test]
		async fn wrap_validation_callback_converts_correctly() {
		let info = ServerInfo {
		net_id: TEST_NET_ID,
		url: Url::parse(LOCALHOST_URL).unwrap(),
		peer_addr: LOOPBACK_ADDR.parse().unwrap(),
		domain: None,
		sk_mark: 0,
		cert_path: None,
		};

		wrap_validation_callback(success_cb)(&info, true).await;
		wrap_validation_callback(fail_cb)(&info, false).await;
		}

		extern "C" fn tag_socket_cb(raw_fd: RawFd) {
		assert!(raw_fd > 0)
		}

		#[tokio::test]
		async fn wrap_tag_socket_callback_converts_correctly() {
		let sock = std::net::UdpSocket::bind("127.0.0.1:0").unwrap();
		wrap_tag_socket_callback(tag_socket_cb)(&sock).await;
		}
		}