1490 lines
56 KiB
C++
1490 lines
56 KiB
C++
/* $NetBSD: res_send.c,v 1.9 2006/01/24 17:41:25 christos Exp $ */
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/*
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* Copyright (c) 1985, 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Portions Copyright (c) 1993 by Digital Equipment Corporation.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies, and that
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* the name of Digital Equipment Corporation not be used in advertising or
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* publicity pertaining to distribution of the document or software without
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* specific, written prior permission.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
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* WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
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* CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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/*
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* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
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* Portions Copyright (c) 1996-1999 by Internet Software Consortium.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
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* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* Send query to name server and wait for reply.
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*/
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#define LOG_TAG "resolv"
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#include <chrono>
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#include <sys/param.h>
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#include <sys/socket.h>
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#include <sys/time.h>
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#include <sys/uio.h>
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#include <arpa/inet.h>
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#include <arpa/nameser.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <netdb.h>
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#include <poll.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <span>
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#include <android-base/logging.h>
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#include <android-base/result.h>
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#include <android/multinetwork.h> // ResNsendFlags
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#include <netdutils/Slice.h>
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#include <netdutils/Stopwatch.h>
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#include "DnsTlsDispatcher.h"
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#include "DnsTlsTransport.h"
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#include "Experiments.h"
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#include "PrivateDnsConfiguration.h"
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#include "netd_resolv/resolv.h"
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#include "private/android_filesystem_config.h"
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#include "doh.h"
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#include "res_comp.h"
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#include "res_debug.h"
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#include "resolv_cache.h"
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#include "stats.h"
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#include "stats.pb.h"
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#include "util.h"
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using namespace std::chrono_literals;
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// TODO: use the namespace something like android::netd_resolv for libnetd_resolv
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using android::base::ErrnoError;
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using android::base::Result;
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using android::base::unique_fd;
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using android::net::CacheStatus;
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using android::net::DnsQueryEvent;
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using android::net::DnsTlsDispatcher;
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using android::net::DnsTlsServer;
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using android::net::DnsTlsTransport;
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using android::net::Experiments;
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using android::net::IpVersion;
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using android::net::IV_IPV4;
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using android::net::IV_IPV6;
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using android::net::IV_UNKNOWN;
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using android::net::LinuxErrno;
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using android::net::NetworkDnsEventReported;
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using android::net::NS_T_AAAA;
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using android::net::NS_T_INVALID;
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using android::net::NsRcode;
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using android::net::NsType;
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using android::net::PrivateDnsConfiguration;
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using android::net::PrivateDnsMode;
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using android::net::PrivateDnsModes;
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using android::net::PrivateDnsStatus;
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using android::net::PROTO_DOH;
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using android::net::PROTO_MDNS;
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using android::net::PROTO_TCP;
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using android::net::PROTO_UDP;
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using android::netdutils::IPSockAddr;
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using android::netdutils::Slice;
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using android::netdutils::Stopwatch;
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using std::span;
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const std::vector<IPSockAddr> mdns_addrs = {IPSockAddr::toIPSockAddr("ff02::fb", 5353),
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IPSockAddr::toIPSockAddr("224.0.0.251", 5353)};
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static int setupUdpSocket(ResState* statp, const sockaddr* sockap, unique_fd* fd_out, int* terrno);
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static int send_dg(ResState* statp, res_params* params, span<const uint8_t> msg, span<uint8_t> ans,
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int* terrno, size_t* ns, int* v_circuit, int* gotsomewhere, time_t* at,
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int* rcode, int* delay);
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static int send_vc(ResState* statp, res_params* params, span<const uint8_t> msg, span<uint8_t> ans,
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int* terrno, size_t ns, time_t* at, int* rcode, int* delay);
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static int send_mdns(ResState* statp, span<const uint8_t> msg, span<uint8_t> ans, int* terrno,
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int* rcode);
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static void dump_error(const char*, const struct sockaddr*);
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static int sock_eq(struct sockaddr*, struct sockaddr*);
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static int connect_with_timeout(int sock, const struct sockaddr* nsap, socklen_t salen,
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const struct timespec timeout);
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static int retrying_poll(const int sock, short events, const struct timespec* finish);
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static int res_private_dns_send(ResState*, const Slice query, const Slice answer, int* rcode,
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bool* fallback);
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static int res_tls_send(const std::list<DnsTlsServer>& tlsServers, ResState*, const Slice query,
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const Slice answer, int* rcode, PrivateDnsMode mode);
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static ssize_t res_doh_send(ResState*, const Slice query, const Slice answer, int* rcode);
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NsType getQueryType(span<const uint8_t> msg) {
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ns_msg handle;
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ns_rr rr;
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if (ns_initparse(msg.data(), msg.size(), &handle) < 0 ||
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ns_parserr(&handle, ns_s_qd, 0, &rr) < 0) {
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return NS_T_INVALID;
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}
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return static_cast<NsType>(ns_rr_type(rr));
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}
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IpVersion ipFamilyToIPVersion(const int ipFamily) {
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switch (ipFamily) {
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case AF_INET:
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return IV_IPV4;
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case AF_INET6:
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return IV_IPV6;
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default:
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return IV_UNKNOWN;
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}
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}
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// BEGIN: Code copied from ISC eventlib
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// TODO: move away from this code
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#define BILLION 1000000000
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static struct timespec evConsTime(time_t sec, long nsec) {
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struct timespec x;
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x.tv_sec = sec;
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x.tv_nsec = nsec;
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return (x);
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}
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static struct timespec evAddTime(struct timespec addend1, struct timespec addend2) {
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struct timespec x;
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x.tv_sec = addend1.tv_sec + addend2.tv_sec;
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x.tv_nsec = addend1.tv_nsec + addend2.tv_nsec;
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if (x.tv_nsec >= BILLION) {
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x.tv_sec++;
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x.tv_nsec -= BILLION;
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}
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return (x);
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}
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static struct timespec evSubTime(struct timespec minuend, struct timespec subtrahend) {
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struct timespec x;
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x.tv_sec = minuend.tv_sec - subtrahend.tv_sec;
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if (minuend.tv_nsec >= subtrahend.tv_nsec)
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x.tv_nsec = minuend.tv_nsec - subtrahend.tv_nsec;
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else {
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x.tv_nsec = BILLION - subtrahend.tv_nsec + minuend.tv_nsec;
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x.tv_sec--;
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}
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return (x);
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}
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static int evCmpTime(struct timespec a, struct timespec b) {
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#define SGN(x) ((x) < 0 ? (-1) : (x) > 0 ? (1) : (0));
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time_t s = a.tv_sec - b.tv_sec;
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long n;
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if (s != 0) return SGN(s);
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n = a.tv_nsec - b.tv_nsec;
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return SGN(n);
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}
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static struct timespec evNowTime(void) {
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struct timespec tsnow;
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clock_gettime(CLOCK_REALTIME, &tsnow);
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return tsnow;
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}
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// END: Code copied from ISC eventlib
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/* BIONIC-BEGIN: implement source port randomization */
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static int random_bind(int s, int family) {
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sockaddr_union u;
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int j;
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socklen_t slen;
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/* clear all, this also sets the IP4/6 address to 'any' */
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memset(&u, 0, sizeof u);
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switch (family) {
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case AF_INET:
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u.sin.sin_family = family;
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slen = sizeof u.sin;
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break;
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case AF_INET6:
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u.sin6.sin6_family = family;
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slen = sizeof u.sin6;
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break;
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default:
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errno = EPROTO;
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return -1;
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}
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/* first try to bind to a random source port a few times */
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for (j = 0; j < 10; j++) {
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/* find a random port between 1025 .. 65534 */
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int port = 1025 + (arc4random_uniform(65535 - 1025));
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// RFC 6762 section 5.1: Don't use 5353 source port on one-shot Multicast DNS queries. DNS
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// resolver does not fully compliant mDNS.
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if (port == 5353) continue;
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if (family == AF_INET)
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u.sin.sin_port = htons(port);
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else
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u.sin6.sin6_port = htons(port);
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if (!bind(s, &u.sa, slen)) return 0;
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}
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// nothing after 10 attempts, our network table is probably busy
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// let the system decide which port is best
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if (family == AF_INET)
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u.sin.sin_port = 0;
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else
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u.sin6.sin6_port = 0;
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return bind(s, &u.sa, slen);
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}
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/* BIONIC-END */
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// Disables all nameservers other than selectedServer
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static void res_set_usable_server(int selectedServer, int nscount, bool usable_servers[]) {
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int usableIndex = 0;
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for (int ns = 0; ns < nscount; ns++) {
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if (usable_servers[ns]) ++usableIndex;
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if (usableIndex != selectedServer) usable_servers[ns] = false;
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}
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}
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// Looks up the nameserver address in res.nsaddrs[], returns the ns number if found, otherwise -1.
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static int res_ourserver_p(ResState* statp, const sockaddr* sa) {
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const sockaddr_in *inp, *srv;
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const sockaddr_in6 *in6p, *srv6;
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int ns = 0;
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switch (sa->sa_family) {
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case AF_INET:
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inp = (const struct sockaddr_in*) (const void*) sa;
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for (const IPSockAddr& ipsa : statp->nsaddrs) {
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sockaddr_storage ss = ipsa;
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srv = reinterpret_cast<sockaddr_in*>(&ss);
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if (srv->sin_family == inp->sin_family && srv->sin_port == inp->sin_port &&
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(srv->sin_addr.s_addr == INADDR_ANY ||
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srv->sin_addr.s_addr == inp->sin_addr.s_addr))
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return ns;
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++ns;
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}
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break;
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case AF_INET6:
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in6p = (const struct sockaddr_in6*) (const void*) sa;
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for (const IPSockAddr& ipsa : statp->nsaddrs) {
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sockaddr_storage ss = ipsa;
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srv6 = reinterpret_cast<sockaddr_in6*>(&ss);
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if (srv6->sin6_family == in6p->sin6_family && srv6->sin6_port == in6p->sin6_port &&
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#ifdef HAVE_SIN6_SCOPE_ID
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(srv6->sin6_scope_id == 0 || srv6->sin6_scope_id == in6p->sin6_scope_id) &&
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#endif
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(IN6_IS_ADDR_UNSPECIFIED(&srv6->sin6_addr) ||
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IN6_ARE_ADDR_EQUAL(&srv6->sin6_addr, &in6p->sin6_addr)))
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return ns;
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++ns;
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}
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break;
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default:
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break;
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}
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return -1;
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}
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/* int
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* res_nameinquery(name, type, cl, msg, eom)
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* look for (name, type, cl) in the query section of packet (msg, eom)
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* requires:
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* msg + HFIXEDSZ <= eom
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* returns:
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* -1 : format error
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* 0 : not found
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* >0 : found
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* author:
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* paul vixie, 29may94
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*/
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int res_nameinquery(const char* name, int type, int cl, const uint8_t* msg, const uint8_t* eom) {
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const uint8_t* cp = msg + HFIXEDSZ;
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int qdcount = ntohs(((const HEADER*)(const void*)msg)->qdcount);
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while (qdcount-- > 0) {
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char tname[MAXDNAME + 1];
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int n = dn_expand(msg, eom, cp, tname, sizeof tname);
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if (n < 0) return (-1);
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cp += n;
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if (cp + 2 * INT16SZ > eom) return (-1);
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int ttype = ntohs(*reinterpret_cast<const uint16_t*>(cp));
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cp += INT16SZ;
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int tclass = ntohs(*reinterpret_cast<const uint16_t*>(cp));
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cp += INT16SZ;
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if (ttype == type && tclass == cl && ns_samename(tname, name) == 1) return (1);
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}
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return (0);
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}
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/* int
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* res_queriesmatch(buf1, eom1, buf2, eom2)
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* is there a 1:1 mapping of (name,type,class)
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* in (buf1,eom1) and (buf2,eom2)?
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* returns:
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* -1 : format error
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* 0 : not a 1:1 mapping
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* >0 : is a 1:1 mapping
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* author:
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* paul vixie, 29may94
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*/
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int res_queriesmatch(const uint8_t* buf1, const uint8_t* eom1, const uint8_t* buf2,
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const uint8_t* eom2) {
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const uint8_t* cp = buf1 + HFIXEDSZ;
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int qdcount = ntohs(((const HEADER*) (const void*) buf1)->qdcount);
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if (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2) return (-1);
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/*
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* Only header section present in replies to
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* dynamic update packets.
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*/
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if ((((const HEADER*) (const void*) buf1)->opcode == ns_o_update) &&
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(((const HEADER*) (const void*) buf2)->opcode == ns_o_update))
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return (1);
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if (qdcount != ntohs(((const HEADER*) (const void*) buf2)->qdcount)) return (0);
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while (qdcount-- > 0) {
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char tname[MAXDNAME + 1];
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int n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
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if (n < 0) return (-1);
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cp += n;
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if (cp + 2 * INT16SZ > eom1) return (-1);
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int ttype = ntohs(*reinterpret_cast<const uint16_t*>(cp));
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cp += INT16SZ;
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int tclass = ntohs(*reinterpret_cast<const uint16_t*>(cp));
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cp += INT16SZ;
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if (!res_nameinquery(tname, ttype, tclass, buf2, eom2)) return (0);
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}
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return (1);
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}
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static DnsQueryEvent* addDnsQueryEvent(NetworkDnsEventReported* event) {
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return event->mutable_dns_query_events()->add_dns_query_event();
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}
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static bool isNetworkRestricted(int terrno) {
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// It's possible that system was in some network restricted mode, which blocked
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// the operation of sending packet and resulted in EPERM errno.
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// It would be no reason to keep retrying on that case.
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// TODO: Check the system status to know if network restricted mode is
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// enabled.
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return (terrno == EPERM);
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}
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int res_nsend(ResState* statp, span<const uint8_t> msg, span<uint8_t> ans, int* rcode,
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uint32_t flags, std::chrono::milliseconds sleepTimeMs) {
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LOG(DEBUG) << __func__;
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// Should not happen
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if (ans.size() < HFIXEDSZ) {
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// TODO: Remove errno once callers stop using it
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errno = EINVAL;
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return -EINVAL;
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}
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res_pquery(msg);
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int anslen = 0;
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Stopwatch cacheStopwatch;
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ResolvCacheStatus cache_status = resolv_cache_lookup(statp->netid, msg, ans, &anslen, flags);
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const int32_t cacheLatencyUs = saturate_cast<int32_t>(cacheStopwatch.timeTakenUs());
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if (cache_status == RESOLV_CACHE_FOUND) {
|
|
HEADER* hp = (HEADER*)(void*)ans.data();
|
|
*rcode = hp->rcode;
|
|
DnsQueryEvent* dnsQueryEvent = addDnsQueryEvent(statp->event);
|
|
dnsQueryEvent->set_latency_micros(cacheLatencyUs);
|
|
dnsQueryEvent->set_cache_hit(static_cast<CacheStatus>(cache_status));
|
|
dnsQueryEvent->set_type(getQueryType(msg));
|
|
return anslen;
|
|
} else if (cache_status != RESOLV_CACHE_UNSUPPORTED) {
|
|
// had a cache miss for a known network, so populate the thread private
|
|
// data so the normal resolve path can do its thing
|
|
resolv_populate_res_for_net(statp);
|
|
}
|
|
|
|
// MDNS
|
|
if (isMdnsResolution(statp->flags)) {
|
|
// Use an impossible error code as default value.
|
|
int terrno = ETIME;
|
|
int resplen = 0;
|
|
*rcode = RCODE_INTERNAL_ERROR;
|
|
Stopwatch queryStopwatch;
|
|
resplen = send_mdns(statp, msg, ans, &terrno, rcode);
|
|
const IPSockAddr& receivedMdnsAddr =
|
|
(getQueryType(msg) == NS_T_AAAA) ? mdns_addrs[0] : mdns_addrs[1];
|
|
DnsQueryEvent* mDnsQueryEvent = addDnsQueryEvent(statp->event);
|
|
mDnsQueryEvent->set_cache_hit(static_cast<CacheStatus>(cache_status));
|
|
mDnsQueryEvent->set_latency_micros(saturate_cast<int32_t>(queryStopwatch.timeTakenUs()));
|
|
mDnsQueryEvent->set_ip_version(ipFamilyToIPVersion(receivedMdnsAddr.family()));
|
|
mDnsQueryEvent->set_rcode(static_cast<NsRcode>(*rcode));
|
|
mDnsQueryEvent->set_protocol(PROTO_MDNS);
|
|
mDnsQueryEvent->set_type(getQueryType(msg));
|
|
mDnsQueryEvent->set_linux_errno(static_cast<LinuxErrno>(terrno));
|
|
resolv_stats_add(statp->netid, receivedMdnsAddr, mDnsQueryEvent);
|
|
|
|
if (resplen > 0) {
|
|
LOG(DEBUG) << __func__ << ": got answer from mDNS:";
|
|
res_pquery(ans.first(resplen));
|
|
|
|
if (cache_status == RESOLV_CACHE_NOTFOUND) {
|
|
resolv_cache_add(statp->netid, msg, {ans.data(), resplen});
|
|
}
|
|
return resplen;
|
|
}
|
|
}
|
|
|
|
if (statp->nameserverCount() == 0) {
|
|
// We have no nameservers configured and it's not a MDNS resolution, so there's no
|
|
// point trying. Tell the cache the query failed, or any retries and anyone else
|
|
// asking the same question will block for PENDING_REQUEST_TIMEOUT seconds instead
|
|
// of failing fast.
|
|
_resolv_cache_query_failed(statp->netid, msg, flags);
|
|
|
|
// TODO: Remove errno once callers stop using it
|
|
errno = ESRCH;
|
|
return -ESRCH;
|
|
}
|
|
|
|
// Private DNS
|
|
if (!(statp->netcontext_flags & NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS)) {
|
|
bool fallback = false;
|
|
int resplen =
|
|
res_private_dns_send(statp, Slice(const_cast<uint8_t*>(msg.data()), msg.size()),
|
|
Slice(ans.data(), ans.size()), rcode, &fallback);
|
|
if (resplen > 0) {
|
|
LOG(DEBUG) << __func__ << ": got answer from Private DNS";
|
|
res_pquery(ans.first(resplen));
|
|
if (cache_status == RESOLV_CACHE_NOTFOUND) {
|
|
resolv_cache_add(statp->netid, msg, ans.first(resplen));
|
|
}
|
|
return resplen;
|
|
}
|
|
if (!fallback) {
|
|
_resolv_cache_query_failed(statp->netid, msg, flags);
|
|
return -ETIMEDOUT;
|
|
}
|
|
}
|
|
|
|
// If parallel_lookup is enabled, it might be required to wait some time to avoid
|
|
// gateways from dropping packets if queries are sent too close together.
|
|
if (sleepTimeMs != 0ms) {
|
|
std::this_thread::sleep_for(sleepTimeMs);
|
|
}
|
|
|
|
res_stats stats[MAXNS]{};
|
|
res_params params;
|
|
int revision_id = resolv_cache_get_resolver_stats(statp->netid, ¶ms, stats, statp->nsaddrs);
|
|
if (revision_id < 0) {
|
|
// TODO: Remove errno once callers stop using it
|
|
errno = ESRCH;
|
|
return -ESRCH;
|
|
}
|
|
|
|
bool usable_servers[MAXNS];
|
|
int usableServersCount = android_net_res_stats_get_usable_servers(
|
|
¶ms, stats, statp->nameserverCount(), usable_servers);
|
|
|
|
if (statp->sort_nameservers) {
|
|
// It's unnecessary to mark a DNS server as unusable since broken servers will be less
|
|
// likely to be chosen.
|
|
for (int i = 0; i < statp->nameserverCount(); i++) {
|
|
usable_servers[i] = true;
|
|
}
|
|
}
|
|
|
|
// TODO: Let it always choose the first nameserver when sort_nameservers is enabled.
|
|
if ((flags & ANDROID_RESOLV_NO_RETRY) && usableServersCount > 1) {
|
|
auto hp = reinterpret_cast<const HEADER*>(msg.data());
|
|
|
|
// Select a random server based on the query id
|
|
int selectedServer = (hp->id % usableServersCount) + 1;
|
|
res_set_usable_server(selectedServer, statp->nameserverCount(), usable_servers);
|
|
}
|
|
|
|
// Send request, RETRY times, or until successful.
|
|
int retryTimes = (flags & ANDROID_RESOLV_NO_RETRY) ? 1 : params.retry_count;
|
|
int useTcp = msg.size() > PACKETSZ;
|
|
int gotsomewhere = 0;
|
|
|
|
// Use an impossible error code as default value
|
|
int terrno = ETIME;
|
|
// plaintext DNS
|
|
for (int attempt = 0; attempt < retryTimes; ++attempt) {
|
|
for (size_t ns = 0; ns < statp->nsaddrs.size(); ++ns) {
|
|
if (!usable_servers[ns]) continue;
|
|
|
|
*rcode = RCODE_INTERNAL_ERROR;
|
|
|
|
// Get server addr
|
|
const IPSockAddr& serverSockAddr = statp->nsaddrs[ns];
|
|
LOG(DEBUG) << __func__ << ": Querying server (# " << ns + 1
|
|
<< ") address = " << serverSockAddr.toString();
|
|
|
|
::android::net::Protocol query_proto = useTcp ? PROTO_TCP : PROTO_UDP;
|
|
time_t query_time = 0;
|
|
int delay = 0;
|
|
bool fallbackTCP = false;
|
|
const bool shouldRecordStats = (attempt == 0);
|
|
int resplen;
|
|
Stopwatch queryStopwatch;
|
|
int retry_count_for_event = 0;
|
|
size_t actualNs = ns;
|
|
// Use an impossible error code as default value
|
|
terrno = ETIME;
|
|
if (useTcp) {
|
|
// TCP; at most one attempt per server.
|
|
attempt = retryTimes;
|
|
resplen =
|
|
send_vc(statp, ¶ms, msg, ans, &terrno, ns, &query_time, rcode, &delay);
|
|
|
|
if (msg.size() <= PACKETSZ && resplen <= 0 &&
|
|
statp->tc_mode == aidl::android::net::IDnsResolver::TC_MODE_UDP_TCP) {
|
|
// reset to UDP for next query on next DNS server if resolver is currently doing
|
|
// TCP fallback retry and current server does not support TCP connectin
|
|
useTcp = false;
|
|
}
|
|
LOG(INFO) << __func__ << ": used send_vc " << resplen << " terrno: " << terrno;
|
|
} else {
|
|
// UDP
|
|
resplen = send_dg(statp, ¶ms, msg, ans, &terrno, &actualNs, &useTcp,
|
|
&gotsomewhere, &query_time, rcode, &delay);
|
|
fallbackTCP = useTcp ? true : false;
|
|
retry_count_for_event = attempt;
|
|
LOG(INFO) << __func__ << ": used send_dg " << resplen << " terrno: " << terrno;
|
|
}
|
|
|
|
const IPSockAddr& receivedServerAddr = statp->nsaddrs[actualNs];
|
|
DnsQueryEvent* dnsQueryEvent = addDnsQueryEvent(statp->event);
|
|
dnsQueryEvent->set_cache_hit(static_cast<CacheStatus>(cache_status));
|
|
// When |retryTimes| > 1, we cannot actually know the correct latency value if we
|
|
// received the answer from the previous server. So temporarily set the latency as -1 if
|
|
// that condition happened.
|
|
// TODO: make the latency value accurate.
|
|
dnsQueryEvent->set_latency_micros(
|
|
(actualNs == ns) ? saturate_cast<int32_t>(queryStopwatch.timeTakenUs()) : -1);
|
|
dnsQueryEvent->set_dns_server_index(actualNs);
|
|
dnsQueryEvent->set_ip_version(ipFamilyToIPVersion(receivedServerAddr.family()));
|
|
dnsQueryEvent->set_retry_times(retry_count_for_event);
|
|
dnsQueryEvent->set_rcode(static_cast<NsRcode>(*rcode));
|
|
dnsQueryEvent->set_protocol(query_proto);
|
|
dnsQueryEvent->set_type(getQueryType(msg));
|
|
dnsQueryEvent->set_linux_errno(static_cast<LinuxErrno>(terrno));
|
|
|
|
// Only record stats the first time we try a query. This ensures that
|
|
// queries that deterministically fail (e.g., a name that always returns
|
|
// SERVFAIL or times out) do not unduly affect the stats.
|
|
if (shouldRecordStats) {
|
|
// (b/151166599): This is a workaround to prevent that DnsResolver calculates the
|
|
// reliability of DNS servers from being broken when network restricted mode is
|
|
// enabled.
|
|
// TODO: Introduce the new server selection instead of skipping stats recording.
|
|
if (!isNetworkRestricted(terrno)) {
|
|
res_sample sample;
|
|
res_stats_set_sample(&sample, query_time, *rcode, delay);
|
|
// KeepListening UDP mechanism is incompatible with usable_servers of legacy
|
|
// stats, so keep the old logic for now.
|
|
// TODO: Replace usable_servers of legacy stats with new one.
|
|
resolv_cache_add_resolver_stats_sample(
|
|
statp->netid, revision_id, serverSockAddr, sample, params.max_samples);
|
|
resolv_stats_add(statp->netid, receivedServerAddr, dnsQueryEvent);
|
|
}
|
|
}
|
|
|
|
if (resplen == 0) continue;
|
|
if (fallbackTCP) {
|
|
ns--;
|
|
continue;
|
|
}
|
|
if (resplen < 0) {
|
|
_resolv_cache_query_failed(statp->netid, msg, flags);
|
|
statp->closeSockets();
|
|
return -terrno;
|
|
}
|
|
|
|
LOG(DEBUG) << __func__ << ": got answer:";
|
|
res_pquery(ans.first(resplen));
|
|
|
|
if (cache_status == RESOLV_CACHE_NOTFOUND) {
|
|
resolv_cache_add(statp->netid, msg, {ans.data(), resplen});
|
|
}
|
|
statp->closeSockets();
|
|
return (resplen);
|
|
} // for each ns
|
|
} // for each retry
|
|
statp->closeSockets();
|
|
terrno = useTcp ? terrno : gotsomewhere ? ETIMEDOUT : ECONNREFUSED;
|
|
// TODO: Remove errno once callers stop using it
|
|
errno = useTcp ? terrno
|
|
: gotsomewhere ? ETIMEDOUT /* no answer obtained */
|
|
: ECONNREFUSED /* no nameservers found */;
|
|
|
|
_resolv_cache_query_failed(statp->netid, msg, flags);
|
|
return -terrno;
|
|
}
|
|
|
|
static struct timespec get_timeout(ResState* statp, const res_params* params, const int addrIndex) {
|
|
int msec;
|
|
msec = params->base_timeout_msec << addrIndex;
|
|
// Legacy algorithm which scales the timeout by nameserver number.
|
|
// For instance, with 4 nameservers: 5s, 2.5s, 5s, 10s
|
|
// This has no effect with 1 or 2 nameservers
|
|
if (addrIndex > 0) {
|
|
msec /= statp->nameserverCount();
|
|
}
|
|
// For safety, don't allow OEMs and experiments to configure a timeout shorter than 1s.
|
|
if (msec < 1000) {
|
|
msec = 1000; // Use at least 1000ms
|
|
}
|
|
LOG(INFO) << __func__ << ": using timeout of " << msec << " msec";
|
|
|
|
struct timespec result;
|
|
result.tv_sec = msec / 1000;
|
|
result.tv_nsec = (msec % 1000) * 1000000;
|
|
return result;
|
|
}
|
|
|
|
static int send_vc(ResState* statp, res_params* params, span<const uint8_t> msg, span<uint8_t> ans,
|
|
int* terrno, size_t ns, time_t* at, int* rcode, int* delay) {
|
|
*at = time(NULL);
|
|
*delay = 0;
|
|
const HEADER* hp = (const HEADER*)(const void*)msg.data();
|
|
HEADER* anhp = (HEADER*)(void*)ans.data();
|
|
struct sockaddr* nsap;
|
|
int nsaplen;
|
|
int truncating, connreset, n;
|
|
uint8_t* cp;
|
|
|
|
LOG(INFO) << __func__ << ": using send_vc";
|
|
|
|
// It should never happen, but just in case.
|
|
if (ns >= statp->nsaddrs.size()) {
|
|
LOG(ERROR) << __func__ << ": Out-of-bound indexing: " << ns;
|
|
*terrno = EINVAL;
|
|
return -1;
|
|
}
|
|
|
|
sockaddr_storage ss = statp->nsaddrs[ns];
|
|
nsap = reinterpret_cast<sockaddr*>(&ss);
|
|
nsaplen = sockaddrSize(nsap);
|
|
|
|
connreset = 0;
|
|
same_ns:
|
|
truncating = 0;
|
|
|
|
struct timespec start_time = evNowTime();
|
|
|
|
/* Are we still talking to whom we want to talk to? */
|
|
if (statp->tcp_nssock >= 0 && (statp->flags & RES_F_VC) != 0) {
|
|
struct sockaddr_storage peer;
|
|
socklen_t size = sizeof peer;
|
|
unsigned old_mark;
|
|
socklen_t mark_size = sizeof(old_mark);
|
|
if (getpeername(statp->tcp_nssock, (struct sockaddr*)(void*)&peer, &size) < 0 ||
|
|
!sock_eq((struct sockaddr*)(void*)&peer, nsap) ||
|
|
getsockopt(statp->tcp_nssock, SOL_SOCKET, SO_MARK, &old_mark, &mark_size) < 0 ||
|
|
old_mark != statp->mark) {
|
|
statp->closeSockets();
|
|
}
|
|
}
|
|
|
|
if (statp->tcp_nssock < 0 || (statp->flags & RES_F_VC) == 0) {
|
|
if (statp->tcp_nssock >= 0) statp->closeSockets();
|
|
|
|
statp->tcp_nssock.reset(socket(nsap->sa_family, SOCK_STREAM | SOCK_CLOEXEC, 0));
|
|
if (statp->tcp_nssock < 0) {
|
|
*terrno = errno;
|
|
PLOG(DEBUG) << __func__ << ": socket(vc): ";
|
|
switch (errno) {
|
|
case EPROTONOSUPPORT:
|
|
case EPFNOSUPPORT:
|
|
case EAFNOSUPPORT:
|
|
return 0;
|
|
default:
|
|
return -1;
|
|
}
|
|
}
|
|
const uid_t uid = statp->enforce_dns_uid ? AID_DNS : statp->uid;
|
|
resolv_tag_socket(statp->tcp_nssock, uid, statp->pid);
|
|
if (statp->mark != MARK_UNSET) {
|
|
if (setsockopt(statp->tcp_nssock, SOL_SOCKET, SO_MARK, &statp->mark,
|
|
sizeof(statp->mark)) < 0) {
|
|
*terrno = errno;
|
|
PLOG(DEBUG) << __func__ << ": setsockopt: ";
|
|
return -1;
|
|
}
|
|
}
|
|
errno = 0;
|
|
if (random_bind(statp->tcp_nssock, nsap->sa_family) < 0) {
|
|
*terrno = errno;
|
|
dump_error("bind/vc", nsap);
|
|
statp->closeSockets();
|
|
return (0);
|
|
}
|
|
if (connect_with_timeout(statp->tcp_nssock, nsap, (socklen_t)nsaplen,
|
|
get_timeout(statp, params, ns)) < 0) {
|
|
*terrno = errno;
|
|
dump_error("connect/vc", nsap);
|
|
statp->closeSockets();
|
|
/*
|
|
* The way connect_with_timeout() is implemented prevents us from reliably
|
|
* determining whether this was really a timeout or e.g. ECONNREFUSED. Since
|
|
* currently both cases are handled in the same way, there is no need to
|
|
* change this (yet). If we ever need to reliably distinguish between these
|
|
* cases, both connect_with_timeout() and retrying_poll() need to be
|
|
* modified, though.
|
|
*/
|
|
*rcode = RCODE_TIMEOUT;
|
|
return (0);
|
|
}
|
|
statp->flags |= RES_F_VC;
|
|
}
|
|
|
|
/*
|
|
* Send length & message
|
|
*/
|
|
uint16_t len = htons(static_cast<uint16_t>(msg.size()));
|
|
const iovec iov[] = {
|
|
{.iov_base = &len, .iov_len = INT16SZ},
|
|
{.iov_base = const_cast<uint8_t*>(msg.data()),
|
|
.iov_len = static_cast<size_t>(msg.size())},
|
|
};
|
|
if (writev(statp->tcp_nssock, iov, 2) != (INT16SZ + msg.size())) {
|
|
*terrno = errno;
|
|
PLOG(DEBUG) << __func__ << ": write failed: ";
|
|
statp->closeSockets();
|
|
return (0);
|
|
}
|
|
/*
|
|
* Receive length & response
|
|
*/
|
|
read_len:
|
|
cp = ans.data();
|
|
len = INT16SZ;
|
|
while ((n = read(statp->tcp_nssock, (char*)cp, (size_t)len)) > 0) {
|
|
cp += n;
|
|
if ((len -= n) == 0) break;
|
|
}
|
|
if (n <= 0) {
|
|
*terrno = errno;
|
|
PLOG(DEBUG) << __func__ << ": read failed: ";
|
|
statp->closeSockets();
|
|
/*
|
|
* A long running process might get its TCP
|
|
* connection reset if the remote server was
|
|
* restarted. Requery the server instead of
|
|
* trying a new one. When there is only one
|
|
* server, this means that a query might work
|
|
* instead of failing. We only allow one reset
|
|
* per query to prevent looping.
|
|
*/
|
|
if (*terrno == ECONNRESET && !connreset) {
|
|
connreset = 1;
|
|
goto same_ns;
|
|
}
|
|
return (0);
|
|
}
|
|
uint16_t resplen = ntohs(*reinterpret_cast<const uint16_t*>(ans.data()));
|
|
if (resplen > ans.size()) {
|
|
LOG(DEBUG) << __func__ << ": response truncated";
|
|
truncating = 1;
|
|
len = ans.size();
|
|
} else
|
|
len = resplen;
|
|
if (len < HFIXEDSZ) {
|
|
/*
|
|
* Undersized message.
|
|
*/
|
|
LOG(DEBUG) << __func__ << ": undersized: " << len;
|
|
*terrno = EMSGSIZE;
|
|
statp->closeSockets();
|
|
return (0);
|
|
}
|
|
cp = ans.data();
|
|
while (len != 0 && (n = read(statp->tcp_nssock, (char*)cp, (size_t)len)) > 0) {
|
|
cp += n;
|
|
len -= n;
|
|
}
|
|
if (n <= 0) {
|
|
*terrno = errno;
|
|
PLOG(DEBUG) << __func__ << ": read(vc): ";
|
|
statp->closeSockets();
|
|
return (0);
|
|
}
|
|
|
|
if (truncating) {
|
|
/*
|
|
* Flush rest of answer so connection stays in synch.
|
|
*/
|
|
anhp->tc = 1;
|
|
len = resplen - ans.size();
|
|
while (len != 0) {
|
|
char junk[PACKETSZ];
|
|
|
|
n = read(statp->tcp_nssock, junk, (len > sizeof junk) ? sizeof junk : len);
|
|
if (n > 0)
|
|
len -= n;
|
|
else
|
|
break;
|
|
}
|
|
LOG(WARNING) << __func__ << ": resplen " << resplen << " exceeds buf size " << ans.size();
|
|
// return size should never exceed container size
|
|
resplen = ans.size();
|
|
}
|
|
/*
|
|
* If the calling application has bailed out of
|
|
* a previous call and failed to arrange to have
|
|
* the circuit closed or the server has got
|
|
* itself confused, then drop the packet and
|
|
* wait for the correct one.
|
|
*/
|
|
if (hp->id != anhp->id) {
|
|
LOG(DEBUG) << __func__ << ": ld answer (unexpected):";
|
|
res_pquery({ans.data(), resplen});
|
|
goto read_len;
|
|
}
|
|
|
|
/*
|
|
* All is well, or the error is fatal. Signal that the
|
|
* next nameserver ought not be tried.
|
|
*/
|
|
if (resplen > 0) {
|
|
struct timespec done = evNowTime();
|
|
*delay = res_stats_calculate_rtt(&done, &start_time);
|
|
*rcode = anhp->rcode;
|
|
}
|
|
*terrno = 0;
|
|
return (resplen);
|
|
}
|
|
|
|
/* return -1 on error (errno set), 0 on success */
|
|
static int connect_with_timeout(int sock, const sockaddr* nsap, socklen_t salen,
|
|
const timespec timeout) {
|
|
int res, origflags;
|
|
|
|
origflags = fcntl(sock, F_GETFL, 0);
|
|
fcntl(sock, F_SETFL, origflags | O_NONBLOCK);
|
|
|
|
res = connect(sock, nsap, salen);
|
|
if (res < 0 && errno != EINPROGRESS) {
|
|
res = -1;
|
|
goto done;
|
|
}
|
|
if (res != 0) {
|
|
timespec now = evNowTime();
|
|
timespec finish = evAddTime(now, timeout);
|
|
LOG(INFO) << __func__ << ": " << sock << " send_vc";
|
|
res = retrying_poll(sock, POLLIN | POLLOUT, &finish);
|
|
if (res <= 0) {
|
|
res = -1;
|
|
}
|
|
}
|
|
done:
|
|
fcntl(sock, F_SETFL, origflags);
|
|
LOG(INFO) << __func__ << ": " << sock << " connect_with_const timeout returning " << res;
|
|
return res;
|
|
}
|
|
|
|
static int retrying_poll(const int sock, const short events, const struct timespec* finish) {
|
|
struct timespec now, timeout;
|
|
|
|
retry:
|
|
LOG(INFO) << __func__ << ": " << sock << " retrying_poll";
|
|
|
|
now = evNowTime();
|
|
if (evCmpTime(*finish, now) > 0)
|
|
timeout = evSubTime(*finish, now);
|
|
else
|
|
timeout = evConsTime(0L, 0L);
|
|
struct pollfd fds = {.fd = sock, .events = events};
|
|
int n = ppoll(&fds, 1, &timeout, /*__mask=*/NULL);
|
|
if (n == 0) {
|
|
LOG(INFO) << __func__ << ": " << sock << " retrying_poll timeout";
|
|
errno = ETIMEDOUT;
|
|
return 0;
|
|
}
|
|
if (n < 0) {
|
|
if (errno == EINTR) goto retry;
|
|
PLOG(INFO) << __func__ << ": " << sock << " retrying_poll failed";
|
|
return n;
|
|
}
|
|
if (fds.revents & (POLLIN | POLLOUT | POLLERR)) {
|
|
int error;
|
|
socklen_t len = sizeof(error);
|
|
if (getsockopt(sock, SOL_SOCKET, SO_ERROR, &error, &len) < 0 || error) {
|
|
errno = error;
|
|
PLOG(INFO) << __func__ << ": " << sock << " retrying_poll getsockopt failed";
|
|
return -1;
|
|
}
|
|
}
|
|
LOG(INFO) << __func__ << ": " << sock << " retrying_poll returning " << n;
|
|
return n;
|
|
}
|
|
|
|
static std::vector<pollfd> extractUdpFdset(ResState* statp, const short events = POLLIN) {
|
|
std::vector<pollfd> fdset(statp->nsaddrs.size());
|
|
for (size_t i = 0; i < statp->nsaddrs.size(); ++i) {
|
|
fdset[i] = {.fd = statp->udpsocks[i], .events = events};
|
|
}
|
|
return fdset;
|
|
}
|
|
|
|
static Result<std::vector<int>> udpRetryingPoll(ResState* statp, const timespec* finish) {
|
|
for (;;) {
|
|
LOG(DEBUG) << __func__ << ": poll";
|
|
timespec start_time = evNowTime();
|
|
timespec timeout = (evCmpTime(*finish, start_time) > 0) ? evSubTime(*finish, start_time)
|
|
: evConsTime(0L, 0L);
|
|
std::vector<pollfd> fdset = extractUdpFdset(statp);
|
|
const int n = ppoll(fdset.data(), fdset.size(), &timeout, /*__mask=*/nullptr);
|
|
if (n <= 0) {
|
|
if (errno == EINTR && n < 0) continue;
|
|
if (n == 0) errno = ETIMEDOUT;
|
|
PLOG(INFO) << __func__ << ": failed";
|
|
return ErrnoError();
|
|
}
|
|
std::vector<int> fdsToRead;
|
|
for (const auto& pollfd : fdset) {
|
|
if (pollfd.revents & (POLLIN | POLLERR)) {
|
|
fdsToRead.push_back(pollfd.fd);
|
|
}
|
|
}
|
|
LOG(DEBUG) << __func__ << ": "
|
|
<< " returning fd size: " << fdsToRead.size();
|
|
return fdsToRead;
|
|
}
|
|
}
|
|
|
|
static Result<std::vector<int>> udpRetryingPollWrapper(ResState* statp, int addrInfo,
|
|
const timespec* finish) {
|
|
const bool keepListeningUdp =
|
|
android::net::Experiments::getInstance()->getFlag("keep_listening_udp", 0);
|
|
if (keepListeningUdp) return udpRetryingPoll(statp, finish);
|
|
|
|
if (int n = retrying_poll(statp->udpsocks[addrInfo], POLLIN, finish); n <= 0) {
|
|
return ErrnoError();
|
|
}
|
|
return std::vector<int>{statp->udpsocks[addrInfo]};
|
|
}
|
|
|
|
bool ignoreInvalidAnswer(ResState* statp, const sockaddr_storage& from, span<const uint8_t> msg,
|
|
span<uint8_t> ans, int* receivedFromNs) {
|
|
const HEADER* hp = (const HEADER*)(const void*)msg.data();
|
|
HEADER* anhp = (HEADER*)(void*)ans.data();
|
|
if (hp->id != anhp->id) {
|
|
// response from old query, ignore it.
|
|
LOG(DEBUG) << __func__ << ": old answer:";
|
|
return true;
|
|
}
|
|
if (*receivedFromNs = res_ourserver_p(statp, (sockaddr*)(void*)&from); *receivedFromNs < 0) {
|
|
// response from wrong server? ignore it.
|
|
LOG(DEBUG) << __func__ << ": not our server:";
|
|
return true;
|
|
}
|
|
if (!res_queriesmatch(msg.data(), msg.data() + msg.size(), ans.data(),
|
|
ans.data() + ans.size())) {
|
|
// response contains wrong query? ignore it.
|
|
LOG(DEBUG) << __func__ << ": wrong query name:";
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// return 1 - setup udp socket success.
|
|
// return 0 - bind error, protocol error.
|
|
// return -1 - create socket fail, except |EPROTONOSUPPORT| EPFNOSUPPORT |EAFNOSUPPORT|.
|
|
// set socket option fail.
|
|
static int setupUdpSocket(ResState* statp, const sockaddr* sockap, unique_fd* fd_out, int* terrno) {
|
|
fd_out->reset(socket(sockap->sa_family, SOCK_DGRAM | SOCK_CLOEXEC, 0));
|
|
|
|
if (*fd_out < 0) {
|
|
*terrno = errno;
|
|
PLOG(ERROR) << __func__ << ": socket: ";
|
|
switch (errno) {
|
|
case EPROTONOSUPPORT:
|
|
case EPFNOSUPPORT:
|
|
case EAFNOSUPPORT:
|
|
return 0;
|
|
default:
|
|
return -1;
|
|
}
|
|
}
|
|
const uid_t uid = statp->enforce_dns_uid ? AID_DNS : statp->uid;
|
|
resolv_tag_socket(*fd_out, uid, statp->pid);
|
|
if (statp->mark != MARK_UNSET) {
|
|
if (setsockopt(*fd_out, SOL_SOCKET, SO_MARK, &(statp->mark), sizeof(statp->mark)) < 0) {
|
|
*terrno = errno;
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
if (random_bind(*fd_out, sockap->sa_family) < 0) {
|
|
*terrno = errno;
|
|
dump_error("bind", sockap);
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static int send_dg(ResState* statp, res_params* params, span<const uint8_t> msg, span<uint8_t> ans,
|
|
int* terrno, size_t* ns, int* v_circuit, int* gotsomewhere, time_t* at,
|
|
int* rcode, int* delay) {
|
|
// It should never happen, but just in case.
|
|
if (*ns >= statp->nsaddrs.size()) {
|
|
LOG(ERROR) << __func__ << ": Out-of-bound indexing: " << ns;
|
|
*terrno = EINVAL;
|
|
return -1;
|
|
}
|
|
|
|
*at = time(nullptr);
|
|
*delay = 0;
|
|
const sockaddr_storage ss = statp->nsaddrs[*ns];
|
|
const sockaddr* nsap = reinterpret_cast<const sockaddr*>(&ss);
|
|
|
|
if (statp->udpsocks[*ns] == -1) {
|
|
int result = setupUdpSocket(statp, nsap, &statp->udpsocks[*ns], terrno);
|
|
if (result <= 0) return result;
|
|
|
|
// Use a "connected" datagram socket to receive an ECONNREFUSED error
|
|
// on the next socket operation when the server responds with an
|
|
// ICMP port-unreachable error. This way we can detect the absence of
|
|
// a nameserver without timing out.
|
|
if (connect(statp->udpsocks[*ns], nsap, sockaddrSize(nsap)) < 0) {
|
|
*terrno = errno;
|
|
dump_error("connect(dg)", nsap);
|
|
statp->closeSockets();
|
|
return 0;
|
|
}
|
|
LOG(DEBUG) << __func__ << ": new DG socket";
|
|
}
|
|
if (send(statp->udpsocks[*ns], msg.data(), msg.size(), 0) != msg.size()) {
|
|
*terrno = errno;
|
|
PLOG(DEBUG) << __func__ << ": send: ";
|
|
statp->closeSockets();
|
|
return 0;
|
|
}
|
|
|
|
timespec timeout = get_timeout(statp, params, *ns);
|
|
timespec start_time = evNowTime();
|
|
timespec finish = evAddTime(start_time, timeout);
|
|
for (;;) {
|
|
// Wait for reply.
|
|
auto result = udpRetryingPollWrapper(statp, *ns, &finish);
|
|
|
|
if (!result.has_value()) {
|
|
const bool isTimeout = (result.error().code() == ETIMEDOUT);
|
|
*rcode = (isTimeout) ? RCODE_TIMEOUT : *rcode;
|
|
*terrno = (isTimeout) ? ETIMEDOUT : errno;
|
|
*gotsomewhere = (isTimeout) ? 1 : *gotsomewhere;
|
|
// Leave the UDP sockets open on timeout so we can keep listening for
|
|
// a late response from this server while retrying on the next server.
|
|
if (!isTimeout) statp->closeSockets();
|
|
LOG(DEBUG) << __func__ << ": " << (isTimeout ? "timeout" : "poll");
|
|
return 0;
|
|
}
|
|
bool needRetry = false;
|
|
for (int fd : result.value()) {
|
|
needRetry = false;
|
|
sockaddr_storage from;
|
|
socklen_t fromlen = sizeof(from);
|
|
int resplen =
|
|
recvfrom(fd, ans.data(), ans.size(), 0, (sockaddr*)(void*)&from, &fromlen);
|
|
if (resplen <= 0) {
|
|
*terrno = errno;
|
|
PLOG(DEBUG) << __func__ << ": recvfrom: ";
|
|
continue;
|
|
}
|
|
*gotsomewhere = 1;
|
|
if (resplen < HFIXEDSZ) {
|
|
// Undersized message.
|
|
LOG(DEBUG) << __func__ << ": undersized: " << resplen;
|
|
*terrno = EMSGSIZE;
|
|
continue;
|
|
}
|
|
|
|
int receivedFromNs = *ns;
|
|
if (needRetry = ignoreInvalidAnswer(statp, from, msg, ans, &receivedFromNs);
|
|
needRetry) {
|
|
res_pquery({ans.data(), (resplen > ans.size()) ? ans.size() : resplen});
|
|
continue;
|
|
}
|
|
|
|
HEADER* anhp = (HEADER*)(void*)ans.data();
|
|
if (anhp->rcode == FORMERR && (statp->netcontext_flags & NET_CONTEXT_FLAG_USE_EDNS)) {
|
|
// Do not retry if the server do not understand EDNS0.
|
|
// The case has to be captured here, as FORMERR packet do not
|
|
// carry query section, hence res_queriesmatch() returns 0.
|
|
LOG(DEBUG) << __func__ << ": server rejected query with EDNS0:";
|
|
res_pquery({ans.data(), (resplen > ans.size()) ? ans.size() : resplen});
|
|
// record the error
|
|
statp->flags |= RES_F_EDNS0ERR;
|
|
*terrno = EREMOTEIO;
|
|
continue;
|
|
}
|
|
|
|
timespec done = evNowTime();
|
|
*delay = res_stats_calculate_rtt(&done, &start_time);
|
|
if (anhp->rcode == SERVFAIL || anhp->rcode == NOTIMP || anhp->rcode == REFUSED) {
|
|
LOG(DEBUG) << __func__ << ": server rejected query:";
|
|
res_pquery({ans.data(), (resplen > ans.size()) ? ans.size() : resplen});
|
|
*rcode = anhp->rcode;
|
|
continue;
|
|
}
|
|
if (anhp->tc) {
|
|
// To get the rest of answer,
|
|
// use TCP with same server.
|
|
LOG(DEBUG) << __func__ << ": truncated answer";
|
|
*terrno = E2BIG;
|
|
*v_circuit = 1;
|
|
return 1;
|
|
}
|
|
// All is well, or the error is fatal. Signal that the
|
|
// next nameserver ought not be tried.
|
|
|
|
*rcode = anhp->rcode;
|
|
*ns = receivedFromNs;
|
|
*terrno = 0;
|
|
return resplen;
|
|
}
|
|
if (!needRetry) return 0;
|
|
}
|
|
}
|
|
|
|
// return length - when receiving valid packets.
|
|
// return 0 - when mdns packets transfer error.
|
|
static int send_mdns(ResState* statp, span<const uint8_t> msg, span<uint8_t> ans, int* terrno,
|
|
int* rcode) {
|
|
const sockaddr_storage ss = (getQueryType(msg) == NS_T_AAAA) ? mdns_addrs[0] : mdns_addrs[1];
|
|
const sockaddr* mdnsap = reinterpret_cast<const sockaddr*>(&ss);
|
|
unique_fd fd;
|
|
|
|
if (setupUdpSocket(statp, mdnsap, &fd, terrno) <= 0) return 0;
|
|
|
|
if (sendto(fd, msg.data(), msg.size(), 0, mdnsap, sockaddrSize(mdnsap)) != msg.size()) {
|
|
*terrno = errno;
|
|
return 0;
|
|
}
|
|
// RFC 6762: Typically, the timeout would also be shortened to two or three seconds.
|
|
const struct timespec finish = evAddTime(evNowTime(), {2, 2000000});
|
|
|
|
// Wait for reply.
|
|
if (retrying_poll(fd, POLLIN, &finish) <= 0) {
|
|
*terrno = errno;
|
|
if (*terrno == ETIMEDOUT) *rcode = RCODE_TIMEOUT;
|
|
LOG(ERROR) << __func__ << ": " << ((*terrno == ETIMEDOUT) ? "timeout" : "poll failed");
|
|
return 0;
|
|
}
|
|
|
|
sockaddr_storage from;
|
|
socklen_t fromlen = sizeof(from);
|
|
int resplen = recvfrom(fd, ans.data(), ans.size(), 0, (sockaddr*)(void*)&from, &fromlen);
|
|
|
|
if (resplen <= 0) {
|
|
*terrno = errno;
|
|
return 0;
|
|
}
|
|
|
|
if (resplen < HFIXEDSZ) {
|
|
// Undersized message.
|
|
LOG(ERROR) << __func__ << ": undersized: " << resplen;
|
|
*terrno = EMSGSIZE;
|
|
return 0;
|
|
}
|
|
|
|
HEADER* anhp = (HEADER*)(void*)ans.data();
|
|
if (anhp->tc) {
|
|
LOG(DEBUG) << __func__ << ": truncated answer";
|
|
*terrno = E2BIG;
|
|
return 0;
|
|
}
|
|
|
|
*rcode = anhp->rcode;
|
|
*terrno = 0;
|
|
return resplen;
|
|
}
|
|
|
|
static void dump_error(const char* str, const struct sockaddr* address) {
|
|
char hbuf[NI_MAXHOST];
|
|
char sbuf[NI_MAXSERV];
|
|
constexpr int niflags = NI_NUMERICHOST | NI_NUMERICSERV;
|
|
const int err = errno;
|
|
|
|
if (!WOULD_LOG(DEBUG)) return;
|
|
|
|
if (getnameinfo(address, sockaddrSize(address), hbuf, sizeof(hbuf), sbuf, sizeof(sbuf),
|
|
niflags)) {
|
|
strncpy(hbuf, "?", sizeof(hbuf) - 1);
|
|
hbuf[sizeof(hbuf) - 1] = '\0';
|
|
strncpy(sbuf, "?", sizeof(sbuf) - 1);
|
|
sbuf[sizeof(sbuf) - 1] = '\0';
|
|
}
|
|
errno = err;
|
|
PLOG(DEBUG) << __func__ << ": " << str << " ([" << hbuf << "]." << sbuf << "): ";
|
|
}
|
|
|
|
static int sock_eq(struct sockaddr* a, struct sockaddr* b) {
|
|
struct sockaddr_in *a4, *b4;
|
|
struct sockaddr_in6 *a6, *b6;
|
|
|
|
if (a->sa_family != b->sa_family) return 0;
|
|
switch (a->sa_family) {
|
|
case AF_INET:
|
|
a4 = (struct sockaddr_in*) (void*) a;
|
|
b4 = (struct sockaddr_in*) (void*) b;
|
|
return a4->sin_port == b4->sin_port && a4->sin_addr.s_addr == b4->sin_addr.s_addr;
|
|
case AF_INET6:
|
|
a6 = (struct sockaddr_in6*) (void*) a;
|
|
b6 = (struct sockaddr_in6*) (void*) b;
|
|
return a6->sin6_port == b6->sin6_port &&
|
|
#ifdef HAVE_SIN6_SCOPE_ID
|
|
a6->sin6_scope_id == b6->sin6_scope_id &&
|
|
#endif
|
|
IN6_ARE_ADDR_EQUAL(&a6->sin6_addr, &b6->sin6_addr);
|
|
default:
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
PrivateDnsModes convertEnumType(PrivateDnsMode privateDnsmode) {
|
|
switch (privateDnsmode) {
|
|
case PrivateDnsMode::OFF:
|
|
return PrivateDnsModes::PDM_OFF;
|
|
case PrivateDnsMode::OPPORTUNISTIC:
|
|
return PrivateDnsModes::PDM_OPPORTUNISTIC;
|
|
case PrivateDnsMode::STRICT:
|
|
return PrivateDnsModes::PDM_STRICT;
|
|
default:
|
|
return PrivateDnsModes::PDM_UNKNOWN;
|
|
}
|
|
}
|
|
|
|
static int res_private_dns_send(ResState* statp, const Slice query, const Slice answer, int* rcode,
|
|
bool* fallback) {
|
|
const unsigned netId = statp->netid;
|
|
|
|
auto& privateDnsConfiguration = PrivateDnsConfiguration::getInstance();
|
|
PrivateDnsStatus privateDnsStatus = privateDnsConfiguration.getStatus(netId);
|
|
statp->event->set_private_dns_modes(convertEnumType(privateDnsStatus.mode));
|
|
|
|
const bool enableDoH = isDoHEnabled();
|
|
ssize_t result = -1;
|
|
switch (privateDnsStatus.mode) {
|
|
case PrivateDnsMode::OFF: {
|
|
*fallback = true;
|
|
return -1;
|
|
}
|
|
case PrivateDnsMode::OPPORTUNISTIC: {
|
|
*fallback = true;
|
|
if (enableDoH && privateDnsStatus.hasValidatedDohServers()) {
|
|
result = res_doh_send(statp, query, answer, rcode);
|
|
if (result != DOH_RESULT_CAN_NOT_SEND) return result;
|
|
}
|
|
return res_tls_send(privateDnsStatus.validatedServers(), statp, query, answer, rcode,
|
|
privateDnsStatus.mode);
|
|
}
|
|
case PrivateDnsMode::STRICT: {
|
|
*fallback = false;
|
|
if (enableDoH && privateDnsStatus.hasValidatedDohServers()) {
|
|
result = res_doh_send(statp, query, answer, rcode);
|
|
if (result != DOH_RESULT_CAN_NOT_SEND) return result;
|
|
}
|
|
if (privateDnsStatus.validatedServers().empty()) {
|
|
// Sleep and iterate some small number of times checking for the
|
|
// arrival of resolved and validated server IP addresses, instead
|
|
// of returning an immediate error.
|
|
// This is needed because as soon as a network becomes the default network, apps
|
|
// will send DNS queries on that network. If no servers have yet validated, and we
|
|
// do not block those queries, they would immediately fail, causing
|
|
// application-visible errors. Note that this can happen even before the network
|
|
// validates, since an unvalidated network can become the default network if no
|
|
// validated networks are available.
|
|
//
|
|
// TODO: see if there is a better way to address this problem, such as buffering the
|
|
// queries in a queue or only blocking queries for the first few seconds after a
|
|
// default network change.
|
|
for (int i = 0; i < 42; i++) {
|
|
std::this_thread::sleep_for(std::chrono::milliseconds(100));
|
|
|
|
// Calling getStatus() to merely check if there's any validated server seems
|
|
// wasteful. Consider adding a new method in PrivateDnsConfiguration for speed
|
|
// ups.
|
|
privateDnsStatus = privateDnsConfiguration.getStatus(netId);
|
|
|
|
if (enableDoH && privateDnsStatus.hasValidatedDohServers()) {
|
|
result = res_doh_send(statp, query, answer, rcode);
|
|
if (result != DOH_RESULT_CAN_NOT_SEND) return result;
|
|
}
|
|
|
|
// Switch to use the DoT servers if they are validated.
|
|
if (!privateDnsStatus.validatedServers().empty()) {
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
return res_tls_send(privateDnsStatus.validatedServers(), statp, query, answer, rcode,
|
|
privateDnsStatus.mode);
|
|
}
|
|
}
|
|
LOG(ERROR) << __func__ << ": unknown private DNS mode";
|
|
return -1;
|
|
}
|
|
|
|
ssize_t res_doh_send(ResState* statp, const Slice query, const Slice answer, int* rcode) {
|
|
auto& privateDnsConfiguration = PrivateDnsConfiguration::getInstance();
|
|
const unsigned netId = statp->netid;
|
|
LOG(INFO) << __func__ << ": performing query over Https";
|
|
Stopwatch queryStopwatch;
|
|
int queryTimeout = Experiments::getInstance()->getFlag(
|
|
"doh_query_timeout_ms", PrivateDnsConfiguration::kDohQueryDefaultTimeoutMs);
|
|
if (queryTimeout < 1000) {
|
|
queryTimeout = 1000;
|
|
}
|
|
ssize_t result = privateDnsConfiguration.dohQuery(netId, query, answer, queryTimeout);
|
|
LOG(INFO) << __func__ << ": Https query result: " << result << ", netid=" << netId;
|
|
|
|
if (result == DOH_RESULT_CAN_NOT_SEND) return DOH_RESULT_CAN_NOT_SEND;
|
|
|
|
DnsQueryEvent* dnsQueryEvent = statp->event->mutable_dns_query_events()->add_dns_query_event();
|
|
dnsQueryEvent->set_latency_micros(saturate_cast<int32_t>(queryStopwatch.timeTakenUs()));
|
|
// TODO: Make this information available.
|
|
// dnsQueryEvent->set_ip_version(ipFamilyToIPVersion(?));
|
|
if (result > 0) {
|
|
*rcode = reinterpret_cast<HEADER*>(answer.base())->rcode;
|
|
} else {
|
|
*rcode = -result;
|
|
}
|
|
dnsQueryEvent->set_rcode(static_cast<NsRcode>(*rcode));
|
|
dnsQueryEvent->set_protocol(PROTO_DOH);
|
|
span<const uint8_t> msg(query.base(), query.size());
|
|
dnsQueryEvent->set_type(getQueryType(msg));
|
|
|
|
auto dohServerAddr = privateDnsConfiguration.getDohServer(netId);
|
|
if (dohServerAddr.ok()) {
|
|
resolv_stats_add(netId, dohServerAddr.value(), dnsQueryEvent);
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
int res_tls_send(const std::list<DnsTlsServer>& tlsServers, ResState* statp, const Slice query,
|
|
const Slice answer, int* rcode, PrivateDnsMode mode) {
|
|
if (tlsServers.empty()) return -1;
|
|
LOG(INFO) << __func__ << ": performing query over TLS";
|
|
const bool dotQuickFallback =
|
|
(mode == PrivateDnsMode::STRICT)
|
|
? 0
|
|
: Experiments::getInstance()->getFlag("dot_quick_fallback", 1);
|
|
int resplen = 0;
|
|
const auto response = DnsTlsDispatcher::getInstance().query(tlsServers, statp, query, answer,
|
|
&resplen, dotQuickFallback);
|
|
|
|
LOG(INFO) << __func__ << ": TLS query result: " << static_cast<int>(response);
|
|
if (mode == PrivateDnsMode::OPPORTUNISTIC) {
|
|
// In opportunistic mode, handle falling back to cleartext in some
|
|
// cases (DNS shouldn't fail if a validated opportunistic mode server
|
|
// becomes unreachable for some reason).
|
|
switch (response) {
|
|
case DnsTlsTransport::Response::success:
|
|
*rcode = reinterpret_cast<HEADER*>(answer.base())->rcode;
|
|
return resplen;
|
|
// It's OPPORTUNISTIC mode,
|
|
// hence it's not required to do anything because it'll fallback to UDP.
|
|
case DnsTlsTransport::Response::network_error:
|
|
[[fallthrough]];
|
|
case DnsTlsTransport::Response::internal_error:
|
|
[[fallthrough]];
|
|
default:
|
|
return -1;
|
|
}
|
|
} else {
|
|
// Strict mode
|
|
switch (response) {
|
|
case DnsTlsTransport::Response::success:
|
|
*rcode = reinterpret_cast<HEADER*>(answer.base())->rcode;
|
|
return resplen;
|
|
case DnsTlsTransport::Response::network_error:
|
|
// This case happens when the query stored in DnsTlsTransport is expired since
|
|
// either 1) the query has been tried for 3 times but no response or 2) fail to
|
|
// establish the connection with the server.
|
|
*rcode = RCODE_TIMEOUT;
|
|
[[fallthrough]];
|
|
default:
|
|
return -1;
|
|
}
|
|
}
|
|
}
|
|
|
|
int resolv_res_nsend(const android_net_context* netContext, span<const uint8_t> msg,
|
|
span<uint8_t> ans, int* rcode, uint32_t flags,
|
|
NetworkDnsEventReported* event) {
|
|
assert(event != nullptr);
|
|
ResState res(netContext, event);
|
|
resolv_populate_res_for_net(&res);
|
|
*rcode = NOERROR;
|
|
return res_nsend(&res, msg, ans, rcode, flags);
|
|
}
|