Snap for 7498549 from 9aa6603f1dfebc4f46bbfbd331d8f8e319d9239e to tm-release (df4d510e) · Commits · e / os / android_packages_modules_DnsResolver

getaddrinfo.cpp

+6 −3

Original line number	Diff line number	Diff line
		@@ -1437,6 +1437,8 @@ static int dns_getaddrinfo(const char* name, const addrinfo* pai,

		ResState res(netcontext, event);

		setMdnsFlag(name, &(res._flags));

		int he;
		if (res_searchN(name, &q, &res, &he) < 0) {
		// Return h_errno (he) to catch more detailed errors rather than EAI_NODATA.
		@@ -1839,8 +1841,9 @@ static int res_searchN(const char* name, res_target* target, res_state res, int*
		* We do at least one level of search if
		* - there is no dot, or
		* - there is at least one dot and there is no trailing dot.
		* - this is not a .local mDNS lookup.
		*/
		if ((!dots) \|\| (dots && !trailing_dot)) {
		if ((!dots \|\| (dots && !trailing_dot)) && !isMdnsResolution(res->_flags)) {
		int done = 0;

		/* Unfortunately we need to set stuff up before

gethnamaddr.cpp

+13 −0

Original line number	Diff line number	Diff line
		@@ -72,6 +72,7 @@
		#include <functional>
		#include <vector>

		#include "Experiments.h"
		#include "hostent.h"
		#include "netd_resolv/resolv.h"
		#include "res_comp.h"
		@@ -374,6 +375,8 @@ int resolv_gethostbyname(const char* name, int af, hostent* hp, char* buf, size_
		getnamaddr info;
		ResState res(netcontext, event);

		setMdnsFlag(name, &(res._flags));

		size_t size;
		switch (af) {
		case AF_INET:
		@@ -749,3 +752,13 @@ int herrnoToAiErrno(int he) {
		return EAI_FAIL; // TODO: Perhaps convert default to EAI_MAX (unknown error) instead
		}
		}

		void setMdnsFlag(std::string_view hostname, uint32_t* flags) {
		if (hostname.ends_with(".local") &&
		android::net::Experiments::getInstance()->getFlag("mdns_resolution", 1))
		*flags \|= RES_F_MDNS;
		}

		bool isMdnsResolution(uint32_t flags) {
		return flags & RES_F_MDNS;
		}

res_query.cpp

+1 −1

Original line number	Diff line number	Diff line
		@@ -240,7 +240,7 @@ int res_nsearch(res_state statp, const char* name, /* domain name */
		* - there is no dot, or
		* - there is at least one dot and there is no trailing dot.
		*/
		if ((!dots) \|\| (dots && !trailing_dot)) {
		if ((!dots \|\| (dots && !trailing_dot)) && !isMdnsResolution(statp->_flags)) {
		int done = 0;

		/* Unfortunately we need to load network-specific info

res_send.cpp

+129 −31

Original line number	Diff line number	Diff line
		@@ -95,6 +95,7 @@
		#include <string.h>
		#include <time.h>
		#include <unistd.h>
		#include <span>

		#include <android-base/logging.h>
		#include <android-base/result.h>
		@@ -120,6 +121,7 @@ using namespace std::chrono_literals;
		// TODO: use the namespace something like android::netd_resolv for libnetd_resolv
		using android::base::ErrnoError;
		using android::base::Result;
		using android::base::unique_fd;
		using android::net::CacheStatus;
		using android::net::DnsQueryEvent;
		using android::net::DnsTlsDispatcher;
		@@ -137,20 +139,25 @@ using android::net::PrivateDnsConfiguration;
		using android::net::PrivateDnsMode;
		using android::net::PrivateDnsModes;
		using android::net::PrivateDnsStatus;
		using android::net::PROTO_MDNS;
		using android::net::PROTO_TCP;
		using android::net::PROTO_UDP;
		using android::netdutils::IPSockAddr;
		using android::netdutils::Slice;
		using android::netdutils::Stopwatch;

		static int send_vc(res_state statp, res_params* params, const uint8_t* buf, int buflen,
		uint8_t* ans, int anssiz, int* terrno, size_t ns, time_t* at, int* rcode,
		int* delay);
		static int setupUdpSocket(ResState* statp, const sockaddr* sockap, size_t addrIndex, int* terrno);
		const std::vector<IPSockAddr> mdns_addrs = {IPSockAddr::toIPSockAddr("ff02::fb", 5353),
		IPSockAddr::toIPSockAddr("224.0.0.251", 5353)};

		static int setupUdpSocket(ResState* statp, const sockaddr* sockap, unique_fd* fd_out, int* terrno);
		static int send_dg(res_state statp, res_params* params, const uint8_t* buf, int buflen,
		uint8_t* ans, int anssiz, int* terrno, size_t* ns, int* v_circuit,
		int* gotsomewhere, time_t* at, int* rcode, int* delay);

		static int send_vc(res_state statp, res_params* params, const uint8_t* buf, int buflen,
		uint8_t* ans, int anssiz, int* terrno, size_t ns, time_t* at, int* rcode,
		int* delay);
		static int send_mdns(ResState* statp, std::span<const uint8_t> buf, uint8_t* ans, int anssiz,
		int* terrno, int* rcode);
		static void dump_error(const char, const struct sockaddr);

		static int sock_eq(struct sockaddr, struct sockaddr);
		@@ -448,10 +455,46 @@ int res_nsend(res_state statp, const uint8_t* buf, int buflen, uint8_t* ans, int
		// 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;
		std::span<const uint8_t> buffer(buf, buflen);
		Stopwatch queryStopwatch;
		resplen = send_mdns(statp, buffer, ans, anssiz, &terrno, rcode);
		const IPSockAddr& receivedMdnsAddr =
		(getQueryType(buf, buflen) == 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(buf, buflen));
		mDnsQueryEvent->set_linux_errno(static_cast<LinuxErrno>(terrno));
		resolv_stats_add(statp->netid, receivedMdnsAddr, mDnsQueryEvent);

		if (resplen <= 0) {
		_resolv_cache_query_failed(statp->netid, buf, buflen, flags);
		return -terrno;
		}
		LOG(DEBUG) << __func__ << ": got answer:";
		res_pquery(ans, (resplen > anssiz) ? anssiz : resplen);

		if (cache_status == RESOLV_CACHE_NOTFOUND) {
		resolv_cache_add(statp->netid, buf, buflen, ans, resplen);
		}
		return resplen;
		}

		if (statp->nameserverCount() == 0) {
		// We have no nameservers configured, 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.
		// 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, buf, buflen, flags);

		// TODO: Remove errno once callers stop using it
		@@ -465,7 +508,8 @@ int res_nsend(res_state statp, const uint8_t* buf, int buflen, uint8_t* ans, int
		std::this_thread::sleep_for(sleepTimeMs);
		}
		// DoT
		if (!(statp->netcontext_flags & NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS)) {
		if (!(statp->netcontext_flags & NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS) &&
		!isMdnsResolution(statp->_flags)) {
		bool fallback = false;
		int resplen = res_tls_send(statp, Slice(const_cast<uint8_t*>(buf), buflen),
		Slice(ans, anssiz), rcode, &fallback);
		@@ -491,6 +535,7 @@ int res_nsend(res_state statp, const uint8_t* buf, int buflen, uint8_t* ans, int
		errno = ESRCH;
		return -ESRCH;
		}

		bool usable_servers[MAXNS];
		int usableServersCount = android_net_res_stats_get_usable_servers(
		&params, stats, statp->nameserverCount(), usable_servers);
		@@ -516,9 +561,10 @@ int res_nsend(res_state statp, const uint8_t* buf, int buflen, uint8_t* ans, int
		int retryTimes = (flags & ANDROID_RESOLV_NO_RETRY) ? 1 : params.retry_count;
		int useTcp = buflen > 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;
		@@ -609,7 +655,7 @@ int res_nsend(res_state statp, const uint8_t* buf, int buflen, uint8_t* ans, int
		_resolv_cache_query_failed(statp->netid, buf, buflen, flags);
		statp->closeSockets();
		return -terrno;
		};
		}

		LOG(DEBUG) << __func__ << ": got answer:";
		res_pquery(ans, (resplen > anssiz) ? anssiz : resplen);
		@@ -632,13 +678,13 @@ int res_nsend(res_state statp, const uint8_t* buf, int buflen, uint8_t* ans, int
		return -terrno;
		}

		static struct timespec get_timeout(res_state statp, const res_params* params, const int ns) {
		static struct timespec get_timeout(res_state 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
		msec = params->base_timeout_msec << ns;
		if (ns > 0) {
		if (addrIndex > 0) {
		msec /= statp->nameserverCount();
		}
		// For safety, don't allow OEMs and experiments to configure a timeout shorter than 1s.
		@@ -964,16 +1010,16 @@ static Result<std::vector<int>> udpRetryingPoll(res_state statp, const timespec*
		}
		}

		static Result<std::vector<int>> udpRetryingPollWrapper(res_state statp, int ns,
		static Result<std::vector<int>> udpRetryingPollWrapper(res_state 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[ns], POLLIN, finish); n <= 0) {
		if (int n = retrying_poll(statp->udpsocks[addrInfo], POLLIN, finish); n <= 0) {
		return ErrnoError();
		}
		return std::vector<int>{statp->udpsocks[ns]};
		return std::vector<int>{statp->udpsocks[addrInfo]};
		}

		bool ignoreInvalidAnswer(res_state statp, const sockaddr_storage& from, const uint8_t* buf,
		@@ -998,13 +1044,14 @@ bool ignoreInvalidAnswer(res_state statp, const sockaddr_storage& from, const ui
		return false;
		}

		// return 1 when setup udp socket success.
		// return 0 when timeout , bind error, network error(ex: Protocol not supported ...).
		// return -1 when create socket fail, set socket option fail.
		static int setupUdpSocket(ResState* statp, const sockaddr* sockap, size_t addrIndex, int* terrno) {
		statp->udpsocks[addrIndex].reset(socket(sockap->sa_family, SOCK_DGRAM \| SOCK_CLOEXEC, 0));
		// 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 (statp->udpsocks[addrIndex] < 0) {
		if (*fd_out < 0) {
		*terrno = errno;
		PLOG(ERROR) << __func__ << ": socket: ";
		switch (errno) {
		@@ -1017,20 +1064,17 @@ static int setupUdpSocket(ResState* statp, const sockaddr* sockap, size_t addrIn
		}
		}
		const uid_t uid = statp->enforce_dns_uid ? AID_DNS : statp->uid;
		resolv_tag_socket(statp->udpsocks[addrIndex], uid, statp->pid);
		resolv_tag_socket(*fd_out, uid, statp->pid);
		if (statp->_mark != MARK_UNSET) {
		if (setsockopt(statp->udpsocks[addrIndex], SOL_SOCKET, SO_MARK, &(statp->_mark),
		sizeof(statp->_mark)) < 0) {
		if (setsockopt(*fd_out, SOL_SOCKET, SO_MARK, &(statp->_mark), sizeof(statp->_mark)) < 0) {
		*terrno = errno;
		statp->closeSockets();
		return -1;
		}
		}

		if (random_bind(statp->udpsocks[addrIndex], sockap->sa_family) < 0) {
		if (random_bind(*fd_out, sockap->sa_family) < 0) {
		*terrno = errno;
		dump_error("bind", sockap);
		statp->closeSockets();
		return 0;
		}
		return 1;
		@@ -1052,7 +1096,7 @@ static int send_dg(res_state statp, res_params* params, const uint8_t* buf, int
		const sockaddr* nsap = reinterpret_cast<const sockaddr*>(&ss);

		if (statp->udpsocks[*ns] == -1) {
		int result = setupUdpSocket(statp, nsap, *ns, terrno);
		int result = setupUdpSocket(statp, nsap, &statp->udpsocks[*ns], terrno);
		if (result <= 0) return result;

		// Use a "connected" datagram socket to receive an ECONNREFUSED error
		@@ -1063,7 +1107,7 @@ static int send_dg(res_state statp, res_params* params, const uint8_t* buf, int
		*terrno = errno;
		dump_error("connect(dg)", nsap);
		statp->closeSockets();
		return (0);
		return 0;
		}
		LOG(DEBUG) << __func__ << ": new DG socket";
		}
		@@ -1161,6 +1205,60 @@ static int send_dg(res_state statp, res_params* params, const uint8_t* buf, int
		}
		}

		// return length - when receiving valid packets.
		// return 0 - when mdns packets transfer error.
		static int send_mdns(ResState* statp, std::span<const uint8_t> buf, uint8_t* ans, int anssiz,
		int* terrno, int* rcode) {
		const sockaddr_storage ss =
		(getQueryType(buf.data(), buf.size()) == 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, buf.data(), buf.size(), 0, mdnsap, sockaddrSize(mdnsap)) != buf.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";
		return 0;
		}

		sockaddr_storage from;
		socklen_t fromlen = sizeof(from);
		int resplen = recvfrom(fd, (char)ans, (size_t)anssiz, 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;
		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];

resolv_private.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -78,6 +78,7 @@
		// Flags for res_state->_flags
		#define RES_F_VC 0x00000001 // socket is TCP
		#define RES_F_EDNS0ERR 0x00000004 // EDNS0 caused errors
		#define RES_F_MDNS 0x00000008 // MDNS packet

		// Holds either a sockaddr_in or a sockaddr_in6.
		union sockaddr_union {
		@@ -183,6 +184,12 @@ int getaddrinfo_numeric(const char* hostname, const char* servname, addrinfo hin
		// Helper function for converting h_errno to the error codes visible to netd
		int herrnoToAiErrno(int herrno);

		// Helper function to enable MDNS resolution.
		void setMdnsFlag(std::string_view hostname, uint32_t* flags);

		// Helper function for checking MDNS resolution is enabled or not.
		bool isMdnsResolution(uint32_t flags);

		// switch resolver log severity
		android::base::LogSeverity logSeverityStrToEnum(const std::string& logSeverityStr);