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android / platform / packages / modules / DnsResolver / 607f74e7efc42d0cac9ea6298973013be0177742 / . / DnsProxyListener.cpp
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/*
* Copyright (C) 2010 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.
*/
#include "DnsProxyListener.h"
#include <arpa/inet.h>
#include <dirent.h>
#include <linux/if.h>
#include <math.h>
#include <net/if.h>
#include <netdb.h>
#include <netinet/in.h>
#include <resolv.h> // b64_pton()
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#define LOG_TAG "resolv"
#include <algorithm>
#include <vector>
#include <android-base/parseint.h>
#include <android/multinetwork.h> // ResNsendFlags
#include <cutils/misc.h> // FIRST_APPLICATION_UID
#include <cutils/multiuser.h>
#include <netdutils/InternetAddresses.h>
#include <netdutils/ResponseCode.h>
#include <netdutils/Stopwatch.h>
#include <netdutils/ThreadUtil.h>
#include <private/android_filesystem_config.h> // AID_SYSTEM
#include <statslog_resolv.h>
#include <sysutils/SocketClient.h>
#include "DnsResolver.h"
#include "Experiments.h"
#include "NetdPermissions.h"
#include "OperationLimiter.h"
#include "PrivateDnsConfiguration.h"
#include "ResolverEventReporter.h"
#include "dnsproxyd_protocol/DnsProxydProtocol.h" // NETID_USE_LOCAL_NAMESERVERS
#include "getaddrinfo.h"
#include "gethnamaddr.h"
#include "res_send.h"
#include "resolv_cache.h"
#include "resolv_private.h"
#include "stats.h" // RCODE_TIMEOUT
#include "stats.pb.h"
#include "util.h"
using aidl::android::net::metrics::INetdEventListener;
using aidl::android::net::resolv::aidl::DnsHealthEventParcel;
using aidl::android::net::resolv::aidl::IDnsResolverUnsolicitedEventListener;
using android::base::ParseInt;
using android::base::ParseUint;
using std::span;
namespace android {
using netdutils::ResponseCode;
using netdutils::Stopwatch;
namespace net {
namespace {
// Limits the number of outstanding DNS queries by client UID.
constexpr int MAX_QUERIES_PER_UID = 256;
android::netdutils::OperationLimiter<uid_t> queryLimiter(MAX_QUERIES_PER_UID);
bool startQueryLimiter(uid_t uid) {
const int globalLimit =
android::net::Experiments::getInstance()->getFlag("max_queries_global", INT_MAX);
return queryLimiter.start(uid, globalLimit);
}
void endQueryLimiter(uid_t uid) {
queryLimiter.finish(uid);
}
void logArguments(int argc, char** argv) {
if (!WOULD_LOG(VERBOSE)) return;
for (int i = 0; i < argc; i++) {
LOG(VERBOSE) << __func__ << ": argv[" << i << "]=" << (argv[i] ? argv[i] : "null");
}
}
bool checkAndClearUseLocalNameserversFlag(unsigned* netid) {
if (netid == nullptr || ((*netid) & NETID_USE_LOCAL_NAMESERVERS) == 0) {
return false;
}
*netid = (*netid) & ~NETID_USE_LOCAL_NAMESERVERS;
return true;
}
constexpr bool requestingUseLocalNameservers(unsigned flags) {
return (flags & NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS) != 0;
}
bool queryingViaTls(unsigned dns_netid) {
const auto privateDnsStatus = PrivateDnsConfiguration::getInstance().getStatus(dns_netid);
switch (privateDnsStatus.mode) {
case PrivateDnsMode::OPPORTUNISTIC:
return !privateDnsStatus.validatedServers().empty();
case PrivateDnsMode::STRICT:
return true;
default:
return false;
}
}
bool hasPermissionToBypassPrivateDns(uid_t uid) {
static_assert(AID_SYSTEM >= 0 && AID_SYSTEM < FIRST_APPLICATION_UID,
"Calls from AID_SYSTEM must not result in a permission check to avoid deadlock.");
if (uid >= 0 && uid < FIRST_APPLICATION_UID) {
return true;
}
for (const char* const permission :
{PERM_CONNECTIVITY_USE_RESTRICTED_NETWORKS, PERM_NETWORK_BYPASS_PRIVATE_DNS,
PERM_MAINLINE_NETWORK_STACK}) {
if (gResNetdCallbacks.check_calling_permission(permission)) {
return true;
}
}
return false;
}
void maybeFixupNetContext(android_net_context* ctx, pid_t pid) {
if (requestingUseLocalNameservers(ctx->flags) && !hasPermissionToBypassPrivateDns(ctx->uid)) {
// Not permitted; clear the flag.
ctx->flags &= ~NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS;
}
if (!requestingUseLocalNameservers(ctx->flags)) {
// If we're not explicitly bypassing DNS-over-TLS servers, check whether
// DNS-over-TLS is in use as an indicator for when to use more modern
// DNS resolution mechanics.
if (queryingViaTls(ctx->dns_netid)) {
ctx->flags |= NET_CONTEXT_FLAG_USE_DNS_OVER_TLS | NET_CONTEXT_FLAG_USE_EDNS;
}
}
ctx->pid = pid;
}
void addIpAddrWithinLimit(std::vector<std::string>* ip_addrs, const sockaddr* addr,
socklen_t addrlen);
int extractResNsendAnswers(std::span<const uint8_t> answer, int ipType,
std::vector<std::string>* ip_addrs) {
int total_ip_addr_count = 0;
ns_msg handle;
if (ns_initparse(answer.data(), answer.size(), &handle) < 0) {
return 0;
}
int ancount = ns_msg_count(handle, ns_s_an);
ns_rr rr;
for (int i = 0; i < ancount; i++) {
if (ns_parserr(&handle, ns_s_an, i, &rr) < 0) {
continue;
}
const uint8_t* rdata = ns_rr_rdata(rr);
if (ipType == ns_t_a) {
sockaddr_in sin = {.sin_family = AF_INET};
memcpy(&sin.sin_addr, rdata, sizeof(sin.sin_addr));
addIpAddrWithinLimit(ip_addrs, (sockaddr*)&sin, sizeof(sin));
total_ip_addr_count++;
} else if (ipType == ns_t_aaaa) {
sockaddr_in6 sin6 = {.sin6_family = AF_INET6};
memcpy(&sin6.sin6_addr, rdata, sizeof(sin6.sin6_addr));
addIpAddrWithinLimit(ip_addrs, (sockaddr*)&sin6, sizeof(sin6));
total_ip_addr_count++;
}
}
return total_ip_addr_count;
}
int extractGetAddrInfoAnswers(const addrinfo* result, std::vector<std::string>* ip_addrs) {
int total_ip_addr_count = 0;
if (result == nullptr) {
return 0;
}
for (const addrinfo* ai = result; ai; ai = ai->ai_next) {
sockaddr* ai_addr = ai->ai_addr;
if (ai_addr) {
addIpAddrWithinLimit(ip_addrs, ai_addr, ai->ai_addrlen);
total_ip_addr_count++;
}
}
return total_ip_addr_count;
}
int extractGetHostByNameAnswers(const hostent* hp, std::vector<std::string>* ip_addrs) {
int total_ip_addr_count = 0;
if (hp == nullptr) {
return 0;
}
if (hp->h_addrtype == AF_INET) {
in_addr** list = (in_addr**)hp->h_addr_list;
for (int i = 0; list[i] != nullptr; i++) {
sockaddr_in sin = {.sin_family = AF_INET, .sin_addr = *list[i]};
addIpAddrWithinLimit(ip_addrs, (sockaddr*)&sin, sizeof(sin));
total_ip_addr_count++;
}
} else if (hp->h_addrtype == AF_INET6) {
in6_addr** list = (in6_addr**)hp->h_addr_list;
for (int i = 0; list[i] != nullptr; i++) {
sockaddr_in6 sin6 = {.sin6_family = AF_INET6, .sin6_addr = *list[i]};
addIpAddrWithinLimit(ip_addrs, (sockaddr*)&sin6, sizeof(sin6));
total_ip_addr_count++;
}
}
return total_ip_addr_count;
}
int rcodeToAiError(int rcode) {
switch (rcode) {
case NOERROR:
return 0;
case RCODE_TIMEOUT:
return NETD_RESOLV_TIMEOUT;
default:
return EAI_NODATA;
}
}
int resNSendToAiError(int err, int rcode) {
if (err > 0) {
return rcodeToAiError(rcode);
}
if (err == -ETIMEDOUT) {
return NETD_RESOLV_TIMEOUT;
}
return EAI_SYSTEM;
}
bool setQueryId(span<uint8_t> msg, uint16_t query_id) {
if ((size_t)msg.size() < sizeof(HEADER)) {
LOG(ERROR) << __func__ << ": Invalid parameter";
return false;
}
auto hp = reinterpret_cast<HEADER*>(msg.data());
hp->id = htons(query_id);
return true;
}
bool parseQuery(span<const uint8_t> msg, uint16_t* query_id, int* rr_type, std::string* rr_name) {
ns_msg handle;
ns_rr rr;
if (ns_initparse(msg.data(), msg.size(), &handle) < 0 ||
ns_parserr(&handle, ns_s_qd, 0, &rr) < 0) {
return false;
}
*query_id = ns_msg_id(handle);
*rr_name = ns_rr_name(rr);
*rr_type = ns_rr_type(rr);
return true;
}
// Note: Even if it returns PDM_OFF, it doesn't mean there's no DoT stats in the message
// because Private DNS mode can change at any time.
PrivateDnsModes getPrivateDnsModeForMetrics(uint32_t netId) {
// If the network `netId` doesn't exist, getStatus() sets the mode to PrivateDnsMode::OFF and
// returns it. This is incorrect for the metrics. Consider returning PDM_UNKNOWN in such case.
return convertEnumType(PrivateDnsConfiguration::getInstance().getStatus(netId).mode);
}
void initDnsEvent(NetworkDnsEventReported* event, const android_net_context& netContext) {
// The value 0 has the special meaning of unset/unknown in Statsd atoms. So, we set both
// flags to -1 as default value.
// 1. The hints flag is only used in resolv_getaddrinfo. When user set it to -1 in
// resolv_getaddrinfo, the flag will cause validation (validateHints) failure in
// getaddrinfo, so it will not do DNS query and will upload DNS stats log with
// return_code = RC_EAI_BADFLAGS.
// 2. The res_nsend flags are only used in resolv_res_nsend. When user set it to -1 in
// resolv_res_nsend,res_nsend will do nothing special by the setting.
event->set_hints_ai_flags(-1);
event->set_res_nsend_flags(-1);
event->set_private_dns_modes(getPrivateDnsModeForMetrics(netContext.dns_netid));
}
// Return 0 if the event should not be logged.
// Otherwise, return subsampling_denom
uint32_t getDnsEventSubsamplingRate(int netid, int returnCode, bool isMdns) {
uint32_t subsampling_denom = resolv_cache_get_subsampling_denom(netid, returnCode, isMdns);
if (subsampling_denom == 0) return 0;
// Sample the event with a chance of 1 / denom.
return (arc4random_uniform(subsampling_denom) == 0) ? subsampling_denom : 0;
}
void maybeLogQuery(int eventType, const android_net_context& netContext,
const NetworkDnsEventReported& event, const std::string& query_name,
const std::vector<std::string>& ip_addrs) {
// Skip reverse queries.
if (eventType == INetdEventListener::EVENT_GETHOSTBYADDR) return;
for (const auto& query : event.dns_query_events().dns_query_event()) {
// Log it when the cache misses.
if (query.cache_hit() != CS_FOUND) {
const int timeTakenMs = event.latency_micros() / 1000;
DnsQueryLog::Record record(netContext.dns_netid, netContext.uid, netContext.pid,
query_name, ip_addrs, timeTakenMs);
gDnsResolv->dnsQueryLog().push(std::move(record));
return;
}
}
}
void reportDnsEvent(int eventType, const android_net_context& netContext, int latencyUs,
int returnCode, NetworkDnsEventReported& event, const std::string& query_name,
const std::vector<std::string>& ip_addrs = {}, int total_ip_addr_count = 0) {
uint32_t rate =
(query_name.ends_with(".local") && is_mdns_supported_network(netContext.dns_netid) &&
android::net::Experiments::getInstance()->getFlag("mdns_resolution", 1))
? getDnsEventSubsamplingRate(netContext.dns_netid, returnCode, true)
: getDnsEventSubsamplingRate(netContext.dns_netid, returnCode, false);
if (rate) {
const std::string& dnsQueryStats = event.dns_query_events().SerializeAsString();
stats::BytesField dnsQueryBytesField{dnsQueryStats.c_str(), dnsQueryStats.size()};
event.set_return_code(static_cast<ReturnCode>(returnCode));
event.set_network_type(resolv_get_network_types_for_net(netContext.dns_netid));
android::net::stats::stats_write(android::net::stats::NETWORK_DNS_EVENT_REPORTED,
event.event_type(), event.return_code(),
event.latency_micros(), event.hints_ai_flags(),
event.res_nsend_flags(), event.network_type(),
event.private_dns_modes(), dnsQueryBytesField, rate);
}
maybeLogQuery(eventType, netContext, event, query_name, ip_addrs);
const auto& listeners = ResolverEventReporter::getInstance().getListeners();
if (listeners.empty()) {
LOG(ERROR) << __func__
<< ": DNS event not sent since no INetdEventListener receiver is available.";
}
const int latencyMs = latencyUs / 1000;
for (const auto& it : listeners) {
it->onDnsEvent(netContext.dns_netid, eventType, returnCode, latencyMs, query_name, ip_addrs,
total_ip_addr_count, netContext.uid);
}
const auto& unsolEventListeners = ResolverEventReporter::getInstance().getUnsolEventListeners();
if (returnCode == NETD_RESOLV_TIMEOUT) {
const DnsHealthEventParcel dnsHealthEvent = {
.netId = static_cast<int32_t>(netContext.dns_netid),
.healthResult = IDnsResolverUnsolicitedEventListener::DNS_HEALTH_RESULT_TIMEOUT,
};
for (const auto& it : unsolEventListeners) {
it->onDnsHealthEvent(dnsHealthEvent);
}
} else if (returnCode == NOERROR) {
DnsHealthEventParcel dnsHealthEvent = {
.netId = static_cast<int32_t>(netContext.dns_netid),
.healthResult = IDnsResolverUnsolicitedEventListener::DNS_HEALTH_RESULT_OK,
};
for (const auto& query : event.dns_query_events().dns_query_event()) {
if (query.cache_hit() != CS_FOUND && query.rcode() == NS_R_NO_ERROR) {
dnsHealthEvent.successRttMicros.push_back(query.latency_micros());
}
}
if (!dnsHealthEvent.successRttMicros.empty()) {
for (const auto& it : unsolEventListeners) {
it->onDnsHealthEvent(dnsHealthEvent);
}
}
}
}
bool onlyIPv4Answers(const addrinfo* res) {
// Null addrinfo pointer isn't checked because the caller doesn't pass null pointer.
for (const addrinfo* ai = res; ai; ai = ai->ai_next)
if (ai->ai_family != AF_INET) return false;
return true;
}
bool isSpecialUseIPv4Address(const struct in_addr& ia) {
const uint32_t addr = ntohl(ia.s_addr);
// Only check necessary IP ranges in RFC 5735 section 4
return ((addr & 0xff000000) == 0x00000000) || // "This" Network
((addr & 0xff000000) == 0x7f000000) || // Loopback
((addr & 0xffff0000) == 0xa9fe0000) || // Link Local
((addr & 0xf0000000) == 0xe0000000) || // Multicast
(addr == INADDR_BROADCAST); // Limited Broadcast
}
bool isSpecialUseIPv4Address(const struct sockaddr* sa) {
if (sa->sa_family != AF_INET) return false;
return isSpecialUseIPv4Address(((struct sockaddr_in*)sa)->sin_addr);
}
bool onlyNonSpecialUseIPv4Addresses(struct hostent* hp) {
// Null hostent pointer isn't checked because the caller doesn't pass null pointer.
if (hp->h_addrtype != AF_INET) return false;
for (int i = 0; hp->h_addr_list[i] != nullptr; i++)
if (isSpecialUseIPv4Address(*(struct in_addr*)hp->h_addr_list[i])) return false;
return true;
}
bool onlyNonSpecialUseIPv4Addresses(const addrinfo* res) {
// Null addrinfo pointer isn't checked because the caller doesn't pass null pointer.
for (const addrinfo* ai = res; ai; ai = ai->ai_next) {
if (ai->ai_family != AF_INET) return false;
if (isSpecialUseIPv4Address(ai->ai_addr)) return false;
}
return true;
}
void logDnsQueryResult(const struct hostent* hp) {
if (!WOULD_LOG(DEBUG)) return;
if (hp == nullptr) return;
LOG(DEBUG) << __func__ << ": DNS records:";
for (int i = 0; hp->h_addr_list[i] != nullptr; i++) {
char ip_addr[INET6_ADDRSTRLEN];
if (inet_ntop(hp->h_addrtype, hp->h_addr_list[i], ip_addr, sizeof(ip_addr)) != nullptr) {
LOG(DEBUG) << __func__ << ": [" << i << "] " << hp->h_addrtype;
} else {
PLOG(DEBUG) << __func__ << ": [" << i << "] numeric hostname translation fail";
}
}
}
void logDnsQueryResult(const addrinfo* res) {
if (!WOULD_LOG(DEBUG)) return;
if (res == nullptr) return;
int i;
const addrinfo* ai;
LOG(DEBUG) << __func__ << ": DNS records:";
for (ai = res, i = 0; ai; ai = ai->ai_next, i++) {
if ((ai->ai_family != AF_INET) && (ai->ai_family != AF_INET6)) continue;
// Reassign it to a local variable to avoid -Wnullable-to-nonnull-conversion on calling
// getnameinfo.
const sockaddr* ai_addr = ai->ai_addr;
char ip_addr[INET6_ADDRSTRLEN];
const int ret = getnameinfo(ai_addr, ai->ai_addrlen, ip_addr, sizeof(ip_addr), nullptr, 0,
NI_NUMERICHOST);
if (!ret) {
LOG(DEBUG) << __func__ << ": [" << i << "] " << ai->ai_flags << " " << ai->ai_family
<< " " << ai->ai_socktype << " " << ai->ai_protocol << " " << ip_addr;
} else {
LOG(DEBUG) << __func__ << ": [" << i << "] numeric hostname translation fail " << ret;
}
}
}
bool isValidNat64Prefix(const netdutils::IPPrefix prefix) {
if (prefix.family() != AF_INET6) {
LOG(ERROR) << __func__ << ": Only IPv6 NAT64 prefixes are supported " << prefix.family();
return false;
}
if (prefix.length() != 96) {
LOG(ERROR) << __func__ << ": Only /96 NAT64 prefixes are supported " << prefix.length();
return false;
}
return true;
}
bool synthesizeNat64PrefixWithARecord(const netdutils::IPPrefix& prefix, struct hostent* hp) {
if (hp == nullptr) return false;
if (!onlyNonSpecialUseIPv4Addresses(hp)) return false;
if (!isValidNat64Prefix(prefix)) return false;
struct sockaddr_storage ss = netdutils::IPSockAddr(prefix.ip());
struct sockaddr_in6* v6prefix = (struct sockaddr_in6*)&ss;
for (int i = 0; hp->h_addr_list[i] != nullptr; i++) {
struct in_addr iaOriginal = *(struct in_addr*)hp->h_addr_list[i];
struct in6_addr* ia6 = (struct in6_addr*)hp->h_addr_list[i];
memset(ia6, 0, sizeof(struct in6_addr));
// Synthesize /96 NAT64 prefix in place. The space has reserved by getanswer() and
// _hf_gethtbyname2() in system/netd/resolv/gethnamaddr.cpp and
// system/netd/resolv/sethostent.cpp.
*ia6 = v6prefix->sin6_addr;
ia6->s6_addr32[3] = iaOriginal.s_addr;
if (WOULD_LOG(VERBOSE)) {
char buf[INET6_ADDRSTRLEN]; // big enough for either IPv4 or IPv6
inet_ntop(AF_INET, &iaOriginal.s_addr, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": DNS A record: " << buf;
inet_ntop(AF_INET6, &v6prefix->sin6_addr, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": NAT64 prefix: " << buf;
inet_ntop(AF_INET6, ia6, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": DNS64 Synthesized AAAA record: " << buf;
}
}
hp->h_addrtype = AF_INET6;
hp->h_length = sizeof(in6_addr);
logDnsQueryResult(hp);
return true;
}
bool synthesizeNat64PrefixWithARecord(const netdutils::IPPrefix& prefix, addrinfo** res,
bool unspecWantedButNoIPv6,
const android_net_context* netcontext) {
if (*res == nullptr) return false;
if (!onlyNonSpecialUseIPv4Addresses(*res)) return false;
if (!isValidNat64Prefix(prefix)) return false;
const sockaddr_storage ss = netdutils::IPSockAddr(prefix.ip());
const sockaddr_in6* v6prefix = (sockaddr_in6*)&ss;
addrinfo* const head4 = *res;
addrinfo* head6 = nullptr;
addrinfo* cur6 = nullptr;
// Build a synthesized AAAA addrinfo list from the queried A addrinfo list. Here is the diagram
// for the relationship of pointers.
//
// head4: point to the first queried A addrinfo
// |
// v
// +-------------+ +-------------+
// | addrinfo4#1 |-->| addrinfo4#2 |--> .. queried A addrinfo(s) for DNS64 synthesis
// +-------------+ +-------------+
// ^
// |
// cur4: current worked-on queried A addrinfo
//
// head6: point to the first synthesized AAAA addrinfo
// |
// v
// +-------------+ +-------------+
// | addrinfo6#1 |-->| addrinfo6#2 |--> .. synthesized DNS64 AAAA addrinfo(s)
// +-------------+ +-------------+
// ^
// |
// cur6: current worked-on synthesized addrinfo
//
for (const addrinfo* cur4 = head4; cur4; cur4 = cur4->ai_next) {
// Allocate a space for a synthesized AAAA addrinfo. Note that the addrinfo and sockaddr
// occupy one contiguous block of memory and are allocated and freed as a single block.
// See get_ai and freeaddrinfo in packages/modules/DnsResolver/getaddrinfo.cpp.
addrinfo* sa = (addrinfo*)calloc(1, sizeof(addrinfo) + sizeof(sockaddr_in6));
if (sa == nullptr) {
LOG(ERROR) << "allocate memory failed for synthesized result";
freeaddrinfo(head6);
return false;
}
// Initialize the synthesized AAAA addrinfo by the queried A addrinfo. The ai_addr will be
// set lately.
sa->ai_flags = cur4->ai_flags;
sa->ai_family = AF_INET6;
sa->ai_socktype = cur4->ai_socktype;
sa->ai_protocol = cur4->ai_protocol;
sa->ai_addrlen = sizeof(sockaddr_in6);
sa->ai_addr = (sockaddr*)(sa + 1);
sa->ai_canonname = nullptr;
sa->ai_next = nullptr;
if (cur4->ai_canonname != nullptr) {
// Reassign it to a local variable to avoid -Wnullable-to-nonnull-conversion on calling
// strdup.
const char* ai_canonname = cur4->ai_canonname;
sa->ai_canonname = strdup(ai_canonname);
if (sa->ai_canonname == nullptr) {
LOG(ERROR) << "allocate memory failed for canonname";
freeaddrinfo(sa);
freeaddrinfo(head6);
return false;
}
}
// Synthesize /96 NAT64 prefix with the queried IPv4 address.
const sockaddr_in* sin4 = (sockaddr_in*)cur4->ai_addr;
sockaddr_in6* sin6 = (sockaddr_in6*)sa->ai_addr;
sin6->sin6_addr = v6prefix->sin6_addr;
sin6->sin6_addr.s6_addr32[3] = sin4->sin_addr.s_addr;
sin6->sin6_family = AF_INET6;
sin6->sin6_port = sin4->sin_port;
// If the synthesized list is empty, this becomes the first element.
if (head6 == nullptr) {
head6 = sa;
}
// Add this element to the end of the synthesized list.
if (cur6 != nullptr) {
cur6->ai_next = sa;
}
cur6 = sa;
if (WOULD_LOG(VERBOSE)) {
char buf[INET6_ADDRSTRLEN]; // big enough for either IPv4 or IPv6
inet_ntop(AF_INET, &sin4->sin_addr.s_addr, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": DNS A record: " << buf;
inet_ntop(AF_INET6, &v6prefix->sin6_addr, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": NAT64 prefix: " << buf;
inet_ntop(AF_INET6, &sin6->sin6_addr, buf, sizeof(buf));
LOG(VERBOSE) << __func__ << ": DNS64 Synthesized AAAA record: " << buf;
}
}
// Simply concatenate the synthesized AAAA addrinfo list and the queried A addrinfo list when
// AF_UNSPEC is specified. In the other words, the IPv6 addresses are listed first and then
// IPv4 addresses. For example:
// 64:ff9b::102:304 (socktype=2, protocol=17) ->
// 64:ff9b::102:304 (socktype=1, protocol=6) ->
// 1.2.3.4 (socktype=2, protocol=17) ->
// 1.2.3.4 (socktype=1, protocol=6)
// Note that head6 and cur6 should be non-null because there was at least one IPv4 address
// synthesized. From the above example, the synthesized addrinfo list puts IPv6 and IPv4 in
// groups and sort by RFC 6724 later. This ordering is different from no synthesized case
// because resolv_getaddrinfo() sorts results in explore_options. resolv_getaddrinfo() calls
// explore_fqdn() many times by the different items of explore_options. It means that
// resolv_rfc6724_sort() only sorts the results in each explore_options and concatenates each
// results into one. For example, getaddrinfo() is called with null hints for a domain name
// which has both IPv4 and IPv6 addresses. The address order of the result addrinfo may be:
// 2001:db8::102:304 (socktype=2, protocol=17) -> 1.2.3.4 (socktype=2, protocol=17) ->
// 2001:db8::102:304 (socktype=1, protocol=6) -> 1.2.3.4 (socktype=1, protocol=6)
// In above example, the first two results come from one explore option and the last two come
// from another one. They are sorted first, and then concatenate together to be the result.
// See also resolv_getaddrinfo in packages/modules/DnsResolver/getaddrinfo.cpp.
if (unspecWantedButNoIPv6) {
cur6->ai_next = head4;
} else {
freeaddrinfo(head4);
}
// Sort the concatenated addresses by RFC 6724 section 2.1.
struct addrinfo sorting_head = {.ai_next = head6};
resolv_rfc6724_sort(&sorting_head, netcontext->app_mark, netcontext->uid);
*res = sorting_head.ai_next;
logDnsQueryResult(*res);
return true;
}
bool getDns64Prefix(unsigned netId, netdutils::IPPrefix* prefix) {
return !gDnsResolv->resolverCtrl.getPrefix64(netId, prefix);
}
std::string makeThreadName(unsigned netId, uint32_t uid) {
// The maximum of netId and app_id are 5-digit numbers.
return fmt::format("Dns_{}_{}", netId, multiuser_get_app_id(uid));
}
} // namespace
DnsProxyListener::DnsProxyListener() : FrameworkListener(SOCKET_NAME) {
mGetAddrInfoCmd = std::make_unique<GetAddrInfoCmd>();
registerCmd(mGetAddrInfoCmd.get());
mGetHostByAddrCmd = std::make_unique<GetHostByAddrCmd>();
registerCmd(mGetHostByAddrCmd.get());
mGetHostByNameCmd = std::make_unique<GetHostByNameCmd>();
registerCmd(mGetHostByNameCmd.get());
mResNSendCommand = std::make_unique<ResNSendCommand>();
registerCmd(mResNSendCommand.get());
mGetDnsNetIdCommand = std::make_unique<GetDnsNetIdCommand>();
registerCmd(mGetDnsNetIdCommand.get());
}
void DnsProxyListener::Handler::spawn() {
const int rval = netdutils::threadLaunch(this);
if (rval == 0) {
return;
}
char* msg = nullptr;
asprintf(&msg, "%s (%d)", strerror(-rval), -rval);
mClient->sendMsg(ResponseCode::OperationFailed, msg, false);
free(msg);
delete this;
}
DnsProxyListener::GetAddrInfoHandler::GetAddrInfoHandler(SocketClient* c, std::string host,
std::string service,
std::unique_ptr<addrinfo> hints,
const android_net_context& netcontext)
: Handler(c),
mHost(std::move(host)),
mService(std::move(service)),
mHints(std::move(hints)),
mNetContext(netcontext) {}
// Before U, the Netd callback is implemented by OEM to evaluate if a DNS query for the provided
// hostname is allowed. On U+, the Netd callback also checks if the user is allowed to send DNS on
// the specified network.
static bool evaluate_domain_name(const android_net_context& netcontext, const char* host) {
if (!gResNetdCallbacks.evaluate_domain_name) return true;
return gResNetdCallbacks.evaluate_domain_name(netcontext, host);
}
static int HandleArgumentError(SocketClient* cli, int errorcode, std::string strerrormessage,
int argc, char** argv) {
for (int i = 0; i < argc; i++) {
strerrormessage += "argv[" + std::to_string(i) + "]=" + (argv[i] ? argv[i] : "null") + " ";
}
LOG(WARNING) << strerrormessage;
cli->sendMsg(errorcode, strerrormessage.c_str(), false);
return -1;
}
static bool sendBE32(SocketClient* c, uint32_t data) {
uint32_t be_data = htonl(data);
return c->sendData(&be_data, sizeof(be_data)) == 0;
}
// Sends 4 bytes of big-endian length, followed by the data.
// Returns true on success.
static bool sendLenAndData(SocketClient* c, const int len, const void* data) {
return sendBE32(c, len) && (len == 0 || c->sendData(data, len) == 0);
}
// Returns true on success
static bool sendhostent(SocketClient* c, hostent* hp) {
bool success = true;
int i;
if (hp->h_name != nullptr) {
const char* h_name = hp->h_name;
success &= sendLenAndData(c, strlen(h_name) + 1, hp->h_name);
} else {
success &= sendLenAndData(c, 0, "") == 0;
}
for (i = 0; hp->h_aliases[i] != nullptr; i++) {
const char* h_aliases = hp->h_aliases[i];
success &= sendLenAndData(c, strlen(h_aliases) + 1, hp->h_aliases[i]);
}
success &= sendLenAndData(c, 0, ""); // null to indicate we're done
uint32_t buf = htonl(hp->h_addrtype);
success &= c->sendData(&buf, sizeof(buf)) == 0;
buf = htonl(hp->h_length);
success &= c->sendData(&buf, sizeof(buf)) == 0;
for (i = 0; hp->h_addr_list[i] != nullptr; i++) {
success &= sendLenAndData(c, 16, hp->h_addr_list[i]);
}
success &= sendLenAndData(c, 0, ""); // null to indicate we're done
return success;
}
static bool sendaddrinfo(SocketClient* c, addrinfo* ai) {
// struct addrinfo {
// int ai_flags; /* AI_PASSIVE, AI_CANONNAME, AI_NUMERICHOST */
// int ai_family; /* PF_xxx */
// int ai_socktype; /* SOCK_xxx */
// int ai_protocol; /* 0 or IPPROTO_xxx for IPv4 and IPv6 */
// socklen_t ai_addrlen; /* length of ai_addr */
// char *ai_canonname; /* canonical name for hostname */
// struct sockaddr *ai_addr; /* binary address */
// struct addrinfo *ai_next; /* next structure in linked list */
// };
// Write the struct piece by piece because we might be a 64-bit netd
// talking to a 32-bit process.
bool success = sendBE32(c, ai->ai_flags) && sendBE32(c, ai->ai_family) &&
sendBE32(c, ai->ai_socktype) && sendBE32(c, ai->ai_protocol);
if (!success) {
return false;
}
// ai_addrlen and ai_addr.
if (!sendLenAndData(c, ai->ai_addrlen, ai->ai_addr)) {
return false;
}
// strlen(ai_canonname) and ai_canonname.
int len = 0;
if (ai->ai_canonname != nullptr) {
const char* ai_canonname = ai->ai_canonname;
len = strlen(ai_canonname) + 1;
}
if (!sendLenAndData(c, len, ai->ai_canonname)) {
return false;
}
return true;
}
void DnsProxyListener::GetAddrInfoHandler::doDns64Synthesis(int32_t* rv, addrinfo** res,
NetworkDnsEventReported* event) {
const bool ipv6WantedButNoData = (mHints && mHints->ai_family == AF_INET6 && *rv == EAI_NODATA);
const bool unspecWantedButNoIPv6 =
((!mHints || mHints->ai_family == AF_UNSPEC) && *rv == 0 && onlyIPv4Answers(*res));
if (!ipv6WantedButNoData && !unspecWantedButNoIPv6) {
return;
}
netdutils::IPPrefix prefix{};
if (!getDns64Prefix(mNetContext.dns_netid, &prefix)) {
return;
}
if (ipv6WantedButNoData) {
// If caller wants IPv6 answers but no data, try to query IPv4 answers for synthesis
const uid_t uid = mClient->getUid();
if (startQueryLimiter(uid)) {
const char* host = mHost.starts_with('^') ? nullptr : mHost.c_str();
const char* service = mService.starts_with('^') ? nullptr : mService.c_str();
mHints->ai_family = AF_INET;
// Don't need to do freeaddrinfo(res) before starting new DNS lookup because previous
// DNS lookup is failed with error EAI_NODATA.
*rv = resolv_getaddrinfo(host, service, mHints.get(), &mNetContext, res, event);
endQueryLimiter(uid);
if (*rv) {
*rv = EAI_NODATA; // return original error code
return;
}
} else {
LOG(ERROR) << __func__ << ": from UID " << uid << ", max concurrent queries reached";
return;
}
}
if (!synthesizeNat64PrefixWithARecord(prefix, res, unspecWantedButNoIPv6, &mNetContext)) {
if (ipv6WantedButNoData) {
// If caller wants IPv6 answers but no data and failed to synthesize IPv6 answers,
// don't return the IPv4 answers.
*rv = EAI_NODATA; // return original error code
if (*res) {
freeaddrinfo(*res);
*res = nullptr;
}
}
}
}
void DnsProxyListener::GetAddrInfoHandler::run() {
LOG(INFO) << "GetAddrInfoHandler::run: {" << mNetContext.toString() << "}";
addrinfo* result = nullptr;
Stopwatch s;
maybeFixupNetContext(&mNetContext, mClient->getPid());
const uid_t uid = mClient->getUid();
int32_t rv = 0;
NetworkDnsEventReported event;
initDnsEvent(&event, mNetContext);
if (startQueryLimiter(uid)) {
const char* host = mHost.starts_with('^') ? nullptr : mHost.c_str();
const char* service = mService.starts_with('^') ? nullptr : mService.c_str();
if (evaluate_domain_name(mNetContext, host)) {
rv = resolv_getaddrinfo(host, service, mHints.get(), &mNetContext, &result, &event);
} else {
rv = EAI_SYSTEM;
}
endQueryLimiter(uid);
} else {
// Note that this error code is currently not passed down to the client.
// android_getaddrinfo_proxy() returns EAI_NODATA on any error.
rv = EAI_MEMORY;
LOG(ERROR) << "GetAddrInfoHandler::run: from UID " << uid
<< ", max concurrent queries reached";
}
doDns64Synthesis(&rv, &result, &event);
const int32_t latencyUs = saturate_cast<int32_t>(s.timeTakenUs());
event.set_latency_micros(latencyUs);
event.set_event_type(EVENT_GETADDRINFO);
event.set_hints_ai_flags((mHints ? mHints->ai_flags : 0));
bool success = true;
if (rv) {
// getaddrinfo failed
success = !mClient->sendBinaryMsg(ResponseCode::DnsProxyOperationFailed, &rv, sizeof(rv));
} else {
success = !mClient->sendCode(ResponseCode::DnsProxyQueryResult);
addrinfo* ai = result;
while (ai && success) {
success = sendBE32(mClient, 1) && sendaddrinfo(mClient, ai);
ai = ai->ai_next;
}
success = success && sendBE32(mClient, 0);
}
if (!success) {
PLOG(WARNING) << "GetAddrInfoHandler::run: Error writing DNS result to client uid " << uid
<< " pid " << mClient->getPid();
}
std::vector<std::string> ip_addrs;
const int total_ip_addr_count = extractGetAddrInfoAnswers(result, &ip_addrs);
reportDnsEvent(INetdEventListener::EVENT_GETADDRINFO, mNetContext, latencyUs, rv, event, mHost,
ip_addrs, total_ip_addr_count);
freeaddrinfo(result);
}
std::string DnsProxyListener::GetAddrInfoHandler::threadName() {
return makeThreadName(mNetContext.dns_netid, mClient->getUid());
}
namespace {
void addIpAddrWithinLimit(std::vector<std::string>* ip_addrs, const sockaddr* addr,
socklen_t addrlen) {
// ipAddresses array is limited to first INetdEventListener::DNS_REPORTED_IP_ADDRESSES_LIMIT
// addresses for A and AAAA. Total count of addresses is provided, to be able to tell whether
// some addresses didn't get logged.
if (ip_addrs->size() < INetdEventListener::DNS_REPORTED_IP_ADDRESSES_LIMIT) {
char ip_addr[INET6_ADDRSTRLEN];
if (getnameinfo(addr, addrlen, ip_addr, sizeof(ip_addr), nullptr, 0, NI_NUMERICHOST) == 0) {
ip_addrs->push_back(std::string(ip_addr));
}
}
}
} // namespace
DnsProxyListener::GetAddrInfoCmd::GetAddrInfoCmd() : FrameworkCommand("getaddrinfo") {}
int DnsProxyListener::GetAddrInfoCmd::runCommand(SocketClient* cli, int argc, char** argv) {
logArguments(argc, argv);
int ai_flags = 0;
int ai_family = 0;
int ai_socktype = 0;
int ai_protocol = 0;
unsigned netId = 0;
std::string strErr = "GetAddrInfoCmd::runCommand: ";
if (argc != 8) {
strErr = strErr + "invalid number of arguments: " + std::to_string(argc);
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, 0, NULL);
}
const std::string name = argv[1];
const std::string service = argv[2];
if (!ParseInt(argv[3], &ai_flags))
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, argc, argv);
if (!ParseInt(argv[4], &ai_family))
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, argc, argv);
if (!ParseInt(argv[5], &ai_socktype))
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, argc, argv);
if (!ParseInt(argv[6], &ai_protocol))
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, argc, argv);
if (!ParseUint(argv[7], &netId))
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, argc, argv);
const bool useLocalNameservers = checkAndClearUseLocalNameserversFlag(&netId);
const uid_t uid = cli->getUid();
android_net_context netcontext;
gResNetdCallbacks.get_network_context(netId, uid, &netcontext);
if (useLocalNameservers) {
netcontext.flags |= NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS;
}
std::unique_ptr<addrinfo> hints;
if (ai_flags != -1 || ai_family != -1 || ai_socktype != -1 || ai_protocol != -1) {
hints.reset((addrinfo*)calloc(1, sizeof(addrinfo)));
hints->ai_flags = ai_flags;
hints->ai_family = ai_family;
hints->ai_socktype = ai_socktype;
hints->ai_protocol = ai_protocol;
}
(new GetAddrInfoHandler(cli, name, service, std::move(hints), netcontext))->spawn();
return 0;
}
/*******************************************************
* ResNSendCommand *
*******************************************************/
DnsProxyListener::ResNSendCommand::ResNSendCommand() : FrameworkCommand("resnsend") {}
int DnsProxyListener::ResNSendCommand::runCommand(SocketClient* cli, int argc, char** argv) {
logArguments(argc, argv);
const uid_t uid = cli->getUid();
if (argc != 4) {
LOG(WARNING) << "ResNSendCommand::runCommand: resnsend: from UID " << uid
<< ", invalid number of arguments to resnsend: " << argc;
sendBE32(cli, -EINVAL);
return -1;
}
unsigned netId;
if (!ParseUint(argv[1], &netId)) {
LOG(WARNING) << "ResNSendCommand::runCommand: resnsend: from UID " << uid
<< ", invalid netId";
sendBE32(cli, -EINVAL);
return -1;
}
uint32_t flags;
if (!ParseUint(argv[2], &flags)) {
LOG(WARNING) << "ResNSendCommand::runCommand: resnsend: from UID " << uid
<< ", invalid flags";
sendBE32(cli, -EINVAL);
return -1;
}
const bool useLocalNameservers = checkAndClearUseLocalNameserversFlag(&netId);
android_net_context netcontext;
gResNetdCallbacks.get_network_context(netId, uid, &netcontext);
if (useLocalNameservers) {
netcontext.flags |= NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS;
}
(new ResNSendHandler(cli, argv[3], flags, netcontext))->spawn();
return 0;
}
DnsProxyListener::ResNSendHandler::ResNSendHandler(SocketClient* c, std::string msg, uint32_t flags,
const android_net_context& netcontext)
: Handler(c), mMsg(std::move(msg)), mFlags(flags), mNetContext(netcontext) {}
void DnsProxyListener::ResNSendHandler::run() {
LOG(INFO) << "ResNSendHandler::run: " << mFlags << " / {" << mNetContext.toString() << "}";
Stopwatch s;
maybeFixupNetContext(&mNetContext, mClient->getPid());
// Decode
std::vector<uint8_t> msg(MAXPACKET, 0);
// Max length of mMsg is less than 1024 since the CMD_BUF_SIZE in FrameworkListener is 1024
int msgLen = b64_pton(mMsg.c_str(), msg.data(), MAXPACKET);
if (msgLen == -1) {
// Decode fail
sendBE32(mClient, -EILSEQ);
return;
}
const uid_t uid = mClient->getUid();
int rr_type = 0;
std::string rr_name;
uint16_t original_query_id = 0;
// TODO: Handle the case which is msg contains more than one query
if (!parseQuery({msg.data(), msgLen}, &original_query_id, &rr_type, &rr_name) ||
!setQueryId({msg.data(), msgLen}, arc4random_uniform(65536))) {
// If the query couldn't be parsed, block the request.
LOG(WARNING) << "ResNSendHandler::run: resnsend: from UID " << uid << ", invalid query";
sendBE32(mClient, -EINVAL);
return;
}
// Send DNS query
std::vector<uint8_t> ansBuf(MAXPACKET, 0);
int rcode = ns_r_noerror;
int ansLen = -1;
NetworkDnsEventReported event;
initDnsEvent(&event, mNetContext);
if (startQueryLimiter(uid)) {
if (evaluate_domain_name(mNetContext, rr_name.c_str())) {
ansLen = resolv_res_nsend(&mNetContext, {msg.data(), msgLen}, ansBuf, &rcode,
static_cast<ResNsendFlags>(mFlags), &event);
} else {
ansLen = -EAI_SYSTEM;
}
endQueryLimiter(uid);
} else {
LOG(WARNING) << "ResNSendHandler::run: resnsend: from UID " << uid
<< ", max concurrent queries reached";
ansLen = -EBUSY;
}
const int32_t latencyUs = saturate_cast<int32_t>(s.timeTakenUs());
event.set_latency_micros(latencyUs);
event.set_event_type(EVENT_RES_NSEND);
event.set_res_nsend_flags(static_cast<ResNsendFlags>(mFlags));
// Fail, send -errno
if (ansLen < 0) {
if (!sendBE32(mClient, ansLen)) {
PLOG(WARNING) << "ResNSendHandler::run: resnsend: failed to send errno to uid " << uid
<< " pid " << mClient->getPid();
}
if (rr_type == ns_t_a || rr_type == ns_t_aaaa) {
reportDnsEvent(INetdEventListener::EVENT_RES_NSEND, mNetContext, latencyUs,
resNSendToAiError(ansLen, rcode), event, rr_name);
}
return;
}
// Send rcode
if (!sendBE32(mClient, rcode)) {
PLOG(WARNING) << "ResNSendHandler::run: resnsend: failed to send rcode to uid " << uid
<< " pid " << mClient->getPid();
return;
}
// Restore query id
if (!setQueryId({ansBuf.data(), ansLen}, original_query_id)) {
LOG(WARNING) << "ResNSendHandler::run: resnsend: failed to restore query id";
return;
}
// Send answer
if (!sendLenAndData(mClient, ansLen, ansBuf.data())) {
PLOG(WARNING) << "ResNSendHandler::run: resnsend: failed to send answer to uid " << uid
<< " pid " << mClient->getPid();
return;
}
if (rr_type == ns_t_a || rr_type == ns_t_aaaa) {
std::vector<std::string> ip_addrs;
const int total_ip_addr_count =
extractResNsendAnswers({ansBuf.data(), ansLen}, rr_type, &ip_addrs);
reportDnsEvent(INetdEventListener::EVENT_RES_NSEND, mNetContext, latencyUs,
resNSendToAiError(ansLen, rcode), event, rr_name, ip_addrs,
total_ip_addr_count);
}
}
std::string DnsProxyListener::ResNSendHandler::threadName() {
return makeThreadName(mNetContext.dns_netid, mClient->getUid());
}
namespace {
bool sendCodeAndBe32(SocketClient* c, int code, int data) {
return !c->sendCode(code) && sendBE32(c, data);
}
} // namespace
/*******************************************************
* GetDnsNetId *
*******************************************************/
DnsProxyListener::GetDnsNetIdCommand::GetDnsNetIdCommand() : FrameworkCommand("getdnsnetid") {}
int DnsProxyListener::GetDnsNetIdCommand::runCommand(SocketClient* cli, int argc, char** argv) {
logArguments(argc, argv);
const uid_t uid = cli->getUid();
if (argc != 2) {
LOG(WARNING) << "GetDnsNetIdCommand::runCommand: getdnsnetid: from UID " << uid
<< ", invalid number of arguments to getdnsnetid: " << argc;
sendCodeAndBe32(cli, ResponseCode::DnsProxyQueryResult, -EINVAL);
return -1;
}
unsigned netId;
if (!ParseUint(argv[1], &netId)) {
LOG(WARNING) << "GetDnsNetIdCommand::runCommand: getdnsnetid: from UID " << uid
<< ", invalid netId";
sendCodeAndBe32(cli, ResponseCode::DnsProxyQueryResult, -EINVAL);
return -1;
}
const bool useLocalNameservers = checkAndClearUseLocalNameserversFlag(&netId);
android_net_context netcontext;
gResNetdCallbacks.get_network_context(netId, uid, &netcontext);
if (useLocalNameservers) {
netcontext.app_netid |= NETID_USE_LOCAL_NAMESERVERS;
}
const bool success =
sendCodeAndBe32(cli, ResponseCode::DnsProxyQueryResult, netcontext.app_netid);
if (!success) {
PLOG(WARNING)
<< "GetDnsNetIdCommand::runCommand: getdnsnetid: failed to send result to uid "
<< uid << " pid " << cli->getPid();
}
return success ? 0 : -1;
}
/*******************************************************
* GetHostByName *
*******************************************************/
DnsProxyListener::GetHostByNameCmd::GetHostByNameCmd() : FrameworkCommand("gethostbyname") {}
int DnsProxyListener::GetHostByNameCmd::runCommand(SocketClient* cli, int argc, char** argv) {
logArguments(argc, argv);
unsigned netId = 0;
int af = 0;
std::string strErr = "GetHostByNameCmd::runCommand: ";
if (argc != 4) {
strErr = strErr + "invalid number of arguments: " + std::to_string(argc);
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, 0, NULL);
}
if (!ParseUint(argv[1], &netId))
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, argc, argv);
std::string name = argv[2];
if (!ParseInt(argv[3], &af))
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, argc, argv);
uid_t uid = cli->getUid();
const bool useLocalNameservers = checkAndClearUseLocalNameserversFlag(&netId);
android_net_context netcontext;
gResNetdCallbacks.get_network_context(netId, uid, &netcontext);
if (useLocalNameservers) {
netcontext.flags |= NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS;
}
(new GetHostByNameHandler(cli, name, af, netcontext))->spawn();
return 0;
}
DnsProxyListener::GetHostByNameHandler::GetHostByNameHandler(SocketClient* c, std::string name,
int af,
const android_net_context& netcontext)
: Handler(c), mName(std::move(name)), mAf(af), mNetContext(netcontext) {}
void DnsProxyListener::GetHostByNameHandler::doDns64Synthesis(int32_t* rv, hostent* hbuf, char* buf,
size_t buflen, struct hostent** hpp,
NetworkDnsEventReported* event) {
// Don't have to consider family AF_UNSPEC case because gethostbyname{, 2} only supports
// family AF_INET or AF_INET6.
const bool ipv6WantedButNoData = (mAf == AF_INET6 && *rv == EAI_NODATA);
if (!ipv6WantedButNoData) {
return;
}
netdutils::IPPrefix prefix{};
if (!getDns64Prefix(mNetContext.dns_netid, &prefix)) {
return;
}
// If caller wants IPv6 answers but no data, try to query IPv4 answers for synthesis
const uid_t uid = mClient->getUid();
if (startQueryLimiter(uid)) {
const char* name = mName.starts_with('^') ? nullptr : mName.c_str();
*rv = resolv_gethostbyname(name, AF_INET, hbuf, buf, buflen, &mNetContext, hpp, event);
endQueryLimiter(uid);
if (*rv) {
*rv = EAI_NODATA; // return original error code
return;
}
} else {
LOG(ERROR) << __func__ << ": from UID " << uid << ", max concurrent queries reached";
return;
}
if (!synthesizeNat64PrefixWithARecord(prefix, *hpp)) {
// If caller wants IPv6 answers but no data and failed to synthesize IPv4 answers,
// don't return the IPv4 answers.
*hpp = nullptr;
}
}
void DnsProxyListener::GetHostByNameHandler::run() {
LOG(INFO) << "GetHostByNameHandler::run: {" << mNetContext.toString() << "}";
Stopwatch s;
maybeFixupNetContext(&mNetContext, mClient->getPid());
const uid_t uid = mClient->getUid();
hostent* hp = nullptr;
hostent hbuf;
char tmpbuf[MAXPACKET];
int32_t rv = 0;
NetworkDnsEventReported event;
initDnsEvent(&event, mNetContext);
if (startQueryLimiter(uid)) {
const char* name = mName.starts_with('^') ? nullptr : mName.c_str();
if (evaluate_domain_name(mNetContext, name)) {
rv = resolv_gethostbyname(name, mAf, &hbuf, tmpbuf, sizeof tmpbuf, &mNetContext, &hp,
&event);
} else {
rv = EAI_SYSTEM;
}
endQueryLimiter(uid);
} else {
rv = EAI_MEMORY;
LOG(ERROR) << "GetHostByNameHandler::run: from UID " << uid
<< ", max concurrent queries reached";
}
doDns64Synthesis(&rv, &hbuf, tmpbuf, sizeof tmpbuf, &hp, &event);
const int32_t latencyUs = saturate_cast<int32_t>(s.timeTakenUs());
event.set_latency_micros(latencyUs);
event.set_event_type(EVENT_GETHOSTBYNAME);
if (rv) {
LOG(DEBUG) << "GetHostByNameHandler::run: result failed: " << gai_strerror(rv);
}
bool success = true;
if (hp) {
// hp is not nullptr iff. rv is 0.
success = mClient->sendCode(ResponseCode::DnsProxyQueryResult) == 0;
success &= sendhostent(mClient, hp);
} else {
success = mClient->sendBinaryMsg(ResponseCode::DnsProxyOperationFailed, nullptr, 0) == 0;
}
if (!success) {
PLOG(WARNING) << "GetHostByNameHandler::run: Error writing DNS result to client uid " << uid
<< " pid " << mClient->getPid();
}
std::vector<std::string> ip_addrs;
const int total_ip_addr_count = extractGetHostByNameAnswers(hp, &ip_addrs);
reportDnsEvent(INetdEventListener::EVENT_GETHOSTBYNAME, mNetContext, latencyUs, rv, event,
mName, ip_addrs, total_ip_addr_count);
}
std::string DnsProxyListener::GetHostByNameHandler::threadName() {
return makeThreadName(mNetContext.dns_netid, mClient->getUid());
}
/*******************************************************
* GetHostByAddr *
*******************************************************/
DnsProxyListener::GetHostByAddrCmd::GetHostByAddrCmd() : FrameworkCommand("gethostbyaddr") {}
int DnsProxyListener::GetHostByAddrCmd::runCommand(SocketClient* cli, int argc, char** argv) {
logArguments(argc, argv);
int addrLen = 0;
int addrFamily = 0;
unsigned netId = 0;
std::string strErr = "GetHostByAddrCmd::runCommand: ";
if (argc != 5) {
strErr = strErr + "invalid number of arguments: " + std::to_string(argc);
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, 0, NULL);
}
char* addrStr = argv[1];
if (!ParseInt(argv[2], &addrLen))
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, argc, argv);
if (!ParseInt(argv[3], &addrFamily))
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, argc, argv);
if (!ParseUint(argv[4], &netId))
return HandleArgumentError(cli, ResponseCode::CommandParameterError, strErr, argc, argv);
uid_t uid = cli->getUid();
const bool useLocalNameservers = checkAndClearUseLocalNameserversFlag(&netId);
in6_addr addr;
errno = 0;
int result = inet_pton(addrFamily, addrStr, &addr);
if (result <= 0) {
strErr = strErr + "inet_pton(\"" + addrStr + "\") failed " + strerror(errno);
return HandleArgumentError(cli, ResponseCode::OperationFailed, strErr, 0, NULL);
}
android_net_context netcontext;
gResNetdCallbacks.get_network_context(netId, uid, &netcontext);
if (useLocalNameservers) {
netcontext.flags |= NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS;
}
(new GetHostByAddrHandler(cli, addr, addrLen, addrFamily, netcontext))->spawn();
return 0;
}
DnsProxyListener::GetHostByAddrHandler::GetHostByAddrHandler(SocketClient* c, in6_addr address,
int addressLen, int addressFamily,
const android_net_context& netcontext)
: Handler(c),
mAddress(address),
mAddressLen(addressLen),
mAddressFamily(addressFamily),
mNetContext(netcontext) {}
void DnsProxyListener::GetHostByAddrHandler::doDns64ReverseLookup(hostent* hbuf, char* buf,
size_t buflen,
struct hostent** hpp,
NetworkDnsEventReported* event) {
if (*hpp != nullptr || mAddressFamily != AF_INET6) {
return;
}
netdutils::IPPrefix prefix{};
if (!getDns64Prefix(mNetContext.dns_netid, &prefix)) {
return;
}
if (!isValidNat64Prefix(prefix)) {
return;
}
struct sockaddr_storage ss = netdutils::IPSockAddr(prefix.ip());
struct sockaddr_in6* v6prefix = (struct sockaddr_in6*)&ss;
struct in6_addr v6addr = mAddress;
// Check if address has NAT64 prefix. Only /96 IPv6 NAT64 prefixes are supported
if ((v6addr.s6_addr32[0] != v6prefix->sin6_addr.s6_addr32[0]) ||
(v6addr.s6_addr32[1] != v6prefix->sin6_addr.s6_addr32[1]) ||
(v6addr.s6_addr32[2] != v6prefix->sin6_addr.s6_addr32[2])) {
return;
}
const uid_t uid = mClient->getUid();
if (startQueryLimiter(uid)) {
// Remove NAT64 prefix and do reverse DNS query
struct in_addr v4addr = {.s_addr = v6addr.s6_addr32[3]};
resolv_gethostbyaddr(&v4addr, sizeof(v4addr), AF_INET, hbuf, buf, buflen, &mNetContext, hpp,
event);
endQueryLimiter(uid);
if (*hpp && (*hpp)->h_addr_list[0]) {
// Replace IPv4 address with original queried IPv6 address in place. The space has
// reserved by dns_gethtbyaddr() and netbsd_gethostent_r() in
// system/netd/resolv/gethnamaddr.cpp.
// Note that resolv_gethostbyaddr() returns only one entry in result.
char* addr = (*hpp)->h_addr_list[0];
memcpy(addr, &v6addr, sizeof(v6addr));
(*hpp)->h_addrtype = AF_INET6;
(*hpp)->h_length = sizeof(struct in6_addr);
} else {
LOG(ERROR) << __func__ << ": hpp or (*hpp)->h_addr_list[0] is null";
}
} else {
LOG(ERROR) << __func__ << ": from UID " << uid << ", max concurrent queries reached";
}
}
void DnsProxyListener::GetHostByAddrHandler::run() {
LOG(INFO) << "GetHostByAddrHandler::run: {" << mNetContext.toString() << "}";
Stopwatch s;
maybeFixupNetContext(&mNetContext, mClient->getPid());
const uid_t uid = mClient->getUid();
hostent* hp = nullptr;
hostent hbuf;
char tmpbuf[MAXPACKET];
int32_t rv = 0;
NetworkDnsEventReported event;
initDnsEvent(&event, mNetContext);
if (startQueryLimiter(uid)) {
// From Android U, evaluate_domain_name() is not only for OEM customization, but also tells
// DNS resolver whether the UID can send DNS on the specified network. The function needs
// to be called even when there is no domain name to evaluate (GetHostByAddr). This is
// applied on U+ only so that the behavior won’t change on T- OEM devices.
// TODO: pass the actual name into evaluate_domain_name, e.g., 238.26.217.172.in-addr.arpa
// when the lookup address is 172.217.26.238.
if (isAtLeastU() && !evaluate_domain_name(mNetContext, nullptr)) {
rv = EAI_SYSTEM;
} else {
rv = resolv_gethostbyaddr(&mAddress, mAddressLen, mAddressFamily, &hbuf, tmpbuf,
sizeof tmpbuf, &mNetContext, &hp, &event);
}
endQueryLimiter(uid);
} else {
rv = EAI_MEMORY;
LOG(ERROR) << "GetHostByAddrHandler::run: from UID " << uid
<< ", max concurrent queries reached";
}
doDns64ReverseLookup(&hbuf, tmpbuf, sizeof tmpbuf, &hp, &event);
const int32_t latencyUs = saturate_cast<int32_t>(s.timeTakenUs());
event.set_latency_micros(latencyUs);
event.set_event_type(EVENT_GETHOSTBYADDR);
if (rv) {
LOG(DEBUG) << "GetHostByAddrHandler::run: result failed: " << gai_strerror(rv);
}
bool success = true;
if (hp) {
success = mClient->sendCode(ResponseCode::DnsProxyQueryResult) == 0;
success &= sendhostent(mClient, hp);
} else {
success = mClient->sendBinaryMsg(ResponseCode::DnsProxyOperationFailed, nullptr, 0) == 0;
}
if (!success) {
PLOG(WARNING) << "GetHostByAddrHandler::run: Error writing DNS result to client uid " << uid
<< " pid " << mClient->getPid();
}
reportDnsEvent(INetdEventListener::EVENT_GETHOSTBYADDR, mNetContext, latencyUs, rv, event,
(hp && hp->h_name) ? hp->h_name : "null", {}, 0);
}
std::string DnsProxyListener::GetHostByAddrHandler::threadName() {
return makeThreadName(mNetContext.dns_netid, mClient->getUid());
}
} // namespace net
} // namespace android