// // // Copyright 2016 gRPC authors. // // 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 <grpc/support/port_platform.h> #include <algorithm> #include <initializer_list> #include <vector> #include "absl/strings/string_view.h" #include <grpc/grpc.h> #include "src/core/lib/gprpp/status_helper.h" #include "src/core/lib/iomgr/sockaddr.h" // IWYU pragma: no_include <arpa/inet.h> // IWYU pragma: no_include <arpa/nameser.h> // IWYU pragma: no_include <inttypes.h> // IWYU pragma: no_include <netdb.h> // IWYU pragma: no_include <netinet/in.h> // IWYU pragma: no_include <stdlib.h> // IWYU pragma: no_include <sys/socket.h> #if GRPC_ARES == 1 #include <string.h> #include <sys/types.h> // IWYU pragma: keep #include <string> #include <utility> #include <address_sorting/address_sorting.h> #include <ares.h> #include "absl/status/status.h" #include "absl/status/statusor.h" #include "absl/strings/str_cat.h" #include "absl/strings/str_format.h" #include <grpc/support/alloc.h> #include <grpc/support/log.h> #include <grpc/support/string_util.h> #include <grpc/support/sync.h> #include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h" #include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h" #include "src/core/lib/address_utils/parse_address.h" #include "src/core/lib/address_utils/sockaddr_utils.h" #include "src/core/lib/channel/channel_args.h" #include "src/core/lib/gpr/string.h" #include "src/core/lib/gprpp/debug_location.h" #include "src/core/lib/gprpp/host_port.h" #include "src/core/lib/gprpp/time.h" #include "src/core/lib/iomgr/error.h" #include "src/core/lib/iomgr/exec_ctx.h" #include "src/core/lib/iomgr/nameser.h" // IWYU pragma: keep #include "src/core/lib/iomgr/resolved_address.h" #include "src/core/lib/iomgr/timer.h" using grpc_core::ServerAddress; using grpc_core::ServerAddressList; grpc_core::TraceFlag grpc_trace_cares_address_sorting(false, "cares_address_sorting"); grpc_core::TraceFlag grpc_trace_cares_resolver(false, "cares_resolver"); typedef struct fd_node { // default constructor exists only for linked list manipulation fd_node() : ev_driver(nullptr) {} explicit fd_node(grpc_ares_ev_driver* ev_driver) : ev_driver(ev_driver) {} /// the owner of this fd node grpc_ares_ev_driver* const ev_driver; /// a closure wrapping on_readable_locked, which should be /// invoked when the grpc_fd in this node becomes readable. grpc_closure read_closure ABSL_GUARDED_BY(&grpc_ares_request::mu); /// a closure wrapping on_writable_locked, which should be /// invoked when the grpc_fd in this node becomes writable. grpc_closure write_closure ABSL_GUARDED_BY(&grpc_ares_request::mu); /// next fd node in the list struct fd_node* next ABSL_GUARDED_BY(&grpc_ares_request::mu); /// wrapped fd that's polled by grpc's poller for the current platform grpc_core::GrpcPolledFd* grpc_polled_fd ABSL_GUARDED_BY(&grpc_ares_request::mu); /// if the readable closure has been registered bool readable_registered ABSL_GUARDED_BY(&grpc_ares_request::mu); /// if the writable closure has been registered bool writable_registered ABSL_GUARDED_BY(&grpc_ares_request::mu); /// if the fd has been shutdown yet from grpc iomgr perspective bool already_shutdown ABSL_GUARDED_BY(&grpc_ares_request::mu); } fd_node; struct grpc_ares_ev_driver { explicit grpc_ares_ev_driver(grpc_ares_request* request) : request(request) {} /// the ares_channel owned by this event driver ares_channel channel ABSL_GUARDED_BY(&grpc_ares_request::mu); /// pollset set for driving the IO events of the channel grpc_pollset_set* pollset_set ABSL_GUARDED_BY(&grpc_ares_request::mu); /// refcount of the event driver gpr_refcount refs; /// a list of grpc_fd that this event driver is currently using. fd_node* fds ABSL_GUARDED_BY(&grpc_ares_request::mu); /// is this event driver being shut down bool shutting_down ABSL_GUARDED_BY(&grpc_ares_request::mu); /// request object that's using this ev driver grpc_ares_request* const request; /// Owned by the ev_driver. Creates new GrpcPolledFd's std::unique_ptr<grpc_core::GrpcPolledFdFactory> polled_fd_factory ABSL_GUARDED_BY(&grpc_ares_request::mu); /// query timeout in milliseconds int query_timeout_ms ABSL_GUARDED_BY(&grpc_ares_request::mu); /// alarm to cancel active queries grpc_timer query_timeout ABSL_GUARDED_BY(&grpc_ares_request::mu); /// cancels queries on a timeout grpc_closure on_timeout_locked ABSL_GUARDED_BY(&grpc_ares_request::mu); /// alarm to poll ares_process on in case fd events don't happen grpc_timer ares_backup_poll_alarm ABSL_GUARDED_BY(&grpc_ares_request::mu); /// polls ares_process on a periodic timer grpc_closure on_ares_backup_poll_alarm_locked ABSL_GUARDED_BY(&grpc_ares_request::mu); }; // TODO(apolcyn): make grpc_ares_hostbyname_request a sub-class // of GrpcAresQuery. typedef struct grpc_ares_hostbyname_request { /// following members are set in create_hostbyname_request_locked /// /// the top-level request instance grpc_ares_request* parent_request; /// host to resolve, parsed from the name to resolve char* host; /// port to fill in sockaddr_in, parsed from the name to resolve uint16_t port; /// is it a grpclb address bool is_balancer; /// for logging and errors: the query type ("A" or "AAAA") const char* qtype; } grpc_ares_hostbyname_request; static void grpc_ares_request_ref_locked(grpc_ares_request* r) ABSL_EXCLUSIVE_LOCKS_REQUIRED(r->mu); static void grpc_ares_request_unref_locked(grpc_ares_request* r) ABSL_EXCLUSIVE_LOCKS_REQUIRED(r->mu); // TODO(apolcyn): as a part of C++-ification, find a way to // organize per-query and per-resolution information in such a way // that doesn't involve allocating a number of different data // structures. class GrpcAresQuery { public: explicit GrpcAresQuery(grpc_ares_request* r, const std::string& name) : r_(r), name_(name) { grpc_ares_request_ref_locked(r_); } ~GrpcAresQuery() { grpc_ares_request_unref_locked(r_); } grpc_ares_request* parent_request() { return r_; } const std::string& name() { return name_; } private: // the top level request instance grpc_ares_request* r_; /// for logging and errors const std::string name_; }; static grpc_ares_ev_driver* grpc_ares_ev_driver_ref( grpc_ares_ev_driver* ev_driver) ABSL_EXCLUSIVE_LOCKS_REQUIRED(&grpc_ares_request::mu) { GRPC_CARES_TRACE_LOG("request:%p Ref ev_driver %p", ev_driver->request, ev_driver); gpr_ref(&ev_driver->refs); return ev_driver; } static void grpc_ares_complete_request_locked(grpc_ares_request* r) ABSL_EXCLUSIVE_LOCKS_REQUIRED(r->mu); static void grpc_ares_ev_driver_unref(grpc_ares_ev_driver* ev_driver) ABSL_EXCLUSIVE_LOCKS_REQUIRED(&grpc_ares_request::mu) { GRPC_CARES_TRACE_LOG("request:%p Unref ev_driver %p", ev_driver->request, ev_driver); if (gpr_unref(&ev_driver->refs)) { GRPC_CARES_TRACE_LOG("request:%p destroy ev_driver %p", ev_driver->request, ev_driver); GPR_ASSERT(ev_driver->fds == nullptr); ares_destroy(ev_driver->channel); grpc_ares_complete_request_locked(ev_driver->request); delete ev_driver; } } static void fd_node_destroy_locked(fd_node* fdn) ABSL_EXCLUSIVE_LOCKS_REQUIRED(&grpc_ares_request::mu) { GRPC_CARES_TRACE_LOG("request:%p delete fd: %s", fdn->ev_driver->request, fdn->grpc_polled_fd->GetName()); GPR_ASSERT(!fdn->readable_registered); GPR_ASSERT(!fdn->writable_registered); GPR_ASSERT(fdn->already_shutdown); delete fdn->grpc_polled_fd; delete fdn; } static void fd_node_shutdown_locked(fd_node* fdn, const char* reason) ABSL_EXCLUSIVE_LOCKS_REQUIRED(&grpc_ares_request::mu) { if (!fdn->already_shutdown) { fdn->already_shutdown = true; fdn->grpc_polled_fd->ShutdownLocked(GRPC_ERROR_CREATE(reason)); } } void grpc_ares_ev_driver_on_queries_complete_locked( grpc_ares_ev_driver* ev_driver) ABSL_EXCLUSIVE_LOCKS_REQUIRED(&grpc_ares_request::mu) { // We mark the event driver as being shut down. // grpc_ares_notify_on_event_locked will shut down any remaining // fds. ev_driver->shutting_down = true; grpc_timer_cancel(&ev_driver->query_timeout); grpc_timer_cancel(&ev_driver->ares_backup_poll_alarm); grpc_ares_ev_driver_unref(ev_driver); } void grpc_ares_ev_driver_shutdown_locked(grpc_ares_ev_driver* ev_driver) ABSL_EXCLUSIVE_LOCKS_REQUIRED(&grpc_ares_request::mu) { ev_driver->shutting_down = true; fd_node* fn = ev_driver->fds; while (fn != nullptr) { fd_node_shutdown_locked(fn, "grpc_ares_ev_driver_shutdown"); fn = fn->next; } } // Search fd in the fd_node list head. This is an O(n) search, the max possible // value of n is ARES_GETSOCK_MAXNUM (16). n is typically 1 - 2 in our tests. static fd_node* pop_fd_node_locked(fd_node** head, ares_socket_t as) ABSL_EXCLUSIVE_LOCKS_REQUIRED(&grpc_ares_request::mu) { fd_node phony_head; phony_head.next = *head; fd_node* node = &phony_head; while (node->next != nullptr) { if (node->next->grpc_polled_fd->GetWrappedAresSocketLocked() == as) { fd_node* ret = node->next; node->next = node->next->next; *head = phony_head.next; return ret; } node = node->next; } return nullptr; } static grpc_core::Timestamp calculate_next_ares_backup_poll_alarm( grpc_ares_ev_driver* driver) ABSL_EXCLUSIVE_LOCKS_REQUIRED(&grpc_ares_request::mu) { // An alternative here could be to use ares_timeout to try to be more // accurate, but that would require using "struct timeval"'s, which just makes // things a bit more complicated. So just poll every second, as suggested // by the c-ares code comments. grpc_core::Duration until_next_ares_backup_poll_alarm = grpc_core::Duration::Seconds(1); GRPC_CARES_TRACE_LOG( "request:%p ev_driver=%p. next ares process poll time in " "%" PRId64 " ms", driver->request, driver, until_next_ares_backup_poll_alarm.millis()); return grpc_core::Timestamp::Now() + until_next_ares_backup_poll_alarm; } static void on_timeout(void* arg, grpc_error_handle error) { grpc_ares_ev_driver* driver = static_cast<grpc_ares_ev_driver*>(arg); grpc_core::MutexLock lock(&driver->request->mu); GRPC_CARES_TRACE_LOG( "request:%p ev_driver=%p on_timeout_locked. driver->shutting_down=%d. " "err=%s", driver->request, driver, driver->shutting_down, grpc_core::StatusToString(error).c_str()); if (!driver->shutting_down && error.ok()) { grpc_ares_ev_driver_shutdown_locked(driver); } grpc_ares_ev_driver_unref(driver); } static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver) ABSL_EXCLUSIVE_LOCKS_REQUIRED(&grpc_ares_request::mu); // In case of non-responsive DNS servers, dropped packets, etc., c-ares has // intelligent timeout and retry logic, which we can take advantage of by // polling ares_process_fd on time intervals. Overall, the c-ares library is // meant to be called into and given a chance to proceed name resolution: // a) when fd events happen // b) when some time has passed without fd events having happened // For the latter, we use this backup poller. Also see // https://github.com/grpc/grpc/pull/17688 description for more details. static void on_ares_backup_poll_alarm(void* arg, grpc_error_handle error) { grpc_ares_ev_driver* driver = static_cast<grpc_ares_ev_driver*>(arg); grpc_core::MutexLock lock(&driver->request->mu); GRPC_CARES_TRACE_LOG( "request:%p ev_driver=%p on_ares_backup_poll_alarm_locked. " "driver->shutting_down=%d. " "err=%s", driver->request, driver, driver->shutting_down, grpc_core::StatusToString(error).c_str()); if (!driver->shutting_down && error.ok()) { fd_node* fdn = driver->fds; while (fdn != nullptr) { if (!fdn->already_shutdown) { GRPC_CARES_TRACE_LOG( "request:%p ev_driver=%p on_ares_backup_poll_alarm_locked; " "ares_process_fd. fd=%s", driver->request, driver, fdn->grpc_polled_fd->GetName()); ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked(); ares_process_fd(driver->channel, as, as); } fdn = fdn->next; } if (!driver->shutting_down) { // InvalidateNow to avoid getting stuck re-initializing this timer // in a loop while draining the currently-held WorkSerializer. // Also see https://github.com/grpc/grpc/issues/26079. grpc_core::ExecCtx::Get()->InvalidateNow(); grpc_core::Timestamp next_ares_backup_poll_alarm = calculate_next_ares_backup_poll_alarm(driver); grpc_ares_ev_driver_ref(driver); GRPC_CLOSURE_INIT(&driver->on_ares_backup_poll_alarm_locked, on_ares_backup_poll_alarm, driver, grpc_schedule_on_exec_ctx); grpc_timer_init(&driver->ares_backup_poll_alarm, next_ares_backup_poll_alarm, &driver->on_ares_backup_poll_alarm_locked); } grpc_ares_notify_on_event_locked(driver); } grpc_ares_ev_driver_unref(driver); } static void on_readable(void* arg, grpc_error_handle error) { fd_node* fdn = static_cast<fd_node*>(arg); grpc_core::MutexLock lock(&fdn->ev_driver->request->mu); GPR_ASSERT(fdn->readable_registered); grpc_ares_ev_driver* ev_driver = fdn->ev_driver; const ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked(); fdn->readable_registered = false; GRPC_CARES_TRACE_LOG("request:%p readable on %s", fdn->ev_driver->request, fdn->grpc_polled_fd->GetName()); if (error.ok() && !ev_driver->shutting_down) { do { ares_process_fd(ev_driver->channel, as, ARES_SOCKET_BAD); } while (fdn->grpc_polled_fd->IsFdStillReadableLocked()); } else { // If error is not absl::OkStatus() or the resolution was cancelled, it // means the fd has been shutdown or timed out. The pending lookups made on // this ev_driver will be cancelled by the following ares_cancel() and the // on_done callbacks will be invoked with a status of ARES_ECANCELLED. The // remaining file descriptors in this ev_driver will be cleaned up in the // follwing grpc_ares_notify_on_event_locked(). ares_cancel(ev_driver->channel); } grpc_ares_notify_on_event_locked(ev_driver); grpc_ares_ev_driver_unref(ev_driver); } static void on_writable(void* arg, grpc_error_handle error) { fd_node* fdn = static_cast<fd_node*>(arg); grpc_core::MutexLock lock(&fdn->ev_driver->request->mu); GPR_ASSERT(fdn->writable_registered); grpc_ares_ev_driver* ev_driver = fdn->ev_driver; const ares_socket_t as = fdn->grpc_polled_fd->GetWrappedAresSocketLocked(); fdn->writable_registered = false; GRPC_CARES_TRACE_LOG("request:%p writable on %s", ev_driver->request, fdn->grpc_polled_fd->GetName()); if (error.ok() && !ev_driver->shutting_down) { ares_process_fd(ev_driver->channel, ARES_SOCKET_BAD, as); } else { // If error is not absl::OkStatus() or the resolution was cancelled, it // means the fd has been shutdown or timed out. The pending lookups made on // this ev_driver will be cancelled by the following ares_cancel() and the // on_done callbacks will be invoked with a status of ARES_ECANCELLED. The // remaining file descriptors in this ev_driver will be cleaned up in the // follwing grpc_ares_notify_on_event_locked(). ares_cancel(ev_driver->channel); } grpc_ares_notify_on_event_locked(ev_driver); grpc_ares_ev_driver_unref(ev_driver); } // Get the file descriptors used by the ev_driver's ares channel, register // driver_closure with these filedescriptors. static void grpc_ares_notify_on_event_locked(grpc_ares_ev_driver* ev_driver) ABSL_EXCLUSIVE_LOCKS_REQUIRED(&grpc_ares_request::mu) { fd_node* new_list = nullptr; if (!ev_driver->shutting_down) { ares_socket_t socks[ARES_GETSOCK_MAXNUM]; int socks_bitmask = ares_getsock(ev_driver->channel, socks, ARES_GETSOCK_MAXNUM); for (size_t i = 0; i < ARES_GETSOCK_MAXNUM; i++) { if (ARES_GETSOCK_READABLE(socks_bitmask, i) || ARES_GETSOCK_WRITABLE(socks_bitmask, i)) { fd_node* fdn = pop_fd_node_locked(&ev_driver->fds, socks[i]); // Create a new fd_node if sock[i] is not in the fd_node list. if (fdn == nullptr) { fdn = new fd_node(ev_driver); fdn->grpc_polled_fd = ev_driver->polled_fd_factory->NewGrpcPolledFdLocked( socks[i], ev_driver->pollset_set); GRPC_CARES_TRACE_LOG("request:%p new fd: %s", ev_driver->request, fdn->grpc_polled_fd->GetName()); fdn->readable_registered = false; fdn->writable_registered = false; fdn->already_shutdown = false; } fdn->next = new_list; new_list = fdn; // Register read_closure if the socket is readable and read_closure has // not been registered with this socket. if (ARES_GETSOCK_READABLE(socks_bitmask, i) && !fdn->readable_registered) { grpc_ares_ev_driver_ref(ev_driver); GRPC_CARES_TRACE_LOG("request:%p notify read on: %s", ev_driver->request, fdn->grpc_polled_fd->GetName()); GRPC_CLOSURE_INIT(&fdn->read_closure, on_readable, fdn, grpc_schedule_on_exec_ctx); fdn->grpc_polled_fd->RegisterForOnReadableLocked(&fdn->read_closure); fdn->readable_registered = true; } // Register write_closure if the socket is writable and write_closure // has not been registered with this socket. if (ARES_GETSOCK_WRITABLE(socks_bitmask, i) && !fdn->writable_registered) { GRPC_CARES_TRACE_LOG("request:%p notify write on: %s", ev_driver->request, fdn->grpc_polled_fd->GetName()); grpc_ares_ev_driver_ref(ev_driver); GRPC_CLOSURE_INIT(&fdn->write_closure, on_writable, fdn, grpc_schedule_on_exec_ctx); fdn->grpc_polled_fd->RegisterForOnWriteableLocked( &fdn->write_closure); fdn->writable_registered = true; } } } } // Any remaining fds in ev_driver->fds were not returned by ares_getsock() and // are therefore no longer in use, so they can be shut down and removed from // the list. while (ev_driver->fds != nullptr) { fd_node* cur = ev_driver->fds; ev_driver->fds = ev_driver->fds->next; fd_node_shutdown_locked(cur, "c-ares fd shutdown"); if (!cur->readable_registered && !cur->writable_registered) { fd_node_destroy_locked(cur); } else { cur->next = new_list; new_list = cur; } } ev_driver->fds = new_list; } void grpc_ares_ev_driver_start_locked(grpc_ares_ev_driver* ev_driver) ABSL_EXCLUSIVE_LOCKS_REQUIRED(&grpc_ares_request::mu) { grpc_ares_notify_on_event_locked(ev_driver); // Initialize overall DNS resolution timeout alarm grpc_core::Duration timeout = ev_driver->query_timeout_ms == 0 ? grpc_core::Duration::Infinity() : grpc_core::Duration::Milliseconds(ev_driver->query_timeout_ms); GRPC_CARES_TRACE_LOG( "request:%p ev_driver=%p grpc_ares_ev_driver_start_locked. timeout in " "%" PRId64 " ms", ev_driver->request, ev_driver, timeout.millis()); grpc_ares_ev_driver_ref(ev_driver); GRPC_CLOSURE_INIT(&ev_driver->on_timeout_locked, on_timeout, ev_driver, grpc_schedule_on_exec_ctx); grpc_timer_init(&ev_driver->query_timeout, grpc_core::Timestamp::Now() + timeout, &ev_driver->on_timeout_locked); // Initialize the backup poll alarm grpc_core::Timestamp next_ares_backup_poll_alarm = calculate_next_ares_backup_poll_alarm(ev_driver); grpc_ares_ev_driver_ref(ev_driver); GRPC_CLOSURE_INIT(&ev_driver->on_ares_backup_poll_alarm_locked, on_ares_backup_poll_alarm, ev_driver, grpc_schedule_on_exec_ctx); grpc_timer_init(&ev_driver->ares_backup_poll_alarm, next_ares_backup_poll_alarm, &ev_driver->on_ares_backup_poll_alarm_locked); } static void noop_inject_channel_config(ares_channel /*channel*/) {} void (*grpc_ares_test_only_inject_config)(ares_channel channel) = noop_inject_channel_config; grpc_error_handle grpc_ares_ev_driver_create_locked( grpc_ares_ev_driver** ev_driver, grpc_pollset_set* pollset_set, int query_timeout_ms, grpc_ares_request* request) ABSL_EXCLUSIVE_LOCKS_REQUIRED(request->mu) { *ev_driver = new grpc_ares_ev_driver(request); ares_options opts; memset(&opts, 0, sizeof(opts)); opts.flags |= ARES_FLAG_STAYOPEN; int status = ares_init_options(&(*ev_driver)->channel, &opts, ARES_OPT_FLAGS); grpc_ares_test_only_inject_config((*ev_driver)->channel); GRPC_CARES_TRACE_LOG("request:%p grpc_ares_ev_driver_create_locked", request); if (status != ARES_SUCCESS) { grpc_error_handle err = GRPC_ERROR_CREATE(absl::StrCat( "Failed to init ares channel. C-ares error: ", ares_strerror(status))); delete *ev_driver; return err; } gpr_ref_init(&(*ev_driver)->refs, 1); (*ev_driver)->pollset_set = pollset_set; (*ev_driver)->fds = nullptr; (*ev_driver)->shutting_down = false; (*ev_driver)->polled_fd_factory = grpc_core::NewGrpcPolledFdFactory(&(*ev_driver)->request->mu); (*ev_driver) ->polled_fd_factory->ConfigureAresChannelLocked((*ev_driver)->channel); (*ev_driver)->query_timeout_ms = query_timeout_ms; return absl::OkStatus(); } static void log_address_sorting_list(const grpc_ares_request* r, const ServerAddressList& addresses, const char* input_output_str) { for (size_t i = 0; i < addresses.size(); i++) { auto addr_str = grpc_sockaddr_to_string(&addresses[i].address(), true); gpr_log(GPR_INFO, "(c-ares resolver) request:%p c-ares address sorting: %s[%" PRIuPTR "]=%s", r, input_output_str, i, addr_str.ok() ? addr_str->c_str() : addr_str.status().ToString().c_str()); } } void grpc_cares_wrapper_address_sorting_sort(const grpc_ares_request* r, ServerAddressList* addresses) { if (GRPC_TRACE_FLAG_ENABLED(grpc_trace_cares_address_sorting)) { log_address_sorting_list(r, *addresses, "input"); } address_sorting_sortable* sortables = static_cast<address_sorting_sortable*>( gpr_zalloc(sizeof(address_sorting_sortable) * addresses->size())); for (size_t i = 0; i < addresses->size(); ++i) { sortables[i].user_data = &(*addresses)[i]; memcpy(&sortables[i].dest_addr.addr, &(*addresses)[i].address().addr, (*addresses)[i].address().len); sortables[i].dest_addr.len = (*addresses)[i].address().len; } address_sorting_rfc_6724_sort(sortables, addresses->size()); ServerAddressList sorted; sorted.reserve(addresses->size()); for (size_t i = 0; i < addresses->size(); ++i) { sorted.emplace_back(*static_cast<ServerAddress*>(sortables[i].user_data)); } gpr_free(sortables); *addresses = std::move(sorted); if (GRPC_TRACE_FLAG_ENABLED(grpc_trace_cares_address_sorting)) { log_address_sorting_list(r, *addresses, "output"); } } static void grpc_ares_request_ref_locked(grpc_ares_request* r) ABSL_EXCLUSIVE_LOCKS_REQUIRED(r->mu) { r->pending_queries++; } static void grpc_ares_request_unref_locked(grpc_ares_request* r) ABSL_EXCLUSIVE_LOCKS_REQUIRED(r->mu) { r->pending_queries--; if (r->pending_queries == 0u) { grpc_ares_ev_driver_on_queries_complete_locked(r->ev_driver); } } void grpc_ares_complete_request_locked(grpc_ares_request* r) ABSL_EXCLUSIVE_LOCKS_REQUIRED(r->mu) { // Invoke on_done callback and destroy the request r->ev_driver = nullptr; if (r->addresses_out != nullptr && *r->addresses_out != nullptr) { grpc_cares_wrapper_address_sorting_sort(r, r->addresses_out->get()); r->error = absl::OkStatus(); // TODO(apolcyn): allow c-ares to return a service config // with no addresses along side it } if (r->balancer_addresses_out != nullptr) { ServerAddressList* balancer_addresses = r->balancer_addresses_out->get(); if (balancer_addresses != nullptr) { grpc_cares_wrapper_address_sorting_sort(r, balancer_addresses); } } grpc_core::ExecCtx::Run(DEBUG_LOCATION, r->on_done, r->error); } // Note that the returned object takes a reference to qtype, so // qtype must outlive it. static grpc_ares_hostbyname_request* create_hostbyname_request_locked( grpc_ares_request* parent_request, const char* host, uint16_t port, bool is_balancer, const char* qtype) ABSL_EXCLUSIVE_LOCKS_REQUIRED(parent_request->mu) { GRPC_CARES_TRACE_LOG( "request:%p create_hostbyname_request_locked host:%s port:%d " "is_balancer:%d qtype:%s", parent_request, host, port, is_balancer, qtype); grpc_ares_hostbyname_request* hr = new grpc_ares_hostbyname_request(); hr->parent_request = parent_request; hr->host = gpr_strdup(host); hr->port = port; hr->is_balancer = is_balancer; hr->qtype = qtype; grpc_ares_request_ref_locked(parent_request); return hr; } static void destroy_hostbyname_request_locked(grpc_ares_hostbyname_request* hr) ABSL_EXCLUSIVE_LOCKS_REQUIRED(hr->parent_request->mu) { grpc_ares_request_unref_locked(hr->parent_request); gpr_free(hr->host); delete hr; } static void on_hostbyname_done_locked(void* arg, int status, int /*timeouts*/, struct hostent* hostent) ABSL_NO_THREAD_SAFETY_ANALYSIS { // This callback is invoked from the c-ares library, so disable thread safety // analysis. Note that we are guaranteed to be holding r->mu, though. grpc_ares_hostbyname_request* hr = static_cast<grpc_ares_hostbyname_request*>(arg); grpc_ares_request* r = hr->parent_request; if (status == ARES_SUCCESS) { GRPC_CARES_TRACE_LOG( "request:%p on_hostbyname_done_locked qtype=%s host=%s ARES_SUCCESS", r, hr->qtype, hr->host); std::unique_ptr<ServerAddressList>* address_list_ptr = hr->is_balancer ? r->balancer_addresses_out : r->addresses_out; if (*address_list_ptr == nullptr) { *address_list_ptr = std::make_unique<ServerAddressList>(); } ServerAddressList& addresses = **address_list_ptr; for (size_t i = 0; hostent->h_addr_list[i] != nullptr; ++i) { grpc_core::ChannelArgs args; if (hr->is_balancer) { args = args.Set(GRPC_ARG_DEFAULT_AUTHORITY, hr->host); } switch (hostent->h_addrtype) { case AF_INET6: { size_t addr_len = sizeof(struct sockaddr_in6); struct sockaddr_in6 addr; memset(&addr, 0, addr_len); memcpy(&addr.sin6_addr, hostent->h_addr_list[i], sizeof(struct in6_addr)); addr.sin6_family = static_cast<unsigned char>(hostent->h_addrtype); addr.sin6_port = hr->port; addresses.emplace_back(&addr, addr_len, args); char output[INET6_ADDRSTRLEN]; ares_inet_ntop(AF_INET6, &addr.sin6_addr, output, INET6_ADDRSTRLEN); GRPC_CARES_TRACE_LOG( "request:%p c-ares resolver gets a AF_INET6 result: \n" " addr: %s\n port: %d\n sin6_scope_id: %d\n", r, output, ntohs(hr->port), addr.sin6_scope_id); break; } case AF_INET: { size_t addr_len = sizeof(struct sockaddr_in); struct sockaddr_in addr; memset(&addr, 0, addr_len); memcpy(&addr.sin_addr, hostent->h_addr_list[i], sizeof(struct in_addr)); addr.sin_family = static_cast<unsigned char>(hostent->h_addrtype); addr.sin_port = hr->port; addresses.emplace_back(&addr, addr_len, args); char output[INET_ADDRSTRLEN]; ares_inet_ntop(AF_INET, &addr.sin_addr, output, INET_ADDRSTRLEN); GRPC_CARES_TRACE_LOG( "request:%p c-ares resolver gets a AF_INET result: \n" " addr: %s\n port: %d\n", r, output, ntohs(hr->port)); break; } } } } else { std::string error_msg = absl::StrFormat( "C-ares status is not ARES_SUCCESS qtype=%s name=%s is_balancer=%d: %s", hr->qtype, hr->host, hr->is_balancer, ares_strerror(status)); GRPC_CARES_TRACE_LOG("request:%p on_hostbyname_done_locked: %s", r, error_msg.c_str()); grpc_error_handle error = GRPC_ERROR_CREATE(error_msg); r->error = grpc_error_add_child(error, r->error); } destroy_hostbyname_request_locked(hr); } static void on_srv_query_done_locked(void* arg, int status, int /*timeouts*/, unsigned char* abuf, int alen) ABSL_NO_THREAD_SAFETY_ANALYSIS { // This callback is invoked from the c-ares library, so disable thread safety // analysis. Note that we are guaranteed to be holding r->mu, though. GrpcAresQuery* q = static_cast<GrpcAresQuery*>(arg); grpc_ares_request* r = q->parent_request(); if (status == ARES_SUCCESS) { GRPC_CARES_TRACE_LOG( "request:%p on_srv_query_done_locked name=%s ARES_SUCCESS", r, q->name().c_str()); struct ares_srv_reply* reply; const int parse_status = ares_parse_srv_reply(abuf, alen, &reply); GRPC_CARES_TRACE_LOG("request:%p ares_parse_srv_reply: %d", r, parse_status); if (parse_status == ARES_SUCCESS) { for (struct ares_srv_reply* srv_it = reply; srv_it != nullptr; srv_it = srv_it->next) { if (grpc_ares_query_ipv6()) { grpc_ares_hostbyname_request* hr = create_hostbyname_request_locked( r, srv_it->host, htons(srv_it->port), true /* is_balancer */, "AAAA"); ares_gethostbyname(r->ev_driver->channel, hr->host, AF_INET6, on_hostbyname_done_locked, hr); } grpc_ares_hostbyname_request* hr = create_hostbyname_request_locked( r, srv_it->host, htons(srv_it->port), true /* is_balancer */, "A"); ares_gethostbyname(r->ev_driver->channel, hr->host, AF_INET, on_hostbyname_done_locked, hr); } } if (reply != nullptr) { ares_free_data(reply); } } else { std::string error_msg = absl::StrFormat( "C-ares status is not ARES_SUCCESS qtype=SRV name=%s: %s", q->name(), ares_strerror(status)); GRPC_CARES_TRACE_LOG("request:%p on_srv_query_done_locked: %s", r, error_msg.c_str()); grpc_error_handle error = GRPC_ERROR_CREATE(error_msg); r->error = grpc_error_add_child(error, r->error); } delete q; } static const char g_service_config_attribute_prefix[] = "grpc_config="; static void on_txt_done_locked(void* arg, int status, int /*timeouts*/, unsigned char* buf, int len) ABSL_NO_THREAD_SAFETY_ANALYSIS { // This callback is invoked from the c-ares library, so disable thread safety // analysis. Note that we are guaranteed to be holding r->mu, though. GrpcAresQuery* q = static_cast<GrpcAresQuery*>(arg); std::unique_ptr<GrpcAresQuery> query_deleter(q); grpc_ares_request* r = q->parent_request(); const size_t prefix_len = sizeof(g_service_config_attribute_prefix) - 1; struct ares_txt_ext* result = nullptr; struct ares_txt_ext* reply = nullptr; grpc_error_handle error; if (status != ARES_SUCCESS) goto fail; GRPC_CARES_TRACE_LOG("request:%p on_txt_done_locked name=%s ARES_SUCCESS", r, q->name().c_str()); status = ares_parse_txt_reply_ext(buf, len, &reply); if (status != ARES_SUCCESS) goto fail; // Find service config in TXT record. for (result = reply; result != nullptr; result = result->next) { if (result->record_start && memcmp(result->txt, g_service_config_attribute_prefix, prefix_len) == 0) { break; } } // Found a service config record. if (result != nullptr) { size_t service_config_len = result->length - prefix_len; *r->service_config_json_out = static_cast<char*>(gpr_malloc(service_config_len + 1)); memcpy(*r->service_config_json_out, result->txt + prefix_len, service_config_len); for (result = result->next; result != nullptr && !result->record_start; result = result->next) { *r->service_config_json_out = static_cast<char*>( gpr_realloc(*r->service_config_json_out, service_config_len + result->length + 1)); memcpy(*r->service_config_json_out + service_config_len, result->txt, result->length); service_config_len += result->length; } (*r->service_config_json_out)[service_config_len] = '\0'; GRPC_CARES_TRACE_LOG("request:%p found service config: %s", r, *r->service_config_json_out); } // Clean up. ares_free_data(reply); grpc_ares_request_unref_locked(r); return; fail: std::string error_msg = absl::StrFormat("C-ares status is not ARES_SUCCESS qtype=TXT name=%s: %s", q->name(), ares_strerror(status)); GRPC_CARES_TRACE_LOG("request:%p on_txt_done_locked %s", r, error_msg.c_str()); error = GRPC_ERROR_CREATE(error_msg); r->error = grpc_error_add_child(error, r->error); } grpc_error_handle set_request_dns_server(grpc_ares_request* r, absl::string_view dns_server) ABSL_EXCLUSIVE_LOCKS_REQUIRED(r->mu) { if (!dns_server.empty()) { GRPC_CARES_TRACE_LOG("request:%p Using DNS server %s", r, dns_server.data()); grpc_resolved_address addr; if (grpc_parse_ipv4_hostport(dns_server, &addr, /*log_errors=*/false)) { r->dns_server_addr.family = AF_INET; struct sockaddr_in* in = reinterpret_cast<struct sockaddr_in*>(addr.addr); memcpy(&r->dns_server_addr.addr.addr4, &in->sin_addr, sizeof(struct in_addr)); r->dns_server_addr.tcp_port = grpc_sockaddr_get_port(&addr); r->dns_server_addr.udp_port = grpc_sockaddr_get_port(&addr); } else if (grpc_parse_ipv6_hostport(dns_server, &addr, /*log_errors=*/false)) { r->dns_server_addr.family = AF_INET6; struct sockaddr_in6* in6 = reinterpret_cast<struct sockaddr_in6*>(addr.addr); memcpy(&r->dns_server_addr.addr.addr6, &in6->sin6_addr, sizeof(struct in6_addr)); r->dns_server_addr.tcp_port = grpc_sockaddr_get_port(&addr); r->dns_server_addr.udp_port = grpc_sockaddr_get_port(&addr); } else { return GRPC_ERROR_CREATE( absl::StrCat("cannot parse authority ", dns_server)); } int status = ares_set_servers_ports(r->ev_driver->channel, &r->dns_server_addr); if (status != ARES_SUCCESS) { return GRPC_ERROR_CREATE(absl::StrCat( "C-ares status is not ARES_SUCCESS: ", ares_strerror(status))); } } return absl::OkStatus(); } // Common logic for all lookup methods. // If an error occurs, callers must run the client callback. grpc_error_handle grpc_dns_lookup_ares_continued( grpc_ares_request* r, const char* dns_server, const char* name, const char* default_port, grpc_pollset_set* interested_parties, int query_timeout_ms, std::string* host, std::string* port, bool check_port) ABSL_EXCLUSIVE_LOCKS_REQUIRED(r->mu) { grpc_error_handle error; // parse name, splitting it into host and port parts grpc_core::SplitHostPort(name, host, port); if (host->empty()) { error = grpc_error_set_str(GRPC_ERROR_CREATE("unparseable host:port"), grpc_core::StatusStrProperty::kTargetAddress, name); return error; } else if (check_port && port->empty()) { if (default_port == nullptr || strlen(default_port) == 0) { error = grpc_error_set_str(GRPC_ERROR_CREATE("no port in name"), grpc_core::StatusStrProperty::kTargetAddress, name); return error; } *port = default_port; } error = grpc_ares_ev_driver_create_locked(&r->ev_driver, interested_parties, query_timeout_ms, r); if (!error.ok()) return error; // If dns_server is specified, use it. error = set_request_dns_server(r, dns_server); return error; } static bool inner_resolve_as_ip_literal_locked( const char* name, const char* default_port, std::unique_ptr<grpc_core::ServerAddressList>* addrs, std::string* host, std::string* port, std::string* hostport) { if (!grpc_core::SplitHostPort(name, host, port)) { gpr_log(GPR_ERROR, "Failed to parse %s to host:port while attempting to resolve as ip " "literal.", name); return false; } if (port->empty()) { if (default_port == nullptr || strlen(default_port) == 0) { gpr_log(GPR_ERROR, "No port or default port for %s while attempting to resolve as " "ip literal.", name); return false; } *port = default_port; } grpc_resolved_address addr; *hostport = grpc_core::JoinHostPort(*host, atoi(port->c_str())); if (grpc_parse_ipv4_hostport(hostport->c_str(), &addr, false /* log errors */) || grpc_parse_ipv6_hostport(hostport->c_str(), &addr, false /* log errors */)) { GPR_ASSERT(*addrs == nullptr); *addrs = std::make_unique<ServerAddressList>(); (*addrs)->emplace_back(addr.addr, addr.len, grpc_core::ChannelArgs()); return true; } return false; } static bool resolve_as_ip_literal_locked( const char* name, const char* default_port, std::unique_ptr<grpc_core::ServerAddressList>* addrs) { std::string host; std::string port; std::string hostport; bool out = inner_resolve_as_ip_literal_locked(name, default_port, addrs, &host, &port, &hostport); return out; } static bool target_matches_localhost_inner(const char* name, std::string* host, std::string* port) { if (!grpc_core::SplitHostPort(name, host, port)) { gpr_log(GPR_ERROR, "Unable to split host and port for name: %s", name); return false; } return gpr_stricmp(host->c_str(), "localhost") == 0; } static bool target_matches_localhost(const char* name) { std::string host; std::string port; return target_matches_localhost_inner(name, &host, &port); } #ifdef GRPC_ARES_RESOLVE_LOCALHOST_MANUALLY static bool inner_maybe_resolve_localhost_manually_locked( const grpc_ares_request* r, const char* name, const char* default_port, std::unique_ptr<grpc_core::ServerAddressList>* addrs, std::string* host, std::string* port) { grpc_core::SplitHostPort(name, host, port); if (host->empty()) { gpr_log(GPR_ERROR, "Failed to parse %s into host:port during manual localhost " "resolution check.", name); return false; } if (port->empty()) { if (default_port == nullptr || strlen(default_port) == 0) { gpr_log(GPR_ERROR, "No port or default port for %s during manual localhost " "resolution check.", name); return false; } *port = default_port; } if (gpr_stricmp(host->c_str(), "localhost") == 0) { GPR_ASSERT(*addrs == nullptr); *addrs = std::make_unique<grpc_core::ServerAddressList>(); uint16_t numeric_port = grpc_strhtons(port->c_str()); // Append the ipv6 loopback address. struct sockaddr_in6 ipv6_loopback_addr; memset(&ipv6_loopback_addr, 0, sizeof(ipv6_loopback_addr)); ((char*)&ipv6_loopback_addr.sin6_addr)[15] = 1; ipv6_loopback_addr.sin6_family = AF_INET6; ipv6_loopback_addr.sin6_port = numeric_port; (*addrs)->emplace_back(&ipv6_loopback_addr, sizeof(ipv6_loopback_addr), grpc_core::ChannelArgs() /* args */); // Append the ipv4 loopback address. struct sockaddr_in ipv4_loopback_addr; memset(&ipv4_loopback_addr, 0, sizeof(ipv4_loopback_addr)); ((char*)&ipv4_loopback_addr.sin_addr)[0] = 0x7f; ((char*)&ipv4_loopback_addr.sin_addr)[3] = 0x01; ipv4_loopback_addr.sin_family = AF_INET; ipv4_loopback_addr.sin_port = numeric_port; (*addrs)->emplace_back(&ipv4_loopback_addr, sizeof(ipv4_loopback_addr), grpc_core::ChannelArgs() /* args */); // Let the address sorter figure out which one should be tried first. grpc_cares_wrapper_address_sorting_sort(r, addrs->get()); return true; } return false; } static bool grpc_ares_maybe_resolve_localhost_manually_locked( const grpc_ares_request* r, const char* name, const char* default_port, std::unique_ptr<grpc_core::ServerAddressList>* addrs) { std::string host; std::string port; return inner_maybe_resolve_localhost_manually_locked(r, name, default_port, addrs, &host, &port); } #else // GRPC_ARES_RESOLVE_LOCALHOST_MANUALLY static bool grpc_ares_maybe_resolve_localhost_manually_locked( const grpc_ares_request* /*r*/, const char* /*name*/, const char* /*default_port*/, std::unique_ptr<grpc_core::ServerAddressList>* /*addrs*/) { return false; } #endif // GRPC_ARES_RESOLVE_LOCALHOST_MANUALLY static grpc_ares_request* grpc_dns_lookup_hostname_ares_impl( const char* dns_server, const char* name, const char* default_port, grpc_pollset_set* interested_parties, grpc_closure* on_done, std::unique_ptr<grpc_core::ServerAddressList>* addrs, int query_timeout_ms) { grpc_ares_request* r = new grpc_ares_request(); grpc_core::MutexLock lock(&r->mu); r->ev_driver = nullptr; r->on_done = on_done; r->addresses_out = addrs; GRPC_CARES_TRACE_LOG( "request:%p c-ares grpc_dns_lookup_hostname_ares_impl name=%s, " "default_port=%s", r, name, default_port); // Early out if the target is an ipv4 or ipv6 literal. if (resolve_as_ip_literal_locked(name, default_port, addrs)) { grpc_ares_complete_request_locked(r); return r; } // Early out if the target is localhost and we're on Windows. if (grpc_ares_maybe_resolve_localhost_manually_locked(r, name, default_port, addrs)) { grpc_ares_complete_request_locked(r); return r; } // Look up name using c-ares lib. std::string host; std::string port; grpc_error_handle error = grpc_dns_lookup_ares_continued( r, dns_server, name, default_port, interested_parties, query_timeout_ms, &host, &port, true); if (!error.ok()) { grpc_core::ExecCtx::Run(DEBUG_LOCATION, r->on_done, error); return r; } r->pending_queries = 1; grpc_ares_hostbyname_request* hr = nullptr; if (grpc_ares_query_ipv6()) { hr = create_hostbyname_request_locked(r, host.c_str(), grpc_strhtons(port.c_str()), /*is_balancer=*/false, "AAAA"); ares_gethostbyname(r->ev_driver->channel, hr->host, AF_INET6, on_hostbyname_done_locked, hr); } hr = create_hostbyname_request_locked(r, host.c_str(), grpc_strhtons(port.c_str()), /*is_balancer=*/false, "A"); ares_gethostbyname(r->ev_driver->channel, hr->host, AF_INET, on_hostbyname_done_locked, hr); grpc_ares_ev_driver_start_locked(r->ev_driver); grpc_ares_request_unref_locked(r); return r; } grpc_ares_request* grpc_dns_lookup_srv_ares_impl( const char* dns_server, const char* name, grpc_pollset_set* interested_parties, grpc_closure* on_done, std::unique_ptr<grpc_core::ServerAddressList>* balancer_addresses, int query_timeout_ms) { grpc_ares_request* r = new grpc_ares_request(); grpc_core::MutexLock lock(&r->mu); r->ev_driver = nullptr; r->on_done = on_done; r->balancer_addresses_out = balancer_addresses; GRPC_CARES_TRACE_LOG( "request:%p c-ares grpc_dns_lookup_srv_ares_impl name=%s", r, name); grpc_error_handle error; // Don't query for SRV records if the target is "localhost" if (target_matches_localhost(name)) { grpc_core::ExecCtx::Run(DEBUG_LOCATION, r->on_done, error); return r; } // Look up name using c-ares lib. std::string host; std::string port; error = grpc_dns_lookup_ares_continued(r, dns_server, name, nullptr, interested_parties, query_timeout_ms, &host, &port, false); if (!error.ok()) { grpc_core::ExecCtx::Run(DEBUG_LOCATION, r->on_done, error); return r; } r->pending_queries = 1; // Query the SRV record std::string service_name = absl::StrCat("_grpclb._tcp.", host); GrpcAresQuery* srv_query = new GrpcAresQuery(r, service_name); ares_query(r->ev_driver->channel, service_name.c_str(), ns_c_in, ns_t_srv, on_srv_query_done_locked, srv_query); grpc_ares_ev_driver_start_locked(r->ev_driver); grpc_ares_request_unref_locked(r); return r; } grpc_ares_request* grpc_dns_lookup_txt_ares_impl( const char* dns_server, const char* name, grpc_pollset_set* interested_parties, grpc_closure* on_done, char** service_config_json, int query_timeout_ms) { grpc_ares_request* r = new grpc_ares_request(); grpc_core::MutexLock lock(&r->mu); r->ev_driver = nullptr; r->on_done = on_done; r->service_config_json_out = service_config_json; GRPC_CARES_TRACE_LOG( "request:%p c-ares grpc_dns_lookup_txt_ares_impl name=%s", r, name); grpc_error_handle error; // Don't query for TXT records if the target is "localhost" if (target_matches_localhost(name)) { grpc_core::ExecCtx::Run(DEBUG_LOCATION, r->on_done, error); return r; } // Look up name using c-ares lib. std::string host; std::string port; error = grpc_dns_lookup_ares_continued(r, dns_server, name, nullptr, interested_parties, query_timeout_ms, &host, &port, false); if (!error.ok()) { grpc_core::ExecCtx::Run(DEBUG_LOCATION, r->on_done, error); return r; } r->pending_queries = 1; // Query the TXT record std::string config_name = absl::StrCat("_grpc_config.", host); GrpcAresQuery* txt_query = new GrpcAresQuery(r, config_name); ares_search(r->ev_driver->channel, config_name.c_str(), ns_c_in, ns_t_txt, on_txt_done_locked, txt_query); grpc_ares_ev_driver_start_locked(r->ev_driver); grpc_ares_request_unref_locked(r); return r; } grpc_ares_request* (*grpc_dns_lookup_hostname_ares)( const char* dns_server, const char* name, const char* default_port, grpc_pollset_set* interested_parties, grpc_closure* on_done, std::unique_ptr<grpc_core::ServerAddressList>* addrs, int query_timeout_ms) = grpc_dns_lookup_hostname_ares_impl; grpc_ares_request* (*grpc_dns_lookup_srv_ares)( const char* dns_server, const char* name, grpc_pollset_set* interested_parties, grpc_closure* on_done, std::unique_ptr<grpc_core::ServerAddressList>* balancer_addresses, int query_timeout_ms) = grpc_dns_lookup_srv_ares_impl; grpc_ares_request* (*grpc_dns_lookup_txt_ares)( const char* dns_server, const char* name, grpc_pollset_set* interested_parties, grpc_closure* on_done, char** service_config_json, int query_timeout_ms) = grpc_dns_lookup_txt_ares_impl; static void grpc_cancel_ares_request_impl(grpc_ares_request* r) { GPR_ASSERT(r != nullptr); grpc_core::MutexLock lock(&r->mu); GRPC_CARES_TRACE_LOG("request:%p grpc_cancel_ares_request ev_driver:%p", r, r->ev_driver); if (r->ev_driver != nullptr) { grpc_ares_ev_driver_shutdown_locked(r->ev_driver); } } void (*grpc_cancel_ares_request)(grpc_ares_request* r) = grpc_cancel_ares_request_impl; // ares_library_init and ares_library_cleanup are currently no-op except under // Windows. Calling them may cause race conditions when other parts of the // binary calls these functions concurrently. #ifdef GPR_WINDOWS grpc_error_handle grpc_ares_init(void) { int status = ares_library_init(ARES_LIB_INIT_ALL); if (status != ARES_SUCCESS) { return GRPC_ERROR_CREATE( absl::StrCat("ares_library_init failed: ", ares_strerror(status))); } return absl::OkStatus(); } void grpc_ares_cleanup(void) { ares_library_cleanup(); } #else grpc_error_handle grpc_ares_init(void) { return absl::OkStatus(); } void grpc_ares_cleanup(void) {} #endif // GPR_WINDOWS #endif // GRPC_ARES == 1
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