--- /dev/null
+/*
+ *
+ * Copyright 2015 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 <inttypes.h>
+#include <climits>
+#include <cstring>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/time.h>
+
+#include "src/core/ext/filters/client_channel/resolver/dns/dns_resolver_selection.h"
+#include "src/core/ext/filters/client_channel/resolver_registry.h"
+#include "src/core/ext/filters/client_channel/server_address.h"
+#include "src/core/lib/backoff/backoff.h"
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gprpp/manual_constructor.h"
+#include "src/core/lib/iomgr/combiner.h"
+#include "src/core/lib/iomgr/resolve_address.h"
+#include "src/core/lib/iomgr/timer.h"
+
+#define GRPC_DNS_INITIAL_CONNECT_BACKOFF_SECONDS 1
+#define GRPC_DNS_RECONNECT_BACKOFF_MULTIPLIER 1.6
+#define GRPC_DNS_RECONNECT_MAX_BACKOFF_SECONDS 120
+#define GRPC_DNS_RECONNECT_JITTER 0.2
+
+namespace grpc_core {
+
+namespace {
+
+const char kDefaultPort[] = "https";
+
+class NativeDnsResolver : public Resolver {
+ public:
+ explicit NativeDnsResolver(ResolverArgs args);
+
+ void StartLocked() override;
+
+ void RequestReresolutionLocked() override;
+
+ void ResetBackoffLocked() override;
+
+ void ShutdownLocked() override;
+
+ private:
+ virtual ~NativeDnsResolver();
+
+ void MaybeStartResolvingLocked();
+ void StartResolvingLocked();
+
+ static void OnNextResolutionLocked(void* arg, grpc_error* error);
+ static void OnResolvedLocked(void* arg, grpc_error* error);
+
+ /// name to resolve
+ char* name_to_resolve_ = nullptr;
+ /// channel args
+ grpc_channel_args* channel_args_ = nullptr;
+ /// pollset_set to drive the name resolution process
+ grpc_pollset_set* interested_parties_ = nullptr;
+ /// are we shutting down?
+ bool shutdown_ = false;
+ /// are we currently resolving?
+ bool resolving_ = false;
+ grpc_closure on_resolved_;
+ /// next resolution timer
+ bool have_next_resolution_timer_ = false;
+ grpc_timer next_resolution_timer_;
+ grpc_closure on_next_resolution_;
+ /// min time between DNS requests
+ grpc_millis min_time_between_resolutions_;
+ /// timestamp of last DNS request
+ grpc_millis last_resolution_timestamp_ = -1;
+ /// retry backoff state
+ BackOff backoff_;
+ /// currently resolving addresses
+ grpc_resolved_addresses* addresses_ = nullptr;
+};
+
+NativeDnsResolver::NativeDnsResolver(ResolverArgs args)
+ : Resolver(args.combiner, std::move(args.result_handler)),
+ backoff_(
+ BackOff::Options()
+ .set_initial_backoff(GRPC_DNS_INITIAL_CONNECT_BACKOFF_SECONDS *
+ 1000)
+ .set_multiplier(GRPC_DNS_RECONNECT_BACKOFF_MULTIPLIER)
+ .set_jitter(GRPC_DNS_RECONNECT_JITTER)
+ .set_max_backoff(GRPC_DNS_RECONNECT_MAX_BACKOFF_SECONDS * 1000)) {
+ char* path = args.uri->path;
+ if (path[0] == '/') ++path;
+ name_to_resolve_ = gpr_strdup(path);
+ channel_args_ = grpc_channel_args_copy(args.args);
+ const grpc_arg* arg = grpc_channel_args_find(
+ args.args, GRPC_ARG_DNS_MIN_TIME_BETWEEN_RESOLUTIONS_MS);
+ min_time_between_resolutions_ =
+ grpc_channel_arg_get_integer(arg, {1000 * 30, 0, INT_MAX});
+ interested_parties_ = grpc_pollset_set_create();
+ if (args.pollset_set != nullptr) {
+ grpc_pollset_set_add_pollset_set(interested_parties_, args.pollset_set);
+ }
+ GRPC_CLOSURE_INIT(&on_next_resolution_,
+ NativeDnsResolver::OnNextResolutionLocked, this,
+ grpc_combiner_scheduler(args.combiner));
+ GRPC_CLOSURE_INIT(&on_resolved_, NativeDnsResolver::OnResolvedLocked, this,
+ grpc_combiner_scheduler(args.combiner));
+}
+
+NativeDnsResolver::~NativeDnsResolver() {
+ grpc_channel_args_destroy(channel_args_);
+ grpc_pollset_set_destroy(interested_parties_);
+ gpr_free(name_to_resolve_);
+}
+
+void NativeDnsResolver::StartLocked() { MaybeStartResolvingLocked(); }
+
+void NativeDnsResolver::RequestReresolutionLocked() {
+ if (!resolving_) {
+ MaybeStartResolvingLocked();
+ }
+}
+
+void NativeDnsResolver::ResetBackoffLocked() {
+ if (have_next_resolution_timer_) {
+ grpc_timer_cancel(&next_resolution_timer_);
+ }
+ backoff_.Reset();
+}
+
+void NativeDnsResolver::ShutdownLocked() {
+ shutdown_ = true;
+ if (have_next_resolution_timer_) {
+ grpc_timer_cancel(&next_resolution_timer_);
+ }
+}
+
+void NativeDnsResolver::OnNextResolutionLocked(void* arg, grpc_error* error) {
+ NativeDnsResolver* r = static_cast<NativeDnsResolver*>(arg);
+ r->have_next_resolution_timer_ = false;
+ if (error == GRPC_ERROR_NONE && !r->resolving_) {
+ r->StartResolvingLocked();
+ }
+ r->Unref(DEBUG_LOCATION, "retry-timer");
+}
+
+void NativeDnsResolver::OnResolvedLocked(void* arg, grpc_error* error) {
+ NativeDnsResolver* r = static_cast<NativeDnsResolver*>(arg);
+ GPR_ASSERT(r->resolving_);
+ r->resolving_ = false;
+ if (r->shutdown_) {
+ r->Unref(DEBUG_LOCATION, "dns-resolving");
+ return;
+ }
+ if (r->addresses_ != nullptr) {
+ Result result;
+ for (size_t i = 0; i < r->addresses_->naddrs; ++i) {
+ result.addresses.emplace_back(&r->addresses_->addrs[i].addr,
+ r->addresses_->addrs[i].len,
+ nullptr /* args */);
+ }
+ grpc_resolved_addresses_destroy(r->addresses_);
+ result.args = grpc_channel_args_copy(r->channel_args_);
+ r->result_handler()->ReturnResult(std::move(result));
+ // Reset backoff state so that we start from the beginning when the
+ // next request gets triggered.
+ r->backoff_.Reset();
+ } else {
+ gpr_log(GPR_INFO, "dns resolution failed (will retry): %s",
+ grpc_error_string(error));
+ // Return transient error.
+ r->result_handler()->ReturnError(grpc_error_set_int(
+ GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
+ "DNS resolution failed", &error, 1),
+ GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAVAILABLE));
+ // Set up for retry.
+ grpc_millis next_try = r->backoff_.NextAttemptTime();
+ grpc_millis timeout = next_try - ExecCtx::Get()->Now();
+ GPR_ASSERT(!r->have_next_resolution_timer_);
+ r->have_next_resolution_timer_ = true;
+ // TODO(roth): We currently deal with this ref manually. Once the
+ // new closure API is done, find a way to track this ref with the timer
+ // callback as part of the type system.
+ r->Ref(DEBUG_LOCATION, "next_resolution_timer").release();
+ if (timeout > 0) {
+ gpr_log(GPR_DEBUG, "retrying in %" PRId64 " milliseconds", timeout);
+ } else {
+ gpr_log(GPR_DEBUG, "retrying immediately");
+ }
+ grpc_timer_init(&r->next_resolution_timer_, next_try,
+ &r->on_next_resolution_);
+ }
+ r->Unref(DEBUG_LOCATION, "dns-resolving");
+}
+
+void NativeDnsResolver::MaybeStartResolvingLocked() {
+ // If there is an existing timer, the time it fires is the earliest time we
+ // can start the next resolution.
+ if (have_next_resolution_timer_) return;
+ if (last_resolution_timestamp_ >= 0) {
+ const grpc_millis earliest_next_resolution =
+ last_resolution_timestamp_ + min_time_between_resolutions_;
+ const grpc_millis ms_until_next_resolution =
+ earliest_next_resolution - grpc_core::ExecCtx::Get()->Now();
+ if (ms_until_next_resolution > 0) {
+ const grpc_millis last_resolution_ago =
+ grpc_core::ExecCtx::Get()->Now() - last_resolution_timestamp_;
+ gpr_log(GPR_DEBUG,
+ "In cooldown from last resolution (from %" PRId64
+ " ms ago). Will resolve again in %" PRId64 " ms",
+ last_resolution_ago, ms_until_next_resolution);
+ have_next_resolution_timer_ = true;
+ // TODO(roth): We currently deal with this ref manually. Once the
+ // new closure API is done, find a way to track this ref with the timer
+ // callback as part of the type system.
+ Ref(DEBUG_LOCATION, "next_resolution_timer_cooldown").release();
+ grpc_timer_init(&next_resolution_timer_,
+ ExecCtx::Get()->Now() + ms_until_next_resolution,
+ &on_next_resolution_);
+ return;
+ }
+ }
+ StartResolvingLocked();
+}
+
+void NativeDnsResolver::StartResolvingLocked() {
+ gpr_log(GPR_DEBUG, "Start resolving.");
+ // TODO(roth): We currently deal with this ref manually. Once the
+ // new closure API is done, find a way to track this ref with the timer
+ // callback as part of the type system.
+ Ref(DEBUG_LOCATION, "dns-resolving").release();
+ GPR_ASSERT(!resolving_);
+ resolving_ = true;
+ addresses_ = nullptr;
+ grpc_resolve_address(name_to_resolve_, kDefaultPort, interested_parties_,
+ &on_resolved_, &addresses_);
+ last_resolution_timestamp_ = grpc_core::ExecCtx::Get()->Now();
+}
+
+//
+// Factory
+//
+
+class NativeDnsResolverFactory : public ResolverFactory {
+ public:
+ bool IsValidUri(const grpc_uri* uri) const override {
+ if (GPR_UNLIKELY(0 != strcmp(uri->authority, ""))) {
+ gpr_log(GPR_ERROR, "authority based dns uri's not supported");
+ return false;
+ }
+ return true;
+ }
+
+ OrphanablePtr<Resolver> CreateResolver(ResolverArgs args) const override {
+ if (!IsValidUri(args.uri)) return nullptr;
+ return OrphanablePtr<Resolver>(New<NativeDnsResolver>(std::move(args)));
+ }
+
+ const char* scheme() const override { return "dns"; }
+};
+
+} // namespace
+
+} // namespace grpc_core
+
+void grpc_resolver_dns_native_init() {
+ grpc_core::UniquePtr<char> resolver =
+ GPR_GLOBAL_CONFIG_GET(grpc_dns_resolver);
+ if (gpr_stricmp(resolver.get(), "native") == 0) {
+ gpr_log(GPR_DEBUG, "Using native dns resolver");
+ grpc_core::ResolverRegistry::Builder::RegisterResolverFactory(
+ grpc_core::UniquePtr<grpc_core::ResolverFactory>(
+ grpc_core::New<grpc_core::NativeDnsResolverFactory>()));
+ } else {
+ grpc_core::ResolverRegistry::Builder::InitRegistry();
+ grpc_core::ResolverFactory* existing_factory =
+ grpc_core::ResolverRegistry::LookupResolverFactory("dns");
+ if (existing_factory == nullptr) {
+ gpr_log(GPR_DEBUG, "Using native dns resolver");
+ grpc_core::ResolverRegistry::Builder::RegisterResolverFactory(
+ grpc_core::UniquePtr<grpc_core::ResolverFactory>(
+ grpc_core::New<grpc_core::NativeDnsResolverFactory>()));
+ }
+ }
+}
+
+void grpc_resolver_dns_native_shutdown() {}
git://repos.xcallymotion.com / motion2.git / blobdiff