| /* |
| * |
| * 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 <string.h> |
| |
| #include <grpc/support/alloc.h> |
| #include <grpc/support/host_port.h> |
| #include <grpc/support/string_util.h> |
| |
| #include "src/core/ext/filters/client_channel/lb_policy_registry.h" |
| #include "src/core/ext/filters/client_channel/resolver_registry.h" |
| #include "src/core/lib/backoff/backoff.h" |
| #include "src/core/lib/channel/channel_args.h" |
| #include "src/core/lib/iomgr/combiner.h" |
| #include "src/core/lib/iomgr/resolve_address.h" |
| #include "src/core/lib/iomgr/timer.h" |
| #include "src/core/lib/support/env.h" |
| #include "src/core/lib/support/string.h" |
| |
| #define GRPC_DNS_MIN_CONNECT_TIMEOUT_SECONDS 1 |
| #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 |
| |
| typedef struct { |
| /** base class: must be first */ |
| grpc_resolver base; |
| /** name to resolve */ |
| char* name_to_resolve; |
| /** default port to use */ |
| char* default_port; |
| /** channel args. */ |
| grpc_channel_args* channel_args; |
| /** pollset_set to drive the name resolution process */ |
| grpc_pollset_set* interested_parties; |
| |
| /** are we currently resolving? */ |
| bool resolving; |
| /** which version of the result have we published? */ |
| int published_version; |
| /** which version of the result is current? */ |
| int resolved_version; |
| /** pending next completion, or NULL */ |
| grpc_closure* next_completion; |
| /** target result address for next completion */ |
| grpc_channel_args** target_result; |
| /** current (fully resolved) result */ |
| grpc_channel_args* resolved_result; |
| /** retry timer */ |
| bool have_retry_timer; |
| grpc_timer retry_timer; |
| grpc_closure on_retry; |
| /** retry backoff state */ |
| grpc_backoff backoff_state; |
| |
| /** currently resolving addresses */ |
| grpc_resolved_addresses* addresses; |
| } dns_resolver; |
| |
| static void dns_destroy(grpc_exec_ctx* exec_ctx, grpc_resolver* r); |
| |
| static void dns_start_resolving_locked(grpc_exec_ctx* exec_ctx, |
| dns_resolver* r); |
| static void dns_maybe_finish_next_locked(grpc_exec_ctx* exec_ctx, |
| dns_resolver* r); |
| |
| static void dns_shutdown_locked(grpc_exec_ctx* exec_ctx, grpc_resolver* r); |
| static void dns_channel_saw_error_locked(grpc_exec_ctx* exec_ctx, |
| grpc_resolver* r); |
| static void dns_next_locked(grpc_exec_ctx* exec_ctx, grpc_resolver* r, |
| grpc_channel_args** target_result, |
| grpc_closure* on_complete); |
| |
| static const grpc_resolver_vtable dns_resolver_vtable = { |
| dns_destroy, dns_shutdown_locked, dns_channel_saw_error_locked, |
| dns_next_locked}; |
| |
| static void dns_shutdown_locked(grpc_exec_ctx* exec_ctx, |
| grpc_resolver* resolver) { |
| dns_resolver* r = (dns_resolver*)resolver; |
| if (r->have_retry_timer) { |
| grpc_timer_cancel(exec_ctx, &r->retry_timer); |
| } |
| if (r->next_completion != nullptr) { |
| *r->target_result = nullptr; |
| GRPC_CLOSURE_SCHED( |
| exec_ctx, r->next_completion, |
| GRPC_ERROR_CREATE_FROM_STATIC_STRING("Resolver Shutdown")); |
| r->next_completion = nullptr; |
| } |
| } |
| |
| static void dns_channel_saw_error_locked(grpc_exec_ctx* exec_ctx, |
| grpc_resolver* resolver) { |
| dns_resolver* r = (dns_resolver*)resolver; |
| if (!r->resolving) { |
| grpc_backoff_reset(&r->backoff_state); |
| dns_start_resolving_locked(exec_ctx, r); |
| } |
| } |
| |
| static void dns_next_locked(grpc_exec_ctx* exec_ctx, grpc_resolver* resolver, |
| grpc_channel_args** target_result, |
| grpc_closure* on_complete) { |
| dns_resolver* r = (dns_resolver*)resolver; |
| GPR_ASSERT(!r->next_completion); |
| r->next_completion = on_complete; |
| r->target_result = target_result; |
| if (r->resolved_version == 0 && !r->resolving) { |
| grpc_backoff_reset(&r->backoff_state); |
| dns_start_resolving_locked(exec_ctx, r); |
| } else { |
| dns_maybe_finish_next_locked(exec_ctx, r); |
| } |
| } |
| |
| static void dns_on_retry_timer_locked(grpc_exec_ctx* exec_ctx, void* arg, |
| grpc_error* error) { |
| dns_resolver* r = (dns_resolver*)arg; |
| |
| r->have_retry_timer = false; |
| if (error == GRPC_ERROR_NONE) { |
| if (!r->resolving) { |
| dns_start_resolving_locked(exec_ctx, r); |
| } |
| } |
| |
| GRPC_RESOLVER_UNREF(exec_ctx, &r->base, "retry-timer"); |
| } |
| |
| static void dns_on_resolved_locked(grpc_exec_ctx* exec_ctx, void* arg, |
| grpc_error* error) { |
| dns_resolver* r = (dns_resolver*)arg; |
| grpc_channel_args* result = nullptr; |
| GPR_ASSERT(r->resolving); |
| r->resolving = false; |
| GRPC_ERROR_REF(error); |
| error = grpc_error_set_str(error, GRPC_ERROR_STR_TARGET_ADDRESS, |
| grpc_slice_from_copied_string(r->name_to_resolve)); |
| if (r->addresses != nullptr) { |
| grpc_lb_addresses* addresses = grpc_lb_addresses_create( |
| r->addresses->naddrs, nullptr /* user_data_vtable */); |
| for (size_t i = 0; i < r->addresses->naddrs; ++i) { |
| grpc_lb_addresses_set_address( |
| addresses, i, &r->addresses->addrs[i].addr, |
| r->addresses->addrs[i].len, false /* is_balancer */, |
| nullptr /* balancer_name */, nullptr /* user_data */); |
| } |
| grpc_arg new_arg = grpc_lb_addresses_create_channel_arg(addresses); |
| result = grpc_channel_args_copy_and_add(r->channel_args, &new_arg, 1); |
| grpc_resolved_addresses_destroy(r->addresses); |
| grpc_lb_addresses_destroy(exec_ctx, addresses); |
| } else { |
| grpc_millis next_try = |
| grpc_backoff_step(exec_ctx, &r->backoff_state).next_attempt_start_time; |
| grpc_millis timeout = next_try - grpc_exec_ctx_now(exec_ctx); |
| gpr_log(GPR_INFO, "dns resolution failed (will retry): %s", |
| grpc_error_string(error)); |
| GPR_ASSERT(!r->have_retry_timer); |
| r->have_retry_timer = true; |
| GRPC_RESOLVER_REF(&r->base, "retry-timer"); |
| if (timeout > 0) { |
| gpr_log(GPR_DEBUG, "retrying in %" PRIdPTR " milliseconds", timeout); |
| } else { |
| gpr_log(GPR_DEBUG, "retrying immediately"); |
| } |
| GRPC_CLOSURE_INIT(&r->on_retry, dns_on_retry_timer_locked, r, |
| grpc_combiner_scheduler(r->base.combiner)); |
| grpc_timer_init(exec_ctx, &r->retry_timer, next_try, &r->on_retry); |
| } |
| if (r->resolved_result != nullptr) { |
| grpc_channel_args_destroy(exec_ctx, r->resolved_result); |
| } |
| r->resolved_result = result; |
| r->resolved_version++; |
| dns_maybe_finish_next_locked(exec_ctx, r); |
| GRPC_ERROR_UNREF(error); |
| |
| GRPC_RESOLVER_UNREF(exec_ctx, &r->base, "dns-resolving"); |
| } |
| |
| static void dns_start_resolving_locked(grpc_exec_ctx* exec_ctx, |
| dns_resolver* r) { |
| GRPC_RESOLVER_REF(&r->base, "dns-resolving"); |
| GPR_ASSERT(!r->resolving); |
| r->resolving = true; |
| r->addresses = nullptr; |
| grpc_resolve_address( |
| exec_ctx, r->name_to_resolve, r->default_port, r->interested_parties, |
| GRPC_CLOSURE_CREATE(dns_on_resolved_locked, r, |
| grpc_combiner_scheduler(r->base.combiner)), |
| &r->addresses); |
| } |
| |
| static void dns_maybe_finish_next_locked(grpc_exec_ctx* exec_ctx, |
| dns_resolver* r) { |
| if (r->next_completion != nullptr && |
| r->resolved_version != r->published_version) { |
| *r->target_result = r->resolved_result == nullptr |
| ? nullptr |
| : grpc_channel_args_copy(r->resolved_result); |
| GRPC_CLOSURE_SCHED(exec_ctx, r->next_completion, GRPC_ERROR_NONE); |
| r->next_completion = nullptr; |
| r->published_version = r->resolved_version; |
| } |
| } |
| |
| static void dns_destroy(grpc_exec_ctx* exec_ctx, grpc_resolver* gr) { |
| dns_resolver* r = (dns_resolver*)gr; |
| if (r->resolved_result != nullptr) { |
| grpc_channel_args_destroy(exec_ctx, r->resolved_result); |
| } |
| grpc_pollset_set_destroy(exec_ctx, r->interested_parties); |
| gpr_free(r->name_to_resolve); |
| gpr_free(r->default_port); |
| grpc_channel_args_destroy(exec_ctx, r->channel_args); |
| gpr_free(r); |
| } |
| |
| static grpc_resolver* dns_create(grpc_exec_ctx* exec_ctx, |
| grpc_resolver_args* args, |
| const char* default_port) { |
| if (0 != strcmp(args->uri->authority, "")) { |
| gpr_log(GPR_ERROR, "authority based dns uri's not supported"); |
| return nullptr; |
| } |
| // Get name from args. |
| char* path = args->uri->path; |
| if (path[0] == '/') ++path; |
| // Create resolver. |
| dns_resolver* r = (dns_resolver*)gpr_zalloc(sizeof(dns_resolver)); |
| grpc_resolver_init(&r->base, &dns_resolver_vtable, args->combiner); |
| r->name_to_resolve = gpr_strdup(path); |
| r->default_port = gpr_strdup(default_port); |
| r->channel_args = grpc_channel_args_copy(args->args); |
| r->interested_parties = grpc_pollset_set_create(); |
| if (args->pollset_set != nullptr) { |
| grpc_pollset_set_add_pollset_set(exec_ctx, r->interested_parties, |
| args->pollset_set); |
| } |
| grpc_backoff_init( |
| &r->backoff_state, GRPC_DNS_INITIAL_CONNECT_BACKOFF_SECONDS * 1000, |
| GRPC_DNS_RECONNECT_BACKOFF_MULTIPLIER, GRPC_DNS_RECONNECT_JITTER, |
| GRPC_DNS_MIN_CONNECT_TIMEOUT_SECONDS * 1000, |
| GRPC_DNS_RECONNECT_MAX_BACKOFF_SECONDS * 1000); |
| return &r->base; |
| } |
| |
| /* |
| * FACTORY |
| */ |
| |
| static void dns_factory_ref(grpc_resolver_factory* factory) {} |
| |
| static void dns_factory_unref(grpc_resolver_factory* factory) {} |
| |
| static grpc_resolver* dns_factory_create_resolver( |
| grpc_exec_ctx* exec_ctx, grpc_resolver_factory* factory, |
| grpc_resolver_args* args) { |
| return dns_create(exec_ctx, args, "https"); |
| } |
| |
| static char* dns_factory_get_default_host_name(grpc_resolver_factory* factory, |
| grpc_uri* uri) { |
| const char* path = uri->path; |
| if (path[0] == '/') ++path; |
| return gpr_strdup(path); |
| } |
| |
| static const grpc_resolver_factory_vtable dns_factory_vtable = { |
| dns_factory_ref, dns_factory_unref, dns_factory_create_resolver, |
| dns_factory_get_default_host_name, "dns"}; |
| static grpc_resolver_factory dns_resolver_factory = {&dns_factory_vtable}; |
| |
| static grpc_resolver_factory* dns_resolver_factory_create() { |
| return &dns_resolver_factory; |
| } |
| |
| extern "C" void grpc_resolver_dns_native_init(void) { |
| char* resolver = gpr_getenv("GRPC_DNS_RESOLVER"); |
| if (resolver != nullptr && gpr_stricmp(resolver, "native") == 0) { |
| gpr_log(GPR_DEBUG, "Using native dns resolver"); |
| grpc_register_resolver_type(dns_resolver_factory_create()); |
| } else { |
| grpc_resolver_factory* existing_factory = |
| grpc_resolver_factory_lookup("dns"); |
| if (existing_factory == nullptr) { |
| gpr_log(GPR_DEBUG, "Using native dns resolver"); |
| grpc_register_resolver_type(dns_resolver_factory_create()); |
| } else { |
| grpc_resolver_factory_unref(existing_factory); |
| } |
| } |
| gpr_free(resolver); |
| } |
| |
| extern "C" void grpc_resolver_dns_native_shutdown(void) {} |