| /* |
| * |
| * Copyright 2015, Google Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| * |
| */ |
| |
| #include <string.h> |
| |
| #include <grpc/support/alloc.h> |
| #include <grpc/support/host_port.h> |
| #include <grpc/support/string_util.h> |
| |
| #include "src/core/ext/client_channel/lb_policy_registry.h" |
| #include "src/core/ext/client_channel/resolver_registry.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/backoff.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 */ |
| gpr_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 != NULL) { |
| *r->target_result = NULL; |
| grpc_closure_sched(exec_ctx, r->next_completion, |
| GRPC_ERROR_CREATE("Resolver Shutdown")); |
| r->next_completion = NULL; |
| } |
| } |
| |
| static void dns_channel_saw_error_locked(grpc_exec_ctx *exec_ctx, |
| grpc_resolver *resolver) { |
| dns_resolver *r = (dns_resolver *)resolver; |
| if (!r->resolving) { |
| gpr_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) { |
| gpr_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 = 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 = arg; |
| grpc_channel_args *result = NULL; |
| GPR_ASSERT(r->resolving); |
| r->resolving = false; |
| if (r->addresses != NULL) { |
| grpc_lb_addresses *addresses = grpc_lb_addresses_create( |
| r->addresses->naddrs, NULL /* 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 */, |
| NULL /* balancer_name */, NULL /* 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 { |
| gpr_timespec now = gpr_now(GPR_CLOCK_MONOTONIC); |
| gpr_timespec next_try = gpr_backoff_step(&r->backoff_state, now); |
| gpr_timespec timeout = gpr_time_sub(next_try, now); |
| 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 (gpr_time_cmp(timeout, gpr_time_0(timeout.clock_type)) > 0) { |
| gpr_log(GPR_DEBUG, "retrying in %" PRId64 ".%09d seconds", timeout.tv_sec, |
| timeout.tv_nsec); |
| } 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, false)); |
| grpc_timer_init(exec_ctx, &r->retry_timer, next_try, &r->on_retry, now); |
| } |
| if (r->resolved_result != NULL) { |
| 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_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 = NULL; |
| 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, false)), |
| &r->addresses); |
| } |
| |
| static void dns_maybe_finish_next_locked(grpc_exec_ctx *exec_ctx, |
| dns_resolver *r) { |
| if (r->next_completion != NULL && |
| r->resolved_version != r->published_version) { |
| *r->target_result = r->resolved_result == NULL |
| ? NULL |
| : grpc_channel_args_copy(r->resolved_result); |
| grpc_closure_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE); |
| r->next_completion = NULL; |
| 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 != NULL) { |
| 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 NULL; |
| } |
| // Get name from args. |
| char *path = args->uri->path; |
| if (path[0] == '/') ++path; |
| // Create resolver. |
| dns_resolver *r = gpr_malloc(sizeof(dns_resolver)); |
| memset(r, 0, sizeof(*r)); |
| 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 != NULL) { |
| grpc_pollset_set_add_pollset_set(exec_ctx, r->interested_parties, |
| args->pollset_set); |
| } |
| gpr_backoff_init(&r->backoff_state, GRPC_DNS_INITIAL_CONNECT_BACKOFF_SECONDS, |
| 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; |
| } |
| |
| void grpc_resolver_dns_native_init(void) { |
| grpc_register_resolver_type(dns_resolver_factory_create()); |
| } |
| |
| void grpc_resolver_dns_native_shutdown(void) {} |