/* * * 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 #include #include #include #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/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 */ 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_FROM_STATIC_STRING("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_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 != 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) { char *resolver = gpr_getenv("GRPC_DNS_RESOLVER"); if (resolver != NULL && 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 == NULL) { 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); } void grpc_resolver_dns_native_shutdown(void) {}