/* * * 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/http_connect_handshaker.h" #include "src/core/ext/client_channel/lb_policy_registry.h" #include "src/core/ext/client_channel/resolver_registry.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 BACKOFF_MULTIPLIER 1.6 #define BACKOFF_JITTER 0.2 #define BACKOFF_MIN_SECONDS 1 #define BACKOFF_MAX_SECONDS 120 typedef struct { /** base class: must be first */ grpc_resolver base; /** target name */ char *target_name; /** name to resolve (usually the same as target_name) */ char *name_to_resolve; /** default port to use */ char *default_port; /** mutex guarding the rest of the state */ gpr_mu mu; /** 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_resolver_result **target_result; /** current (fully resolved) result */ grpc_resolver_result *resolved_result; /** retry timer */ bool have_retry_timer; grpc_timer retry_timer; /** 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(grpc_exec_ctx *exec_ctx, grpc_resolver *r); static void dns_channel_saw_error(grpc_exec_ctx *exec_ctx, grpc_resolver *r); static void dns_next(grpc_exec_ctx *exec_ctx, grpc_resolver *r, grpc_resolver_result **target_result, grpc_closure *on_complete); static const grpc_resolver_vtable dns_resolver_vtable = { dns_destroy, dns_shutdown, dns_channel_saw_error, dns_next}; static void dns_shutdown(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver) { dns_resolver *r = (dns_resolver *)resolver; gpr_mu_lock(&r->mu); if (r->have_retry_timer) { grpc_timer_cancel(exec_ctx, &r->retry_timer); } if (r->next_completion != NULL) { *r->target_result = NULL; grpc_exec_ctx_sched(exec_ctx, r->next_completion, GRPC_ERROR_CREATE("Resolver Shutdown"), NULL); r->next_completion = NULL; } gpr_mu_unlock(&r->mu); } static void dns_channel_saw_error(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver) { dns_resolver *r = (dns_resolver *)resolver; gpr_mu_lock(&r->mu); if (!r->resolving) { gpr_backoff_reset(&r->backoff_state); dns_start_resolving_locked(exec_ctx, r); } gpr_mu_unlock(&r->mu); } static void dns_next(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver, grpc_resolver_result **target_result, grpc_closure *on_complete) { dns_resolver *r = (dns_resolver *)resolver; gpr_mu_lock(&r->mu); 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); } gpr_mu_unlock(&r->mu); } static void dns_on_retry_timer(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) { dns_resolver *r = arg; gpr_mu_lock(&r->mu); r->have_retry_timer = false; if (error == GRPC_ERROR_NONE) { if (!r->resolving) { dns_start_resolving_locked(exec_ctx, r); } } gpr_mu_unlock(&r->mu); GRPC_RESOLVER_UNREF(exec_ctx, &r->base, "retry-timer"); } static void dns_on_resolved(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) { dns_resolver *r = arg; grpc_resolver_result *result = NULL; gpr_mu_lock(&r->mu); GPR_ASSERT(r->resolving); r->resolving = false; if (r->addresses != NULL) { grpc_lb_addresses *addresses = grpc_lb_addresses_create(r->addresses->naddrs); 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_resolved_addresses_destroy(r->addresses); result = grpc_resolver_result_create(r->target_name, addresses, NULL /* lb_policy_name */, NULL); } 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); const char *msg = grpc_error_string(error); gpr_log(GPR_DEBUG, "dns resolution failed: %s", msg); grpc_error_free_string(msg); 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_timer_init(exec_ctx, &r->retry_timer, next_try, dns_on_retry_timer, r, now); } if (r->resolved_result) { grpc_resolver_result_unref(exec_ctx, r->resolved_result); } r->resolved_result = result; r->resolved_version++; dns_maybe_finish_next_locked(exec_ctx, r); gpr_mu_unlock(&r->mu); 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, grpc_closure_create(dns_on_resolved, r), &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; if (r->resolved_result) { grpc_resolver_result_ref(r->resolved_result); } grpc_exec_ctx_sched(exec_ctx, r->next_completion, GRPC_ERROR_NONE, NULL); 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; gpr_mu_destroy(&r->mu); if (r->resolved_result) { grpc_resolver_result_unref(exec_ctx, r->resolved_result); } gpr_free(r->target_name); gpr_free(r->name_to_resolve); gpr_free(r->default_port); gpr_free(r); } static grpc_resolver *dns_create(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. const char *path = args->uri->path; if (path[0] == '/') ++path; // Get proxy name, if any. char *proxy_name = grpc_get_http_proxy_server(); // Create resolver. dns_resolver *r = gpr_malloc(sizeof(dns_resolver)); memset(r, 0, sizeof(*r)); gpr_mu_init(&r->mu); grpc_resolver_init(&r->base, &dns_resolver_vtable); r->target_name = gpr_strdup(path); r->name_to_resolve = proxy_name == NULL ? gpr_strdup(path) : proxy_name; r->default_port = gpr_strdup(default_port); gpr_backoff_init(&r->backoff_state, BACKOFF_MULTIPLIER, BACKOFF_JITTER, BACKOFF_MIN_SECONDS * 1000, BACKOFF_MAX_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_resolver_factory *factory, grpc_resolver_args *args) { return dns_create(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) {}