From 1e4c44bfe66942bb878de3e8b84f68c19cd1fbc1 Mon Sep 17 00:00:00 2001
From: Yuchen Zeng <zyc@google.com>
Date: Fri, 5 Aug 2016 10:54:59 -0700
Subject: [PATCH] Check in c_ares/dns_resolver.c
---
.../ext/resolver/dns/c_ares/dns_resolver.c | 347 ++++++++++++++++++
1 file changed, 347 insertions(+)
create mode 100644 src/core/ext/resolver/dns/c_ares/dns_resolver.c
diff --git a/src/core/ext/resolver/dns/c_ares/dns_resolver.c b/src/core/ext/resolver/dns/c_ares/dns_resolver.c
new file mode 100644
index 0000000000..da328bf4f0
--- /dev/null
+++ b/src/core/ext/resolver/dns/c_ares/dns_resolver.c
@@ -0,0 +1,347 @@
+/*
+ *
+ * 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 <grpc/support/port_platform.h>
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/host_port.h>
+#include <grpc/support/string_util.h>
+
+#include <ares.h>
+#include "src/core/ext/client_config/lb_policy_registry.h"
+#include "src/core/ext/client_config/resolver_registry.h"
+#include "src/core/ext/resolver/dns/c_ares/grpc_ares_wrapper.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;
+ /** refcount */
+ gpr_refcount refs;
+ /** name to resolve */
+ char *name;
+ /** default port to use */
+ char *default_port;
+ /** subchannel factory */
+ grpc_client_channel_factory *client_channel_factory;
+ /** load balancing policy name */
+ char *lb_policy_name;
+
+ /** mutex guarding the rest of the state */
+ gpr_mu mu;
+ /** are we currently resolving? */
+ int resolving;
+ /** which version of resolved_config have we published? */
+ int published_version;
+ /** which version of resolved_config is current? */
+ int resolved_version;
+ /** pending next completion, or NULL */
+ grpc_closure *next_completion;
+ /** target config address for next completion */
+ grpc_client_config **target_config;
+ /** current (fully resolved) config */
+ grpc_client_config *resolved_config;
+ /** retry timer */
+ bool have_retry_timer;
+ grpc_timer retry_timer;
+ /** retry backoff state */
+ gpr_backoff backoff_state;
+
+ /** currently resolving addresses */
+ grpc_resolved_addresses *addresses;
+
+ grpc_ares_request *request;
+
+ grpc_polling_entity *pollent;
+} 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_polling_entity *pollent,
+ grpc_client_config **target_config,
+ 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_config = 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_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) {
+ gpr_log(GPR_ERROR, "dns_on_resolved");
+ dns_resolver *r = arg;
+ grpc_client_config *config = NULL;
+ grpc_lb_policy *lb_policy;
+ gpr_log(GPR_ERROR, "before mu");
+ gpr_mu_lock(&r->mu);
+ gpr_log(GPR_ERROR, "after mu");
+ GPR_ASSERT(r->resolving);
+ r->resolving = 0;
+ grpc_resolved_addresses *addresses = r->addresses;
+ if (addresses != NULL) {
+ gpr_log(GPR_ERROR, "addresses != NULL");
+ grpc_lb_policy_args lb_policy_args;
+ config = grpc_client_config_create();
+ memset(&lb_policy_args, 0, sizeof(lb_policy_args));
+ lb_policy_args.addresses = addresses;
+ lb_policy_args.client_channel_factory = r->client_channel_factory;
+ lb_policy =
+ grpc_lb_policy_create(exec_ctx, r->lb_policy_name, &lb_policy_args);
+ if (lb_policy != NULL) {
+ grpc_client_config_set_lb_policy(config, lb_policy);
+ GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "construction");
+ }
+ grpc_resolved_addresses_destroy(addresses);
+ } else {
+ gpr_log(GPR_ERROR, "addresses == NULL");
+ 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_config) {
+ grpc_client_config_unref(exec_ctx, r->resolved_config);
+ }
+ r->resolved_config = config;
+ r->resolved_version++;
+ dns_maybe_finish_next_locked(exec_ctx, r);
+ gpr_mu_unlock(&r->mu);
+ gpr_log(GPR_ERROR, "mu_unlock");
+ GRPC_RESOLVER_UNREF(exec_ctx, &r->base, "dns-resolving");
+ gpr_log(GPR_ERROR, "after GRPC_RESOLVER_UNREF");
+}
+
+static void dns_next(grpc_exec_ctx *exec_ctx, grpc_resolver *resolver,
+ grpc_polling_entity *pollent,
+ grpc_client_config **target_config,
+ 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_config = target_config;
+ if (r->resolved_version == 0 && !r->resolving) {
+ gpr_backoff_reset(&r->backoff_state);
+ gpr_log(GPR_ERROR, "dns_start_resolving_locked");
+ GRPC_RESOLVER_REF(&r->base, "dns-resolving");
+ GPR_ASSERT(!r->resolving);
+ if (pollent) {
+ r->pollent = pollent;
+ grpc_polling_entity_add_to_pollset_set(exec_ctx, pollent,
+ r->base.pollset_set);
+ }
+ r->resolving = 1;
+ r->addresses = NULL;
+ r->request = grpc_resolve_address_ares(
+ exec_ctx, r->name, r->default_port, r->base.pollset_set,
+ grpc_closure_create(dns_on_resolved, r), &r->addresses);
+ } else {
+ dns_maybe_finish_next_locked(exec_ctx, r);
+ }
+ gpr_mu_unlock(&r->mu);
+}
+
+static void dns_start_resolving_locked(grpc_exec_ctx *exec_ctx,
+ dns_resolver *r) {
+ gpr_log(GPR_ERROR, "dns_start_resolving_locked");
+ GRPC_RESOLVER_REF(&r->base, "dns-resolving");
+ GPR_ASSERT(!r->resolving);
+ r->resolving = 1;
+ r->addresses = NULL;
+ r->request = grpc_resolve_address_ares(
+ exec_ctx, r->name, r->default_port, r->base.pollset_set,
+ grpc_closure_create(dns_on_resolved, r), &r->addresses);
+ // grpc_resolve_address(exec_ctx, r->name, 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_config = r->resolved_config;
+ if (r->resolved_config) {
+ grpc_client_config_ref(r->resolved_config);
+ }
+ 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_config) {
+ grpc_client_config_unref(exec_ctx, r->resolved_config);
+ }
+ grpc_client_channel_factory_unref(exec_ctx, r->client_channel_factory);
+ gpr_free(r->name);
+ gpr_free(r->default_port);
+ gpr_free(r->lb_policy_name);
+ gpr_free(r);
+}
+
+static grpc_resolver *dns_create(grpc_resolver_args *args,
+ const char *default_port,
+ const char *lb_policy_name) {
+ dns_resolver *r;
+ const char *path = args->uri->path;
+
+ if (0 != strcmp(args->uri->authority, "")) {
+ gpr_log(GPR_ERROR, "authority based dns uri's not supported");
+ return NULL;
+ }
+
+ if (path[0] == '/') ++path;
+
+ r = gpr_malloc(sizeof(dns_resolver));
+ memset(r, 0, sizeof(*r));
+ gpr_ref_init(&r->refs, 1);
+ gpr_mu_init(&r->mu);
+ grpc_resolver_init(&r->base, &dns_resolver_vtable);
+ r->name = gpr_strdup(path);
+ r->default_port = gpr_strdup(default_port);
+ r->client_channel_factory = args->client_channel_factory;
+ gpr_backoff_init(&r->backoff_state, BACKOFF_MULTIPLIER, BACKOFF_JITTER,
+ BACKOFF_MIN_SECONDS * 1000, BACKOFF_MAX_SECONDS * 1000);
+ grpc_client_channel_factory_ref(r->client_channel_factory);
+ r->lb_policy_name = gpr_strdup(lb_policy_name);
+ grpc_ares_init();
+ 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", "pick_first");
+}
+
+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_ares_init(void) {
+ grpc_register_resolver_type(dns_resolver_factory_create());
+}
+
+void grpc_resolver_dns_ares_shutdown(void) {}
--
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