Check in c_ares/dns_resolver.c

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) {}