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/*
*
* 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_config/http_connect_handshaker.h"
#include "src/core/ext/client_config/lb_policy_registry.h"
#include "src/core/ext/client_config/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) {}
|