src/core/lib/client_config/resolver_registry.c

/*
 *
 * Copyright 2015-2016, 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,
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */

#include "src/core/client_config/resolver_registry.h"

#include <string.h>

#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/string_util.h>

#define MAX_RESOLVERS 10

static grpc_resolver_factory *g_all_of_the_resolvers[MAX_RESOLVERS];
static int g_number_of_resolvers = 0;

static char *g_default_resolver_prefix;

void grpc_resolver_registry_init(const char *default_resolver_prefix) {
  g_number_of_resolvers = 0;
  g_default_resolver_prefix = gpr_strdup(default_resolver_prefix);
}

void grpc_resolver_registry_shutdown(void) {
  int i;
  for (i = 0; i < g_number_of_resolvers; i++) {
    grpc_resolver_factory_unref(g_all_of_the_resolvers[i]);
  }
  gpr_free(g_default_resolver_prefix);
}

void grpc_register_resolver_type(grpc_resolver_factory *factory) {
  int i;
  for (i = 0; i < g_number_of_resolvers; i++) {
    GPR_ASSERT(0 != strcmp(factory->vtable->scheme,
                           g_all_of_the_resolvers[i]->vtable->scheme));
  }
  GPR_ASSERT(g_number_of_resolvers != MAX_RESOLVERS);
  grpc_resolver_factory_ref(factory);
  g_all_of_the_resolvers[g_number_of_resolvers++] = factory;
}

static grpc_resolver_factory *lookup_factory(grpc_uri *uri) {
  int i;

  /* handling NULL uri's here simplifies grpc_resolver_create */
  if (!uri) return NULL;

  for (i = 0; i < g_number_of_resolvers; i++) {
    if (0 == strcmp(uri->scheme, g_all_of_the_resolvers[i]->vtable->scheme)) {
      return g_all_of_the_resolvers[i];
    }
  }

  return NULL;
}

static grpc_resolver_factory *resolve_factory(const char *target,
                                              grpc_uri **uri) {
  char *tmp;
  grpc_resolver_factory *factory = NULL;

  GPR_ASSERT(uri != NULL);
  *uri = grpc_uri_parse(target, 1);
  factory = lookup_factory(*uri);
  if (factory == NULL) {
    if (g_default_resolver_prefix != NULL) {
      grpc_uri_destroy(*uri);
      gpr_asprintf(&tmp, "%s%s", g_default_resolver_prefix, target);
      *uri = grpc_uri_parse(tmp, 1);
      factory = lookup_factory(*uri);
      if (factory == NULL) {
        grpc_uri_destroy(grpc_uri_parse(target, 0));
        grpc_uri_destroy(grpc_uri_parse(tmp, 0));
        gpr_log(GPR_ERROR, "don't know how to resolve '%s' or '%s'", target,
                tmp);
      }
      gpr_free(tmp);
    } else {
      grpc_uri_destroy(grpc_uri_parse(target, 0));
      gpr_log(GPR_ERROR, "don't know how to resolve '%s'", target);
    }
  }
  return factory;
}

grpc_resolver *grpc_resolver_create(
    const char *target, grpc_subchannel_factory *subchannel_factory) {
  grpc_uri *uri = NULL;
  grpc_resolver_factory *factory = resolve_factory(target, &uri);
  grpc_resolver *resolver;
  grpc_resolver_args args;
  memset(&args, 0, sizeof(args));
  args.uri = uri;
  args.subchannel_factory = subchannel_factory;
  resolver = grpc_resolver_factory_create_resolver(factory, &args);
  grpc_uri_destroy(uri);
  return resolver;
}

char *grpc_get_default_authority(const char *target) {
  grpc_uri *uri = NULL;
  grpc_resolver_factory *factory = resolve_factory(target, &uri);
  char *authority = grpc_resolver_factory_get_default_authority(factory, uri);
  grpc_uri_destroy(uri);
  return authority;
}