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 * modification, are permitted provided that the following conditions are
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 * in the documentation and/or other materials provided with the
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#include "src/cpp/client/secure_credentials.h"
#include <grpc++/channel.h>
#include <grpc++/impl/grpc_library.h>
#include <grpc++/support/channel_arguments.h>
#include <grpc/support/log.h>
#include "src/cpp/client/create_channel_internal.h"
#include "src/cpp/common/secure_auth_context.h"

namespace grpc {

static internal::GrpcLibraryInitializer g_gli_initializer;
SecureChannelCredentials::SecureChannelCredentials(
    grpc_channel_credentials* c_creds)
    : c_creds_(c_creds) {
  g_gli_initializer.summon();
}

std::shared_ptr<grpc::Channel> SecureChannelCredentials::CreateChannel(
    const string& target, const grpc::ChannelArguments& args) {
  grpc_channel_args channel_args;
  args.SetChannelArgs(&channel_args);
  return CreateChannelInternal(
      args.GetSslTargetNameOverride(),
      grpc_secure_channel_create(c_creds_, target.c_str(), &channel_args,
                                 nullptr));
}

SecureCallCredentials::SecureCallCredentials(grpc_call_credentials* c_creds)
    : c_creds_(c_creds) {
  g_gli_initializer.summon();
}

bool SecureCallCredentials::ApplyToCall(grpc_call* call) {
  return grpc_call_set_credentials(call, c_creds_) == GRPC_CALL_OK;
}

namespace {
std::shared_ptr<ChannelCredentials> WrapChannelCredentials(
    grpc_channel_credentials* creds) {
  return creds == nullptr ? nullptr : std::shared_ptr<ChannelCredentials>(
                                          new SecureChannelCredentials(creds));
}

std::shared_ptr<CallCredentials> WrapCallCredentials(
    grpc_call_credentials* creds) {
  return creds == nullptr ? nullptr : std::shared_ptr<CallCredentials>(
                                          new SecureCallCredentials(creds));
}
}  // namespace

std::shared_ptr<ChannelCredentials> GoogleDefaultCredentials() {
  GrpcLibraryCodegen init;  // To call grpc_init().
  return WrapChannelCredentials(grpc_google_default_credentials_create());
}

// Builds SSL Credentials given SSL specific options
std::shared_ptr<ChannelCredentials> SslCredentials(
    const SslCredentialsOptions& options) {
  GrpcLibraryCodegen init;  // To call grpc_init().
  grpc_ssl_pem_key_cert_pair pem_key_cert_pair = {
      options.pem_private_key.c_str(), options.pem_cert_chain.c_str()};

  grpc_channel_credentials* c_creds = grpc_ssl_credentials_create(
      options.pem_root_certs.empty() ? nullptr : options.pem_root_certs.c_str(),
      options.pem_private_key.empty() ? nullptr : &pem_key_cert_pair, nullptr);
  return WrapChannelCredentials(c_creds);
}

// Builds credentials for use when running in GCE
std::shared_ptr<CallCredentials> GoogleComputeEngineCredentials() {
  GrpcLibraryCodegen init;  // To call grpc_init().
  return WrapCallCredentials(
      grpc_google_compute_engine_credentials_create(nullptr));
}

// Builds JWT credentials.
std::shared_ptr<CallCredentials> ServiceAccountJWTAccessCredentials(
    const grpc::string& json_key, long token_lifetime_seconds) {
  GrpcLibraryCodegen init;  // To call grpc_init().
  if (token_lifetime_seconds <= 0) {
    gpr_log(GPR_ERROR,
            "Trying to create JWTCredentials with non-positive lifetime");
    return WrapCallCredentials(nullptr);
  }
  gpr_timespec lifetime =
      gpr_time_from_seconds(token_lifetime_seconds, GPR_TIMESPAN);
  return WrapCallCredentials(grpc_service_account_jwt_access_credentials_create(
      json_key.c_str(), lifetime, nullptr));
}

// Builds refresh token credentials.
std::shared_ptr<CallCredentials> GoogleRefreshTokenCredentials(
    const grpc::string& json_refresh_token) {
  GrpcLibraryCodegen init;  // To call grpc_init().
  return WrapCallCredentials(grpc_google_refresh_token_credentials_create(
      json_refresh_token.c_str(), nullptr));
}

// Builds access token credentials.
std::shared_ptr<CallCredentials> AccessTokenCredentials(
    const grpc::string& access_token) {
  GrpcLibraryCodegen init;  // To call grpc_init().
  return WrapCallCredentials(
      grpc_access_token_credentials_create(access_token.c_str(), nullptr));
}

// Builds IAM credentials.
std::shared_ptr<CallCredentials> GoogleIAMCredentials(
    const grpc::string& authorization_token,
    const grpc::string& authority_selector) {
  GrpcLibraryCodegen init;  // To call grpc_init().
  return WrapCallCredentials(grpc_google_iam_credentials_create(
      authorization_token.c_str(), authority_selector.c_str(), nullptr));
}

// Combines one channel credentials and one call credentials into a channel
// composite credentials.
std::shared_ptr<ChannelCredentials> CompositeChannelCredentials(
    const std::shared_ptr<ChannelCredentials>& channel_creds,
    const std::shared_ptr<CallCredentials>& call_creds) {
  // Note that we are not saving shared_ptrs to the two credentials passed in
  // here. This is OK because the underlying C objects (i.e., channel_creds and
  // call_creds) into grpc_composite_credentials_create will see their refcounts
  // incremented.
  SecureChannelCredentials* s_channel_creds =
      channel_creds->AsSecureCredentials();
  SecureCallCredentials* s_call_creds = call_creds->AsSecureCredentials();
  if (s_channel_creds && s_call_creds) {
    return WrapChannelCredentials(grpc_composite_channel_credentials_create(
        s_channel_creds->GetRawCreds(), s_call_creds->GetRawCreds(), nullptr));
  }
  return nullptr;
}

void MetadataCredentialsPluginWrapper::Destroy(void* wrapper) {
  if (wrapper == nullptr) return;
  MetadataCredentialsPluginWrapper* w =
      reinterpret_cast<MetadataCredentialsPluginWrapper*>(wrapper);
  delete w;
}

void MetadataCredentialsPluginWrapper::GetMetadata(
    void* wrapper, grpc_auth_metadata_context context,
    grpc_credentials_plugin_metadata_cb cb, void* user_data) {
  GPR_ASSERT(wrapper);
  MetadataCredentialsPluginWrapper* w =
      reinterpret_cast<MetadataCredentialsPluginWrapper*>(wrapper);
  if (!w->plugin_) {
    cb(user_data, NULL, 0, GRPC_STATUS_OK, NULL);
    return;
  }
  if (w->plugin_->IsBlocking()) {
    w->thread_pool_->Add(
        std::bind(&MetadataCredentialsPluginWrapper::InvokePlugin, w, context,
                  cb, user_data));
  } else {
    w->InvokePlugin(context, cb, user_data);
  }
}

void MetadataCredentialsPluginWrapper::InvokePlugin(
    grpc_auth_metadata_context context, grpc_credentials_plugin_metadata_cb cb,
    void* user_data) {
  std::multimap<grpc::string, grpc::string> metadata;

  // const_cast is safe since the SecureAuthContext does not take owndership and
  // the object is passed as a const ref to plugin_->GetMetadata.
  SecureAuthContext cpp_channel_auth_context(
      const_cast<grpc_auth_context*>(context.channel_auth_context), false);

  Status status = plugin_->GetMetadata(context.service_url, context.method_name,
                                       cpp_channel_auth_context, &metadata);
  std::vector<grpc_metadata> md;
  for (auto it = metadata.begin(); it != metadata.end(); ++it) {
    grpc_metadata md_entry;
    md_entry.key = SliceFromCopiedString(it->first);
    md_entry.value = SliceFromCopiedString(it->second);
    md_entry.flags = 0;
    md.push_back(md_entry);
  }
  cb(user_data, md.empty() ? nullptr : &md[0], md.size(),
     static_cast<grpc_status_code>(status.error_code()),
     status.error_message().c_str());
  for (auto it = md.begin(); it != md.end(); ++it) {
    grpc_slice_unref(it->key);
    grpc_slice_unref(it->value);
  }
}

MetadataCredentialsPluginWrapper::MetadataCredentialsPluginWrapper(
    std::unique_ptr<MetadataCredentialsPlugin> plugin)
    : thread_pool_(CreateDefaultThreadPool()), plugin_(std::move(plugin)) {}

std::shared_ptr<CallCredentials> MetadataCredentialsFromPlugin(
    std::unique_ptr<MetadataCredentialsPlugin> plugin) {
  GrpcLibraryCodegen init;  // To call grpc_init().
  const char* type = plugin->GetType();
  MetadataCredentialsPluginWrapper* wrapper =
      new MetadataCredentialsPluginWrapper(std::move(plugin));
  grpc_metadata_credentials_plugin c_plugin = {
      MetadataCredentialsPluginWrapper::GetMetadata,
      MetadataCredentialsPluginWrapper::Destroy, wrapper, type};
  return WrapCallCredentials(
      grpc_metadata_credentials_create_from_plugin(c_plugin, nullptr));
}

}  // namespace grpc