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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 "src/core/security/credentials.h"
#include <string.h>
#include <grpc/support/alloc.h>
#include <grpc/support/log.h>
#include <grpc/support/sync.h>
#include "src/core/httpcli/httpcli.h"
#include "src/core/support/env.h"
#include "src/core/support/file.h"
/* -- Constants. -- */
#define GRPC_COMPUTE_ENGINE_DETECTION_HOST "metadata.google.internal"
#define GRPC_GOOGLE_CREDENTIALS_ENV_VAR "GOOGLE_APPLICATION_CREDENTIALS"
/* -- Default credentials. -- */
static grpc_credentials *default_credentials = NULL;
static int compute_engine_detection_done = 0;
static gpr_mu g_mu;
static gpr_once g_once = GPR_ONCE_INIT;
static void init_default_credentials(void) {
gpr_mu_init(&g_mu);
}
typedef struct {
gpr_cv cv;
gpr_mu mu;
int is_done;
int success;
} compute_engine_detector;
static void on_compute_engine_detection_http_response(
void *user_data, const grpc_httpcli_response *response) {
compute_engine_detector *detector = (compute_engine_detector *)user_data;
if (response != NULL && response->status == 200 && response->hdr_count > 0) {
/* Internet providers can return a generic response to all requests, so
it is necessary to check that metadata header is present also. */
size_t i;
for (i = 0; i < response->hdr_count; i++) {
grpc_httpcli_header *header = &response->hdrs[i];
if (strcmp(header->key, "Metadata-Flavor") == 0 &&
strcmp(header->value, "Google") == 0) {
detector->success = 1;
break;
}
}
}
gpr_mu_lock(&detector->mu);
detector->is_done = 1;
gpr_mu_unlock(&detector->mu);
gpr_cv_signal(&detector->cv);
}
static int is_stack_running_on_compute_engine(void) {
compute_engine_detector detector;
grpc_httpcli_request request;
/* The http call is local. If it takes more than one sec, it is for sure not
on compute engine. */
gpr_timespec max_detection_delay = {1, 0};
gpr_mu_init(&detector.mu);
gpr_cv_init(&detector.cv);
detector.is_done = 0;
detector.success = 0;
memset(&request, 0, sizeof(grpc_httpcli_request));
request.host = GRPC_COMPUTE_ENGINE_DETECTION_HOST;
request.path = "/";
grpc_httpcli_get(&request, gpr_time_add(gpr_now(), max_detection_delay),
on_compute_engine_detection_http_response, &detector);
/* Block until we get the response. This is not ideal but this should only be
called once for the lifetime of the process by the default credentials. */
gpr_mu_lock(&detector.mu);
while (!detector.is_done) {
gpr_cv_wait(&detector.cv, &detector.mu, gpr_inf_future);
}
gpr_mu_unlock(&detector.mu);
gpr_mu_destroy(&detector.mu);
gpr_cv_destroy(&detector.cv);
return detector.success;
}
/* Takes ownership of creds_path if not NULL. */
static grpc_credentials *create_jwt_creds_from_path(char *creds_path) {
grpc_credentials *result = NULL;
gpr_slice creds_data;
int file_ok = 0;
if (creds_path == NULL) return NULL;
creds_data = gpr_load_file(creds_path, &file_ok);
gpr_free(creds_path);
if (file_ok) {
result = grpc_jwt_credentials_create(
(const char *)GPR_SLICE_START_PTR(creds_data),
grpc_max_auth_token_lifetime);
gpr_slice_unref(creds_data);
}
return result;
}
grpc_credentials *grpc_google_default_credentials_create(void) {
grpc_credentials *result = NULL;
int serving_cached_credentials = 0;
gpr_once_init(&g_once, init_default_credentials);
gpr_mu_lock(&g_mu);
if (default_credentials != NULL) {
result = default_credentials;
serving_cached_credentials = 1;
goto end;
}
/* First, try the environment variable. */
result =
create_jwt_creds_from_path(gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR));
if (result != NULL) goto end;
/* Then the well-known file. */
result = create_jwt_creds_from_path(
grpc_get_well_known_google_credentials_file_path());
if (result != NULL) goto end;
/* At last try to see if we're on compute engine (do the detection only once
since it requires a network test). */
if (!compute_engine_detection_done) {
int need_compute_engine_creds = is_stack_running_on_compute_engine();
compute_engine_detection_done = 1;
if (need_compute_engine_creds) {
result = grpc_compute_engine_credentials_create();
}
}
end:
if (!serving_cached_credentials && result != NULL) {
/* Blend with default ssl credentials and add a global reference so that it
can be cached and re-served. */
result = grpc_composite_credentials_create(
grpc_ssl_credentials_create(NULL, NULL), result);
GPR_ASSERT(result != NULL);
default_credentials = grpc_credentials_ref(result);
}
gpr_mu_unlock(&g_mu);
return result;
}
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