tencent cloud

Overview

Errors may occur when data is transferred between the client and the server. COS can not only verify data integrity through MD5 and custom attributes, but also the CRC64 check code.

COS will calculate the CRC64 of the newly uploaded object and store the result as object attributes. It will carry x-cos-hash-crc64ecma in the returned response header, which indicates the CRC64 value of the uploaded object calculated according to ECMA-182 standard. If an object already has a CRC64 value stored before this feature is activated, COS will not calculate its CRC64 value, nor will it be returned when the object is obtained.

Description

APIs that currently support CRC64 include:

• APIs for simple upload
  • PUT Object and POST Object: you can get the CRC64 check value for your file from the response headers.
• Multipart upload APIs
  • Upload Part: you can compare and verify the CRC64 value returned by COS against the value calculated locally.
  • Complete Multipart Upload: returns a CRC64 value for the entire object only if each part has a CRC64 attribute. Otherwise, no value is returned.
• The Upload Part - Copy operation returns a corresponding CRC64 value.
• When you call the PUT Object - Copy, the CRC64 value is returned only if the source object has one.
• The HEAD Object and GET Object operations return the CRC64 value provided the object has one. You can compare and verify the CRC64 value returned by COS against that calculated locally.

API Samples

Upload Part response

The following example shows the response to an Upload Part request. The x-cos-hash-crc64ecma header represents the CRC64 value of a part, which you can compare against the locally calculated CRC64 value to verify the part integrity.

HTTP/1.1 200 OK
content-length: 0
connection: close
date: Thu, 05 Dec 2019 01:58:03 GMT
etag: "358e8c8b1bfa35ee3bd44cb3d2cc416b"
server: tencent-cos
x-cos-hash-crc64ecma: 15060521397700495958
x-cos-request-id: NWRlODY0MmJfMjBiNDU4NjRfNjkyZl80ZjZi****

Complete Multipart Upload response

The following example shows the response to a Complete Multipart Upload request. The x-cos-hash-crc64ecma header represents the CRC64 value of an entire object, which you can compare against the locally calculated CRC64 value to verify the object integrity.

HTTP/1.1 200 OK
content-type: application/xml
transfer-encoding: chunked
connection: close
date: Thu, 05 Dec 2019 02:01:17 GMT
server: tencent-cos
x-cos-hash-crc64ecma: 15060521397700495958
x-cos-request-id: NWRlODY0ZWRfMjNiMjU4NjRfOGQ4Ml81MDEw****
[Object Content]

SDK Samples

Description

This API is used to verify the CRC64 value consistency of the object data when the object is uploaded or downloaded.

Method prototype

cos_status_t *cos_upload_part_from_buffer(const cos_request_options_t *options,
                                        const cos_string_t *bucket, 
                                        const cos_string_t *object, 
                                        const cos_string_t *upload_id, 
                                        int part_num, 
                                        cos_list_t *buffer, 
                                        cos_table_t **resp_headers);
cos_status_t *cos_upload_part_from_file(const cos_request_options_t *options,
                                      const cos_string_t *bucket, 
                                      const cos_string_t *object,
                                      const cos_string_t *upload_id, 
                                      int part_num, 
                                      cos_upload_file_t *upload_file,
                                      cos_table_t **resp_headers);
cos_status_t *cos_download_part_to_file(const cos_request_options_t *options,
                                      const cos_string_t *bucket, 
                                      const cos_string_t *object,
                                      cos_upload_file_t *download_file,
                                      cos_table_t **resp_headers);
cos_status_t *cos_put_object_from_buffer(const cos_request_options_t *options,
                                       const cos_string_t *bucket, 
                                       const cos_string_t *object, 
                                       cos_list_t *buffer,
                                       cos_table_t *headers, 
                                       cos_table_t **resp_headers);
cos_status_t *cos_put_object_from_file(const cos_request_options_t *options,
                                     const cos_string_t *bucket, 
                                     const cos_string_t *object, 
                                     const cos_string_t *filename,
                                     cos_table_t *headers, 
                                     cos_table_t **resp_headers);
cos_status_t *cos_get_object_to_buffer(const cos_request_options_t *options, 
                                     const cos_string_t *bucket, 
                                     const cos_string_t *object,
                                     cos_table_t *headers, 
                                     cos_table_t *params,
                                     cos_list_t *buffer, 
                                     cos_table_t **resp_headers);
cos_status_t *cos_get_object_to_file(const cos_request_options_t *options,
                                   const cos_string_t *bucket, 
                                   const cos_string_t *object,
                                   cos_table_t *headers, 
                                   cos_table_t *params,
                                   cos_string_t *filename, 
                                   cos_table_t **resp_headers);
cos_status_t *cos_append_object_from_buffer(const cos_request_options_t *options,
                                          const cos_string_t *bucket, 
                                          const cos_string_t *object, 
                                          int64_t position,
                                          cos_list_t *buffer, 
                                          cos_table_t *headers, 
                                          cos_table_t **resp_headers);
cos_status_t *cos_append_object_from_file(const cos_request_options_t *options,
                                        const cos_string_t *bucket, 
                                        const cos_string_t *object, 
                                        int64_t position,
                                        const cos_string_t *append_file, 
                                        cos_table_t *headers, 
                                        cos_table_t **resp_headers);
cos_status_t *cos_resumable_download_file(cos_request_options_t *options,
                                          cos_string_t *bucket,
                                          cos_string_t *object,
                                          cos_string_t *filepath,
                                          cos_table_t *headers,
                                          cos_table_t *params,
                                          cos_resumable_clt_params_t *clt_params,
                                          cos_progress_callback progress_callback);

Parameter description

Note：

For other parameters, please see Object Operations.

Response description

Sample

The APIs for simple upload and simple download are used as examples. It is the same with other APIs. You only need to set options > ctl > options > enable_crc to COS_TRUE, which is the default value.

#include "cos_http_io.h"
#include "cos_api.h"
#include "cos_log.h"
#include <unistd.h>
// `endpoint` is the COS access domain name. For more information, see https://www.tencentcloud.com/document/product/436/6224.
static char TEST_COS_ENDPOINT[] = "cos.ap-guangzhou.myqcloud.com";
// A developer-owned secret ID/key used for the project. It can be obtained at https://console.tencentcloud.com/cam/capi.
static char *TEST_ACCESS_KEY_ID;                // Your SecretId
static char *TEST_ACCESS_KEY_SECRET;            // Your SecretKey
// A unique user-level resource identifier for COS access. It can be obtained at https://console.tencentcloud.com/cam/capi.
static char TEST_APPID[] = "<APPID>";    // Your APPID
// COS bucket name, in the format of [bucket]-[appid], for example `mybucket-1253666666`. It can be obtained at https://console.tencentcloud.com/cos5/bucket.
static char TEST_BUCKET_NAME[] = "<bucketname-appid>"; 
// A unique identifier of an object stored in COS. For more information about objects and object keys, please see https://www.tencentcloud.com/document/product/436/13324.
static char TEST_OBJECT_NAME1[] = "1.txt";
void log_status(cos_status_t *s)
{
  cos_warn_log("status->code: %d", s->code);
  if (s->error_code) cos_warn_log("status->error_code: %s", s->error_code);
  if (s->error_msg) cos_warn_log("status->error_msg: %s", s->error_msg);
  if (s->req_id) cos_warn_log("status->req_id: %s", s->req_id);
}
void init_test_config(cos_config_t *config, int is_cname)
{
  cos_str_set(&config->endpoint, TEST_COS_ENDPOINT);
  cos_str_set(&config->access_key_id, TEST_ACCESS_KEY_ID);
  cos_str_set(&config->access_key_secret, TEST_ACCESS_KEY_SECRET);
  cos_str_set(&config->appid, TEST_APPID);
  config->is_cname = is_cname;
}
void init_test_request_options(cos_request_options_t *options, int is_cname)
{
  options->config = cos_config_create(options->pool);
  init_test_config(options->config, is_cname);
  options->ctl = cos_http_controller_create(options->pool, 0);
}
void test_data_crc64()
{
  cos_pool_t *p = NULL;
  int is_cname = 0; 
  cos_status_t *s = NULL;
  cos_request_options_t *options = NULL;
  cos_string_t bucket;
  cos_table_t *resp_headers;
  cos_table_t *headers = NULL;
  cos_list_t buffer;
  cos_list_t download_buffer;
  cos_string_t object;
  cos_buf_t *content = NULL;
  char *str = "This is my test data.";
   // Basic configuration
  cos_pool_create(&p, NULL);
  options = cos_request_options_create(p);
  init_test_request_options(options, is_cname);
  options->ctl->options->enable_crc = COS_TRUE;   // Enable CRC check (enabled by default)
  cos_str_set(&bucket, TEST_BUCKET_NAME);
  cos_str_set(&object, TEST_OBJECT_NAME1);
   // Upload an object and enable CRC check
  cos_list_init(&buffer);
  content = cos_buf_pack(options->pool, str, strlen(str));
  cos_list_add_tail(&content->node, &buffer);
  s = cos_put_object_from_buffer(options, &bucket, &object, 
                  &buffer, headers, &resp_headers);
  log_status(s);
   // Download an object and enable CRC check
  cos_list_init(&download_buffer);
  s = cos_get_object_to_buffer(options, &bucket, &object, 
                      headers, NULL, &download_buffer, &resp_headers);
  log_status(s);
   // Destroy the memory pool
  cos_pool_destroy(p);
}
int main(int argc, char *argv[])
{
  // Get SecretId and SecretKey from environment variables
  TEST_ACCESS_KEY_ID     = getenv("COS_SECRETID");
  TEST_ACCESS_KEY_SECRET = getenv("COS_SECRETKEY");
    if (cos_http_io_initialize(NULL, 0) != COSE_OK) {
     exit(1);
  }
   // Set the log level. Default value: `COS_LOG_WARN`
  cos_log_set_level(COS_LOG_WARN);
   // Set log output. Default value: `stderr`
  cos_log_set_output(NULL);
   test_data_crc64();
   cos_http_io_deinitialize();
   return 0;
}