Overview

The C SDK provides APIs to obtain pre-signed URLs. For detailed directions, see the description and examples below.

Note：

• You are advised to use a temporary key to generate pre-signed URLs for the security of your requests such as uploads and downloads. When you apply for a temporary key, follow the Principle of Least Privilege to avoid leaking resources besides your buckets and objects.
• If you need to use a permanent key to generate a pre-signed URL, you are advised to limit the permission of the permanent key to uploads and downloads only to avoid risks.

Getting a Pre-signed Request URL

Generating pre-signed URL

Description

This API is used to generate a pre-signed URL.

Method prototype

int cos_gen_presigned_url(const cos_request_options_t *options,
                        const cos_string_t *bucket, 
                        const cos_string_t *object,
                        const int64_t expire,
                        http_method_e method,
                        cos_string_t *presigned_url);

Parameter description

Response description

Pre-signed request samples

You can obtain a pre-signed URL by setting a permanent or temporary key using the options parameter.

cos_pool_t *p = NULL;
int is_cname = 0;
cos_request_options_t *options = NULL;
cos_string_t bucket;
cos_string_t object;
cos_string_t presigned_url;
//create memory pool
cos_pool_create(&p, NULL);
//init request options
options = cos_request_options_create(p);
options->config = cos_config_create(options->pool);
init_test_config(options->config, is_cname);
cos_str_set(&options->config->endpoint, TEST_COS_ENDPOINT);
cos_str_set(&options->config->access_key_id, TEST_ACCESS_KEY_ID);
cos_str_set(&options->config->access_key_secret, TEST_ACCESS_KEY_SECRET);
/* You can use a temporary key by setting `sts_token`. When you use a temporary key, you need to set `access_key_id` and `access_key_secret` to its SecretId and SecretKey */
//cos_str_set(&options->config->sts_token, "MyTokenString");
cos_str_set(&options->config->appid, TEST_APPID);
options->config->is_cname = is_cname;
options->ctl = cos_http_controller_create(options->pool, 0);
cos_str_set(&bucket, TEST_BUCKET_NAME);
cos_str_set(&object, TEST_OBJECT_NAME);
//generate presigned URL
cos_gen_presigned_url(options, &bucket, &object, 300, HTTP_GET, &presigned_url);
printf("presigned url: %s\n", presigned_url.data);
//destroy memory pool
cos_pool_destroy(p); 

Securely Getting a Pre-signed Request URL

Securely generating a pre-signed URL

Description

This API is used to securely generate a pre-signed URL.

Method prototype

int cos_gen_presigned_url_safe(const cos_request_options_t *options,
                        const cos_string_t *bucket, 
                        const cos_string_t *object,
                        const int64_t expire,
                        http_method_e method,
                        cos_table_t *headers,
                        cos_table_t *params,
                        int sign_host,
                        cos_string_t *presigned_url);

Parameter description

Response description

Sample request of securely generating a pre-signed URL

You can obtain a pre-signed URL by setting a permanent or temporary key using the options parameter.

cos_pool_t *p = NULL;
int is_cname = 0;
cos_request_options_t *options = NULL;
cos_string_t bucket;
cos_string_t object;
cos_string_t presigned_url;
cos_table_t *params;
cos_table_t *headers;
//create memory pool
cos_pool_create(&p, NULL);
//init request options
options = cos_request_options_create(p);
options->config = cos_config_create(options->pool);
init_test_config(options->config, is_cname);
cos_str_set(&options->config->endpoint, TEST_COS_ENDPOINT);
cos_str_set(&options->config->access_key_id, TEST_ACCESS_KEY_ID);
cos_str_set(&options->config->access_key_secret, TEST_ACCESS_KEY_SECRET);
/* You can use a temporary key by setting `sts_token`. When you use a temporary key, you need to set `access_key_id` and `access_key_secret` to its SecretId and SecretKey */
//cos_str_set(&options->config->sts_token, "MyTokenString");
cos_str_set(&options->config->appid, TEST_APPID);
options->config->is_cname = is_cname;
options->ctl = cos_http_controller_create(options->pool, 0);
cos_str_set(&bucket, TEST_BUCKET_NAME);
cos_str_set(&object, TEST_OBJECT_NAME);
// Add your “params” and “headers”.
params = cos_table_make(p, 0);
headers = cos_table_make(p, 0);
// You are strongly advised to set sign_host to 1. In this way, the host header will be added to the signature list forcibly to avoid unauthorized access.
cos_gen_presigned_url_safe(options, &bucket, &object, 300, HTTP_GET, headers, params, 1, &presigned_url);
printf("presigned_url_safe: %s\n", presigned_url.data);
//destroy memory pool
cos_pool_destroy(p);