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Object Storage Service:CORS

Last Updated:Sep 25, 2023

Cross-origin resource sharing (CORS) is a standard cross-origin solution provided by HTML5 to allow web application servers to control cross-origin access and secure cross-origin data transmission.

Usage notes

  • In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS by using other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about the regions and endpoints supported by OSS, see Regions and endpoints.

  • In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient instance by using custom domain names or Security Token Service (STS), see Create an OSSClient instance.

  • To configure CORS rules, you must have the oss:PutBucketCors permission. To query CORS rules, you must have the oss:GetBucketCors permission. To delete CORS rules, you must have the oss:DeleteBucketCors permission. For more information, see Common examples of RAM policies.

Configure CORS rules

The following sample code provides an example on how to configure CORS rules for a specific bucket:

#include <alibabacloud/oss/OssClient.h>
using namespace AlibabaCloud::OSS;

int main(void)
{
    /* Initialize information about the account that is used to access OSS. */
            
    /* Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
    std::string Endpoint = "yourEndpoint";
    /* Specify the name of the bucket. Example: examplebucket. */
    std::string BucketName = "examplebucket";

    /* Initialize resources such as network resources. */
    InitializeSdk();

    ClientConfiguration conf;
    /* Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);

    SetBucketCorsRequest request(BucketName);

    /* Configure CORS rules. */
    auto rule1 = CORSRule();
    /* Specify the origins from which cross-origin requests are allowed. */
    rule1.addAllowedOrigin("http://example.com");
    /* Specify the methods that can be used to send cross-origin requests, including GET, PUT, POST, DELETE, and HEAD. */
    rule1.addAllowedMethod("POST");
    /* Specify whether the headers that are specified by Access-Control-Request-Headers in the OPTIONS preflight request are allowed. */
    rule1.addAllowedHeader("*");
    /* Specify the response headers for allowed access requests from applications. */
    rule1.addExposeHeader("x-oss-test");
    /* You can configure up to 10 CORS rules for the bucket. */
    request.addCORSRule(rule1);

    auto rule2 = CORSRule();
    rule2.addAllowedOrigin("http://example.net");
    rule2.addAllowedMethod("GET");
    rule2.addExposeHeader("x-oss-test2");
    rule2.setMaxAgeSeconds(100);
    request.addCORSRule(rule2);

    auto outcome = client.SetBucketCors(request);

    if (!outcome.isSuccess()) {
        /* Handle exceptions. */
        std::cout << "SetBucketCors fail" <<
        ",code:" << outcome.error().Code() <<
        ",message:" << outcome.error().Message() <<
        ",requestId:" << outcome.error().RequestId() << std::endl;
        return -1;
    }

    /* Release resources such as network resources. */
    ShutdownSdk();
    return 0;
}

Query CORS rules

The following sample code provides an example on how to query CORS rules that are configured for a specific bucket:

#include <alibabacloud/oss/OssClient.h>
using namespace AlibabaCloud::OSS;

int main(void)
{
    /* Initialize information about the account that is used to access OSS. */
    
    /* Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
    std::string Endpoint = "yourEndpoint";
    /* Specify the name of the bucket. Example: examplebucket. */
    std::string BucketName = "examplebucket";

    /* Initialize resources such as network resources. */
    InitializeSdk();

    ClientConfiguration conf;
    /* Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);


    /* Query CORS rules. */
    auto outcome = client.GetBucketCors(BucketName);

    if (outcome.isSuccess()) {
        std::cout << "GetBucketCors success" << std::endl;
        for (auto const rule : outcome.result().CORSRules()) {
            std::cout << "Get Bucket Cors List:" << std::endl;
            for (auto const origin : rule.AllowedOrigins()) {
                std::cout << "Allowed origin:" << origin << std::endl;
            }
        }
    }
    else {
        /* Handle exceptions. */
        std::cout << "GetBucketCors fail" <<
        ",code:" << outcome.error().Code() <<
        ",message:" << outcome.error().Message() <<
        ",requestId:" << outcome.error().RequestId() << std::endl;
        return -1;
    }

    /* Release resources such as network resources. */
    ShutdownSdk();
    return 0;
}

Delete CORS rules

The following sample code provides an example on how to delete the CORS rules that are configured for a specific bucket:

#include <alibabacloud/oss/OssClient.h>
using namespace AlibabaCloud::OSS;

int main(void)
{
    /* Initialize information about the account that is used to access OSS. */
    
    /* Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
    std::string Endpoint = "yourEndpoint";
    /* Specify the name of the bucket. Example: examplebucket. */
    std::string BucketName = "examplebucket";

    /* Initialize resources such as network resources. */
    InitializeSdk();

    ClientConfiguration conf;
    /* Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);


    /* Delete CORS rules. */
    auto outcome = client.DeleteBucketCors(BucketName);

    if (!outcome.isSuccess()) {
        /* Handle exceptions. */
        std::cout << "DeleteBucketCors fail" <<
        ",code:" << outcome.error().Code() <<
        ",message:" << outcome.error().Message() <<
        ",requestId:" << outcome.error().RequestId() << std::endl;
        return -1;
    }

    /* Release resources such as network resources. */
    ShutdownSdk();
    return 0;
}

References

  • For the complete sample code that is used to manage CORS rules, visit GitHub.

  • For more information about the API operation that you can call to configure CORS rules, see PutBucketCors.

  • For more information about the API operation that you can call to query CORS rules, see GetBucketCors.

  • For more information about the API operation that you can call to delete CORS rules, see DeleteBucketCors.