Cross-origin resource sharing (C++ SDK) - Object Storage Service

Due to the same-origin policy of browsers, cross-origin requests may be rejected when data is exchanged or resources are shared between different domain names. To resolve the issue, you can configure cross-origin resource sharing (CORS) rules. In the CORS rules, you can specify the domain names from which requests can be sent, the methods that can be used to send cross-origin requests, and the allowed headers.

Usage notes

In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS from other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about OSS regions and endpoints, see Regions and endpoints.
In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient 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 Attach a custom policy to a RAM user.

Set cross-origin resource sharing rules

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

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

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

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

    ClientConfiguration conf;
    conf.signatureVersion = SignatureVersionType::V4;
    /* Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);
    client.SetRegion(Region);

    SetBucketCorsRequest request(BucketName);

    /* Set CORS rules. */
    auto rule1 = CORSRule();
    /* Specify the allowed origins for cross-origin requests. */
    rule1.addAllowedOrigin("http://example.com");
    /* Specify the allowed methods for cross-origin requests (GET, PUT, POST, DELETE, or HEAD). */
    rule1.addAllowedMethod("POST");
    /* Specify whether to allow the headers specified by the Access-Control-Request-Headers header in the preflight (OPTIONS) request. */
    rule1.addAllowedHeader("*");
    /* Specify the response headers that users can access from applications. */
    rule1.addExposeHeader("x-oss-test");
    /* Specify a maximum of 10 rules. */
    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 network resources. */
    ShutdownSdk();
    return 0;
}

Get cross-origin resource sharing rules

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

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

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

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

    ClientConfiguration conf;
    conf.signatureVersion = SignatureVersionType::V4;
    /* Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);
    client.SetRegion(Region);


    /* Get 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 network resources. */
    ShutdownSdk();
    return 0;
}

Delete cross-origin resource sharing rules

The following sample code provides an example on how to delete all CORS rules of a specific bucket:

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

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

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

    ClientConfiguration conf;
    conf.signatureVersion = SignatureVersionType::V4;
    /* Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);
    client.SetRegion(Region);


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

References

For the complete sample code for cross-origin resource sharing, see GitHub example.
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.