.NET Core C#

Azure Storage: CORS Preflight Blob Request

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Azure Storage Blob Service REST API: Sample code to send a CORS pre-flight blob request. .NET Core C#

bool success = false;

// Azure Blob Service Example: CORS Preflight Blob Request
// See also: https://msdn.microsoft.com/en-us/library/azure/dn535599.aspx

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Chilkat.Rest rest = new Chilkat.Rest();

// Connect to the Azure Storage Blob Service
bool bTls = true;
int port = 443;
bool bAutoReconnect = true;
// In this example, the storage account name is "chilkat".
success = rest.Connect("chilkat.blob.core.windows.net",port,bTls,bAutoReconnect);
if (success != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

// Provide Azure Cloud credentials for the REST call.
Chilkat.AuthAzureStorage azAuth = new Chilkat.AuthAzureStorage();
azAuth.AccessKey = "AZURE_ACCESS_KEY";
// The account name used here should match the 1st part of the domain passed in the call to Connect (above).
azAuth.Account = "chilkat";
azAuth.Scheme = "SharedKey";
azAuth.Service = "Blob";
// This causes the "x-ms-version: 2021-08-06" header to be automatically added.
azAuth.XMsVersion = "2021-08-06";
success = rest.SetAuthAzureStorage(azAuth);

// Note: The application does not need to explicitly set the following
// headers: x-ms-date, Authorization.  These headers
// are automatically set by Chilkat.

// The preflight blob request requires the following two HTTP headers.
// The Origin is the domain from which the actual request will be issued.
success = rest.AddHeader("Origin","www.contoso.com");
// The Access-Control-Request-Method is the HTTP method (such as GET, POST, PUT, etc.) of the actual request.
success = rest.AddHeader("Access-Control-Request-Method","PUT");

// The expected response is a 202 response status code with no response body.
// The name of the container or blob resource in this example is "test". (Replace "test" with your container name.)
string responseStr = rest.FullRequestNoBody("OPTIONS","/test");
if (rest.LastMethodSuccess != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

// When successful, the Azure Storage service will respond with a 200 response code,
// with no response body.

// If CORS is not enabled or no matching rule is found for the request, 
// then a 403 status code is returned, with the following status text:
// "CORS not enabled or no matching rule found for this request."
if (rest.ResponseStatusCode != 200) {
    // Examine the request/response to see what happened.
    Debug.WriteLine("response status code = " + Convert.ToString(rest.ResponseStatusCode));
    Debug.WriteLine("response status text = " + rest.ResponseStatusText);
    Debug.WriteLine("response header: " + rest.ResponseHeader);
    Debug.WriteLine("response body (if any): " + responseStr);
    Debug.WriteLine("---");
    Debug.WriteLine("LastRequestStartLine: " + rest.LastRequestStartLine);
    Debug.WriteLine("LastRequestHeader: " + rest.LastRequestHeader);
    return;
}

Debug.WriteLine("Success: Preflight Blob Request is accepted.");