Pascal (Lazarus/Delphi)

Azure Storage: CORS Preflight Blob Request

See more Azure Cloud Storage Examples

Azure Storage Blob Service REST API: Sample code to send a CORS pre-flight blob request. Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Rest,
  Chilkat.AuthAzureStorage;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  rest: TRest;
  bTls: Boolean;
  port: Integer;
  bAutoReconnect: Boolean;
  azAuth: TAuthAzureStorage;
  responseStr: string;

begin
  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.

  rest := TRest.Create;

  //  Connect to the Azure Storage Blob Service
  bTls := True;
  port := 443;
  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) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  //  Provide Azure Cloud credentials for the REST call.
  azAuth := TAuthAzureStorage.Create;
  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.)
  responseStr := rest.FullRequestNoBody('OPTIONS','/test');
  if (rest.LastMethodSuccess <> True) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  //  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) then
    begin
      //  Examine the request/response to see what happened.
      WriteLn('response status code = ' + rest.ResponseStatusCode);
      WriteLn('response status text = ' + rest.ResponseStatusText);
      WriteLn('response header: ' + rest.ResponseHeader);
      WriteLn('response body (if any): ' + responseStr);
      WriteLn('---');
      WriteLn('LastRequestStartLine: ' + rest.LastRequestStartLine);
      WriteLn('LastRequestHeader: ' + rest.LastRequestHeader);
      Exit;
    end;

  WriteLn('Success: Preflight Blob Request is accepted.');


  rest.Free;
  azAuth.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.