Delphi DLL

OAuth2 using an HTTP Proxy (for a Desktop Application)

See more OAuth2 Examples

Shows how to send OAuth2 communications through an HTTP proxy in a desktop application, using Microsoft Graph as an example. This method applies to all OAuth2 applications. Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, CkDateTime, OAuth2, FileAccess, JsonObject, Socket;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
socket: HCkSocket;
oauth2: HCkOAuth2;
url: PWideChar;
numMsWaited: Integer;
json: HCkJsonObject;
dtExpire: HCkDateTime;
fac: HCkFileAccess;

begin
success := False;

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

// To use an HTTP proxy with OAuth2, create a Chilkat socket object and specify the details.
socket := CkSocket_Create();
// Use your HTTP proxy server domain or IP address.
CkSocket_putHttpProxyHostname(socket,'myproxyserver.com');
// Change this to the listening port of your HTTP proxy server (if necessary)
CkSocket_putHttpProxyPort(socket,808);
// Specify login/password if needed.
CkSocket_putHttpProxyUsername(socket,'myProxyLogin');
CkSocket_putHttpProxyPassword(socket,'myProxyPassword');
CkSocket_putHttpProxyForHttp(socket,True);

oauth2 := CkOAuth2_Create();

// We don't need to connect the socket beforehand.
// Just tell oauth2 to use the socket which has the HTTP proxy properties.
success := CkOAuth2_UseConnection(oauth2,socket);

// This should be the port in the localhost callback URL for your app.  
// The callback URL would look like "http://localhost:3017/" if the port number is 3017.
CkOAuth2_putListenPort(oauth2,3017);

CkOAuth2_putAuthorizationEndpoint(oauth2,'https://login.microsoftonline.com/common/oauth2/v2.0/authorize');
CkOAuth2_putTokenEndpoint(oauth2,'https://login.microsoftonline.com/common/oauth2/v2.0/token');

// Replace these with actual values.
CkOAuth2_putClientId(oauth2,'MICROSOFT-GRAPH-CLIENT-ID');
// This is your app password:
CkOAuth2_putClientSecret(oauth2,'MICROSOFT-GRAPH-CLIENT-SECRET');

CkOAuth2_putCodeChallenge(oauth2,False);
// Provide a SPACE separated list of scopes.
// See https://developer.microsoft.com/en-us/graph/docs/authorization/permission_scopes 

// Important: To get a refresh token in the final response, you have to ask for "offline_access" scope
CkOAuth2_putScope(oauth2,'openid profile offline_access user.readwrite mail.readwrite mail.send files.readwrite');

// Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
url := CkOAuth2__startAuth(oauth2);
if (CkOAuth2_getLastMethodSuccess(oauth2) <> True) then
  begin
    Memo1.Lines.Add(CkOAuth2__lastErrorText(oauth2));
    Exit;
  end;

Memo1.Lines.Add('url = ' + url);

// Launch the default browser on the system and navigate to the url.
// The LaunchBrowser method was added in Chilkat v10.1.2.
success := CkOAuth2_LaunchBrowser(oauth2,url);
if (success = False) then
  begin
    Memo1.Lines.Add(CkOAuth2__lastErrorText(oauth2));
    Exit;
  end;

// Wait for the user to approve or deny authorization in the browser.
numMsWaited := 0;
while (numMsWaited < 90000) and (CkOAuth2_getAuthFlowState(oauth2) < 3) do
  begin
    CkOAuth2_SleepMs(oauth2,100);
    numMsWaited := numMsWaited + 100;
  end;

// If the browser does not respond within the specified time, AuthFlowState will be:
// 
// 1: Waiting for Redirect - The OAuth2 background thread is waiting for the browser's redirect request.
// 2: Waiting for Final Response - The thread is awaiting the final access token response.
// In either case, cancel the background task initiated by StartAuth.

if (CkOAuth2_getAuthFlowState(oauth2) < 3) then
  begin
    CkOAuth2_Cancel(oauth2);
    Memo1.Lines.Add('No response from the browser!');
    Exit;
  end;

// Check AuthFlowState to determine if authorization was granted, denied, or failed:
// 
// 3: Success - OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
// 4: Access Denied - OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
// 5: Failure - OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

if (CkOAuth2_getAuthFlowState(oauth2) = 5) then
  begin
    Memo1.Lines.Add('OAuth2 failed to complete.');
    Memo1.Lines.Add(CkOAuth2__failureInfo(oauth2));
    Exit;
  end;

if (CkOAuth2_getAuthFlowState(oauth2) = 4) then
  begin
    Memo1.Lines.Add('OAuth2 authorization was denied.');
    Memo1.Lines.Add(CkOAuth2__accessTokenResponse(oauth2));
    Exit;
  end;

if (CkOAuth2_getAuthFlowState(oauth2) <> 3) then
  begin
    Memo1.Lines.Add('Unexpected AuthFlowState:' + IntToStr(CkOAuth2_getAuthFlowState(oauth2)));
    Exit;
  end;

Memo1.Lines.Add('OAuth2 authorization granted!');
Memo1.Lines.Add('Access Token = ' + CkOAuth2__accessToken(oauth2));

// Get the full JSON response:
json := CkJsonObject_Create();
CkJsonObject_Load(json,CkOAuth2__accessTokenResponse(oauth2));
CkJsonObject_putEmitCompact(json,False);

// The JSON response looks like this:

// {
//   "token_type": "Bearer",
//   "scope": "User.Read Mail.ReadWrite Mail.Send",
//   "expires_in": 3600,
//   "ext_expires_in": 0,
//   "access_token": "EwBAA8l6B...",
//   "refresh_token": "MCRMdbe...",
//   "id_token": "eyJ0eXA..."
// }

// If an "expires_on" member does not exist, then add the JSON member by
// getting the current system date/time and adding the "expires_in" seconds.
// This way we'll know when the token expires.
if (CkJsonObject_HasMember(json,'expires_on') <> True) then
  begin
    dtExpire := CkDateTime_Create();
    CkDateTime_SetFromCurrentSystemTime(dtExpire);
    CkDateTime_AddSeconds(dtExpire,CkJsonObject_IntOf(json,'expires_in'));
    CkJsonObject_AppendString(json,'expires_on',CkDateTime__getAsUnixTimeStr(dtExpire,False));
  end;

Memo1.Lines.Add(CkJsonObject__emit(json));

// Save the JSON to a file for future requests.
fac := CkFileAccess_Create();
CkFileAccess_WriteEntireTextFile(fac,'qa_data/tokens/microsoftGraph.json',CkJsonObject__emit(json),'utf-8',False);

CkSocket_Dispose(socket);
CkOAuth2_Dispose(oauth2);
CkJsonObject_Dispose(json);
    CkDateTime_Dispose(dtExpire);
CkFileAccess_Dispose(fac);

end;