DataFlex

Get GMail SMTP OAuth2 Access Token for Desktop App

See more OAuth2 Examples

This example show how to obtain a Gmail SMTP OAuth2 access token from a desktop application or script, enabling the use of XOAUTH2 authentication. DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoOauth2
    String sUrl
    Integer iNumMsWaited
    Handle hoSbJson
    String sTemp1
    Integer iTemp1
    Boolean bTemp1

    Move False To iSuccess

    // To further clarify, see OAuth 2.0 Authorization Flow

    Get Create (RefClass(cComChilkatOAuth2)) To hoOauth2
    If (Not(IsComObjectCreated(hoOauth2))) Begin
        Send CreateComObject of hoOauth2
    End

    // For Google OAuth2, set the listen port equal to the port used
    // in the Authorized Redirect URL for the Client ID.
    // For example, in this case the Authorized Redirect URL would be http://localhost:55568/
    // Your app should choose a port not likely not used by any other application.
    Set ComListenPort Of hoOauth2 To 55568

    Set ComAuthorizationEndpoint Of hoOauth2 To "https://accounts.google.com/o/oauth2/v2/auth"
    Set ComTokenEndpoint Of hoOauth2 To "https://www.googleapis.com/oauth2/v4/token"

    // Replace these with actual values.
    Set ComClientId Of hoOauth2 To "GOOGLE-CLIENT-ID"
    Set ComClientSecret Of hoOauth2 To "GOOGLE-CLIENT-SECRET"

    // To use Gmail's OAuth2 for sending emails via the SMTP protocol, you need to request the https://mail.google.com/ scope. 
    // See About GMail SMTP OAuth2 Scopes
    Set ComScope Of hoOauth2 To "https://mail.google.com/"

    // Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
    Get ComStartAuth Of hoOauth2 To sUrl
    Get ComLastMethodSuccess Of hoOauth2 To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoOauth2 To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Launch the default browser on the system and navigate to the url.
    // The LaunchBrowser method was added in Chilkat v10.1.2.
    Get ComLaunchBrowser Of hoOauth2 sUrl To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoOauth2 To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Wait for the user to approve or deny authorization in the browser.
    Move 0 To iNumMsWaited
    While ((iNumMsWaited < 90000) And ((ComAuthFlowState(hoOauth2)) < 3))
        Send ComSleepMs To hoOauth2 100
        Move (iNumMsWaited + 100) To iNumMsWaited
    Loop

    // 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.

    Get ComAuthFlowState Of hoOauth2 To iTemp1
    If (iTemp1 < 3) Begin
        Get ComCancel Of hoOauth2 To iSuccess
        Showln "No response from the browser!"
        Procedure_Return
    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.

    Get ComAuthFlowState Of hoOauth2 To iTemp1
    If (iTemp1 = 5) Begin
        Showln "OAuth2 failed to complete."
        Get ComFailureInfo Of hoOauth2 To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComAuthFlowState Of hoOauth2 To iTemp1
    If (iTemp1 = 4) Begin
        Showln "OAuth2 authorization was denied."
        Get ComAccessTokenResponse Of hoOauth2 To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComAuthFlowState Of hoOauth2 To iTemp1
    If (iTemp1 <> 3) Begin
        Get ComAuthFlowState Of hoOauth2 To iTemp1
        Showln "Unexpected AuthFlowState:" iTemp1
        Procedure_Return
    End

    // Save the full JSON access token response to a file.
    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbJson
    If (Not(IsComObjectCreated(hoSbJson))) Begin
        Send CreateComObject of hoSbJson
    End
    Get ComAccessTokenResponse Of hoOauth2 To sTemp1
    Get ComAppend Of hoSbJson sTemp1 To iSuccess
    Get ComWriteFile Of hoSbJson "qa_data/tokens/_gmailSmtp.json" "utf-8" False To iSuccess

    // The saved JSON response looks like this:

    // 	{
    // 	 "access_token": "ya39.Ci-XA_C5bGgRDC3UaD-h0_NeL-DVIQnI2gHtBBBHkZzrwlARkwX6R3O0PCDEzRlfaQ",
    // 	 "token_type": "Bearer",
    // 	 "expires_in": 3600,
    // 	 "refresh_token": "1/r_2c_7jddspcdfesrrfKqfXtqo08D6Q-gUU0DsdfVMsx0c"
    // 	}
    // 
    Showln "OAuth2 authorization granted!"
    Get ComAccessToken Of hoOauth2 To sTemp1
    Showln "Access Token = " sTemp1


End_Procedure