(Classic ASP) IMAP Auto-Refresh Office365 Access Token

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Demonstrates how to automatically recover from an expired access token when OAuth2 authentication fails in the IMAP protocol. If the server responds with "NO AUTHENTICATE failed.", then we refresh the access token and retry.

Chilkat ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

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' An Office365 OAuth2 access token must first be obtained prior
' to running this code.

' Getting the OAuth2 access token for the 1st time requires the O365 account owner's 
' interactive authorizaition via a web browser.  Afterwards, the access token
' can be repeatedly refreshed automatically.

' See the following examples for getting and refreshing an OAuth2 access token

' Get Office365 SMTP/IMAP/POP3 OAuth2 Access Token
' Refresh Office365 SMTP/IMAP/POP3 OAuth2 Access Token

' First get our previously obtained OAuth2 access token.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.JsonObject")
set jsonToken = Server.CreateObject("Chilkat.JsonObject")
success = jsonToken.LoadFile("qa_data/tokens/office365.json")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( "Failed to open the office365 OAuth JSON file.") & "</pre>"
    Response.End
End If

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Imap")
set imap = Server.CreateObject("Chilkat.Imap")

imap.Ssl = 1
imap.Port = 993

' Connect to the Office365 IMAP server.
success = imap.Connect("outlook.office365.com")
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( imap.LastErrorText) & "</pre>"
    Response.End
End If

' Use OAuth2 authentication.
imap.AuthMethod = "XOAUTH2"

' Login using our username (i.e. email address) and the access token for the password.
success = imap.Login("OFFICE365_EMAIL_ADDRESS",jsonToken.StringOf("access_token"))
If (success <> 1) Then
    loginLastErrorText = imap.LastErrorText

    ' If we're still connected to the mail server, then it means the server sent a non-success response,
    ' Such as:  NO AUTHENTICATE failed.
    If (imap.IsConnected() = 1) Then

        ' Refresh the OAuth2 access token, and if successful, save the new (refreshed) access token and try authenticating again.
        ' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.OAuth2")
        set oauth2 = Server.CreateObject("Chilkat.OAuth2")

        ' Use your actual Directory (tenant) ID instead of "112d7ed6-71bf-4eba-a866-738364321bfc"
        oauth2.TokenEndpoint = "https://login.microsoftonline.com/112d7ed6-71bf-4eba-a866-738364321bfc/oauth2/v2.0/token"

        ' Replace these with your Azure App Registration's actual values.
        oauth2.ClientId = "CLIENT_ID"
        oauth2.ClientSecret = "CLIENT_SECRET"

        ' Get the "refresh_token"
        oauth2.RefreshToken = jsonToken.StringOf("refresh_token")

        ' Send the HTTP POST to refresh the access token..
        success = oauth2.RefreshAccessToken()
        If (success <> 1) Then
            Response.Write "<pre>" & Server.HTMLEncode( oauth2.LastErrorText) & "</pre>"
            Response.End
        End If

        Response.Write "<pre>" & Server.HTMLEncode( "New access token: " & oauth2.AccessToken) & "</pre>"
        Response.Write "<pre>" & Server.HTMLEncode( "New refresh token: " & oauth2.RefreshToken) & "</pre>"

        ' Update the JSON with the new tokens.
        success = jsonToken.UpdateString("access_token",oauth2.AccessToken)
        success = jsonToken.UpdateString("refresh_token",oauth2.RefreshToken)

        ' Save the new JSON access token response to a file.
        ' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.StringBuilder")
        set sbJson = Server.CreateObject("Chilkat.StringBuilder")
        jsonToken.EmitCompact = 0
        success = jsonToken.EmitSb(sbJson)
        success = sbJson.WriteFile("qa_data/tokens/office365.json","utf-8",0)

        Response.Write "<pre>" & Server.HTMLEncode( "New Access Token = " & oauth2.AccessToken) & "</pre>"

        ' Retry the login.
        success = imap.Login("OFFICE365_EMAIL_ADDRESS",jsonToken.StringOf("access_token"))
        If (success = 0) Then
            Response.Write "<pre>" & Server.HTMLEncode( imap.LastErrorText) & "</pre>"
            Response.End
        End If

    Else
        ' Show the last error text for the call to Login
        Response.Write "<pre>" & Server.HTMLEncode( loginLastErrorText) & "</pre>"
        Response.End
    End If

Else
    Response.Write "<pre>" & Server.HTMLEncode( "O365 OAuth authentication is successful.") & "</pre>"
End If

' Do something...
success = imap.SelectMailbox("Inbox")
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( imap.LastErrorText) & "</pre>"
    Response.End
End If

' Your application can continue to do other things in the IMAP session....

' When finished, logout and close the connection.
success = imap.Logout()
success = imap.Disconnect()

Response.Write "<pre>" & Server.HTMLEncode( "Finished.") & "</pre>"

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