(Visual FoxPro) POP3 Auto-Refresh Office365 Access Token

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Demonstrates how to automatically recover from an expired OAuth2 access token when OAuth2 authentication fails in the POP3 protocol. If the server responds with "-ERR Authentication failure: unknown user name or bad password.", then we refresh the access token and retry.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loMailman
LOCAL loJsonToken
LOCAL lnSuccess
LOCAL loOauth2
LOCAL loSbJson
LOCAL lnNumEmails

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.MailMan')
loMailman = CreateObject('Chilkat.MailMan')

loMailman.MailHost = "outlook.office365.com"
loMailman.MailPort = 995
loMailman.PopSsl = 1

* Use your O365 email address here.
loMailman.PopUsername = "OFFICE365_EMAIL_ADDRESS"

* When using OAuth2 authentication, leave the password empty.
loMailman.PopPassword = ""

* Load our previously obtained OAuth2 access token.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJsonToken = CreateObject('Chilkat.JsonObject')
lnSuccess = loJsonToken.LoadFile("qa_data/tokens/office365.json")
IF (lnSuccess = 0) THEN
    ? loJsonToken.LastErrorText
    RELEASE loMailman
    RELEASE loJsonToken
    CANCEL
ENDIF

loMailman.OAuth2AccessToken = loJsonToken.StringOf("access_token")

* Make the TLS connection to the outlook.office365.com POP3 server.
lnSuccess = loMailman.Pop3Connect()
IF (lnSuccess <> 1) THEN
    ? loMailman.LastErrorText
    RELEASE loMailman
    RELEASE loJsonToken
    CANCEL
ENDIF

* Authenticate using XOAUTH2
lnSuccess = loMailman.Pop3Authenticate()
IF (lnSuccess <> 1) THEN
    * If we're still connected to the mail server, then it means the server sent a non-success response,
    * Such as:  -ERR Authentication failure: unknown user name or bad password.
    IF (loMailman.IsPop3Connected = 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')
        loOauth2 = CreateObject('Chilkat.OAuth2')

        * Use your actual Directory (tenant) ID instead of "112d7ed6-71bf-4eba-a866-738364321bfc"
        loOauth2.TokenEndpoint = "https://login.microsoftonline.com/112d7ed6-71bf-4eba-a866-738364321bfc/oauth2/v2.0/token"

        * Replace these with your Azure App Registration's actual values.
        loOauth2.ClientId = "CLIENT_ID"
        loOauth2.ClientSecret = "CLIENT_SECRET"

        * Get the "refresh_token"
        loOauth2.RefreshToken = loJsonToken.StringOf("refresh_token")

        * Send the HTTP POST to refresh the access token..
        lnSuccess = loOauth2.RefreshAccessToken()
        IF (lnSuccess <> 1) THEN
            ? loOauth2.LastErrorText
            RELEASE loMailman
            RELEASE loJsonToken
            RELEASE loOauth2
            CANCEL
        ENDIF

        ? "New access token: " + loOauth2.AccessToken
        ? "New refresh token: " + loOauth2.RefreshToken

        * Update the JSON with the new tokens.
        loJsonToken.UpdateString("access_token",loOauth2.AccessToken)
        loJsonToken.UpdateString("refresh_token",loOauth2.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')
        loSbJson = CreateObject('Chilkat.StringBuilder')
        loJsonToken.EmitCompact = 0
        loJsonToken.EmitSb(loSbJson)
        loSbJson.WriteFile("qa_data/tokens/office365.json","utf-8",0)

        ? "New Access Token = " + loOauth2.AccessToken

        * Update the mailman with the new access token.
        loMailman.OAuth2AccessToken = loOauth2.AccessToken

        * Retry the authentication.
        lnSuccess = loMailman.Pop3Authenticate()
        IF (lnSuccess = 0) THEN
            ? loMailman.LastErrorText
            RELEASE loMailman
            RELEASE loJsonToken
            RELEASE loOauth2
            RELEASE loSbJson
            CANCEL
        ENDIF

    ELSE
        ? loMailman.LastErrorText
        RELEASE loMailman
        RELEASE loJsonToken
        RELEASE loOauth2
        RELEASE loSbJson
        CANCEL
    ENDIF

ENDIF

* Find out how many emails are on the server..
lnNumEmails = loMailman.CheckMail()
IF (lnNumEmails < 0) THEN
    ? loMailman.LastErrorText
    RELEASE loMailman
    RELEASE loJsonToken
    RELEASE loOauth2
    RELEASE loSbJson
    CANCEL
ENDIF

* Examine the POP3 session log:
? loMailman.Pop3SessionLog

* The POP3 session log will look something like this:

* **** Connected to outlook.office365.com:995
* < +OK The Microsoft Exchange POP3 service is ready. [QwBIADIAUABSADEANgBDAEEAMAAwADEAMgAuAG4AYQBtAHAAcgBkADEANgAuAHAAcgBvAGQALgBvAHUAdABsAG8AbwBrAC4AYwBvAG0A]
* > AUTH XOAUTH2
* < + 
* > <base64 string in XOAUTH2 format>
* < -ERR Authentication failure: unknown user name or bad password.
* > AUTH XOAUTH2
* < + 
* > <base64 string in XOAUTH2 format>
* < +OK User successfully authenticated.
* > STAT
* < +OK 248 46637086

* End the POP3 session and close the connection to the GMail server.
lnSuccess = loMailman.Pop3EndSession()
IF (lnSuccess <> 1) THEN
    ? loMailman.LastErrorText
    RELEASE loMailman
    RELEASE loJsonToken
    RELEASE loOauth2
    RELEASE loSbJson
    CANCEL
ENDIF

? "Finished."

RELEASE loMailman
RELEASE loJsonToken
RELEASE loOauth2
RELEASE loSbJson