PureBasic

Auto-Refresh O365 Access Token when Sending Email

See more Office365 Examples

Demonstrates how to automatically recover from an expired access token when sending email from smtp.office365.com using OAuth2 authentication. If the server responds with an error indicating that the access token is expired, then we refresh the access token and retry. PureBasic

IncludeFile "CkOAuth2.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkEmail.pb"
IncludeFile "CkMailMan.pb"

Procedure ChilkatExample()

    success.i = 0

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

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

    ; First get our previously obtained OAuth2 access token.
    jsonToken.i = CkJsonObject::ckCreate()
    If jsonToken.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkJsonObject::ckLoadFile(jsonToken,"qa_data/tokens/office365.json")

    mailman.i = CkMailMan::ckCreate()
    If mailman.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkMailMan::setCkSmtpHost(mailman, "smtp.office365.com")
    CkMailMan::setCkSmtpPort(mailman, 587)
    CkMailMan::setCkStartTLS(mailman, 1)

    ; Use your Office365 email address for the SmtpUsername.
    CkMailMan::setCkSmtpUsername(mailman, "OFFICE365_EMAIL_ADDRESS")
    CkMailMan::setCkOAuth2AccessToken(mailman, CkJsonObject::ckStringOf(jsonToken,"access_token"))

    ; Create a new email object
    email.i = CkEmail::ckCreate()
    If email.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkEmail::setCkSubject(email, "This is a test")
    CkEmail::setCkBody(email, "This is a test")
    CkEmail::setCkFrom(email, "MY_NAME <OFFICE365_EMAIL_ADDRESS>")
    success = CkEmail::ckAddTo(email,"John Doe","somebody@example.com")

    ; Call SendEmail to connect to the SMTP server and send.
    ; The connection (i.e. session) to the SMTP server remains
    ; open so that subsequent SendEmail calls may use the
    ; same connection.  
    success = CkMailMan::ckSendEmail(mailman,email)
    If success = 1
        Debug "Mail Sent!"
        CkJsonObject::ckDispose(jsonToken)
        CkMailMan::ckDispose(mailman)
        CkEmail::ckDispose(email)
        ProcedureReturn
    EndIf

    ; If we fall through to here, it means something failed.
    ; If we failed because of an invalid or expired access token, we should get this SMTP status code and error message:
    ;    response: 535 5.7.3 Authentication unsuccessful [CH2PR19CA0023.namprd19.prod.outlook.com]
    ;    status code: 535
    If CkMailMan::ckLastSmtpStatus(mailman) <> 535
        Debug CkMailMan::ckLastErrorText(mailman)
        CkJsonObject::ckDispose(jsonToken)
        CkMailMan::ckDispose(mailman)
        CkEmail::ckDispose(email)
        ProcedureReturn
    EndIf

    ; If we get here, it means the SMTP status code equaled 535, which is an authentication failure.
    ; Let's refresh the access token, and then retry..

    oauth2.i = CkOAuth2::ckCreate()
    If oauth2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Update to use your token endpoint.
    ; In the Azure Portal, in "App registrations", go to "Endpoints" (located to the right of the "+ New registration" link.)
    ;    Find your endpoint for the "OAuth 2.0 token endpoint (v2)"
    ;    See Office365 OAuth2 Endpoints

    CkOAuth2::setCkTokenEndpoint(oauth2, "https://login.microsoftonline.com/xxxxxxxxxx-71bf-4ebe-a866-738364321bf2/oauth2/v2.0/token")

    ; Replace these with actual values.
    CkOAuth2::setCkClientId(oauth2, "CLIENT_ID")
    CkOAuth2::setCkClientSecret(oauth2, "CLIENT_SECRET")

    ; Get the "refresh_token"
    CkOAuth2::setCkRefreshToken(oauth2, CkJsonObject::ckStringOf(jsonToken,"refresh_token"))

    ; Send the HTTP POST to refresh the access token..
    success = CkOAuth2::ckRefreshAccessToken(oauth2)
    If success <> 1
        Debug CkOAuth2::ckLastErrorText(oauth2)
        CkJsonObject::ckDispose(jsonToken)
        CkMailMan::ckDispose(mailman)
        CkEmail::ckDispose(email)
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    Debug "New access token: " + CkOAuth2::ckAccessToken(oauth2)
    Debug "New refresh token: " + CkOAuth2::ckRefreshToken(oauth2)

    ; Update the JSON with the new tokens.
    CkJsonObject::ckUpdateString(jsonToken,"access_token",CkOAuth2::ckAccessToken(oauth2))
    CkJsonObject::ckUpdateString(jsonToken,"refresh_token",CkOAuth2::ckRefreshToken(oauth2))

    ; Save the new JSON access token response to a file.
    sbJson.i = CkStringBuilder::ckCreate()
    If sbJson.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::setCkEmitCompact(jsonToken, 0)
    CkJsonObject::ckEmitSb(jsonToken,sbJson)
    CkStringBuilder::ckWriteFile(sbJson,"qa_data/tokens/office365.json","utf-8",0)

    Debug "OAuth2 authorization granted!"
    Debug "New Access Token = " + CkOAuth2::ckAccessToken(oauth2)

    ; -------------------------------------------------
    ; Retry the SMTP send using the refreshed access token.

    Debug "Retrying the send using the refreshed access token."

    CkMailMan::setCkOAuth2AccessToken(mailman, CkOAuth2::ckAccessToken(oauth2))

    success = CkMailMan::ckSendEmail(mailman,email)
    If success = 0
        Debug CkMailMan::ckLastErrorText(mailman)
        CkJsonObject::ckDispose(jsonToken)
        CkMailMan::ckDispose(mailman)
        CkEmail::ckDispose(email)
        CkOAuth2::ckDispose(oauth2)
        CkStringBuilder::ckDispose(sbJson)
        ProcedureReturn
    EndIf

    success = CkMailMan::ckCloseSmtpConnection(mailman)
    If success <> 1
        Debug "Connection to SMTP server not closed cleanly."
    EndIf

    Debug "Email sent!"


    CkJsonObject::ckDispose(jsonToken)
    CkMailMan::ckDispose(mailman)
    CkEmail::ckDispose(email)
    CkOAuth2::ckDispose(oauth2)
    CkStringBuilder::ckDispose(sbJson)


    ProcedureReturn
EndProcedure