Lua Requires Chilkat v10.1.2+

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. Lua

    -- In the following call to loadlib, change the path (./chilkat.dll) to the relative or absolute directory where the chilkat.dll, chilkat.so, or chilkat.dylib is located.
    chilkat = assert(package.loadlib("./chilkat.dll", "luaopen_chilkat"))()
    print(chilkat._VERSION)

    local success = false

    --  To further clarify, see OAuth 2.0 Authorization Flow

    local oauth2 = chilkat.newOAuth2{}

    --  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.
    oauth2:setListenPort(55568)

    oauth2:setAuthorizationEndpoint("https://accounts.google.com/o/oauth2/v2/auth")
    oauth2:setTokenEndpoint("https://www.googleapis.com/oauth2/v4/token")

    --  Replace these with actual values.
    oauth2:setClientId("GOOGLE-CLIENT-ID")
    oauth2:setClientSecret("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
    oauth2:setScope("https://mail.google.com/")

    --  Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
    local url = oauth2:StartAuth()
    if oauth2:LastMethodSuccess() ~= true then
        print(oauth2:LastErrorText())

    end

    --  Launch the default browser on the system and navigate to the url.
    --  The LaunchBrowser method was added in Chilkat v10.1.2.
    success = oauth2:LaunchBrowser(url)
    if success == false then
        print(oauth2:LastErrorText())

    end

    --  Wait for the user to approve or deny authorization in the browser.
    local numMsWaited = 0
    while (numMsWaited < 90000) && (oauth2:AuthFlowState() < 3) do
        oauth2:SleepMs(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 oauth2:AuthFlowState() < 3 then
        oauth2:Cancel()
        print("No response from the browser!")

    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 oauth2:AuthFlowState() == 5 then
        print("OAuth2 failed to complete.")
        print(oauth2:FailureInfo())

    end

    if oauth2:AuthFlowState() == 4 then
        print("OAuth2 authorization was denied.")
        print(oauth2:AccessTokenResponse())

    end

    if oauth2:AuthFlowState() ~= 3 then
        print("Unexpected AuthFlowState:", oauth2:AuthFlowState())

    end

    --  Save the full JSON access token response to a file.
    local sbJson = chilkat.newStringBuilder{}
    sbJson:Append(oauth2:AccessTokenResponse())
    sbJson:WriteFile("qa_data/tokens/_gmailSmtp.json","utf-8",false)

    --  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"
    --  	}
    --  
    print("OAuth2 authorization granted!")
    print("Access Token = ", oauth2:AccessToken())