"Authorization is required to perform that action" in Google Scripts with no way to give authorization

Question

I am trying to create a sort of middleware so some legacy software I am working on can consume Twitter feeds.

Since Twitter has made API 1.0 obsolete and 1.1 requires OAuth and because for this project I only have client-side scripting available to me, I opted to use a Google script to perform the OAuth negotiation:

Source: http://www.labnol.org/internet/twitter-rss-feeds/27931/

function start() {
    // Get your Twitter keys from dev.twitter.com
    var CONSUMER_KEY = "-----";
    var CONSUMER_SECRET = "----";

  // Ignore everything after this line
    initialize(CONSUMER_KEY, CONSUMER_SECRET);
}



function initialize(key, secret) {

    ScriptProperties.setProperty("TWITTER_CONSUMER_KEY", key);
    ScriptProperties.setProperty("TWITTER_CONSUMER_SECRET", secret);

    var url = ScriptApp.getService().getUrl();
    if (url) {
        connectTwitter();
        var msg = "";

        msg += "Sample RSS Feeds for Twitter\n";
        msg += "============================";
        msg += "\n\nTwitter Timeline of user @labnol";
        msg += "\n" + url + "?action=timeline&q=labnol";
        msg += "\n\nTwitter Favorites of user @labnol";
        msg += "\n" + url + "?action=favorites&q=labnol";
        msg += "\n\nTwitter List labnol/friends-in-india";
        msg += "\n" + url + "?action=list&q=labnol/friends-in-india";
        msg += "\n\nTwitter Search for New York";
        msg += "\n" + url + "?action=search&q=new+york";
        msg += "\n\nYou should replace the value of 'q' parameter in the URLs as per requirement.";
        msg += "\n\nFor help, please refer to http://www.labnol.org/?p=27931";

        MailApp.sendEmail(Session.getActiveUser().getEmail(), "Twitter RSS Feeds", msg);

    }

}

function doGet(e) {

    var a = e.parameter.action;
    var q = e.parameter.q;
    var feed;

  switch (a) {
    case "timeline":
        feed = "https://api.twitter.com/1.1/statuses/user_timeline.json?screen_name=" + q;
        break;
    case "search":
        feed = "https://api.twitter.com/1.1/search/tweets.json?q=" + encodeString(q);
        break;
    case "favorites":
        feed = "https://api.twitter.com/1.1/favorites/list.json?screen_name=" + q;
        break;
    case "list":
        var i = q.split("/");
        feed = "https://api.twitter.com/1.1/lists/statuses.json?slug=" + i[1] + "&owner_screen_name=" + i[0];
        break;
    default:
        feed = "https://api.twitter.com/1.1/statuses/user_timeline.json";
        break;
    }

    var id = Utilities.base64Encode(feed);
    var cache = CacheService.getPublicCache();
    var rss = cache.get(id);

    if ((!rss) || (rss == "undefined")) {
        rss = JSONtoRSS(feed, a, q);
        cache.put(id, rss, 3600);
    }

    return ContentService.createTextOutput(rss)
        .setMimeType(ContentService.MimeType.RSS);
}


function JSONtoRSS(json, type, key) {
    oAuth();
    var options = {
        "method": "get",
        "oAuthServiceName": "twitter",
        "oAuthUseToken": "always"
    };

  try {
        var result = UrlFetchApp.fetch(json, options);
        if (result.getResponseCode() === 200) {
            var tweets = Utilities.jsonParse(result.getContentText());

          if (type == "search")
                tweets = tweets.statuses;

          if (tweets) {
                var len = tweets.length;
                var rss = "";

              if (len) {

                    rss = '<?xml version="1.0"?><rss version="2.0">';
                    rss += ' <channel><title>Twitter ' + type + ': ' + key + '</title>';
                    rss += ' <link>' + htmlentities(json) + '</link>';
                    rss += ' <pubDate>' + new Date() + '</pubDate>';

                    for (var i = 0; i < len; i++) {

                        var sender = tweets[i].user.screen_name;
                        var tweet = htmlentities(tweets[i].text);

                        rss += "<item><title>" + sender + ": " + tweet + "</title>";
                        rss += " <author>" + tweets[i].user.name + " (@" + sender + ")</author>";
                        rss += " <pubDate>" + tweets[i].created_at + "</pubDate>";
                        rss += " <guid isPermaLink='false'>" + tweets[i].id_str + "</guid>";
                        rss += " <link>https://twitter.com/" + sender + "/statuses/" + tweets[i].id_str + "</link>";
                        rss += " <description>" + tweet + "</description>";
                        rss += "</item>";

                    }

                    rss += "</channel></rss>";

                    return rss;

                }

            }

        }

    } catch (e) {
        Logger.log(e.toString());
    }

}

function connectTwitter() {

    oAuth();

    var search = "https://api.twitter.com/1.1/application/rate_limit_status.json";

    var options = {
        "method": "get",
        "oAuthServiceName": "twitter",
        "oAuthUseToken": "always"
    };

    try {

        var result = UrlFetchApp.fetch(search, options);

    } catch (e) {
        Logger.log(e.toString());
    }
}


function encodeString(q) {

    var str = encodeURIComponent(q);
    str = str.replace(/!/g, '%21');
    str = str.replace(/\*/g, '%2A');
    str = str.replace(/\(/g, '%28');
    str = str.replace(/\)/g, '%29');
    str = str.replace(/'/g, '%27');
    return str;

}

function htmlentities(str) {

    str = str.replace(/&/g, "&amp;");
    str = str.replace(/>/g, "&gt;");
    str = str.replace(/</g, "&lt;");
    str = str.replace(/"/g, "&quot;");
    str = str.replace(/'/g, "&#039;");
    return str;

}

function oAuth() {

    var oauthConfig = UrlFetchApp.addOAuthService("twitter");
    oauthConfig.setAccessTokenUrl("https://api.twitter.com/oauth/access_token");
    oauthConfig.setRequestTokenUrl("https://api.twitter.com/oauth/request_token");
    oauthConfig.setAuthorizationUrl("https://api.twitter.com/oauth/authorize");
    oauthConfig.setConsumerKey(ScriptProperties.getProperty("TWITTER_CONSUMER_KEY"));
    oauthConfig.setConsumerSecret(ScriptProperties.getProperty("TWITTER_CONSUMER_SECRET"));

}

I have followed all of the instructions prescribed in the guide including running 'start' twice... and all that does is send my email account an email with the various URLs. When I try to access the URLs provided in the email (and the plan is to drop that URL into our legacy javascript that currently points to the Twitter 1.0 API), i get the error "Authorization is required to perform that action"

I have confirmed countless times that it is set up to "Execute the app as [me]" and "Anyone, even anonymous can access app"

I am not sure what I am missing or what got screwed up.

Answer 1

Turns out, I forgot to set up the callback URL within the Twitter app setup as specified in the source instructions. Oops!

This would explain why it wasn't working even though everything on the Google side was correct.