Post a photo to Tumblr with Node.js

Question

I'm trying to post a canvas generated image (like "data:image/png;base64,iVBORw0KGgoAAAANSUh…") to Tumblr via Node.js with Tumblr.js, but I'm really having a hard time.

I registered my app on Tumblr, I have my tumblrConsumerKey, my tumblrConsumerSecret, I managed to get the Oauth to work and to post text posts without problems. My code works just fine, but when I try to post an image, everything crumbles apart.

The API documentation says that I can post with data method and that the image should be an Array (URL-encoded binary contents). At the beginning I thought that my "data:image/png;base64..." would work just fine, but it didn't. Then I tried to URI encode it, then to URI encode it and binary convert it. Neither worked. Then I found a guy that went trough the trouble of writing a js convertor specifically for Tumblr but it doesn't work either. And now I'm really stuck, I'm have ZERO ideas on how to convert my image to make it work.

Can someone here help me out or point me in the right direction? Here's my code:

var express = require('express');
var oauth = require('oauth');
var http = require('http');
var tumblr = require('tumblr.js');
 
var app = express();
 
app.set('port', process.env.PORT || 3000);
app.use(express.logger('dev'));
app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(express.errorHandler());
 
/**
 * These four variables will be needed to use tumblr.js
 */
var tumblrConsumerKey = "mytumblrConsumerKey",
    tumblrConsumerSecret = "mytumblrConsumerSecret",
    tumblrOauthAccessToken = undefined,
    tumblrOauthAccessTokenSecret = undefined,
    // Temporary request tokens
    oauthRequestToken,
    oauthRequestTokenSecret;
 
 
/**
 * This object will be used for OAuth
 **/
var consumer = new oauth.OAuth(
    "http://www.tumblr.com/oauth/request_token",
    "http://www.tumblr.com/oauth/access_token",
    tumblrConsumerKey,
    tumblrConsumerSecret,
    "1.0A",
    "http://localhost:3000/auth/callback",
    "HMAC-SHA1"
);
 
app.get('/', function (req, res) {
    if (!tumblrOauthAccessToken || !tumblrOauthAccessTokenSecret) {
        res.redirect('/auth/request');
    }
    res.send('You are logged in and ready to go');
});
 
 
app.get('/auth/request', function (req, res) {
    consumer.getOAuthRequestToken(function(error, oauthToken, oauthTokenSecret){
        if (error) {
            res.send("Error getting OAuth request token: " + error, 500);
        } else {
            oauthRequestToken = oauthToken,
            oauthRequestTokenSecret = oauthTokenSecret;
 
            res.redirect("http://www.tumblr.com/oauth/authorize?oauth_token=" + oauthRequestToken);
        }
    });
});
 
 
app.get('/auth/callback', function (req, res) {
    consumer.getOAuthAccessToken(oauthRequestToken, oauthRequestTokenSecret, req.query.oauth_verifier, function(error, _oauthAccessToken, _oauthAccessTokenSecret) {
        if (error) {
            res.send("Error getting OAuth access token: " + error, 500);
        } else {
            tumblrOauthAccessToken = _oauthAccessToken;
            tumblrOauthAccessTokenSecret = _oauthAccessTokenSecret;
 
            res.send("You are signed in. <a href='/test'>Post the image</a>");
              
        }
    });
});
 
 
app.get('/test', function (req, res) {
    if (!tumblrOauthAccessToken || !tumblrOauthAccessTokenSecret) {
        res.redirect('/auth/request');
    }
 
    var client = tumblr.createClient({
        consumer_key: tumblrConsumerKey,
        consumer_secret: tumblrConsumerSecret,
        token: tumblrOauthAccessToken,
        token_secret: tumblrOauthAccessTokenSecret
    });
    
    /**
     * Post your stuff here
     **/
     
     var img = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==";
     
     
 client.photo('myTumblrName', { source: img }, function (err, resp) {
  console.log(err);
 });
     
});
 
 
http.createServer(app).listen(app.get('port'), function () {
    console.log('Express server listening on port ' + app.get('port'));
});