Develop Reference

Is there a way for Firebase Functions to protect an HTTP Endpoint using domain verification?

This is what I am trying to accomplish: I have a static website hosted with Firebase Hosting and it has a Google Forms Form. Upon clicking the submit button, I want to also send the user an email confirming that we received the form. I have written a Firebase function using an HTTP endpoint. However, that endpoint is exposed to the public. Is there any way I can protect this function? I know that we can do an auth verification with a logged-in user but I don't need the visitor to create an account to submit the form.
Thank you!

HTTP triggers deployed by the Firebase CLI are always accessible to anyone with an internet connection. The only access control is provided by Google Cloud to restrict access by IAM, which is not going to be helpful to you here.
What you should do instead is protect the endpoint to be accessible only by users signed in with Firebase Authentication. There are plenty of examples of this.
How to protect firebase Cloud Function HTTP endpoint to allow only Firebase authenticated users?
Callable functions also make it easy to check if the end user is authenticated at the time of the call.

Another possibility might be, to use req.headers["x-forwarded-for"] in order to compare the request's source IP address. It's not exactly a domain-check, because TCP/IP does not know about the DNS, but it still could be combined with a reverse lookup (or simply a list of IP address/es). It depends on the scenario (what the function actually does), because this would also work while not being authenticated. It is from where vs. who ...be aware the another Firebase hosting on the same IP address could not be told apart, but it would rule out direct access from the client-side .

How can authorization be done on a local web app using Google?

I'm developing a (so far) intra-company website that needs authentication (i.e. a limited set of users are allowed to use it). I don't want to force the users to have a new username/password pair for only this service. The company already uses company-branded Google Mail for e-mail, so every user already has a Google account: my "cunning plan" is let Google authenticate the users.
I found this great question and answer so I know (or at least have an idea) on how to verify on the server side that the web session was authenticated by Google. What I don't know: how to get that accessToken on the client side? How to detect if the user already logged in to Google, and if not, how to present the Google login form to the user?
I found the Using OAuth 2.0 to Access Google APIs documentation, but I don't quite understand this sentence: "The authorization sequence begins when your application redirects a browser to a Google URL; the URL includes query parameters that indicate the type of access being requested.". What is this URL?
I'm fairly new to web development and JavaScript, unfortunately.

"The authorization sequence begins when your application redirects a browser to a Google URL; the URL includes query parameters that indicate the type of access being requested.".
Your application will need to open a webpage which will display a consent screen to the user. This page is opened on Googles identity server not your own. You have probably seen this before.
The url is built up using the client id and redirect URI that you set up on your project in the Google developer console.
https://accounts.google.com/o/oauth2/auth?client_id={clientid}.apps.googleusercontent.com&redirect_uri=urn:ietf:wg:oauth:2.0:oob&scope=https://www.googleapis.com/auth/analytics.readonly&response_type=code
you might find this blog post interesting Google 3 Legged OAuth2 Flow

Youtube Analytics Offline Access Request when Authenticated as Brand instead of User

Apps Script keeps asking for offline permission with Youtube's API
In Google Apps Script, access to YouTube Reporting API is Forbidden
These are very similar questions however, I am logged in as the owner. The script is in the owner's drive.
My problem
I have been trying to access YouTube Analytics Reports from the Content Owner using GAS(Google Apps Script). There are two accounts a Brand account (holds the data i.e. the video content) and a User account. They both use the same credentials(email & pwd). When authorizing as the user, I get a 403(forbidden). When authorizing as the brand, I am asked to authorize offline access again and again, stopping me from ever being able to make a request.
What I've tried...
Running from Node, using OAUTH Playground tokens, and it works. But I need to stick with GAS.
Using google-script-oauth2: to hard code credentials (similarly to the Node solution) but I couldn't set the refresh token. I got a 401(invalid credentials) - I believe the bearer token was expired
Setting up credentials for and enabling both youtube and youtube analytics APIs
scrapping old credentials and attaching a new project to GAS
removing auth in privacy settings and re-authenticating
toggling a use unsafe scripts option and repeating step 3
switching between contentOwner and channel parameters for the ids param
NOTE: I have two OAUTH2 credentials app script and the web client both are set as Web Applications.
GAS Code
function test(){
YouTubeAnalytics.Reports.query("contentOwner==id", "2017-03-01", "2017-03-31", "likes");
}
Final Thoughts
I believe there is a disconnect between the Brand and the user such that the brand is not given the same access to the OAUTH 2 token. Therefore, it never generates a refresh token. So, the request sees that I am the authorized channel owner but it can't finish the OAUTH flow.
If this is true, why, and how do I fix it? If not, what do you think could be the error?
I just realized the script is in the user account and not the brand account. Would that affect the validation?
Also on the actual channel, the user is listed as the Primary Owner.

I think the problem has to do with Apps Script's limited OAuth scopes. Open the Script Editor and navigate to Resources->Advanced Google Services and you'll see that YouTube's Reporting API is not supported. However, you can get around this by using Service Accounts. They are a pain to set up but once you get them up and running you can explicitly request the scopes required to make authorized calls on the API from GAS.
Here are a few links to get you started:
Using OAuth 2.0 for Server to Server Applications
OAuth 2.0 Scopes for Google APIs
For Using OAuth 2.0 for Server to Server Applications you'll want to scroll down to the section titled Preparing to make an authorized API call. Select the HTTP/REST tab and it should walk you thru the steps you'll need to setup a service account (you'll need to create a JWT - JSON Web Token from your Google console for use in your API calls). You'll also need to retrieve the needed OAuth scope urls for YouTube's Reporting API from the second link provided. Once you're all set up you'll be able to make requests to the API directly from Apps Script using URLFetchApp. Best of luck with your project.
One more thing. Check out Google's API Explorer listing for the YouTube Reporting API. You can get the URL endpoints (and request methods) you'll need to use in your UrlFetchApp calls by playing with the Explorer.
UPDATE 4/28/2017
Also be sure to enable the YouTube Reporting API from your Google API Console.

Are Javascript Instagram applications that authenticate with client_id allowed?

A few web-based applications I maintain have been using JavaScript on the page to fetch posts from Instagram* through their API, only authenticating with a client_id. With the Instagram API changes recently (applications are sandboxed until approved) this no longer works.
Is this kind of application allowed by Instagram? Or is it considered a security risk to expose the client_id in the Javascript that performs the request? If it matters, the application is for internal use by a few employees only.
* Specifically, the 10 last posts from a fixed user.

All instagram API endpoints now require a valid access_token rather than client_id. The search endpoint is an example of one that didn't previously require an access_token. You can find this in the Change logs
All API endpoints require a valid access_token
All API endpoints require a specific permission scope granted by the user
You can authorise your own account and grab the last 20 posts, but for any more than that you will need to submit your app for review

Try to create a new app.. My app was deleted instead of going to sandbox mode.
As you need 10 last posts, this should work on sandbox mode.
Content Display for Personal Website. If you are a developer and you want to showcase Instagram content on a website, then you do not need to submit your app for review. By using a client in sandbox mode, you will still be able to access the last 20 media of any sandbox user that grants you permission.

Read Outlook messages with JS app?

I would like to access a user's Outlook emails with my javascript app.
Google makes this very easy using Oauth and it's restful Gmail API.
I have tried researching similar options for Outlook, but I can't seem to find a good way to authenticate a user with Oauth 2.0, then access their message inbox.
Are there any Microsoft technology experts that can point me to some resources to get started here?
I am restricted to using only client-side code as this is for a phonegap mobile application. I would like to continue using oauth-io but I realize that may not be an option.

I was having a hard time tracking down the process for getting the emails as well. Anyway, first things first, you'd need to register your app for OAuth here. This page describes some more details on the registration and also how to access the needed API.
Although you can do the calls via Javascript, there are some security issues because you'd eventually need to send your client secret. It might be safer to do some parts in the server side.
First step is getting the user to login and retrieving the access token.
https://login.live.com/oauth20_authorize.srf?client_id=[CLIENT_ID]&scope=wl.imap wl.offline_access&response_type=code&redirect_uri=[REDIRECT_URI]
On the server side, exchange the access code for an access token:
https://login.live.com/oauth20_token.srf?client_id=[CLIENT_ID]&client_secret=[CLIENT_SECRET]&code=[ACCES_CODE]&grant_type=authorization_code&redirect_uri=[REDIRECT_URI]
Get user's email and other account info (Python sample codes):
https://apis.live.net/v5.0/me?access_token=[AUTH_TOKEN]
Retrieve emails via IMAP using the email address from emails>preferences in previous reply (see more details here). It would look something like this in Python:
import imaplib
mail = imaplib.IMAP4_SSL('imap-mail.outlook.com')
username = [username]
access_token = [access_token]
auth_string = 'user=%s\1auth=Bearer %s\1\1' % (username, access_token)
mail.authenticate('XOAUTH2', lambda x: auth_string)
mail.list()
You can look at existing IMAP libraries to retrieve the actual emails from there. Here's one for python.