ColdFusion and OAuth Part 3 - Google

Welcome to my third and final blog post on ColdFusion and OAuth. (You may find the earlier entries below.) I apologize for the delay but I traveled last week so I'm a bit behind. If you have not yet read the earlier entries (part 1 and part 2), please do so as I will not be repeating the information I wrote about before.

So - hopefully you've gotten an idea of how easy OAuth can be. After I got things working right the first time, the second demo was quite easy. For this demo I decided to get a bit fancier. Google has an OAuth API that lets you authenticate against their servers. What if you wanted to use Google for your user system? In other words, skip the whole custom registration process and offload user management to Google. That's not only possible but actually one of the recommended use cases in their documentation.

Before we begin, please note that you will need to register your application with Google. This is exactly like what you did with Facebook and LinkedIn, except it is done at Google's API Console instead. By now this process should be easy enough where I don't need to explain it to you, just be sure to make note of the client id and client secret.

Since our application is going to use Google for login, I've created a simple Application.cfc that looks for a session variable, and if it doesn't exist, automatically pushes the user to a login page.

component {
    this.name="googleoauthlogin4";
    this.sessionManagement=true;

    public boolean function onApplicationStart() {
        application.clientid="noyb";
        application.clientsecret="stillnoyb";
        application.callback="http://localhost/testingzone/googleoauthlogin/callback.cfm";

        application.google = new google(application.clientid, application.clientsecret);
        return true;
    }

    public boolean function onRequestStart(required string req) {

      if(!findNoCase("/login.cfm", arguments.req) && !findNoCase("/callback.cfm", arguments.req) && !session.loggedin) {
    		location(url="./login.cfm", addToken="false");
    	}
    	return true;
    }

    public boolean function onSessionStart() {
    	session.loggedin = false;

    	return true;
    }
}

The onApplicationStart is virtually a carbon copy of the earlier examples, but the onRequestStart is new. It checks to see if we are logged in, and barring that, checks to see if we are requesting either the login page or the callback page. When the user first hits the application, they are sent to the login page:

Notice that there isn't a form here. Remember, we're sending the user to Google instead. I could have automatically pushed them, but I felt this was more friendly. Here's the code for that template.

<cfset authurl = application.google.generateAuthUrl(application.callback, session.urltoken)>

<h1>Login Required</h1>

<p>
  In order to use this app, you must login with your Google account. Click to login below.
</p>

<cfoutput>
	<p>
	<a href="#authurl#">LOGIN!</a>
	</p>
</cfoutput>

I've put the Google OAuth code into a CFC to abstract a bit, but for now, don't worry about it. The link generation is very similar to the previous two examples. Once the user clicks login, they are sent to Google. In this case, Google recognized my account and preset the login, but I have the option to switch users as well.

As before, the user is sent to a callback page. Here is that template. Again note that I've put much more into the CFC now so this is somewhat simpler.

<!--- Validate the result --->
<cfparam name="url.code" default="">
<cfparam name="url.state" default="">
<cfparam name="url.error" default="">
<cfset result = application.google.validateResult(url.code, url.error, url.state, session.urltoken)>

<cfif not result.status>
  <!--- Imagine a nicer error here. --->
	<cfoutput>
		<h1>Error!</h1>
		#result.message#
	</cfoutput>
	<cfabort>
</cfif>

<cfset session.token = result.token>
<cfset session.loggedin = true>
<cflocation url="index.cfm" addtoken="false">

Finally, the user is directed to the homepage. As part of the Google API, I can get info about the user. I did so and dumped it out:

Here is that template:

<cfset me = application.google.getProfile(session.token.access_token)>

<h1>Home</h1>

<cfdump var="#me#" label="me">

Now let's look at the CFC:

component {

  public function init(clientid, clientsecret) {
		variables.clientid = arguments.clientid;
		variables.clientsecret = arguments.clientsecret;
		return this;
	}

	public string function generateAuthURL(redirecturl, state) {
		/*
		Scope is what you want to do with your access. Since this demo is ONLY for
		auth and user info, we have one hard coded value.
		*/
		return "https://accounts.google.com/o/oauth2/auth?" & 
				 "client_id=#urlEncodedFormat(variables.clientid)#" & 
     			 "&redirect_uri=#urlEncodedFormat(arguments.redirecturl)#" & 
				 "&scope=https://www.googleapis.com/auth/userinfo.profile&response_type=code" & 
				 "&state=#urlEncodedFormat(arguments.state)#";

	}

	public function getProfile(accesstoken) {

		var h = new com.adobe.coldfusion.http();
		h.setURL("https://www.googleapis.com/oauth2/v1/userinfo");
		h.setMethod("get");
		h.addParam(type="header",name="Authorization",value="OAuth #accesstoken#");
		h.addParam(type="header",name="GData-Version",value="3");
		h.setResolveURL(true);
		var result = h.send().getPrefix();
		return deserializeJSON(result.filecontent.toString());
	}

	/*
	I handle validating the code result from Google and automatically getting the auth token.
	I should be able to handle any bad result from Google or the user not allowing crap.
	I also validate the state.
	*/
	public struct function validateResult(code, error, remoteState, clientState) {
		var result = {};

		//If error is anything, we have an error
		if(error != "") {
			result.status = false;
			result.message = error;
			return result;
		}

		//Then, ensure states are equal
		if(remoteState != clientState) {
			result.status = false;
			result.message = "State values did not match.";
			return result;
		}

		var token = getGoogleToken(code);

		if(structKeyExists(token, "error")) {
			result.status = false;
			result.message = token.error;
			return result;
		}
		
		result.status = true;
		result.token = token;

		return result;
	}

	//Credit: http://www.sitekickr.com/blog/http-post-oauth-coldfusion
	private function getGoogleToken(code) {
		var postBody = "code=" & UrlEncodedFormat(arguments.code) & "&";
			 postBody = postBody & "client_id=" & UrlEncodedFormat(application.clientid) & "&";
			 postBody = postBody & "client_secret=" & UrlEncodedFormat(application.clientsecret) & "&";
			 postBody = postBody & "redirect_uri=" & UrlEncodedFormat(application.callback) & "&";
			 postBody = postBody & "grant_type=authorization_code";


			var h = new com.adobe.coldfusion.http();
			h.setURL("https://accounts.google.com/o/oauth2/token");
			h.setMethod("post");
			h.addParam(type="header",name="Content-Type",value="application/x-www-form-urlencoded");
			h.addParam(type="body",value="#postBody#");
			h.setResolveURL(true);
			var result = h.send().getPrefix();
			return deserializeJSON(result.filecontent.toString());

	}

}

For the most part I assume this is self-explanatory, but if anyone has any questions, let me know.

Finally, an interesting twist. What about businesses that make use of Google Apps? Turns out there is an undocumented solution for that. Look at the generateAuthURL function above. If you add the "hd" argument, you can specify a Google Apps domain:

  public string function generateAuthURL(redirecturl, state) {
		/*
		Scope is what you want to do with your access. Since this demo is ONLY for
		auth and user info, we have one hard coded value.
		*/
		return "https://accounts.google.com/o/oauth2/auth?hd=camdenfamily.com&" & 
				 "client_id=#urlEncodedFormat(variables.clientid)#" & 
     			 "&redirect_uri=#urlEncodedFormat(arguments.redirecturl)#" & 
				 "&scope=https://www.googleapis.com/auth/userinfo.profile&response_type=code" & 
				 "&state=#urlEncodedFormat(arguments.state)#";

	}

This works great, but as I said, it isn't documented. A friend of mine is a paying customer of Google Apps and has reached out to tech support, but unfortunately, no one will give him a firm answer. His last email with them resulted in this:

Basically what the rep said is that their technical team said using hd=cbtec.com is a feature, so they didn't specify that in their documentation. He also said that the variable hd is also used to authenticate users in an organization with business units separated by domains.

Frankly that first sentence isn't sensible. "It is a feature and that's why we didn't document it." I'm hoping it was just a typo.

Related Blog Entries

• ColdFusion and OAuth Part 2 - LinkedIn (April 3, 2013)
• ColdFusion and OAuth Part 1 - Facebook (April 1, 2013)