Rails EOF Error when using HTTP.get_response to retrieve Facebook access token

Question

I trying to implement a Login with Facebook feature on my site, and hitting a roadblock trying to get the access token back from Facebook. Here is my code:

if params[:error_reason] == "user_denied" then
  flash[:error] = "To login with Facebook, you must click 'Allow' to let the site access your information"
  redirect_to :login
elsif params[:code] then
  token_uri = URI.parse("https://graph.facebook.com/oauth/access_token?client_id=****************&redirect_uri=http://localhost:3000/auth/fblogin&client_secret=***************&code="+URI.escape(params[:code]))
  response = Net::HTTP.get_response(token_uri)
  session[:response] = response
  data = ActiveSupport::JSON.decode(response)
  access_token = data[:access_token]
  flash[:error] = access_token
  redirect_to :register
end

This is inside a fblogin controller function that is the target of the initial redirect to get an authorization code (the params[:code]).

But when I run through this, I get the following error:

EOFError in AuthController#fblogin

on the Net::HTTP.get_response(token_uri) line. I've searched all over, and can't find anything to indicate what this means. Could it be the obscure characters Facebook uses in their access tokens? I'm totally lost!

Answer 1

You are receiving an EOFError because you are trying to connect to an https URL using code that only works with http. See the section entitled "SSL/HTTPS request" at this Net::HTTP Cheat Sheet for the basics.

However, I would recommend using a third-party library to manage this for you, such as OAuth2 for utilizing Facebook's OAuth2 API, where you'd write code like this:

def client
  OAuth2::Client.new('app_id', 'app_secret', :site => 'https://graph.facebook.com')
end

# in your callback code:
access_token = client.web_server.get_access_token(params[:code], :redirect_uri => 'http://localhost:3000/auth/fblogin')
user = JSON.parse(access_token.get('/me'))

If you really want to make the requests yourself, you can look at libraries like Faraday to execute the HTTPS requests for you.