Invite link can't be used to log in after you set a password or sign in with 3rd party

app/controllers/session_controller.rb

@@ -27,6 +27,9 @@ class SessionController < ApplicationController
         return
       end
 
+      # User signed on with username and password, so let's prevent the invite link
+      # from being used to log in (if one exists).
+      Invite.invalidate_for_email(user.email)
     else
       invalid_credentials
       return

app/controllers/users/omniauth_callbacks_controller.rb

@@ -85,8 +85,8 @@ class Users::OmniauthCallbacksController < ApplicationController
     # log on any account that is active with forum access
     if Guardian.new(user).can_access_forum? && user.active
       log_on_user(user)
-      # don't carry around old auth info, perhaps move elsewhere
-      session[:authentication] = nil
+      Invite.invalidate_for_email(user.email) # invite link can't be used to log in anymore
+      session[:authentication] = nil # don't carry around old auth info, perhaps move elsewhere
       @data.authenticated = true
     else
       if SiteSetting.must_approve_users? && !user.approved?

app/controllers/users_controller.rb

@@ -173,7 +173,10 @@ class UsersController < ApplicationController
       raise Discourse::InvalidParameters.new(:password) unless params[:password].present?
       @user.password = params[:password]
       @user.password_required!
-      logon_after_password_reset if @user.save
+      if @user.save
+        Invite.invalidate_for_email(@user.email) # invite link can't be used to log in anymore
+        logon_after_password_reset
+      end
     end
     render layout: 'no_js'
   end

app/models/invite.rb

@@ -26,7 +26,8 @@ class Invite < ActiveRecord::Base
   def user_doesnt_already_exist
     @email_already_exists = false
     return if email.blank?
-    if User.where("email = ?", Email.downcase(email)).exists?
+    u = User.where("email = ?", Email.downcase(email)).first
+    if u && u.id != self.user_id
       @email_already_exists = true
       errors.add(:email)
     end
@@ -40,8 +41,13 @@ class Invite < ActiveRecord::Base
     created_at < SiteSetting.invite_expiry_days.days.ago
   end
 
+  # link_valid? indicates whether the invite link can be used to log in to the site
+  def link_valid?
+    invalidated_at.nil?
+  end
+
   def redeem
-    InviteRedeemer.new(self).redeem unless expired? || destroyed?
+    InviteRedeemer.new(self).redeem unless expired? || destroyed? || !link_valid?
   end
 
 
@@ -100,6 +106,15 @@ class Invite < ActiveRecord::Base
       rails4? ? all : scoped
     end
   end
+
+  def self.invalidate_for_email(email)
+    i = Invite.where(email: Email.downcase(email)).first
+    if i
+      i.invalidated_at = Time.zone.now
+      i.save
+    end
+    i
+  end
 end
 
 # == Schema Information

db/migrate/20140121204628_add_invalidated_at_to_invites.rb

@@ -0,0 +1,5 @@
+class AddInvalidatedAtToInvites < ActiveRecord::Migration
+  def change
+    add_column :invites, :invalidated_at, :datetime
+  end
+end

spec/models/invite_spec.rb

@@ -167,6 +167,11 @@ describe Invite do
       invite.redeem.should be_blank
     end
 
+    it "won't redeem an invalidated invite" do
+      invite.invalidated_at = 1.day.ago
+      invite.redeem.should be_blank
+    end
+
     context 'invite trust levels' do
 
       it "returns the trust level in default_invitee_trust_level" do
@@ -350,4 +355,28 @@ describe Invite do
       expect(invites.first).to eq redeemed_invite
     end
   end
+
+  describe '.invalidate_for_email' do
+    let(:email) { 'invite.me@example.com' }
+    subject { described_class.invalidate_for_email(email) }
+
+    it 'returns nil if there is no invite for the given email' do
+      subject.should == nil
+    end
+
+    it 'sets the matching invite to be invalid' do
+      invite = Fabricate(:invite, invited_by: Fabricate(:user), user_id: nil, email: email)
+      subject.should == invite
+      subject.link_valid?.should == false
+      subject.should be_valid
+    end
+
+    it 'sets the matching invite to be invalid without being case-sensitive' do
+      invite = Fabricate(:invite, invited_by: Fabricate(:user), user_id: nil, email: 'invite.me2@Example.COM')
+      result = described_class.invalidate_for_email('invite.me2@EXAMPLE.com')
+      result.should == invite
+      result.link_valid?.should == false
+      result.should be_valid
+    end
+  end
 end