FEATURE: Allow specifiying required paths when retrieving userinfo

plugin.rb

@@ -78,6 +78,12 @@ end
 # We'll store the value in the user associated account's extra attribute hash using the full path as the key.
 DiscoursePluginRegistry.define_filtered_register :oauth2_basic_additional_json_paths
 
+# After authentication, we'll use this to confirm that the registered json paths are fulfilled,
+# or display an error message to the user.
+# This requires SiteSetting.oauth2_fetch_user_details? to be true, and can be used with
+# DiscoursePluginRegistry.oauth2_basic_additional_json_paths.
+DiscoursePluginRegistry.define_filtered_register :oauth2_basic_required_json_paths
+
 class ::OAuth2BasicAuthenticator < Auth::ManagedAuthenticator
   def name
     "oauth2_basic"
@@ -312,6 +318,15 @@ class ::OAuth2BasicAuthenticator < Auth::ManagedAuthenticator
         DiscoursePluginRegistry.oauth2_basic_additional_json_paths.each do |detail|
           auth["extra"][detail] = fetched_user_details["extra:#{detail}"]
         end
+
+        DiscoursePluginRegistry.oauth2_basic_required_json_paths.each do |x|
+          if fetched_user_details[x[:path]] != x[:required_value]
+            result = Auth::Result.new
+            result.failed = true
+            result.failed_reason = x[:error_message]
+            return result
+          end
+        end
       else
         result = Auth::Result.new
         result.failed = true

spec/plugin_spec.rb

@@ -122,6 +122,54 @@ describe OAuth2BasicAuthenticator do
           expect(associated_account.extra[custom_path]).to eq("received")
         end
       end
+
+      describe "required attributes" do
+        after { DiscoursePluginRegistry.reset_register!(:oauth2_basic_required_json_paths) }
+
+        it "'authenticates' successfully if required json path is fulfilled" do
+          DiscoursePluginRegistry.register_oauth2_basic_additional_json_path(
+            "account.is_legit",
+            Plugin::Instance.new,
+          )
+          DiscoursePluginRegistry.register_oauth2_basic_required_json_path(
+            { path: "extra:account.is_legit", required_value: true },
+            Plugin::Instance.new,
+          )
+
+          response = {
+            status: 200,
+            body: '{"account":{"email":"newemail@example.com","is_legit":true}}',
+          }
+          stub_request(:get, SiteSetting.oauth2_user_json_url).to_return(response)
+
+          result = authenticator.after_authenticate(auth)
+          expect(result.failed).to eq(false)
+        end
+
+        it "fails 'authentication' if required json path is unfulfilled" do
+          DiscoursePluginRegistry.register_oauth2_basic_additional_json_path(
+            "account.is_legit",
+            Plugin::Instance.new,
+          )
+          DiscoursePluginRegistry.register_oauth2_basic_required_json_path(
+            {
+              path: "extra:account.is_legit",
+              required_value: true,
+              error_message: "You're not legit",
+            },
+            Plugin::Instance.new,
+          )
+          response = {
+            status: 200,
+            body: '{"account":{"email":"newemail@example.com","is_legit":false}}',
+          }
+          stub_request(:get, SiteSetting.oauth2_user_json_url).to_return(response)
+
+          result = authenticator.after_authenticate(auth)
+          expect(result.failed).to eq(true)
+          expect(result.failed_reason).to eq("You're not legit")
+        end
+      end
     end
 
     describe "avatar downloading" do