LTI-375: allow custom pattern for legacy_handler per tenant with text…

… pattern for handler (#248)

app/controllers/message_controller.rb

@@ -85,7 +85,7 @@ def basic_lti_launch_request_legacy
     # Inject the handler_legacy to the lti_launch.
     lti_launch = RailsLti2Provider::LtiLaunch.find_by(nonce: params[:oauth_nonce])
     post_params = lti_launch.message.post_params
-    post_params['custom_handler_legacy'] = handler_legacy
+    post_params['custom_handler_legacy'] = handler_legacy(handler_legacy_patterns(params['tenant']))
     lti_message = IMS::LTI::Models::Messages::Message.generate(post_params)
     lti_launch.update(message: lti_message.post_params)
 
@@ -168,26 +168,22 @@ def process_openid_message
   # rules are needed.
   #   - param-xxx, it is a literal value of parameter xxx.
   #   - fqdn-yyy parses the host obtained from processing the value of parameter yyy as a URL.
+  #   - text-zzz is a literal value zzz.
   #   - | is a fallback in case the value found from the first pattern is empty.
   #
   #   E.g.
   #     konekti: 'param-tool_consumer_instance_guid|fqdn-ext_tc_profile_url,param-context_id,param-resource_link_id'
   #     bbb-lti 'param-resource_link_id,param-oauth_consumer_key' (default)
   #
-  def handler_legacy
+  def handler_legacy(patterns)
     # Hardcoded patterns to support Konekti launches.
-    patterns = Rails.configuration.handler_legacy_patterns
     seed_string = ''
     patterns.split(',').each do |pattern|
       seed = ''
-      if pattern.include?('|')
-        fallbacks = pattern.split('|')
-        fallbacks.each do |fallback|
-          seed = seed_param(fallback)
-          break unless seed.empty?
-        end
-      else
-        seed = seed_param(pattern)
+      fallbacks = pattern.split('|')
+      fallbacks.each do |fallback|
+        seed = seed_param(fallback)
+        break unless seed.empty?
       end
       seed_string += seed
     end
@@ -198,9 +194,23 @@ def handler_legacy
   # E.g. param-resource_link_id
   def seed_param(pattern)
     elements = pattern.split('-')
-    return params[elements[1]] if elements[0] == 'param'
-    return URI.parse(params[elements[1]]).host if elements[0] == 'fqdn'
+
+    case elements[0]
+    when 'param'
+      return params[elements[1]]
+    when 'fqdn'
+      return URI.parse(params[elements[1]]).host unless params[elements[1]].nil?
+    when 'text'
+      return elements[1]
+    end
 
     ''
   end
+
+  def handler_legacy_patterns(tenant_uid)
+    tenant = RailsLti2Provider::Tenant.find_by(uid: tenant_uid)
+    return Rails.configuration.handler_legacy_patterns if tenant.nil? || tenant.settings['handler_legacy_patterns'].blank?
+
+    tenant.settings['handler_legacy_patterns']
+  end
 end

lib/bbb_lti_broker/helpers.rb

@@ -93,19 +93,31 @@ def user_params(tc_instance_guid, params)
     # Core parameters may have to be overriden in order to make the applications behave differently
     # for that, the LTI link in the tool consumer would need to include a custom parameter in the form:
     #
-    # custom_resource_link_id=static:"some value" -> resource_link_id="some value"
-    # custom_resource_link_id=param:contenxt_id   -> resource_link_id=<value obtained from context_id>
-    # custom_resource_link_id="another value"     -> resource_link_id=<no overriding is made>
+    # custom_override_resource_link_id=static:"some value" -> resource_link_id="some value"
+    # custom_override_resource_link_id=param:contenxt_id   -> resource_link_id=<value obtained from context_id>
+    # custom_override_resource_link_id="another value"     -> resource_link_id=<no overriding is made>
     #
     def custom_overrides(message)
       custom_params = message['custom_params'].to_h
-      custom_params.each do |key, value|
-        custom_param = key.delete_prefix('custom_')
+      custom_params.each do |custom_param_name, value|
+        next unless custom_param_name.start_with?('custom_override_')
+
+        param_name = custom_param_name.delete_prefix('custom_override_')
+        next unless safe_custom_override_params.include?(param_name)
+
         pattern = value.split(':')
-        message[custom_param] = pattern[1] if pattern[0] == 'static'
-        message[custom_param] = message[pattern[1]] if pattern[0] == 'param'
+        message[param_name] = pattern[1] if pattern[0] == 'static'
+        message[param_name] = message['custom_params'][pattern[1]] if pattern[0] == 'param'
       end
       message
     end
+
+    # parameters that are safe for custom overriding.
+    def safe_custom_override_params
+      # TODO: Only safe params should be allowed to be overriden, there are two approaches for this.
+      # 1) set them through a tenant setting
+      # 2) set the overriding rules through tenant settings (safest)
+      ['user_image']
+    end
   end
 end