diff options
Diffstat (limited to 'lib/gitlab/graphql/query_analyzers/recursion_analyzer.rb')
-rw-r--r-- | lib/gitlab/graphql/query_analyzers/recursion_analyzer.rb | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/lib/gitlab/graphql/query_analyzers/recursion_analyzer.rb b/lib/gitlab/graphql/query_analyzers/recursion_analyzer.rb new file mode 100644 index 00000000000..ccf9e597307 --- /dev/null +++ b/lib/gitlab/graphql/query_analyzers/recursion_analyzer.rb @@ -0,0 +1,62 @@ +# frozen_string_literal: true + +# Recursive queries, with relatively low effort, can quickly spiral out of control exponentially +# and may not be picked up by depth and complexity alone. +module Gitlab + module Graphql + module QueryAnalyzers + class RecursionAnalyzer + IGNORED_FIELDS = %w(node edges ofType).freeze + RECURSION_THRESHOLD = 2 + + def initial_value(query) + { + recurring_fields: {} + } + end + + def call(memo, visit_type, irep_node) + return memo if skip_node?(irep_node) + + node_name = irep_node.ast_node.name + times_encountered = memo[node_name] || 0 + + if visit_type == :enter + times_encountered += 1 + memo[:recurring_fields][node_name] = times_encountered if recursion_too_deep?(node_name, times_encountered) + else + times_encountered -= 1 + end + + memo[node_name] = times_encountered + memo + end + + def final_value(memo) + recurring_fields = memo[:recurring_fields] + recurring_fields = recurring_fields.select { |k, v| recursion_too_deep?(k, v) } + if recurring_fields.any? + GraphQL::AnalysisError.new("Recursive query - too many of fields '#{recurring_fields}' detected in single branch of the query") + end + end + + private + + def recursion_too_deep?(node_name, times_encountered) + return if IGNORED_FIELDS.include?(node_name) + + times_encountered > recursion_threshold + end + + def skip_node?(irep_node) + ast_node = irep_node.ast_node + !ast_node.is_a?(GraphQL::Language::Nodes::Field) || ast_node.selections.empty? + end + + def recursion_threshold + RECURSION_THRESHOLD + end + end + end + end +end |