1 files changed, 104 insertions, 0 deletions
diff --git a/vendor/github.com/99designs/gqlgen/complexity/complexity.go b/vendor/github.com/99designs/gqlgen/complexity/complexity.go
new file mode 100644
index 00000000..d5b46bf4
--- /dev/null
+++ b/vendor/github.com/99designs/gqlgen/complexity/complexity.go
@@ -0,0 +1,104 @@
+package complexity
+
+import (
+	"github.com/99designs/gqlgen/graphql"
+	"github.com/vektah/gqlparser/ast"
+)
+
+func Calculate(es graphql.ExecutableSchema, op *ast.OperationDefinition, vars map[string]interface{}) int {
+	walker := complexityWalker{
+		es:     es,
+		schema: es.Schema(),
+		vars:   vars,
+	}
+	return walker.selectionSetComplexity(op.SelectionSet)
+}
+
+type complexityWalker struct {
+	es     graphql.ExecutableSchema
+	schema *ast.Schema
+	vars   map[string]interface{}
+}
+
+func (cw complexityWalker) selectionSetComplexity(selectionSet ast.SelectionSet) int {
+	var complexity int
+	for _, selection := range selectionSet {
+		switch s := selection.(type) {
+		case *ast.Field:
+			fieldDefinition := cw.schema.Types[s.Definition.Type.Name()]
+			var childComplexity int
+			switch fieldDefinition.Kind {
+			case ast.Object, ast.Interface, ast.Union:
+				childComplexity = cw.selectionSetComplexity(s.SelectionSet)
+			}
+
+			args := s.ArgumentMap(cw.vars)
+			var fieldComplexity int
+			if s.ObjectDefinition.Kind == ast.Interface {
+				fieldComplexity = cw.interfaceFieldComplexity(s.ObjectDefinition, s.Name, childComplexity, args)
+			} else {
+				fieldComplexity = cw.fieldComplexity(s.ObjectDefinition.Name, s.Name, childComplexity, args)
+			}
+			complexity = safeAdd(complexity, fieldComplexity)
+
+		case *ast.FragmentSpread:
+			complexity = safeAdd(complexity, cw.selectionSetComplexity(s.Definition.SelectionSet))
+
+		case *ast.InlineFragment:
+			complexity = safeAdd(complexity, cw.selectionSetComplexity(s.SelectionSet))
+		}
+	}
+	return complexity
+}
+
+func (cw complexityWalker) interfaceFieldComplexity(def *ast.Definition, field string, childComplexity int, args map[string]interface{}) int {
+	// Interfaces don't have their own separate field costs, so they have to assume the worst case.
+	// We iterate over all implementors and choose the most expensive one.
+	maxComplexity := 0
+	implementors := cw.schema.GetPossibleTypes(def)
+	for _, t := range implementors {
+		fieldComplexity := cw.fieldComplexity(t.Name, field, childComplexity, args)
+		if fieldComplexity > maxComplexity {
+			maxComplexity = fieldComplexity
+		}
+	}
+	return maxComplexity
+}
+
+func (cw complexityWalker) fieldComplexity(object, field string, childComplexity int, args map[string]interface{}) int {
+	if customComplexity, ok := cw.es.Complexity(object, field, childComplexity, args); ok && customComplexity >= childComplexity {
+		return customComplexity
+	}
+	// default complexity calculation
+	return safeAdd(1, childComplexity)
+}
+
+const maxInt = int(^uint(0) >> 1)
+
+// safeAdd is a saturating add of a and b that ignores negative operands.
+// If a + b would overflow through normal Go addition,
+// it returns the maximum integer value instead.
+//
+// Adding complexities with this function prevents attackers from intentionally
+// overflowing the complexity calculation to allow overly-complex queries.
+//
+// It also helps mitigate the impact of custom complexities that accidentally
+// return negative values.
+func safeAdd(a, b int) int {
+	// Ignore negative operands.
+	if a < 0 {
+		if b < 0 {
+			return 1
+		}
+		return b
+	} else if b < 0 {
+		return a
+	}
+
+	c := a + b
+	if c < a {
+		// Set c to maximum integer instead of overflowing.
+		c = maxInt
+	}
+	return c
+}