gosec/core/helpers.go
Grant Murphy c4057545ae Add MatchCall helper that utilizes type checker
This introduces a helper function that will significantly reduce the
number of false positives that occur due to the use of regexp based
call matching.

It resolves the object related to a CallExpr and checks that against the
supplied package and identifier name. If both of these match the
returned value is the CallExpr and Object.
2016-11-04 11:20:28 -07:00

115 lines
3.5 KiB
Go

// (c) Copyright 2016 Hewlett Packard Enterprise Development LP
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package core
import (
"fmt"
"go/ast"
"go/token"
"go/types"
"reflect"
"regexp"
"strconv"
"strings"
)
// helpfull "canned" matching routines ----------------------------------------
func selectName(n ast.Node, s reflect.Type) (string, bool) {
t := reflect.TypeOf(&ast.SelectorExpr{})
if node, ok := SimpleSelect(n, s, t).(*ast.SelectorExpr); ok {
t = reflect.TypeOf(&ast.Ident{})
if ident, ok := SimpleSelect(node.X, t).(*ast.Ident); ok {
return strings.Join([]string{ident.Name, node.Sel.Name}, "."), ok
}
}
return "", false
}
// MatchCall will match an ast.CallNode if its method name obays the given regex.
func MatchCall(n ast.Node, r *regexp.Regexp) *ast.CallExpr {
t := reflect.TypeOf(&ast.CallExpr{})
if name, ok := selectName(n, t); ok && r.MatchString(name) {
return n.(*ast.CallExpr)
}
return nil
}
// MatchCallByObject ses the type checker to resolve the associated object with a
// particular *ast.CallExpr. This object is used to determine if the
// package and identifier name matches the passed in parameters.
//
// Usage:
// node, obj := MatchCall(n, ctx, "math/rand", "Read")
//
func MatchCallByObject(n ast.Node, c *Context, pkg, name string) (*ast.CallExpr, types.Object) {
var obj types.Object
switch node := n.(type) {
case *ast.CallExpr:
switch fn := node.Fun.(type) {
case *ast.Ident:
obj = c.Info.Uses[fn]
case *ast.SelectorExpr:
obj = c.Info.Uses[fn.Sel]
default:
obj = nil
}
if obj != nil && obj.Pkg().Path() == pkg && obj.Name() == name {
return node, obj
}
}
return nil, nil
}
// MatchCompLit will match an ast.CompositeLit if its string value obays the given regex.
func MatchCompLit(n ast.Node, r *regexp.Regexp) *ast.CompositeLit {
t := reflect.TypeOf(&ast.CompositeLit{})
if name, ok := selectName(n, t); ok && r.MatchString(name) {
return n.(*ast.CompositeLit)
}
return nil
}
// GetInt will read and return an integer value from an ast.BasicLit
func GetInt(n ast.Node) (int64, error) {
if node, ok := n.(*ast.BasicLit); ok && node.Kind == token.INT {
return strconv.ParseInt(node.Value, 0, 64)
}
return 0, fmt.Errorf("Unexpected AST node type: %T", n)
}
// GetInt will read and return a float value from an ast.BasicLit
func GetFloat(n ast.Node) (float64, error) {
if node, ok := n.(*ast.BasicLit); ok && node.Kind == token.FLOAT {
return strconv.ParseFloat(node.Value, 64)
}
return 0.0, fmt.Errorf("Unexpected AST node type: %T", n)
}
// GetInt will read and return a char value from an ast.BasicLit
func GetChar(n ast.Node) (byte, error) {
if node, ok := n.(*ast.BasicLit); ok && node.Kind == token.CHAR {
return node.Value[0], nil
}
return 0, fmt.Errorf("Unexpected AST node type: %T", n)
}
// GetInt will read and return a string value from an ast.BasicLit
func GetString(n ast.Node) (string, error) {
if node, ok := n.(*ast.BasicLit); ok && node.Kind == token.STRING {
return strconv.Unquote(node.Value)
}
return "", fmt.Errorf("Unexpected AST node type: %T", n)
}