From afb84ff20c19f90603fffa2d6fc7ee107d75c6d4 Mon Sep 17 00:00:00 2001
From: Tommy Murphy <tommy.murphy@gmail.com>
Date: Sun, 6 Nov 2016 12:31:12 -0500
Subject: [PATCH] rand: use a MatchCallByPackage helper

---
 core/helpers.go |  6 +++---
 rules/rand.go   | 38 ++++----------------------------------
 2 files changed, 7 insertions(+), 37 deletions(-)

diff --git a/core/helpers.go b/core/helpers.go
index 81bd9e8..7573636 100644
--- a/core/helpers.go
+++ b/core/helpers.go
@@ -52,11 +52,11 @@ func MatchCall(n ast.Node, r *regexp.Regexp) *ast.CallExpr {
 // package and identifier name matches the passed in parameters.
 //
 // Usage:
-// 	node, obj := MatchCall(n, ctx, "math/rand", "Read")
+// 	node, obj := MatchCallByPackage(n, ctx, "math/rand", "Read")
 //
-func MatchCallByObject(n ast.Node, c *Context, pkg, name string) (*ast.CallExpr, types.Object) {
+func MatchCallByPackage(n ast.Node, c *Context, pkg, name string) (*ast.CallExpr, types.Object) {
 	call, obj := GetCallObject(n, c)
-	if obj != nil && obj.Pkg().Path() == pkg && obj.Name() == name {
+	if obj != nil && obj.Pkg() != nil && obj.Pkg().Path() == pkg && obj.Name() == name {
 		return call, obj
 	}
 	return nil, nil
diff --git a/rules/rand.go b/rules/rand.go
index ad1d6ef..52469c7 100644
--- a/rules/rand.go
+++ b/rules/rand.go
@@ -16,50 +16,20 @@ package rules
 
 import (
 	"go/ast"
-	"go/types"
-	"regexp"
 
 	gas "github.com/GoASTScanner/gas/core"
 )
 
 type WeakRand struct {
 	gas.MetaData
-	pattern     *regexp.Regexp
+	funcName    string
 	packagePath string
 }
 
-func matchFuncCall(n ast.Node, c *gas.Context) (types.Object, *ast.Ident) {
-	call, ok := n.(*ast.CallExpr)
-	if !ok {
-		return nil, nil
-	}
-
-	sel, ok := call.Fun.(*ast.SelectorExpr)
-	if !ok {
-		return nil, nil
-	}
-
-	id, ok := sel.X.(*ast.Ident)
-	if !ok {
-		return nil, nil
-	}
-
-	return c.Info.ObjectOf(id), sel.Sel
-}
-
 func (w *WeakRand) Match(n ast.Node, c *gas.Context) (*gas.Issue, error) {
-	o, f := matchFuncCall(n, c)
+	node, _ := gas.MatchCallByPackage(n, c, w.packagePath, w.funcName)
 
-	if o == nil || f == nil {
-		return nil, nil
-	}
-
-	pkg, ok := o.(*types.PkgName)
-	if !ok {
-		return nil, nil
-	}
-
-	if pkg.Imported().Path() == w.packagePath && w.pattern.MatchString(f.String()) {
+	if node != nil {
 		return gas.NewIssue(c, n, w.What, w.Severity, w.Confidence), nil
 	}
 
@@ -68,7 +38,7 @@ func (w *WeakRand) Match(n ast.Node, c *gas.Context) (*gas.Issue, error) {
 
 func NewWeakRandCheck(conf map[string]interface{}) (r gas.Rule, n ast.Node) {
 	r = &WeakRand{
-		pattern:     regexp.MustCompile(`^Read$`),
+		funcName:    "Read",
 		packagePath: "math/rand",
 		MetaData: gas.MetaData{
 			Severity:   gas.High,