Added new rule to check for SSRF

rules/ssrf.go

@@ -0,0 +1,70 @@
+// (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 rules
+
+import (
+	"go/ast"
+	"go/types"
+
+	"github.com/GoASTScanner/gas"
+)
+
+type ssrf struct {
+	gas.MetaData
+	gas.CallList
+}
+
+// ID returns the identifier for this rule
+func (r *ssrf) ID() string {
+	return r.MetaData.ID
+}
+
+//	TODO(jovon) identify these calls from type `http.Client`
+//		- https://github.com/go-resty/resty -- looks well maintained and popular
+//
+// Match inspects AST nodes to determine if certain net/http methods are called with variable input
+func (r *ssrf) Match(n ast.Node, c *gas.Context) (*gas.Issue, error) {
+	if node := r.ContainsCallExpr(n, c); node != nil {
+		for _, arg := range node.Args {
+			if ident, ok := arg.(*ast.Ident); ok {
+				obj := c.Info.ObjectOf(ident)
+				if _, ok := obj.(*types.Var); ok && !gas.TryResolve(ident, c) {
+					return gas.NewIssue(c, n, r.What, r.Severity, r.Confidence), nil
+				}
+			}
+		}
+	}
+	return nil, nil
+}
+
+// NewSSRFCheck detects cases where HTTP requests are sent
+func NewSSRFCheck(id string, conf gas.Config) (gas.Rule, []ast.Node) {
+	rule := &readfile{
+		CallList: gas.NewCallList(),
+		MetaData: gas.MetaData{
+			ID:         id,
+			What:       "Potential HTTP request made with variable url",
+			Severity:   gas.Medium,
+			Confidence: gas.High,
+		},
+	}
+	rule.Add("net/http", "Do")
+	rule.Add("net/http", "Get")
+	rule.Add("net/http", "Head")
+	rule.Add("net/http", "Post")
+	rule.Add("net/http", "PostForm")
+	rule.Add("net/http", "RoundTrip")
+	return rule, []ast.Node{(*ast.CallExpr)(nil)}
+}