validate that tasks don't contain slashes

nomad/structs/structs.go

@@ -1741,6 +1741,9 @@ func (t *Task) Validate() error {
 	if t.Name == "" {
 		mErr.Errors = append(mErr.Errors, errors.New("Missing task name"))
 	}
+	if strings.ContainsAny(t.Name, `/\`) {
+		mErr.Errors = append(mErr.Errors, errors.New("Task name can not include slashes"))
+	}
 	if t.Driver == "" {
 		mErr.Errors = append(mErr.Errors, errors.New("Missing task driver"))
 	}

nomad/structs/structs_test.go

@@ -258,6 +258,13 @@ func TestTask_Validate(t *testing.T) {
 		t.Fatalf("err: %s", err)
 	}
 
+	task = &Task{Name: "web/foo"}
+	err = task.Validate()
+	mErr = err.(*multierror.Error)
+	if !strings.Contains(mErr.Errors[0].Error(), "slashes") {
+		t.Fatalf("err: %s", err)
+	}
+
 	task = &Task{
 		Name:   "web",
 		Driver: "docker",