builder/virtualbox: improved validation

builder/virtualbox/builder.go

@@ -109,6 +109,10 @@ func (b *Builder) Prepare(raw interface{}) error {
 		}
 	}
 
+	if b.config.SSHHostPortMin > b.config.SSHHostPortMax {
+		errs = append(errs, errors.New("ssh_host_port_min must be less than ssh_host_port_max"))
+	}
+
 	b.driver, err = b.newDriver()
 	if err != nil {
 		errs = append(errs, fmt.Errorf("Failed creating VirtualBox driver: %s", err))

builder/virtualbox/builder_test.go

@@ -122,3 +122,32 @@ func TestBuilderPrepare_ISOUrl(t *testing.T) {
 		t.Fatalf("iso_url should be modified: %s", b.config.ISOUrl)
 	}
 }
+
+func TestBuilderPrepare_SSHHostPort(t *testing.T) {
+	var b Builder
+	config := testConfig()
+
+	// Bad
+	config["ssh_host_port_min"] = 1000
+	config["ssh_host_port_max"] = 500
+	err := b.Prepare(config)
+	if err == nil {
+		t.Fatal("should have error")
+	}
+
+	// Bad
+	config["ssh_host_port_min"] = -500
+	err = b.Prepare(config)
+	if err == nil {
+		t.Fatal("should have error")
+	}
+
+	// Good
+	config["ssh_host_port_min"] = 500
+	config["ssh_host_port_max"] = 1000
+	err = b.Prepare(config)
+	if err != nil {
+		t.Fatalf("should not have error: %s", err)
+	}
+}
+