frp/pkg/config/proxy.go
2020-11-25 09:44:29 +08:00

905 lines
20 KiB
Go

// Copyright 2016 fatedier, fatedier@gmail.com
//
// 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 config
import (
"fmt"
"reflect"
"strings"
"github.com/fatedier/frp/pkg/consts"
"github.com/fatedier/frp/pkg/msg"
"gopkg.in/ini.v1"
)
// Proxy Conf Loader
// DefaultProxyConf creates a empty ProxyConf object by proxyType.
// If proxyType doesn't exist, return nil.
func DefaultProxyConf(proxyType string) ProxyConf {
var conf ProxyConf
switch proxyType {
case consts.TCPProxy:
conf = &TCPProxyConf{
BaseProxyConf: defaultBaseProxyConf(proxyType),
}
case consts.TCPMuxProxy:
conf = &TCPMuxProxyConf{
BaseProxyConf: defaultBaseProxyConf(proxyType),
}
case consts.UDPProxy:
conf = &UDPProxyConf{
BaseProxyConf: defaultBaseProxyConf(proxyType),
}
case consts.HTTPProxy:
conf = &HTTPProxyConf{
BaseProxyConf: defaultBaseProxyConf(proxyType),
}
case consts.HTTPSProxy:
conf = &HTTPSProxyConf{
BaseProxyConf: defaultBaseProxyConf(proxyType),
}
case consts.STCPProxy:
conf = &STCPProxyConf{
BaseProxyConf: defaultBaseProxyConf(proxyType),
STCPProxySpec: STCPProxySpec{
Role: "server",
},
}
case consts.XTCPProxy:
conf = &XTCPProxyConf{
BaseProxyConf: defaultBaseProxyConf(proxyType),
XTCPProxySpec: XTCPProxySpec{
Role: "server",
},
}
case consts.SUDPProxy:
conf = &SUDPProxyConf{
BaseProxyConf: defaultBaseProxyConf(proxyType),
SUDPProxySpec: SUDPProxySpec{
Role: "server",
},
}
default:
return nil
}
return conf
}
// Proxy loaded from ini
func NewProxyConfFromIni(prefix, name string, section *ini.Section) (ProxyConf, error) {
// section.Key: if key not exists, section will set it with default value.
proxyType := section.Key("type").String()
if proxyType == "" {
proxyType = consts.TCPProxy
}
conf := DefaultProxyConf(proxyType)
if conf == nil {
return nil, fmt.Errorf("proxy [%s] type [%s] error", name, proxyType)
}
if err := conf.UnmarshalFromIni(prefix, name, section); err != nil {
return nil, err
}
if err := conf.CheckForCli(); err != nil {
return nil, err
}
return conf, nil
}
// Proxy loaded from msg
func NewProxyConfFromMsg(pMsg *msg.NewProxy, svrconf ServerCommonConf) (ProxyConf, error) {
if pMsg.ProxyType == "" {
pMsg.ProxyType = consts.TCPProxy
}
conf := DefaultProxyConf(pMsg.ProxyType)
if conf == nil {
return nil, fmt.Errorf("proxy [%s] type [%s] error", pMsg.ProxyName, pMsg.ProxyType)
}
conf.UnmarshalFromMsg(pMsg)
err := conf.CheckForSvr(svrconf)
if err != nil {
return nil, err
}
return conf, nil
}
// Base
func defaultBaseProxyConf(proxyType string) BaseProxyConf {
return BaseProxyConf{
ProxyType: proxyType,
LocalSvrConf: LocalSvrConf{
LocalIP: "127.0.0.1",
},
}
}
func (c *BaseProxyConf) GetBaseInfo() *BaseProxyConf {
return c
}
func (c *BaseProxyConf) compare(cmp *BaseProxyConf) bool {
if c.ProxyName != cmp.ProxyName ||
c.ProxyType != cmp.ProxyType ||
c.UseEncryption != cmp.UseEncryption ||
c.UseCompression != cmp.UseCompression ||
c.Group != cmp.Group ||
c.GroupKey != cmp.GroupKey ||
c.ProxyProtocolVersion != cmp.ProxyProtocolVersion ||
!c.BandwidthLimit.Equal(&cmp.BandwidthLimit) ||
!reflect.DeepEqual(c.Metas, cmp.Metas) {
return false
}
if !reflect.DeepEqual(c.LocalSvrConf, cmp.LocalSvrConf) {
return false
}
if !reflect.DeepEqual(c.HealthCheckConf, cmp.HealthCheckConf) {
return false
}
return true
}
// BaseProxyConf apply custom logic changes.
func (c *BaseProxyConf) decorate(prefix string, name string, section *ini.Section) error {
// proxy_name
c.ProxyName = prefix + name
// metas_xxx
c.Metas = GetMapWithoutPrefix(section.KeysHash(), "meta_")
// bandwidth_limit
if bandwidth, err := section.GetKey("bandwidth_limit"); err == nil {
c.BandwidthLimit, err = NewBandwidthQuantity(bandwidth.String())
if err != nil {
return err
}
}
// plugin_xxx
c.LocalSvrConf.PluginParams = GetMapByPrefix(section.KeysHash(), "plugin_")
// custom logic code
if c.HealthCheckType == "tcp" && c.Plugin == "" {
c.HealthCheckAddr = c.LocalIP + fmt.Sprintf(":%d", c.LocalPort)
}
if c.HealthCheckType == "http" && c.Plugin == "" && c.HealthCheckURL != "" {
s := fmt.Sprintf("http://%s:%d", c.LocalIP, c.LocalPort)
if !strings.HasPrefix(c.HealthCheckURL, "/") {
s += "/"
}
c.HealthCheckURL = s + c.HealthCheckURL
}
return nil
}
func (c *BaseProxyConf) unmarshalFromMsg(pMsg *msg.NewProxy) {
c.ProxyName = pMsg.ProxyName
c.ProxyType = pMsg.ProxyType
c.UseEncryption = pMsg.UseEncryption
c.UseCompression = pMsg.UseCompression
c.Group = pMsg.Group
c.GroupKey = pMsg.GroupKey
c.Metas = pMsg.Metas
}
func (c *BaseProxyConf) marshalToMsg(pMsg *msg.NewProxy) {
pMsg.ProxyName = c.ProxyName
pMsg.ProxyType = c.ProxyType
pMsg.UseEncryption = c.UseEncryption
pMsg.UseCompression = c.UseCompression
pMsg.Group = c.Group
pMsg.GroupKey = c.GroupKey
pMsg.Metas = c.Metas
}
func (c *BaseProxyConf) checkForCli() error {
if c.ProxyProtocolVersion != "" {
if c.ProxyProtocolVersion != "v1" && c.ProxyProtocolVersion != "v2" {
return fmt.Errorf("no support proxy protocol version: %s", c.ProxyProtocolVersion)
}
}
if err := c.LocalSvrConf.validate(); err != nil {
return err
}
if err := c.HealthCheckConf.validate(); err != nil {
return err
}
return nil
}
func (c *BaseProxyConf) checkForSvr(conf ServerCommonConf) error {
return nil
}
// LocalSvrConf
func (c *LocalSvrConf) validate() (err error) {
if c.Plugin == "" {
if c.LocalIP == "" {
err = fmt.Errorf("local ip or plugin is required")
return
}
if c.LocalPort <= 0 {
err = fmt.Errorf("error local_port")
return
}
}
return
}
// HealthCheckConf
func (c *HealthCheckConf) validate() error {
if c.HealthCheckType != "" && c.HealthCheckType != "tcp" && c.HealthCheckType != "http" {
return fmt.Errorf("unsupport health check type")
}
if c.HealthCheckType != "" {
if c.HealthCheckType == "http" && c.HealthCheckURL == "" {
return fmt.Errorf("health_check_url is required for health check type 'http'")
}
}
return nil
}
// DomainSpec
func (c *DomainSpec) validate() error {
if len(c.CustomDomains) == 0 && c.SubDomain == "" {
return fmt.Errorf("custom_domains and subdomain should set at least one of them")
}
return nil
}
func (c *DomainSpec) validateForCli() error {
if err := c.validate(); err != nil {
return err
}
return nil
}
func (c *DomainSpec) validateForSvr(svrconf ServerCommonConf) error {
if err := c.validate(); err != nil {
return err
}
for _, domain := range c.CustomDomains {
if svrconf.SubDomainHost != "" && len(strings.Split(svrconf.SubDomainHost, ".")) < len(strings.Split(domain, ".")) {
if strings.Contains(domain, svrconf.SubDomainHost) {
return fmt.Errorf("custom domain [%s] should not belong to subdomain_host [%s]", domain, svrconf.SubDomainHost)
}
}
}
if c.SubDomain != "" {
if svrconf.SubDomainHost == "" {
return fmt.Errorf("subdomain is not supported because this feature is not enabled in remote frps")
}
if strings.Contains(c.SubDomain, ".") || strings.Contains(c.SubDomain, "*") {
return fmt.Errorf("'.' and '*' is not supported in subdomain")
}
}
return nil
}
// HTTP
var _ ProxyConf = &HTTPProxyConf{}
func (c *HTTPProxyConf) Compare(conf ProxyConf) bool {
cmp, ok := conf.(*HTTPProxyConf)
if !ok {
return false
}
if !c.BaseProxyConf.compare(&cmp.BaseProxyConf) {
return false
}
// Add custom logic equal if exists.
if !reflect.DeepEqual(c.HTTPProxySpec, cmp.HTTPProxySpec) {
return false
}
return true
}
func (c *HTTPProxyConf) UnmarshalFromIni(prefix string, name string, section *ini.Section) error {
err := section.MapTo(c)
if err != nil {
return err
}
err = c.BaseProxyConf.decorate(prefix, name, section)
if err != nil {
return err
}
// Add custom logic unmarshal if exists
c.Headers = GetMapWithoutPrefix(section.KeysHash(), "header_")
return nil
}
func (c *HTTPProxyConf) UnmarshalFromMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.unmarshalFromMsg(pMsg)
// Add custom logic unmarshal if exists
c.CustomDomains = pMsg.CustomDomains
c.SubDomain = pMsg.SubDomain
c.Locations = pMsg.Locations
c.HostHeaderRewrite = pMsg.HostHeaderRewrite
c.HTTPUser = pMsg.HTTPUser
c.HTTPPwd = pMsg.HTTPPwd
c.Headers = pMsg.Headers
}
func (c *HTTPProxyConf) MarshalToMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.marshalToMsg(pMsg)
// Add custom logic marshal if exists
pMsg.CustomDomains = c.CustomDomains
pMsg.SubDomain = c.SubDomain
pMsg.Locations = c.Locations
pMsg.HostHeaderRewrite = c.HostHeaderRewrite
pMsg.HTTPUser = c.HTTPUser
pMsg.HTTPPwd = c.HTTPPwd
pMsg.Headers = c.Headers
}
func (c *HTTPProxyConf) CheckForCli() error {
if err := c.BaseProxyConf.checkForCli(); err != nil {
return err
}
// Add custom logic check if exists
if err := c.DomainSpec.validateForCli(); err != nil {
return err
}
return nil
}
func (c *HTTPProxyConf) CheckForSvr(svrconf ServerCommonConf) error {
if svrconf.VhostHTTPPort == 0 {
return fmt.Errorf("type [http] not support when vhost_http_port is not set")
}
if err := c.DomainSpec.validateForSvr(svrconf); err != nil {
return fmt.Errorf("proxy [%s] domain conf check error: %v", c.ProxyName, err)
}
return nil
}
// HTTPS
var _ ProxyConf = &HTTPSProxyConf{}
func (c *HTTPSProxyConf) Compare(conf ProxyConf) bool {
cmp, ok := conf.(*HTTPSProxyConf)
if !ok {
return false
}
if !c.BaseProxyConf.compare(&cmp.BaseProxyConf) {
return false
}
// Add custom logic equal if exists.
if !reflect.DeepEqual(c.HTTPSProxySpec, cmp.HTTPSProxySpec) {
return false
}
return true
}
func (c *HTTPSProxyConf) UnmarshalFromIni(prefix string, name string, section *ini.Section) error {
err := section.MapTo(c)
if err != nil {
return err
}
err = c.BaseProxyConf.decorate(prefix, name, section)
if err != nil {
return err
}
// Add custom logic unmarshal if exists
return nil
}
func (c *HTTPSProxyConf) UnmarshalFromMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.unmarshalFromMsg(pMsg)
// Add custom logic unmarshal if exists
c.CustomDomains = pMsg.CustomDomains
c.SubDomain = pMsg.SubDomain
}
func (c *HTTPSProxyConf) MarshalToMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.marshalToMsg(pMsg)
// Add custom logic marshal if exists
pMsg.CustomDomains = c.CustomDomains
pMsg.SubDomain = c.SubDomain
}
func (c *HTTPSProxyConf) CheckForCli() error {
if err := c.BaseProxyConf.checkForCli(); err != nil {
return err
}
// Add custom logic check if exists
if err := c.DomainSpec.validateForCli(); err != nil {
return err
}
return nil
}
func (c *HTTPSProxyConf) CheckForSvr(svrconf ServerCommonConf) error {
if svrconf.VhostHTTPSPort == 0 {
return fmt.Errorf("type [https] not support when vhost_https_port is not set")
}
if err := c.DomainSpec.validateForSvr(svrconf); err != nil {
return fmt.Errorf("proxy [%s] domain conf check error: %v", c.ProxyName, err)
}
return nil
}
// TCP
var _ ProxyConf = &TCPProxyConf{}
func (c *TCPProxyConf) Compare(conf ProxyConf) bool {
cmp, ok := conf.(*TCPProxyConf)
if !ok {
return false
}
if !c.BaseProxyConf.compare(&cmp.BaseProxyConf) {
return false
}
// Add custom logic equal if exists.
if !reflect.DeepEqual(c.TCPProxySpec, cmp.TCPProxySpec) {
return false
}
return true
}
func (c *TCPProxyConf) UnmarshalFromIni(prefix string, name string, section *ini.Section) error {
err := section.MapTo(c)
if err != nil {
return err
}
err = c.BaseProxyConf.decorate(prefix, name, section)
if err != nil {
return err
}
// Add custom logic unmarshal if exists
return nil
}
func (c *TCPProxyConf) UnmarshalFromMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.unmarshalFromMsg(pMsg)
// Add custom logic unmarshal if exists
c.RemotePort = pMsg.RemotePort
}
func (c *TCPProxyConf) MarshalToMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.marshalToMsg(pMsg)
// Add custom logic marshal if exists
pMsg.RemotePort = c.RemotePort
}
func (c *TCPProxyConf) CheckForCli() error {
if err := c.BaseProxyConf.checkForCli(); err != nil {
return err
}
// Add custom logic check if exists
return nil
}
func (c *TCPProxyConf) CheckForSvr(svrconf ServerCommonConf) error {
return nil
}
// TCPMux
var _ ProxyConf = &TCPMuxProxyConf{}
func (c *TCPMuxProxyConf) Compare(conf ProxyConf) bool {
cmp, ok := conf.(*TCPMuxProxyConf)
if !ok {
return false
}
if !c.BaseProxyConf.compare(&cmp.BaseProxyConf) {
return false
}
// Add custom logic equal if exists.
if !reflect.DeepEqual(c.TCPMuxProxySpec, cmp.TCPMuxProxySpec) {
return false
}
return true
}
func (c *TCPMuxProxyConf) UnmarshalFromIni(prefix string, name string, section *ini.Section) error {
err := section.MapTo(c)
if err != nil {
return err
}
err = c.BaseProxyConf.decorate(prefix, name, section)
if err != nil {
return err
}
// Add custom logic unmarshal if exists
return nil
}
func (c *TCPMuxProxyConf) UnmarshalFromMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.unmarshalFromMsg(pMsg)
// Add custom logic unmarshal if exists
c.CustomDomains = pMsg.CustomDomains
c.SubDomain = pMsg.SubDomain
c.Multiplexer = pMsg.Multiplexer
}
func (c *TCPMuxProxyConf) MarshalToMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.marshalToMsg(pMsg)
// Add custom logic marshal if exists
pMsg.CustomDomains = c.CustomDomains
pMsg.SubDomain = c.SubDomain
pMsg.Multiplexer = c.Multiplexer
}
func (c *TCPMuxProxyConf) CheckForCli() error {
if err := c.BaseProxyConf.checkForCli(); err != nil {
return err
}
// Add custom logic check if exists
if err := c.DomainSpec.validateForCli(); err != nil {
return err
}
if c.Multiplexer != consts.HTTPConnectTCPMultiplexer {
return fmt.Errorf("parse conf error: incorrect multiplexer [%s]", c.Multiplexer)
}
return nil
}
func (c *TCPMuxProxyConf) CheckForSvr(svrconf ServerCommonConf) error {
if c.Multiplexer != consts.HTTPConnectTCPMultiplexer {
return fmt.Errorf("proxy [%s] incorrect multiplexer [%s]", c.ProxyName, c.Multiplexer)
}
if c.Multiplexer == consts.HTTPConnectTCPMultiplexer && svrconf.TCPMuxHTTPConnectPort == 0 {
return fmt.Errorf("proxy [%s] type [tcpmux] with multiplexer [httpconnect] requires tcpmux_httpconnect_port configuration", c.ProxyName)
}
if err := c.DomainSpec.validateForSvr(svrconf); err != nil {
return fmt.Errorf("proxy [%s] domain conf check error: %v", c.ProxyName, err)
}
return nil
}
// STCP
var _ ProxyConf = &STCPProxyConf{}
func (c *STCPProxyConf) Compare(conf ProxyConf) bool {
cmp, ok := conf.(*STCPProxyConf)
if !ok {
return false
}
if !c.BaseProxyConf.compare(&cmp.BaseProxyConf) {
return false
}
// Add custom logic equal if exists.
if !reflect.DeepEqual(c.STCPProxySpec, cmp.STCPProxySpec) {
return false
}
return true
}
func (c *STCPProxyConf) UnmarshalFromIni(prefix string, name string, section *ini.Section) error {
err := section.MapTo(c)
if err != nil {
return err
}
err = c.BaseProxyConf.decorate(prefix, name, section)
if err != nil {
return err
}
// Add custom logic unmarshal if exists
if c.Role == "" {
c.Role = "server"
}
return nil
}
// Only for role server.
func (c *STCPProxyConf) UnmarshalFromMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.unmarshalFromMsg(pMsg)
// Add custom logic unmarshal if exists
c.Sk = pMsg.Sk
}
func (c *STCPProxyConf) MarshalToMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.marshalToMsg(pMsg)
// Add custom logic marshal if exists
pMsg.Sk = c.Sk
}
func (c *STCPProxyConf) CheckForCli() error {
if err := c.BaseProxyConf.checkForCli(); err != nil {
return err
}
// Add custom logic check if exists
if c.Role != "server" {
return fmt.Errorf("role should be 'server'")
}
return nil
}
func (c *STCPProxyConf) CheckForSvr(svrconf ServerCommonConf) error {
return nil
}
// XTCP
var _ ProxyConf = &XTCPProxyConf{}
func (c *XTCPProxyConf) Compare(conf ProxyConf) bool {
cmp, ok := conf.(*XTCPProxyConf)
if !ok {
return false
}
if !c.BaseProxyConf.compare(&cmp.BaseProxyConf) {
return false
}
// Add custom logic equal if exists.
if !reflect.DeepEqual(c.XTCPProxySpec, cmp.XTCPProxySpec) {
return false
}
return true
}
func (c *XTCPProxyConf) UnmarshalFromIni(prefix string, name string, section *ini.Section) error {
err := section.MapTo(c)
if err != nil {
return err
}
err = c.BaseProxyConf.decorate(prefix, name, section)
if err != nil {
return err
}
// Add custom logic unmarshal if exists
if c.Role == "" {
c.Role = "server"
}
return nil
}
// Only for role server.
func (c *XTCPProxyConf) UnmarshalFromMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.unmarshalFromMsg(pMsg)
// Add custom logic unmarshal if exists
c.Sk = pMsg.Sk
}
func (c *XTCPProxyConf) MarshalToMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.marshalToMsg(pMsg)
// Add custom logic marshal if exists
pMsg.Sk = c.Sk
}
func (c *XTCPProxyConf) CheckForCli() error {
if err := c.BaseProxyConf.checkForCli(); err != nil {
return err
}
// Add custom logic check if exists
if c.Role != "server" {
return fmt.Errorf("role should be 'server'")
}
return nil
}
func (c *XTCPProxyConf) CheckForSvr(svrconf ServerCommonConf) error {
return nil
}
// UDP
var _ ProxyConf = &UDPProxyConf{}
func (c *UDPProxyConf) Compare(conf ProxyConf) bool {
cmp, ok := conf.(*UDPProxyConf)
if !ok {
return false
}
if !c.BaseProxyConf.compare(&cmp.BaseProxyConf) {
return false
}
// Add custom logic equal if exists.
if !reflect.DeepEqual(c.UDPProxySpec, cmp.UDPProxySpec) {
return false
}
return true
}
func (c *UDPProxyConf) UnmarshalFromIni(prefix string, name string, section *ini.Section) error {
err := section.MapTo(c)
if err != nil {
return err
}
err = c.BaseProxyConf.decorate(prefix, name, section)
if err != nil {
return err
}
// Add custom logic unmarshal if exists
return nil
}
func (c *UDPProxyConf) UnmarshalFromMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.unmarshalFromMsg(pMsg)
// Add custom logic unmarshal if exists
c.RemotePort = pMsg.RemotePort
}
func (c *UDPProxyConf) MarshalToMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.marshalToMsg(pMsg)
// Add custom logic marshal if exists
pMsg.RemotePort = c.RemotePort
}
func (c *UDPProxyConf) CheckForCli() error {
if err := c.BaseProxyConf.checkForCli(); err != nil {
return err
}
// Add custom logic check if exists
return nil
}
func (c *UDPProxyConf) CheckForSvr(svrconf ServerCommonConf) error {
return nil
}
// SUDP
var _ ProxyConf = &SUDPProxyConf{}
func (c *SUDPProxyConf) Compare(conf ProxyConf) bool {
cmp, ok := conf.(*SUDPProxyConf)
if !ok {
return false
}
if !c.BaseProxyConf.compare(&cmp.BaseProxyConf) {
return false
}
// Add custom logic equal if exists.
if !reflect.DeepEqual(c.SUDPProxySpec, cmp.SUDPProxySpec) {
return false
}
return true
}
func (c *SUDPProxyConf) UnmarshalFromIni(prefix string, name string, section *ini.Section) error {
err := section.MapTo(c)
if err != nil {
return err
}
err = c.BaseProxyConf.decorate(prefix, name, section)
if err != nil {
return err
}
// Add custom logic unmarshal if exists
return nil
}
// Only for role server.
func (c *SUDPProxyConf) UnmarshalFromMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.unmarshalFromMsg(pMsg)
// Add custom logic unmarshal if exists
c.Sk = pMsg.Sk
}
func (c *SUDPProxyConf) MarshalToMsg(pMsg *msg.NewProxy) {
c.BaseProxyConf.marshalToMsg(pMsg)
// Add custom logic marshal if exists
pMsg.Sk = c.Sk
}
func (c *SUDPProxyConf) CheckForCli() error {
if err := c.BaseProxyConf.checkForCli(); err != nil {
return err
}
// Add custom logic check if exists
if c.Role != "server" {
return fmt.Errorf("role should be 'server'")
}
return nil
}
func (c *SUDPProxyConf) CheckForSvr(svrconf ServerCommonConf) error {
return nil
}