作者：Derek
简介
Github地址：https://github.com/Bytom/bytom
Gitee地址：https://gitee.com/BytomBlockchain/bytom
本章介绍bytom代码P2P网络中upnp端口映射
UPNP介绍
UPNP（Universal Plug and Play）通用即插即用。UPNP端口映射将一个外部端口映射到一个内网ip:port。从而实现p2p网络从外网能够穿透网关访问到内网的bytomd节点。
UPNP协议
SSDP（Simple Service Discovery Protocol 简单服务发现协议）
GENA（Generic Event Notification Architecture 通用事件通知结构）
SOAP（Simple Object Access Protocol 简单对象访问协议）
XML（Extensible Markup Language 可扩张标记语言）
UPNP代码
** p2p/upnp/upnp.go **
发现网络中支持UPNP功能的设备
从网络中发现支持UPNP功能的设备，并得到该设备的location和url等相关信息
type upnpNAT struct {
serviceURL string // 设备的描述文件URL，用于得到该设备的描述信息
ourIP string // 节点本地ip地址
urnDomain string // 设备类型
}
func Discover() (nat NAT, err error) {
ssdp, err := net.ResolveUDPAddr("udp4", "239.255.255.250:1900")
if err != nil {
return
}
conn, err := net.ListenPacket("udp4", ":0")
if err != nil {
return
}
socket := conn.(*net.UDPConn)
defer socket.Close()
err = socket.SetDeadline(time.Now().Add(3 * time.Second))
if err != nil {
return
}
st := "InternetGatewayDevice:1"
// 多播请求：M-SEARCH SSDP协议定义的发现请求。
buf := bytes.NewBufferString(
"M-SEARCH * HTTP/1.1\r\n" +
"HOST: 239.255.255.250:1900\r\n" +
"ST: ssdp:all\r\n" +
"MAN: \"ssdp:discover\"\r\n" +
"MX: 2\r\n\r\n")
message := buf.Bytes()
answerBytes := make([]byte, 1024)
for i := 0; i < 3; i++ {
// 向239.255.255.250:1900发送一条多播请求
_, err = socket.WriteToUDP(message, ssdp)
if err != nil {
return
}
// 如果从网络中发现UPNP设备则会从239.255.255.250:1900收到响应消息
var n int
n, _, err = socket.ReadFromUDP(answerBytes)
for {
n, _, err = socket.ReadFromUDP(answerBytes)
if err != nil {
break
}
answer := string(answerBytes[0:n])
if strings.Index(answer, st) < 0 {
continue
}
// HTTP header field names are case-insensitive.
// http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2
// 获得设备location
locString := "\r\nlocation:"
answer = strings.ToLower(answer)
locIndex := strings.Index(answer, locString)
if locIndex < 0 {
continue
}
loc := answer[locIndex+len(locString):]
endIndex := strings.Index(loc, "\r\n")
if endIndex < 0 {
continue
}
// 获得设备的描述url和设备类型
locURL := strings.TrimSpace(loc[0:endIndex])
var serviceURL, urnDomain string
serviceURL, urnDomain, err = getServiceURL(locURL)
if err != nil {
return
}
var ourIP net.IP
ourIP, err = localIPv4()
if err != nil {
return
}
nat = &upnpNAT{serviceURL: serviceURL, ourIP: ourIP.String(), urnDomain: urnDomain}
return
}
}
err = errors.New("UPnP port discovery failed.")
return
}
添加端口映射
向upnp设备发送一条http post请求，将内部网络ip:port和外部网络ip:port做映射
func (n *upnpNAT) AddPortMapping(protocol string, externalPort, internalPort int, description string, timeout int) (mappedExternalPort int, err error) {
// A single concatenation would break ARM compilation.
message := "<u:AddPortMapping xmlns:u=\"urn:" + n.urnDomain + ":service:WANIPConnection:1\">\r\n" +
"<NewRemoteHost></NewRemoteHost><NewExternalPort>" + strconv.Itoa(externalPort)
message += "</NewExternalPort><NewProtocol>" + protocol + "</NewProtocol>"
message += "<NewInternalPort>" + strconv.Itoa(internalPort) + "</NewInternalPort>" +
"<NewInternalClient>" + n.ourIP + "</NewInternalClient>" +
"<NewEnabled>1</NewEnabled><NewPortMappingDescription>"
message += description +
"</NewPortMappingDescription><NewLeaseDuration>" + strconv.Itoa(timeout) +
"</NewLeaseDuration></u:AddPortMapping>"
var response *http.Response
response, err = soapRequest(n.serviceURL, "AddPortMapping", message, n.urnDomain)
if response != nil {
defer response.Body.Close()
}
if err != nil {
return
}
// TODO: check response to see if the port was forwarded
// log.Println(message, response)
// JAE:
// body, err := ioutil.ReadAll(response.Body)
// fmt.Println(string(body), err)
mappedExternalPort = externalPort
_ = response
return
}
删除端口映射
向upnp设备发送一条http post请求，将内部网络ip:port和外部网络ip:port删除映射关系
func (n *upnpNAT) DeletePortMapping(protocol string, externalPort, internalPort int) (err error) {
message := "<u:DeletePortMapping xmlns:u=\"urn:" + n.urnDomain + ":service:WANIPConnection:1\">\r\n" +
"<NewRemoteHost></NewRemoteHost><NewExternalPort>" + strconv.Itoa(externalPort) +
"</NewExternalPort><NewProtocol>" + protocol + "</NewProtocol>" +
"</u:DeletePortMapping>"
var response *http.Response
response, err = soapRequest(n.serviceURL, "DeletePortMapping", message, n.urnDomain)
if response != nil {
defer response.Body.Close()
}
if err != nil {
return
}
// TODO: check response to see if the port was deleted
// log.Println(message, response)
_ = response
return
}
获取映射后的公网地址
func (n *upnpNAT) GetExternalAddress() (addr net.IP, err error) {
info, err := n.getExternalIPAddress()
if err != nil {
return
}
addr = net.ParseIP(info.externalIpAddress)
return
}
func (n *upnpNAT) getExternalIPAddress() (info statusInfo, err error) {
message := "<u:GetExternalIPAddress xmlns:u=\"urn:" + n.urnDomain + ":service:WANIPConnection:1\">\r\n" +
"</u:GetExternalIPAddress>"
var response *http.Response
response, err = soapRequest(n.serviceURL, "GetExternalIPAddress", message, n.urnDomain)
if response != nil {
defer response.Body.Close()
}
if err != nil {
return
}
var envelope Envelope
data, err := ioutil.ReadAll(response.Body)
reader := bytes.NewReader(data)
xml.NewDecoder(reader).Decode(&envelope)
info = statusInfo{envelope.Soap.ExternalIP.IPAddress}
if err != nil {
return
}
return
}