uPnP端口映射
处于内网的机器，因为没有一个公有的Ip,外面是无法主动连接到内网的设备。如果希望外面可以连接到处于内网的指定设备。UPNP端口映射是一个较简易的方案。当然这并不是唯一方案，穿透和转发也是一个较普遍的方式，本文只讨论UPNP端口映射的实现方式。UPNP端口映射将一个外部端口映射到一个【内网Ip：端口】，当然也指明了使用的协议是UDP,TCP,还是此映射同时适应UDP和TCP。
UPNP使用的常用命令： "GetStatusInfo","GetExternalIPAddress",
"AddPortMapping",
"GetSpecificPortMappingEntry", 1. 建立UDP socket,并绑定到一个自定的端口 2、通过UDP发送组播包：M-search，端口1900，包的内容如下所示 M-SEARCH * HTTP/1.1
HOST: 239.255.255.250:1900
ST: urn:schemas-upnp-org:device:InternetGatewayDevice:1
MAN: "ssdp:discover"
MX: 2 3、接收M-search的回应，并做相应的处理 HTTP/1.1 200 OK
CACHE-CONTROL: max-age=100
DATE: Thu, 01 Jan 1970 21:39:02 GMT
EXT:
LOCATION: http://192.168.1.1:1900/igd.xml
SERVER: Mercury Router MR804 Router, UPnP/1.0
ST: urn:schemas-upnp-org:device:InternetGatewayDevice:1
USN: uuid:6ec73f58-1dd2-11b2-9465-e6838914e4d9::urn:schemas-upnp-org:device:InternetGatewayDevice:1 1》获取path(lacation) ,此为 ： /igd.xml #path# 端口为： 1900 （有些路由并不一定是UPNP的端口1900) #ServerPort# ip:192.168.1.1 (有时候我们的内网中可能存在多个路由，并且都开启了upnp服务，这时候我们要判断哪一个才是网关路由，并且只处理网关路由的回应） 2》获取ST，此为：urn:schemas-upnp-org:device:InternetGatewayDevice:1 #ST# 4、建立tcp连接，--》【网关:ServerPort】 注意：有些路由不支持keep-alive特性，做每一次交互都做一次连接 5、获取path位置的xml数据： GET /igd.xml HTTP/1.1
Host: 192.168.1.1:1900
Connection: Close
User-Agent: MSWindows/6.1.7601, UPnP/1.0, MiniUPnPc/1.6 6、接收并分析得到的xml数据 HTTP/1.1 200 OK
CONTENT-LENGTH: 2733
CONTENT-TYPE: text/xml
DATE: Thu, 01 Jan 1970 21:39:02 GMT
LAST-MODIFIED: Tue, 28 Oct 2003 08:46:08 GMT
SERVER: Mercury Router MR804 Router, UPnP/1.0
CONNECTION: close
<?xml version="1.0"?>
Host: 192.168.1.1:1900
User-Agent: MSWindows/6.1.7601, UPnP/1.0, MiniUPnPc/1.6
Content-Length: 285
Content-Type: text/xml
SOAPAction: "urn:schemas-upnp-org:service:WANIPConnection:1#GetExternalIPAddress"
Connection: Close
Cache-Control: no-cache
Pragma: no-cache
<?xml version="1.0"?>
CONNECTION: close
SERVER: Mercury Router MR804 Router, UPnP/1.0
CONTENT-LENGTH: 404
CONTENT-TYPE: text/xml; charset="utf-8"
<?xml version="1.0"?>
Host: 192.168.1.1:1900
User-Agent: MSWindows/6.1.7601, UPnP/1.0, MiniUPnPc/1.6
Content-Length: 399
Content-Type: text/xml
SOAPAction: "urn:schemas-upnp-org:service:WANIPConnection:1#GetSpecificPortMappingEntry"
Connection: Close
Cache-Control: no-cache
Pragma: no-cache
<?xml version="1.0"?>
CONNECTION: close
SERVER: Mercury Router MR804 Router, UPnP/1.0
CONTENT-LENGTH: 574
CONTENT-TYPE: text/xml; charset="utf-8"
<?xml version="1.0"?>
CONTENT-LENGTH: 481
CONTENT-TYPE: text/xml; charset="utf-8"
DATE: Thu, 01 Jan 1970 00:00:02 GMT
EXT:
SERVER: Mercury Router MR804 Router, UPnP/1.0
Host: 192.168.1.1:1900
User-Agent: MSWindows/6.1.7601, UPnP/1.0, MiniUPnPc/1.6
Content-Length: 589
Content-Type: text/xml
SOAPAction: "urn:schemas-upnp-org:service:WANIPConnection:1#AddPortMapping"
Connection: Close
Cache-Control: no-cache
Pragma: no-cache
<?xml version="1.0"?>
CONNECTION: close
SERVER: Mercury Router MR804 Router, UPnP/1.0
CONTENT-LENGTH: 332
CONTENT-TYPE: text/xml; charset="utf-8"
<?xml version="1.0"?>