我正在尝试使用多播套接字在网络中发现 UPnP 设备，但是，我似乎多次获得相同的设备。这里的发现代码有什么问题。
我得到的结果如下
HTTP/1.1 200 OK CACHE-CONTROL：max-age = 60 EXT：位置：http ://10.2.1.89:5200/Printer.xml 服务器：网络打印机服务器 UPnP/1.0 V4.00.01.31 DEC-23-2014 ST : uuid:16a65700-007c-1000-bb49-30cda79cac19 USN: uuid:16a65700-007c-1000-bb49-30cda79cac19
HTTP/1.1 200 OK CACHE-CONTROL：max-age = 60 EXT：位置：http ://10.2.1.87:5200/Printer.xml 服务器：网络打印机服务器 UPnP/1.0 V4.00.01.31 DEC-23-2014 ST : uuid:16a65700-007c-1000-bb49-30cda79b5419 USN: uuid:16a65700-007c-1000-bb49-30cda79b5419
使用的代码如下
namespace DevManager
{
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
public class UPnPDevDiscovery
{
/// <summary>
/// Device search request
/// </summary>
private const string searchRequest = "M-SEARCH * HTTP/1.1\r\nHOST: {0}:{1}\r\nMAN: \"ssdp:discover\"\r\nMX: {2}\r\nST: {3}\r\n";
/// <summary>
/// Advertisement multicast address
/// </summary>
private const string multicastIP = "239.255.255.250";
/// <summary>
/// Advertisement multicast port
/// </summary>
private const int multicastPort = 1900;
/// <summary>
/// Time to Live (TTL) for multicast messages
/// </summary>
private const int multicastTTL = 4;
private const int unicastPort = 1901;
private const int MaxResultSize = 8096;
private const string DefaultDeviceType = "ssdp:all";
private string deviceType;
private Action<Device> onDeviceFound;
private int searchTimeOut;
private Socket socket;
private Timer timer;
private int sendCount;
private SocketAsyncEventArgs sendEvent;
private bool socketClosed;
private List<Task> taskList = new List<Task>();
public void Initialize(string deviceType, int searchTimeOut, Action<Device> onDeviceFound)
{
if (searchTimeOut < 1 || searchTimeOut > 4)
{
this.searchTimeOut = multicastTTL;
}
else
{
this.searchTimeOut = searchTimeOut;
}
if (string.IsNullOrWhiteSpace(deviceType))
{
this.deviceType = DefaultDeviceType;
}
else
{
this.deviceType = deviceType;
}
this.onDeviceFound = onDeviceFound;
}
public void FindDevices()
{
string request = string.Format(searchRequest, multicastIP, multicastPort, this.searchTimeOut, this.deviceType);
socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
byte[] multiCastData = Encoding.UTF8.GetBytes(request);
socket.SendBufferSize = multiCastData.Length;
sendEvent = new SocketAsyncEventArgs();
sendEvent.RemoteEndPoint = new IPEndPoint(IPAddress.Parse(multicastIP), multicastPort);
sendEvent.SetBuffer(multiCastData, 0, multiCastData.Length);
sendEvent.Completed += OnSocketSendEventCompleted;
// Set a one-shot timer for the Search time plus a second
TimerCallback cb = new TimerCallback((state) =>
{
this.socketClosed = true;
socket.Close();
});
timer = new Timer(cb, null, TimeSpan.FromSeconds(this.searchTimeOut + 1), new TimeSpan(-1));
// Kick off the initial Send
this.sendCount = 3;
this.socketClosed = false;
socket.SendToAsync(sendEvent);
//while (!this.socketClosed)
//{
// Thread.Sleep(200);
//}
//Task.WaitAll(this.taskList.ToArray());
//this.taskList.Clear();
}
private void OnSocketSendEventCompleted(object sender, SocketAsyncEventArgs e)
{
if (e.SocketError != SocketError.Success)
{
this.AddDevice(null);
}
else
{
if (e.LastOperation == SocketAsyncOperation.SendTo)
{
if (--this.sendCount != 0)
{
if (!this.socketClosed)
{
socket.SendToAsync(sendEvent);
}
}
else
{
// When the initial multicast is done, get ready to receive responses
e.RemoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
socket.ReceiveBufferSize = MaxResultSize;
byte[] receiveBuffer = new byte[MaxResultSize];
e.SetBuffer(receiveBuffer, 0, MaxResultSize);
socket.ReceiveFromAsync(e);
}
}
else if (e.LastOperation == SocketAsyncOperation.ReceiveFrom)
{
// Got a response, so decode it
string result = Encoding.UTF8.GetString(e.Buffer, 0, e.BytesTransferred);
if (result.StartsWith("HTTP/1.1 200 OK", StringComparison.InvariantCultureIgnoreCase))
{
//parse device and invoke callback
AddDevice(result);
}
else
{
//Debug.WriteLine("INVALID SEARCH RESPONSE");
}
if (!this.socketClosed)
{
// and kick off another read
socket.ReceiveFromAsync(e);
}
else
{
// unless socket was closed, when declare the scan is complete
//AddDevice(result);
}
}
}
}
private void AddDevice(string response)
{
Console.WriteLine(response);
//Task addDeviceTask = Task.Run(() =>
//{
// // parse the result and download the device description
// if (this.onDeviceFound != null && response != null)
// {
// Dictionary<string, string> ssdpResponse = ParseSSDPResponse(response);
// HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(ssdpResponse["location"]);
// WebResponse webResponse = webRequest.GetResponse();
// using (DeviceXml deviceXml = new DeviceXml(webResponse.GetResponseStream()))
// {
// this.onDeviceFound(deviceXml.GetObject());
// }
// }
//});
//this.taskList.Add(addDeviceTask);
}
// Probably not exactly compliant with RFC 2616 but good enough for now
private Dictionary<string, string> ParseSSDPResponse(string response)
{
StringReader reader = new StringReader(response);
string line = reader.ReadLine();
if (line != "HTTP/1.1 200 OK")
return null;
Dictionary<string, string> result = new Dictionary<string, string>();
for (;;)
{
line = reader.ReadLine();
if (line == null)
break;
if (line != "")
{
int colon = line.IndexOf(':');
if (colon < 1)
{
return null;
}
string name = line.Substring(0, colon).Trim();
string value = line.Substring(colon + 1).Trim();
if (string.IsNullOrEmpty(name))
{
return null;
}
result[name.ToLowerInvariant()] = value;
}
}
return result;
}
}
}