可以使用IdUDPClient发送M-SEARCH请求吗？ [英] Can I use IdUDPClient to send M-SEARCH request?

问题描述

我的网络中有几个uPNP设备。我正在向网络发送M-SEARCH请求，希望收到一些响应。这是我正在尝试的：

There are few uPNP devices in my network. I am trying to send M-SEARCH request to the network and hope receiving some responses from it. This is what I am trying:

var sIP, sOut: string;
    iPort: Word;
    S: TStringBuilder;
begin
  S := TStringBuilder.Create;
  try
    S.Append('M-SEARCH * HTTP/1.1').AppendLine
     .Append('HOST: 239.255.255.250:1900').AppendLine
     .Append('MAN: "ssdp:discover"').AppendLine
     .Append('MX: 10').AppendLine
     .Append('ST: ssdp:all').AppendLine;

    IdUDPClient1.ReceiveTimeout := 3000;
    IdUDPClient1.Broadcast(S.ToString, 1900, '239.255.255.250');
    sOut := IdUDPClient1.ReceiveString(sIP, iPort);
    Memo1.Lines.Add(sIP);
    Memo1.Lines.Add(IntToStr(iPort));
    Memo1.Lines.Add(sOut);
  finally
    S.Free;
  end;
end;

我没有从UDP客户端收到任何内容。我使用Wireshark监控网络流量，并没有从我的主机发送消息。

I receive nothing from the UDP client. I use Wireshark to monitor network traffic and no message was send out from my host.

任何想法？谢谢。

我最终找到答案：

uses
  System.SysUtils, IdUDPClient, IdStack;

var S: TStringBuilder;
    U: TIdUDPClient;
    iPeerPort: Word;
    sPeerIP, sResponse: string;
begin
  U := TIdUDPClient.Create(nil);
  S := TStringBuilder.Create;
  try
    S.Append('M-SEARCH * HTTP/1.1').AppendLine
     .Append('HOST: 239.255.255.250:1900').AppendLine
     .Append('MAN: "ssdp:discover"').AppendLine
     .Append('MX: 3').AppendLine
     .Append('ST: ssdp:all').AppendLine
     .AppendLine;

    U.BoundIP := GStack.LocalAddress;
    U.Send('239.255.255.250', 1900, S.ToString);

    U.ReceiveTimeout := 1000;
    repeat
      sResponse := U.ReceiveString(sPeerIP, iPeerPort);
      if iPeerPort <> 0 then begin
        WriteLn(Format('%s:%d', [sPeerIP, iPeerPort]));
        WriteLn(sResponse);
      end;
    until iPeerPort = 0;
    ReadLn;
  finally
    S.Free;
    U.Free;
  end;
end.

推荐答案

调用 AppendLine（） / code>两次，在字符串构建器的末尾。 HTTP请求标头由两个CRLF对终止，但您只需附加一个对，因此您发送不完整的请求。

Call AppendLine() twice at the end of the string builder. HTTP request headers are terminated by two CRLF pairs, but you are only appending one pair, so you are sending an incomplete request.

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