?? svrsocket,cltsocket控件源碼.htm
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begin<br>
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FActive := False;<br>
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if Assigned(FOnDisconnect) then FOnDisconnect(Self, Socket);<br>
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end;<br>
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seAccept: if Assigned(FOnAccept) then FOnAccept(Self, Socket);<br>
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seRead: if Assigned(FOnRead) then FOnRead(Self, Socket);<br>
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seWrite: if Assigned(FOnWrite) then FOnWrite(Self, Socket);<br>
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end;<br>
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end;<br>
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其中FonAccept等這些都是TCusotmSocket的成員，都是TSocketNotifyEvent類型的，TCustomSocket還通過下面這些屬性，使該類擁有了這些事件處理的能力：<br>
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property OnLookup: TSocketNotifyEvent read FOnLookup write FOnLookup;<br>
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property OnConnecting: TSocketNotifyEvent read FOnConnecting write FOnConnecting;<br>
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property OnConnect: TSocketNotifyEvent read FOnConnect write FOnConnect;<br>
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property OnDisconnect: TSocketNotifyEvent read FOnDisconnect write FOnDisconnect;<br>
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property OnListen: TSocketNotifyEvent read FOnListen write FOnListen;<br>
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property OnAccept: TSocketNotifyEvent read FOnAccept write FOnAccept;<br>
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property OnRead: TSocketNotifyEvent read FOnRead write FOnRead;<br>
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property OnWrite: TSocketNotifyEvent read FOnWrite write FOnWrite;<br>
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而上面的Event實現，我們可以看到它是根據SocketEvent的類型來調用相應的事件指針的，而它的子類ServerSocket和ClientSocket也擁有了這些事件的處理能力，到這里我們終于明白了，它們的事件是怎么樣出來的，但如果想得知這些事件是怎么觸發的，還要看這一句：Socket.OnSocketEvent，OnSocketEvent到后面再說，這里先略。<br>
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錯誤處理事件原理上也是一樣，到后面再說。<br>
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好了，到這里第一步解讀完畢，我們所知道的ServerSocket創建之后所完成事件就是初始化Socket DLL，并指定好事件處理的方法指針和錯誤處理的方法指針。我們接下來看第二步。<br>
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2．我們創建完ServerSocket后，下步要做什么呢，當然是指定端口啦，然后Open開始監視啦，這個過程會觸發一些事件，我們正好看看這些事件是怎么樣發生的。<br>
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由于這一次操作是非阻塞方式的，所以ServerType默認為stNonBlocking，我們開始設置Port，這個屬性的聲明在哪里，這個屬性一直到跟蹤祖先類AbstractSocket中去，因為無論客戶端和服務端都是要設置端口的，所以理所當然要封裝到最高層的類去了，以讓它的子類擁有這些屬性：<br>
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property Port: Integer read FPort write SetPort;<br>
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再看看SetPort方法：<br>
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（21）<br>
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procedure TAbstractSocket.SetPort(Value: Integer);<br>
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begin<br>
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if FPort <> Value then<br>
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begin<br>
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if not (csLoading in ComponentState) and FActive then<br>
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raise ESocketError.CreateRes(@sCantChangeWhileActive);<br>
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FPort := Value;<br>
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end;<br>
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end;<br>
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if not (csLoading in ComponentState) and FActive then<br>
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raise ESocketError.CreateRes(@sCantChangeWhileActive);<br>
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這一句是防止你在運行時改變端口，最后才將值賦給FPort。<br>
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好了，設置后Port后，就要Open了，開始監視客戶端了。<br>
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監視有兩個方式，一種是直接設Active屬性為True，一種直接調用Open方法。<br>
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其中Open方法如下：<br>
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procedure TAbstractSocket.Open;<br>
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begin<br>
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Active := True;<br>
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end;<br>
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它還是用到了屬性Active，所以我們可以集中來討論Active屬性。<br>
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property Active: Boolean read FActive write SetActive;<br>
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看看SetActive：<br>
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（22）<br>
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procedure TAbstractSocket.SetActive(Value: Boolean);<br>
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begin<br>
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if Value <> FActive then<br>
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begin<br>
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if (csDesigning in ComponentState) or (csLoading in ComponentState) then<br>
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FActive := Value;<br>
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if not (csLoading in ComponentState) then<br>
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DoActivate(Value);<br>
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end;<br>
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end;<br>
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我們可以這樣認為，當設計時就直接設FActive，當運行時，就調用DoActivate(Value);<br>
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而TAbstractSocket覆蓋了Loaded方法，則當窗體開始運行，從Form文件中開始流入時，也調用了DoActive方法。<br>
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再看DoActive了:<br>
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（221）<br>
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procedure DoActivate(Value: Boolean); virtual; abstract;又是一種抽象方法，得到它的子類去看了，在它的子類TCustomServerSocket找到這個方法：<br>
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procedure TCustomServerSocket.DoActivate(Value: Boolean);<br>
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begin<br>
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if (Value <> FServerSocket.Connected) and not (csDesigning in ComponentState) then<br>
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begin<br>
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if FServerSocket.Connected then<br>
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FServerSocket.Disconnect(FServerSocket.SocketHandle)<br>
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else FServerSocket.Listen(FHost, FAddress, FService, FPort, SOMAXCONN);<br>
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end;<br>
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end;<br>
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可以這樣理解，不在設計時，當Value不等它的成員FServerSocket.Connected時（我們可先認為這個表示當前的監聽狀態），而如果此時FServerSocket.Connected為True，則表示Value為False,，那么這時要斷開連接，調用FServerSocket.Disconnect(FServerSocket.SocketHandle)<br>
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很多時候ServerSocket都是調用它的成員FServerSocket來完成操作的，這一點我已經看到了，下面還有更多這樣的情況。否則，則Value為True，調用<br>
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FServerSocket.Listen(FHost, FAddress, FService, FPort, SOMAXCONN);來開始進行監視。好的，現在我們就要打開FServerSocket的源碼，看看它是怎么樣完成斷開連接和開始連接的了。<br>
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先看開始監聽的：<br>
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（2211）<br>
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procedure TServerWinSocket.Listen(var Name, Address, Service: string; Port: Word;<br>
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QueueSize: Integer);<br>
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begin<br>
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inherited Listen(Name, Address, Service, Port, QueueSize, ServerType = stThreadBlocking);<br>
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if FConnected and (ServerType = stThreadBlocking) then<br>
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FServerAcceptThread := TServerAcceptThread.Create(False, Self);<br>
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end;<br>
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這里調用其父類的Listen方法，如果它是阻塞方式的，則還要生成一個線程類，由于我用的非阻塞方式，所以暫不去理它，看看他的父類的Listen方法：<br>
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（22111）<br>
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procedure TCustomWinSocket.Listen(const Name, Address, Service: string; Port: Word;<br>
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QueueSize: Integer; Block: Boolean);<br>
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begin<br>
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if FConnected then raise ESocketError.CreateRes(@sCannotListenOnOpen);<br>
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FSocket := socket(PF_INET, SOCK_STREAM, IPPROTO_IP);<br>
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if FSocket = INVALID_SOCKET then raise ESocketError.CreateRes(@sCannotCreateSocket);<br>
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try<br>
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Event(Self, seLookUp);<br>
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if Block then<br>
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begin<br>
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FAddr := InitSocket(Name, Address, Service, Port, False);<br>
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DoListen(QueueSize);<br>
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end else<br>
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AsyncInitSocket(Name, Address, Service, Port, QueueSize, False);<br>
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except<br>
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Disconnect(FSocket);<br>
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raise;<br>
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end;<br>
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end;<br>
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這里第一句重要函數出現了：<br>
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FSocket := socket(PF_INET, SOCK_STREAM, IPPROTO_IP);<br>
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記得上面Fsockeet曾被賦過值嗎，是INVALID_SOCKET;，而這里終于被替回了一個可用的套接字了。<br>
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第二個重要的函數：Event(Self, seLookUp);可以先猜測這個方法最終于會調用事件指針，等一下再看。<br>
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接下來判斷Block的值，回頭看看這一句：<br>
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inherited Listen(Name, Address, Service, Port, QueueSize, ServerType = stThreadBlocking);<br>
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如果為阻塞方式，則為True，否則為False，非阻塞為這時為False，調用下方法：<br>
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AsyncInitSocket(Name, Address, Service, Port, QueueSize, False);<br>
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好了，再看一下Even吧：<br>
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（221111）<br>
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procedure TCustomWinSocket.Event(Socket: TCustomWinSocket; SocketEvent: TSocketEvent);<br>
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begin<br>
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if Assigned(FOnSocketEvent) then FOnSocketEvent(Self, Socket, SocketEvent);<br>
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end;<br>
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不出所料，調用事件指針了，這時ServerSocket的事件就會觸發了，回過頭去看看，<br>
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seLookup: if Assigned(FOnLookup) then FOnLookup(Self, Socket);<br>
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這里CustomSocket的OnLookup事件發生，但ServerSocket并沒有顯化它，ClientSocket就有這個事件。<br>
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按我們所設的方式，接下來要調用如下函數了（另外一些方法以后再說）：<br>
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AsyncInitSocket(Name, Address, Service, Port, QueueSize, False);<br>
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這函數很大，但所用到的技巧也非常精彩，得好好分析它： <br>
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（221112）<br>
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procedure TCustomWinSocket.AsyncInitSocket(const Name, Address,<br>
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Service: string; Port: Word; QueueSize: Integer; Client: Boolean);<br>
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var<br>
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ErrorCode: Integer;<br>
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begin<br>
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try<br>
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case FLookupState of<br>
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lsIdle:<br>
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begin<br>
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if not Client then<br>
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begin<br>
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FLookupState := lsLookupAddress;<br>
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FAddr.sin_addr.S_addr := INADDR_ANY;<br>
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//下面的情況到客戶端時才會用到<br>
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end else if Name <> '' then<br>
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begin<br>
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if FGetHostData = nil then<br>
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FGetHostData := AllocMem(MAXGETHOSTSTRUCT);<br>
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FLookupHandle := WSAAsyncGetHostByName(Handle, CM_LOOKUPCOMPLETE,<br>
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PChar(Name), FGetHostData, MAXGETHOSTSTRUCT);<br>
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CheckSocketResult(Ord(FLookupHandle = 0), 'WSAASyncGetHostByName');<br>
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FService := Service;<br>
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FPort := Port;<br>
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FQueueSize := QueueSize;<br>
<br>
FClient := Client;<br>
<br>
FLookupState := lsLookupAddress;<br>
<br>
Exit;<br>
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end else if Address <> '' then<br>
<br>
begin<br>
<br>
FLookupState := lsLookupAddress;<br>
<br>
FAddr.sin_addr.S_addr := inet_addr(PChar(Address));<br>
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end else<br>
<br>
begin<br>
<br>
ErrorCode := 1110;<br>
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Error(Self, eeLookup, ErrorCode);<br>
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Disconnect(FSocket);<br>
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if ErrorCode <> 0 then<br>
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raise ESocketError.CreateRes(@sNoAddress);<br>
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Exit;<br>
<br>
end;<br>
<br>
end;<br>
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lsLookupAddress:<br>
<br>
begin<br>
<br>
if Service <> '' then<br>
<br>
begin<br>
<br>
if FGetHostData = nil then<br>
<br>
FGetHostData := AllocMem(MAXGETHOSTSTRUCT);<br>
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FLookupHandle := WSAASyncGetServByName(Handle, CM_LOOKUPCOMPLETE,<br>
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PChar(Service), 'tcp' , FGetHostData, MAXGETHOSTSTRUCT);<br>
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CheckSocketResult(Ord(FLookupHandle = 0), 'WSAASyncGetServByName');<br>
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FLookupState := lsLookupService;<br>
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Exit;<br>
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end else<br>
<br>
begin<br>
<br>
FLookupState := lsLookupService;<br>
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FAddr.sin_port := htons(Port);<br>
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end;<br>
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end;<br>
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lsLookupService:<br>
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begin<br>
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FLookupState := lsIdle;<br>
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if Client then<br>
<br>
DoOpen<br>
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