udpclient.cpp

一个用C++ builder6.0做的UDP通信测试程序

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "UDPClient.h"
#include "WinSock.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TLANForm *LANForm;

enum PROTO {TCP=0,UDP=1};
SOCKET m_Socket=INVALID_SOCKET;
PROTO m_Protocol=TCP;

//---------------------------------------------------------------------------
__fastcall TLANForm::TLANForm(TComponent* Owner)
    : TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TLANForm::FormCreate(TObject *Sender)
{
    ::SendMessage(Prot->Handle,CB_SETCURSEL,0,0);
}
//---------------------------------------------------------------------------
//接受数据
void __fastcall TLANForm::OnRecv(TMessage &Message)
{
   char buf[4096];
   int nLen;
   struct sockaddr_in from;
   int nLength=sizeof(struct sockaddr_in);
   switch(WSAGETSELECTEVENT(Message.LParam))
   {
      case FD_READ:
         switch(m_Protocol)
         {
            case TCP:
               nLen=recv(m_Socket,buf,4096,0);
               if(nLen>0){
                  buf[nLen]='\0';
                  TxtEdit->Text="Received Length:"+String(nLen)+"\r\n"+StrPas(buf);
               }
               break;
            case UDP:
               nLen=recvfrom(m_Socket,buf,4096,0,(struct sockaddr*)&from,&nLength);
               if(nLen>0){
                  buf[nLen]='\0';
                  TxtEdit->Text="Received Length:"+String(nLen)+"\r\n"+StrPas(buf);
               }
               break;
         }
         break;
      case FD_CLOSE:
         closesocket(m_Socket);
         break;
   }
}
void __fastcall TLANForm::Button1Click(TObject *Sender)
{
   char szTmp[256],buf[4096];
   int nSize=0;
   UINT m_Port;
   AnsiString addr;
   addr=Addr->Text.Trim();
   if(addr.IsEmpty()){
      ::MessageBox(0,"Please enter the server IP!","Error",MB_OK+MB_ICONERROR);
      return;
   }
   unsigned long nAddr=inet_addr(addr.c_str());
   if(nAddr==INADDR_NONE){
      ::MessageBox(0,"Bad Internet IP!","Error",MB_OK+MB_ICONERROR);
      return;}

   try
   {
      m_Port=Port->Text.ToInt();
   }
   catch(Exception &e)
   {
      ::MessageBox(0,e.Message.c_str(),"Error",MB_OK+MB_ICONERROR);
      return;
   }
   switch(Prot->ItemIndex)
   {
      case 0:
         m_Protocol=TCP;
         break;
      case 1:
         m_Protocol=UDP;
         break;
   }
   if(TxtEdit->Text.IsEmpty()){
      ::MessageBox(0,"Please enter the text you want to send!","Error",MB_OK+MB_ICONERROR);
      return;}

   //Initialize Winsocket
   WSAData wsaData;
   ::ZeroMemory(&wsaData,sizeof(WSAData));
   WORD version=MAKEWORD(2,0);
   if(::WSAStartup(version,&wsaData)){
      wsprintf(szTmp,"Failed to initial winsock enviroment!,error no:%d",::WSAGetLastError());
      return;}

   //Obtain the active connection
   char ComputerName[255];
   gethostname(ComputerName,255);
   struct hostent* he=gethostbyname(ComputerName);
   if(!he){
      wsprintf(szTmp,"Failed to get information to host!","Error",MB_OK+MB_ICONERROR);
      ::WSACleanup();
      return;
   }
   //create new socket
   m_Socket=INVALID_SOCKET;
   switch(m_Protocol)
   {
      case TCP:
         m_Socket=socket(AF_INET,SOCK_STREAM,0);
         break;
      case UDP:
         m_Socket=socket(AF_INET,SOCK_DGRAM,0);
         break;
   }
   if(m_Socket==INVALID_SOCKET){
      wsprintf(szTmp,"Failed to create a new socket!,error no:%d",::WSAGetLastError());
      ::MessageBox(0,szTmp,"Error",MB_OK+MB_ICONERROR);
      ::WSACleanup();
      return;
   }
   //bind socket
   struct sockaddr_in client;
   unsigned long nClient;
   memcpy(&nClient,he->h_addr_list[0],sizeof(int));
   if(nClient==INADDR_NONE){
      wsprintf(szTmp,"Failed to obtain the local machine's IP!","Error",MB_OK+MB_ICONERROR);
      ::MessageBox(0,szTmp,"Error",MB_OK+MB_ICONERROR);
      closesocket(m_Socket);
      ::WSACleanup();
// 本文转自 C++Builder 研究 - http://www.ccrun.com/article.asp?i=569&d=1w5p2y
      return;
   }
   client.sin_family=AF_INET;
   client.sin_port=0;
   client.sin_addr.S_un.S_addr=(int)nClient;
   if(bind(m_Socket,(struct sockaddr*)&client,sizeof(struct sockaddr))){
      wsprintf(szTmp,"Failed to bind socket!","Error",MB_OK+MB_ICONERROR);
      closesocket(m_Socket);
      ::WSACleanup();
      return;}
   //connect socket
   struct sockaddr_in To;
   To.sin_family=AF_INET;
   To.sin_port=htons(m_Port);
   To.sin_addr.S_un.S_addr=(int)nAddr;
   fd_set FDSET;
   FD_ZERO(&FDSET);
   FD_SET(m_Socket,&FDSET);


   if(m_Protocol==TCP){
      if(connect(m_Socket,(struct sockaddr*)&To,sizeof(struct sockaddr))){
         wsprintf(szTmp,"Failed to connect the object!,error no:%d",::WSAGetLastError());
         ::MessageBox(0,szTmp,"Error",MB_OK+MB_ICONERROR);
         closesocket(m_Socket);
         ::WSACleanup();
         return;
      }
      int nError=select(1,0,&FDSET,0,0);
      if(nError<=0){
      wsprintf(szTmp,"Failed to select socket!,error no:%d",::WSAGetLastError());
      closesocket(m_Socket);
      ::WSACleanup();
      return;}
   }
   //Send data
   int nLen=TxtEdit->Text.Length();
   if(nLen>4096){
      wsprintf(szTmp,"The buffer is too size to send,it shoud not be more than 4096 bytes!");
      ::MessageBox(0,szTmp,"Error",MB_OK+MB_ICONERROR);
      closesocket(m_Socket);
      ::WSACleanup();
      return;
   }
   strncpy(buf,TxtEdit->Text.c_str(),nLen);
   switch(m_Protocol)
   {
      case TCP:
         nSize=send(m_Socket,buf,nLen,0);
         //ShowMessage(nSize);
         break;
      case UDP:
         nSize=sendto(m_Socket,buf,nLen,0,(struct sockaddr*)&To,sizeof(struct sockaddr));
         //ShowMessage(nSize);
         break;

   }
   if(::WSAAsyncSelect(m_Socket,Handle,WM_SOCK,FD_READ|FD_CLOSE)){
      wsprintf(szTmp,"Failed to register socket event!,error no:%d",::WSAGetLastError());
      ::MessageBox(0,szTmp,"Error",MB_OK+MB_ICONERROR);
      closesocket(m_Socket);
      ::WSACleanup();
      return;}
    
}
//---------------------------------------------------------------------------
void __fastcall TLANForm::FormDestroy(TObject *Sender)
{
   closesocket(m_Socket);
   ::WSACleanup();
    
}
//---------------------------------------------------------------------------