lc_bcb_103.txt

c++ builder 的一些txt文档

UDP
UDP
一、说明
 使用UDP时，直接使用API代替控件。
 第一个程序(ReadBufferUdp)使用来接收到缓存中。
 "Destino"变量非常重要，如果你从其他地方接收数据到Buffer，你必须设置Destino 
= 0 并且在以后执行的时候赋值你将要发送的包的地址给它（after 
the execution it will have the address which send you the packet.）。
 
如果你只想从一个指定的地址接收数据，你必须设置变量Destino 
= <address>.
 "gvEncerrar" 用来中止处理过程。(gvEncerrar被设置为全局变量。)
 超时时间设置。"Inicio + 12" = 12 sec of 
timeout.
 第三个程序是用来准备WinSock程序。
二、代码
int ReadBufferUdp(unsigned long *Destino,void *T,int Size)
{
 char Buffer[128];
 SOCKADDR_IN SockAddr;
 int LenSockAddr=sizeof(SOCKADDR_IN);
 fd_set FdRead;
 struct timeval t_val;
 int Ret;
 time_t Inicio = time(NULL);
 Application->ProcessMessages();
 if(gvEncerrar)
 return false;
 FD_ZERO(&FdRead);
 FD_SET(gvSocket,&FdRead);
 t_val.tv_sec=0;
 t_val.tv_usec=0;
 while((Ret=select(0,&FdRead,NULL,NULL,&t_val))!=1 
&& (Inicio + 12) >
time(NULL) && !gvEncerrar)
 {
 FD_ZERO(&FdRead);
 FD_SET(gvSocket,&FdRead);
 t_val.tv_sec=0;
 t_val.tv_usec=0;
 Application->ProcessMessages();
 }
 if(Ret != 1)
 return false;
if(recvfrom(gvSocket,Buffer,Size,0,(LPSOCKADDR)&SockAddr,&LenSockAddr)!=Size)
 return false;
 if(*Destino == 0)
 {
 *Destino = SockAddr.sin_addr.s_addr;
 }
 else
 if(*Destino != SockAddr.sin_addr.s_addr)
 return false;
 memcpy(T,Buffer,Size);
 return true;
}
int WriteBufferUdp(unsigned long Destino,void *T,int Size)
{
 SOCKADDR_IN SockAddr;
 int Sent;
 Application->ProcessMessages();
 SockAddr.sin_family = AF_INET;
 SockAddr.sin_port = gvPortUdp;
 SockAddr.sin_addr.s_addr = Destino;
 Sent = sendto(gvSocket,(char
*)T,Size,0,(LPSOCKADDR)&SockAddr,sizeof(SockAddr));
 if(Sent != Size)
 return false;
 else
 return true;
}
void InicializaTCPIP()
{
 WORD wVersionRequested;
 WSADATA wsaData;
 IN_ADDR In;
 PSERVENT PServent;
 SOCKADDR_IN SockAddrIn;
 wVersionRequested = MAKEWORD( 1, 1 );
 if(WSAStartup( wVersionRequested, &wsaData ))
 {
 ShowMessage("Erro na inicializao do 
TCP/IP");
 Application->Terminate();
 return;
 }
 // Get the port on service file
 
if((PServent=getservbyname("your_service_name","udp"))==NULL)
 {
 ShowMessage("Erro obtendo port do servi 
transurb/udp");
 Application->Terminate();
 return;
 }
 gvPortUdp = PServent->s_port;
 sprintf(StrAux,"Servi transurb/udp 
port:%d",ntohs(gvPortUdp));
 Log(StrAux);
 // Open de Socket
 if((gvSocket = socket(AF_INET,SOCK_DGRAM,0))==INVALID_SOCKET)
 {
 ShowMessage("Erro na criao do 
socket");
 Application->Terminate();
 return;
 }
 Log("Socket criado com sucesso");
 // Do the bind
 SockAddrIn.sin_family = AF_INET;
 SockAddrIn.sin_port = gvPortUdp;
 SockAddrIn.sin_addr.s_addr = NULL;
if(bind(gvSocket,(LPSOCKADDR)&SockAddrIn,sizeof(SockAddrIn))==SOCKET_ERROR)
 {
 ShowMessage("Erro no bind do socket");
 Application->Terminate();
 return;
 }
 Log("Bind do socket com sucesso");
}