我开始锁定套接字编程并遇到了一些麻烦:我创建了下面的小程序,它通过 udp 发送消息并在可能的循环中接收消息。我想稍后尝试使用多个套接字,所以我使用select()
.
当我使用 my时127.0.0.1
,select()
在第一个循环中(在 之后)给出超时,send()
但之后它总是返回1
指示套接字是可读的而没有收到消息:
//C++
WSADATA wsa;
SOCKADDR_IN RemoteAddr;
SOCKADDR_IN OwnAddr;
SOCKET UDP_Socket1;
fd_set m_Fds;
struct timeval m_Timeout;
int iRemoteAddrLenght = sizeof(SOCKADDR_IN);
int i = 0;
//--Init
WSAStartup (MAKEWORD (2,2), &wsa);
UDP_Socket1 = socket(AF_INET, SOCK_DGRAM, 0);
m_Timeout.tv_sec = 2;
m_Timeout.tv_usec = 0;
RemoteAddr.sin_family = AF_INET;
RemoteAddr.sin_port = htons (2002);
RemoteAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
OwnAddr.sin_family = AF_INET;
OwnAddr.sin_port = htons (2003);
OwnAddr.sin_addr.s_addr = htonl(INADDR_ANY);
bind(UDP_Socket1, (SOCKADDR*) &OwnAddr, sizeof(OwnAddr));
for(;;)
{
//..//
//--send
sendto(UDP_Socket1, sSend.c_str(), strlen(sSend.c_str()), 0 , (SOCKADDR*)&RemoteAddr, sizeof(RemoteAddr));
//--select & recv
FD_ZERO(&m_Fds);
FD_SET(UDP_Socket1,&m_Fds);
i = select(sizeof(m_Fds)*8, &m_Fds, NULL, NULL, &m_Timeout);
if(i > 0)
{
recvfrom(UDP_Socket1, m_szBuff, 256, 0, (SOCKADDR*) &RemoteAddr, &m_iRemoteAddrLenght);
} //if
else if(i < 1) // "0" in 1st loop, then "1" =(
{
cout << "Udp Timeout" << endl;
} //else if
} //for
send
返回56
(发送字节)WSAGetLastError: 0
recvfrom
返回-1
_WSAGetLastError: 10054
感谢您提供有关为什么在应该超时时select()
返回的帮助1