select操作
服务端
代码语言：javascript复制#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <iostream>
#include <string.h>
#include <sys/time.h>
#include <vector>
#include <errno.h>
//自定义代表无效fd的值
#define INVALID_FD -1
int main(int argc, char* argv[])
{
//创建一个侦听socket
int listenfd = socket(AF_INET, SOCK_STREAM, 0);
if (listenfd == INVALID_FD)
{
std::cout << "create listen socket error." << std::endl;
return -1;
}
//初始化服务器地址
struct sockaddr_in bindaddr;
bindaddr.sin_family = AF_INET;
bindaddr.sin_addr.s_addr = htonl(INADDR_ANY);
bindaddr.sin_port = htons(3000);
if (bind(listenfd, (struct sockaddr *)&bindaddr, sizeof(bindaddr)) == -1)
{
std::cout << "bind listen socket error." << std::endl;
close(listenfd);
return -1;
}
//启动侦听
if (listen(listenfd, SOMAXCONN) == -1)
{
std::cout << "listen error." << std::endl;
close(listenfd);
return -1;
}
//存储客户端socket的数组
std::vector<int> clientfds;
int maxfd;
while (true)
{
fd_set readset;
FD_ZERO(&readset);
//将侦听socket加入到待检测的可读事件中去
FD_SET(listenfd, &readset);
maxfd = listenfd;
//将客户端fd加入到待检测的可读事件中去
int clientfdslength = clientfds.size();
for (int i = 0; i < clientfdslength; i)
{
if (clientfds[i] != INVALID_FD)
{
FD_SET(clientfds[i], &readset);
if (maxfd < clientfds[i])
maxfd = clientfds[i];
}
}
timeval tm;
tm.tv_sec = 1;
tm.tv_usec = 0;
//暂且只检测可读事件，不检测可写和异常事件
int ret = select(maxfd 1, &readset, NULL, NULL, &tm);
if (ret == -1)
{
//出错，退出程序。
if (errno != EINTR)
break;
}
else if (ret == 0)
{
//select 函数超时，下次继续
continue;
}
else
{
//检测到某个socket有事件
if (FD_ISSET(listenfd, &readset))
{
//侦听socket的可读事件，则表明有新的连接到来
struct sockaddr_in clientaddr;
socklen_t clientaddrlen = sizeof(clientaddr);
//4. 接受客户端连接
int clientfd = accept(listenfd, (struct sockaddr *)&clientaddr, &clientaddrlen);
if (clientfd == INVALID_FD)
{
//接受连接出错，退出程序
break;
}
//只接受连接，不调用recv收取任何数据
std:: cout << "accept a client connection, fd: " << clientfd << std::endl;
clientfds.push_back(clientfd);
}
else
{
//假设对端发来的数据长度不超过63个字符
char recvbuf[64];
int clientfdslength = clientfds.size();
for (int i = 0; i < clientfdslength; i)
{
if (clientfds[i] != INVALID_FD && FD_ISSET(clientfds[i], &readset))
{
memset(recvbuf, 0, sizeof(recvbuf));
//非侦听socket，则接收数据
int length = recv(clientfds[i], recvbuf, 64, 0);
if (length <= 0)
{
//收取数据出错了
std::cout << "recv data error, clientfd: " << clientfds[i] << std::endl;
close(clientfds[i]);
//不直接删除该元素，将该位置的元素置位INVALID_FD
clientfds[i] = INVALID_FD;
continue;
}
std::cout << "clientfd: " << clientfds[i] << ", recv data: " << recvbuf << std::endl;
}
}
}
}
}
//关闭所有客户端socket
int clientfdslength = clientfds.size();
for (int i = 0; i < clientfdslength; i)
{
if (clientfds[i] != INVALID_FD)
{
close(clientfds[i]);
}
}
//关闭侦听socket
close(listenfd);
return 0;
}客户端
代码语言：javascript复制#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <iostream>
#define SERVER_ADDRESS "192.168.200.144"
#define SERVER_PORT 3000
int main(int argc, char* argv[])
{
//创建一个socket
int clientfd = socket(AF_INET, SOCK_STREAM, 0);
if (clientfd == -1)
{
std::cout << "create client socket error." << std::endl;
return -1;
}
//连接服务器
struct sockaddr_in serveraddr;
serveraddr.sin_family = AF_INET;
serveraddr.sin_addr.s_addr = inet_addr(SERVER_ADDRESS);
serveraddr.sin_port = htons(SERVER_PORT);
if (connect(clientfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) == -1)
{
std::cout << "connect socket error." << std::endl;
close(clientfd);
return -1;
}
int ret;
while (true)
{
fd_set readset;
FD_ZERO(&readset);
//将侦听socket加入到待检测的可读事件中去
FD_SET(clientfd, &readset);
//timeval tm;
//tm.tv_sec = 0;
//tm.tv_usec = 0;
//暂且只检测可读事件，不检测可写和异常事件
ret = select(clientfd 1, &readset, NULL, NULL, NULL);
if (ret == -1)
{
//除了被信号中断的情形，其他情况都是出错
if (errno != EINTR)
break;
}
else if (ret == 0)
{
//select函数超时
std::cout << "no event in specific time interval." << std::endl;
continue;
}
else
{
if (FD_ISSET(clientfd, &readset))
{
//检测到可读事件
char recvbuf[32];
memset(recvbuf, 0, sizeof(recvbuf));
//假设对端发数据的时候不超过31个字符。
int n = recv(clientfd, recvbuf, 32, 0);
if (n < 0)
{
//除了被信号中断的情形，其他情况都是出错
if (errno != EINTR)
break;
}
else if (n == 0)
{
//对端关闭了连接
break;
}
else
{
std::cout << "recv data: " << recvbuf << std::endl;
}
}
else
{
std::cout << "other socket event." << std::endl;
}
}
}
//关闭socket
close(clientfd);
return 0;
}
