可以直接使用
#include <stdio.h>
#include <netinet/in.h> //for souockaddr_in
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <stdlib.h>
#include <arpa/inet.h>
//for select
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/select.h>
#include <strings.h> //for bzero
#include <string.h>
#define BUFF_SIZE 1024
#define backlog 7
#define ser_port 40002
#define CLI_NUM 3
int client_fds[CLI_NUM];
int main(int agrc,char **argv)
{
int ser_souck_fd;
int i;
char input_message[BUFF_SIZE];
char resv_message[BUFF_SIZE];
struct sockaddr_in ser_addr;
ser_addr.sin_family= AF_INET; //IPV4
ser_addr.sin_port = htons(ser_port);
ser_addr.sin_addr.s_addr = inet_addr("127.0.0.1"); //具體的IP地址
//creat socket
if( (ser_souck_fd = socket(AF_INET,SOCK_STREAM,0)) < 0 )
{
perror("creat failure");
return -1;
}
//bind soucket
if(bind(ser_souck_fd, (const struct sockaddr *)&ser_addr,sizeof(ser_addr)) < 0)
{
perror("bind failure");
return -1;
}
//listen
if(listen(ser_souck_fd, backlog) < 0)
{
perror("listen failure");
return -1;
}
//fd_set
fd_set ser_fdset;
int max_fd=1;
struct timeval mytime;
printf("wait for client connnect!\n");
while(1)
{
mytime.tv_sec=27;
mytime.tv_usec=0;
FD_ZERO(&ser_fdset);
//add standard input
FD_SET(0,&ser_fdset);
if(max_fd < 0)
{
max_fd=0;
}
//add serverce
FD_SET(ser_souck_fd,&ser_fdset);
if(max_fd < ser_souck_fd)
{
max_fd = ser_souck_fd;
}
//add client
for(i=0;i<CLI_NUM;i++) //用數組定義多個客戶端fd
{
if(client_fds[i]!=0)
{
FD_SET(client_fds[i],&ser_fdset);
if(max_fd < client_fds[i])
{
max_fd = client_fds[i];
}
}
}
//select多路複用
int ret = select(max_fd + 1, &ser_fdset, NULL, NULL, &mytime);
if(ret < 0)
{
perror("select failure\n");
continue;
}
else if(ret == 0)
{
printf("time out!");
continue;
}
else
{
/* if(FD_ISSET(0,&ser_fdset)) //標準輸入是否存在於ser_fdset集合中（也就是說，檢測到輸入時，做如下事情）
{
printf("send message to");
bzero(input_message,BUFF_SIZE);
fgets(input_message,BUFF_SIZE,stdin);
for(i=0;i<CLI_NUM;i++)
{
if(client_fds[i] != 0)
{
printf("client_fds[%d]=%d\n", i, client_fds[i]);
send(client_fds[i], input_message, BUFF_SIZE, 0);
}
}
} */
if(FD_ISSET(ser_souck_fd, &ser_fdset))
{
struct sockaddr_in client_address;
socklen_t address_len;
int client_sock_fd = accept(ser_souck_fd,(struct sockaddr *)&client_address, &address_len);
if(client_sock_fd > 0)
{
int flags=-1;
//一個客戶端到來分配一個fd，CLI_NUM=3，則最多隻能有三個客戶端，超過4以後跳出for循環，flags重新被賦值爲-1
for(i=0;i<CLI_NUM;i++)
{
if(client_fds[i] == 0)
{
flags=i;
client_fds[i] = client_sock_fd;
break;
}
}
if (flags >= 0)
{
printf("new user client[%d] add sucessfully!\n",flags);
}
else //flags=-1
{
char full_message[]="the client is full!can't join!\n";
bzero(input_message,BUFF_SIZE);
strncpy(input_message, full_message,100);
send(client_sock_fd, input_message, BUFF_SIZE, 0);
}
}
}
}
//deal with the message
for(i=0; i<CLI_NUM; i++)
{
if(client_fds[i] != 0)
{
if(FD_ISSET(client_fds[i],&ser_fdset))
{
bzero(resv_message,BUFF_SIZE);
int byte_num=read(client_fds[i],resv_message,BUFF_SIZE);
if(byte_num > 0)
{
printf("message form client[%d]:%s\n", i, resv_message);
int write_len = write(client_fds[i], resv_message, byte_num);
if(write_len < 0)
{
close(client_fds[i]);
return 1;
}
memset(resv_message,0,byte_num);
}
else if(byte_num < 0)
{
printf("rescessed error!");
}
//某個客戶端退出
else //cancel fdset and set fd=0
{
printf("clien[%d] exit!\n",i);
FD_CLR(client_fds[i], &ser_fdset);
client_fds[i] = 0;
// printf("clien[%d] exit!\n",i);
continue; //這裏如果用break的話一個客戶端退出會造成服務器也退出。
}
}
}
}
}
return 0;
}