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36.echo_selectserv.c
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36.echo_selectserv.c
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//
// Created by satellite on 2023-05-31.
//
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "unistd.h"
#include "arpa/inet.h"
#include "sys/socket.h"
#include "sys/time.h"
#include "sys/select.h"
#define BUF_SIZE 100
void error_handling(char *message) {
fputs(message, stderr);
fputc('\n', stderr);
exit(1);
}
int main(int argc, char *argv[]) {
int serv_sock, clnt_sock;
struct sockaddr_in serv_adr, clnt_adr;
struct timeval timeout;
fd_set reads, cpy_reads;
socklen_t adr_sz;
int fd_max, str_len, fd_num, i;
char buf[BUF_SIZE];
if (argc != 2) {
printf("Usage : %s <port>\n", argv[0]);
exit(1);
}
serv_sock = socket(PF_INET,SOCK_STREAM,0);
memset(&serv_adr,0,sizeof serv_adr);
serv_adr.sin_family = AF_INET;
serv_adr.sin_port = htons(atoi(argv[1]));
serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
if(bind(serv_sock,(struct sockaddr*)&serv_adr,sizeof(serv_adr)) == -1)
error_handling("bind errror");
if((listen(serv_sock,5)) == -1)
error_handling("listen error");
FD_ZERO(&reads);
FD_SET(serv_sock,&reads);
fd_max = serv_sock;
while (1)
{
cpy_reads = reads;
timeout.tv_usec = 0;
timeout.tv_sec = 5;
if((fd_num = select(fd_max + 1,&cpy_reads,0,0,&timeout)) == -1)
//select的第一参数是最大个数,而文件描述符从0开始一定要加1
break;
if(fd_num == 0) {
printf("time out\n");
continue;
}
for(i=0;i<fd_max + 1;i++)
{
if(FD_ISSET(i,&cpy_reads)) //保证文件描述符是被设置过的且存在待读数据(select被调用)
{
if(i == serv_sock) //当serv_sock中存在待读数据时,说明有连接请求
{
adr_sz = sizeof clnt_adr;
clnt_sock = accept(serv_sock,(struct sockaddr*)&clnt_adr,&adr_sz);
if(clnt_sock == -1)
error_handling("accept error");
FD_SET(clnt_sock,&reads);
if(fd_max < clnt_sock)
fd_max = clnt_sock;
printf("connected client : %d \n",clnt_sock);
}
else
{
str_len = read(i,buf,BUF_SIZE);
if(str_len == 0)
{
FD_CLR(i,&reads);
close(i);
printf("close client : %d \n",i);
}
else
{
write(i,buf, str_len);
}
}
}
}
}
close(serv_sock);
return 0;
}