多进程的服务端,在主进程里面调用accept操作,由于fork创建的子进程与主进程拥有相同的内存空间,也就是服务端和客户端的套接字描述符在子进程的内存空间里面存在相同的一份拷贝,因此,子进程的处理函数首先就要关闭服务端的套接字描述符,避免多个描述符指向同一个套接字,然后再做相关的操作,代码如下所示:
include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd,h>
#include<signal.h>
#include<sys/wait.h>
#include<arpa/inet.h>
#include<sys/socket.h>
#define BUF_SIZE 30
void error_handing(char* message);
void read_childproc(int sig);
int main(int argc,char* argv[])
{
int serv_lock,clnt_sock;
struct sockaddr_in serv_adr,clnt_adr;
pid_t pid;
struct sigaction act;
socklen_t adr_sz;
int str_len,state;
char buf[BUF_SIZE];
if(argc!=2)
{
printf("Usage :%s <port> \n",argc[0]);
exit(1);
}
act.sa_handler = read_childproc;
sigemptyset(&act.sa_mask);
act.sa_flags = 0;
state = sigaction(SIGCHLD,&act,0);
serv_sock = socket(PF_INET,SOCK_STREAM,0); // create a socket
memset(&serv_adr,0,sizeof(serv_adr)); //initialize memory
serv_adr,sin_family = AF_INET;
serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
serv_adr,sin_port = htons(atoi(argv[1]));
if(bind(serv_sock,(struct sockaddr*)&serv_adr,sizeof()serv_adr))==-1)
error_handling("bind() error");
if(listen(serv_sock,5)==-1)
error_handling("listen() error");
while(1)
{
adr_sz = sizeof(clnt_adr);
clnt_sock = accept(serv_sock,(struct sockaddr*)&clnt_adr,&adr_sz);
if(clnt_sock == -1)
continue;
else
puts("new client connected...");
pid = fork();
if(pid == -1)
{
close(clnt_sock);
continue;
}
if(pid == 0)
{
close(serv_sock);
while(str_len = read(clnt_sock,buf,BUF_SIZE)!=0)
write(clnt_sock,buf,str_len);
close(clnt_sock);
}
}
close(serv_sock);
return 0;
}
void read_childproc(int sig)
{
pid_t pid;
int status;
pid =waitpid(-1,&status,WNOHANG);
printf("removed proc id: %d \n",pid);
}
void error_handling(char* message)
{
fputs(message,stderr);
fputc('\n',stderr);
exit(1);
}