server.c

linux server client TCP

#include	<stdio.h>
#include	<stdlib.h>
#include	<unistd.h>
#include	<errno.h>
#include	<string.h>
#include	<sys/types.h>
#include	<sys/socket.h>
#include	<netinet/in.h>
#include	<arpa/inet.h>
#include	<sys/wait.h>
#include	<signal.h>

#define	MYPORT	3490
#define	BACKLOG	10
void	sigchld_handler(int s)
{
	while(wait(NULL)>0);
}

int	main(void)
{
	int	sockfd,sin_size,yes=1,new_fd;
	struct	sockaddr_in	server_addr;
	struct	sockaddr_in	clients_addr;
	struct	sigaction	sa;
//	char	buf[MAXBUFLEN];

	if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
	{
		perror("socket");
		exit(1);
	}
	if(setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(int))==-1)
	{
                perror("setsocopt");
                exit(1);
        }

	server_addr.sin_family=AF_INET;
	server_addr.sin_port=htons(MYPORT);
	server_addr.sin_addr.s_addr=INADDR_ANY;
	memset(&(server_addr.sin_zero),'\0',8);
	
	if(bind(sockfd,(struct sockaddr *)&server_addr,sizeof(struct sockaddr))==-1)
	{
		perror("bind");
		exit(1);
	}	
	if(listen(sockfd,BACKLOG)==-1)
	{
                perror("listen");
                exit(1);
        }
	sa.sa_handler=sigchld_handler;
	sigemptyset(&sa.sa_mask);
	sa.sa_flags=SA_RESTART;
	if(sigaction(SIGCHLD,&sa,NULL)==-1)
	{
                perror("sigaction");
                exit(1);
        }

	while(1)
	{
		sin_size=sizeof(struct sockaddr_in);
		if((new_fd=accept(sockfd,(struct sockaddr *)&clients_addr,&sin_size))==-1)
		{
               		perror("accept");
               		continue;
	        }
		printf("server:got connection from %s\n",inet_ntoa(clients_addr.sin_addr));
		if(!vfork())
		{
			printf("Hello!\n");
			if(send(new_fd,"Hello,world!\n",13,0)==-1)
			{
				perror("send");
				close(new_fd);
				exit(1);
			}
			close(new_fd);
		}
	}
	return 0;
}