socket编程点到点通信

//点到点通信
//服务器设计
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>

#define ERR_EXIT(m) \
	do \
	{ \
		perror(m);	\
		exit(EXIT_FAILURE);\
	}while(0)
void handle(int sig)
{
	exit(EXIT_SUCCESS);
}
int main(void)
{
	int listenfd;//建立套接字
	if((listenfd=socket(PF_INET,SOCK_STREAM,IPPROTO_TCP))<0)
/*	if((listenfd=socket(PF_INET,SOCK_STREAM<0))<0)*/
	ERR_EXIT("socket");
	//建立服务器地址
	struct sockaddr_in servaddr;
	memset(&servaddr,0,sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(5188);
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	/*servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");*/
	/*inet_aton("127.0.0.1",&servaddr.sin_addr);*/

	 int on = 1;
	 //为了使服务器处于TIME_WATTING状态，能再次绑定地址
	 if(setsockopt(listenfd,SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on))<0)
	 ERR_EXIT("setsockopt");
	 //绑定地址
	if(bind(listenfd,(struct sockaddr*)&servaddr,sizeof(servaddr))<0)
	ERR_EXIT("bind");
	//监听套接字
	if(listen(listenfd,SOMAXCONN)<0)//套接字变为被动套接字
	ERR_EXIT("listen");
	//存放客户端地址
	struct sockaddr_in peeraddr;
  	socklen_t peerlen =sizeof(peeraddr);
  	
	int conn;//接受accept的套接字
	if((conn=accept(listenfd, (struct sockaddr*)&peeraddr, &peerlen))<0)//套接字变为主动，且以后使用accept返回的套接字;
		ERR_EXIT("accept");
	printf("ip=%s port=%d\n", inet_ntoa(peeraddr.sin_addr), ntohs(peeraddr.sin_port));
		
	
	
	pid_t pid;
	pid=fork();
	if(pid==-1)
	{
		ERR_EXIT("fork");
	}
	if(pid==0)//发送的子进程
	{
		signal(SIGUSER1, handler);//接受信号，执行handler函数
		char sendbuf[1024] = {0};
		while(fgets(sendbuf,sizeof(sendbuf), stdin) != NULL)//获得发送内容
		{
			write(conn,sendbuf, strlen(sendbuf));
			memset(sendbuf, 0, sizeof(sendbuf));
		}
		exit(EXIT_SUCCESS);
	}
	else{//父进程用来获取数据
		char recvbuf[1024];
		while(1)
		{
			memset(recvbuf,0,sizeof(recvbuf));
			int ret = read(conn, recvbuf, sizeof(recvbuf));
			if(ret==-1)
			{
				ERR_EXIT("read");
			}
			else if(ret==0)
			{
				printf("peer close\n");
				break;
			}
			fputs(recvbuf,stdout);
		}
		kill(pid, SIGUSER1);//发出信号，消除子进程
		exit(EXIT_SUCCESS);
	}
	close(conn);
	close(listenfd);
	return 0;

}

//客户端设计
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>

#define ERR_EXIT(m) \
	do \
	{ \
		perror(m);	\
		exit(EXIT_FAILURE); \
	}while(0)
void handle(int sig)
{
	exit(EXIT_SUCCESS);
}
int main(void)
{
	int sock;
	if((sock=socket(PF_INET,SOCK_STREAM,IPPROTO_TCP))<0)
/*	if((listenfd=socket(PF_INET,SOCK_STREAM<0))<0)*/
	ERR_EXIT("socket");
	
	struct sockaddr_in servaddr;
	memset(&servaddr,0,sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(5188);
	/*servaddr.sin_addr.s_addr = htonl(INADDR_ANY);*/
	servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
	/*inet_aton("127.0.0.1",&servaddr.sin_addr);*/
  	//发起连接
	if(connect(sock,(struct sockaddr*)&servaddr,sizeof(servaddr))<0)
	ERR_EXIT("connect");
	pid_t pid;
	pid = fork();
	if(pid==-1)
		ERR_EXIT("fork");
	if(pid==0)
	{
		char recvbuf[1024] = {0};
		while(1)
		{
			memset(recvbuf, 0, sizeof(recvbuf));
			int ret = read(sock, recvbuf, sizeof(recvbuf));
			if(ret == -1)
			{
				ERR_EXIT("read");
			}
			else if(ret == 0)
			{

			 	printf("peer close\n");
			 	break;
			} 
			fputs(recvbuf, stdout);
		}
		close(sock);
		kill(getppid(), SIGUSER1);//当子进程退出时，告诉父进程退出
	}
	else
	{
		signal(SIGUSER1, handler);//父进程得到信号进行退出
		char sendbuf[1024]={0};
		while(fgets(sendbuf,sizeof(sendbuf), stdin) != NULL)
		{
			write(sock, sendbuf, strlen(sendbuf));
			memset(&sendbuf,0, sizeof(sendbuf));
		}
		close(sock);
	}
	
	return 0;
}