多进程的实现

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


#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <signal.h>

int client(int connfd)	//connfd;
{
	int ret;
	char buf[256];

	while(1) {
		memset(buf, 0, sizeof(buf));
		ret = read(connfd, buf, sizeof(buf));
		if (ret == -1) {
			perror("server->read");
			return -1;
		} else if (ret == 0) {
			return -1;
		}

		printf("buf : %s\n", buf);

		ret = write(connfd, buf, sizeof(buf));
		if (ret == -1) {
			perror("server->write");
			return -1;
		}
	}
	return 0;
}

void fun(int sig) 
{
	printf("client quit\n");
	while(waitpid(-1, NULL, WNOHANG) > 0);
}


int main(int argc, char *argv[])
{
	int listenfd;
	int ret;
	socklen_t addrlen;
	int connfd;
	pid_t pid;
	char buf[256];
	struct sockaddr_in srvaddr;
	struct sockaddr_in cltaddr;
	pthread_t client_pthread;

	signal(SIGCHLD, fun);

	/* 1. 创建服务器（创建一socket套接字）；socket */
	listenfd = socket(AF_INET, SOCK_STREAM, 0);
	if (listenfd == -1) {
		perror("server->socket");
		return -1;
	}
	printf("create listenfd = %d success\n", listenfd);

	/* 2. 设置服务器的IP地址和端口号（将socket和服务器的IP地址和端口号进行绑定）；bind */
	memset(&srvaddr, 0, sizeof(struct sockaddr_in));
	srvaddr.sin_family = AF_INET;
	srvaddr.sin_port = htons(9999);
	srvaddr.sin_addr.s_addr = inet_addr("192.168.2.100");
	ret = bind(listenfd, (const struct sockaddr *)&srvaddr, sizeof(srvaddr));

	printf("port : %d\n", ntohs(srvaddr.sin_port));
	if (ret == -1) {
		perror("server->bind");
		return -1;
	}
	printf("bind success !\n");

	/* 3. 启动监听（启动服务器）；  listen */
	ret = listen(listenfd, 1024);
	if (ret == -1) {
		perror("server->listen");
		return -1;
	}
	printf("listen success !\n");

	while(1) {
		/* 4. 等待服务器的连接请求，如果没有连接请求则等待，如果有连接请求，则建立连接； accept */
		memset(&cltaddr, 0, sizeof(cltaddr));
		addrlen = sizeof(cltaddr);
		connfd = accept(listenfd, (struct sockaddr *)&cltaddr, &addrlen);
		if (connfd == -1) {
			perror("server->accept");
			return -1;
		}
		printf("connect connfd = %d\n", connfd);
		printf("IP : %s\n", inet_ntoa(cltaddr.sin_addr));
		printf("PORT: %d\n", ntohs(cltaddr.sin_port));

		pid_t pid;
		pid = fork();
		if (pid == -1) {
			perror("fork");
			return -1;
		} else if (pid == 0) {
			close(listenfd);
			client(connfd);
			exit(0);
		}
		close(connfd);

	}
	close(listenfd);

	return 0;
}