修改后 简单的 TCP server

/*
 ============================================================================
 Name        : TCPserver.c
 Author      : vestinfo
 Version     : 1.1
 Copyright   : www.cnblogs.com/vestinfo
 Description : TCP server
 ============================================================================
 */

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

#define PORT 8888
#define MAXLENGTH 256

int main()
{
	int listenfd,connfd;
	struct sockaddr_in servaddr;
	struct sockaddr_in clientaddr;
	char msgbuffer[MAXLENGTH];
	socklen_t len;

	/* 创建监听套接字 */
	if((listenfd = socket(AF_INET, SOCK_STREAM,0)) < 0)
	{
		perror("socket");
		exit(1);
	}

	/* 绑定server的端口 */
	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_port = htons(PORT);
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	if(bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0)
	{
		perror("bind");
	}

	/* 开始监听 */
	if(listen(listenfd, 5) < 0)
	{
		perror("listen");
		exit(1);
	}
	else
	{
		printf("socket create、bind successfully!\nlistening......\n");
	}

	for( ; ; )
	{
		/* 接收来自client的连接请求 */
		len = sizeof(clientaddr);
		if((connfd = accept(listenfd, (struct sockaddr *)&clientaddr, &len)) < 0)
		{
			perror("accept");
			continue;
		}

		if( fork() == 0 )					//子进程
		{
			printf("the connect is from:%s\n",inet_ntoa(clientaddr.sin_addr));

			close(listenfd);				//子进程关闭监听套接字。

			for( ; ; )
			{
				bzero(msgbuffer, MAXLENGTH);
				if(read(connfd, msgbuffer, MAXLENGTH) <= 0)
				{
					perror("read from client");
					break;
				} else {
					printf("read from client:%s", msgbuffer);
				}

				if(	write(connfd, msgbuffer, strlen(msgbuffer)) < 0)
				{
					perror("write to client");
					break;
				}
			}
			close(connfd);		//该句可省略，这里为了强调关闭描述符这个操作。
			exit(0);
		} else {			//可以去掉else，直接写close(connfd);此处else为了区分父子进程的执行内容。
			close(connfd);		//父进程关闭accept返回的新的连接描述符。
		}
	}
	return 0;
}