/******* 服务器程序 (server.c) ************/
/********************************************************************************************
**   Name:server.c
**   Used to study the network programming in Linux OS.
**   Showing how to use the functions,
** like socket,bind,listen,accept and write.
**   This is the server program.
**   Author:zeickey
**   Date:2006/9/16       
**   Copyright (c) 2006,All Rights Reserved!
*********************************************************************************************/
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>

int main(int argc, char *argv[])
{
   int sockfd,new_fd;
   struct sockaddr_in server_addr;
   struct sockaddr_in client_addr;
   int sin_size,portnumber;
   char hello[]="Hello! Are You Fine?\n";
   
    if(argc!=2)
    {
        fprintf(stderr,"Usage:%s portnumber\a\n",argv[0]);
        return 1;
    }
    
    if( (portnumber = atoi(argv[1])) < 0 )
    {
        fprintf(stderr,"Usage:%s portnumber\a\n",argv[0]);
        return 1;
    }
    
    /* 服务器端开始建立socket描述符 */
    if( (sockfd = socket(AF_INET,SOCK_STREAM, 0)) == -1 )
    {
        fprintf(stderr,"Socket error:%s\n\a",strerror(errno));
        return 1;
    }
    
    /* 服务器端填充 sockaddr结构 */
    //bzero(&server_addr, sizeof(struct sockaddr_in));
    memset(&server_addr, 0, sizeof(struct sockaddr_in));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(portnumber);
    
    /* 捆绑sockfd描述符，为下面的listen函数作准备 */
    if( bind(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1 )
    {
        fprintf(stderr,"Bind error:%s\n\a",strerror(errno));
        return 1;
    }
    
    /* 监听sockfd描述符 */
    if( -1 == listen(sockfd,5) )
    {
        fprintf(stderr,"Listen error:%s\n\a",strerror(errno));
        return 1;
    }
    
    while(1)
    {
        /* 服务器阻塞,直到客户程序建立连接 */
        sin_size=sizeof(struct sockaddr_in);
        //if( (new_fd = accept(sockfd, (struct sockaddr *)(&client_addr), &sin_size)) == -1)
        new_fd = accept(sockfd, (struct sockaddr *)(&client_addr), &sin_size);
        if( -1 == new_fd )
        {
            fprintf(stderr,"Accept error:%s\n\a",strerror(errno));
            return 1;
        }
        
        fprintf(stderr,"Server get connection from %s\n", inet_ntoa(client_addr.sin_addr));
        if(write(new_fd,hello,strlen(hello))==-1)
        {
            fprintf(stderr,"Write Error:%s\n",strerror(errno));
            return 1;
        }
        /* 这个通讯已经结束 */
        close(new_fd);
        /* 循环下一个 */
    }
    close(sockfd);
    return 0;
}