/*Hello World server*/
#include<stdio.h>
#include<stdlib.h>
#include<errno.h>
#include<string.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<sys/socket.h>
#include<sys/wait.h>
#include<signal.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<netinet/ip.h>
#include<netinet/ip_icmp.h>
#include<netdb.h>
#include<setjmp.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 ;
    int nbytes ;
    char buffer[1024];
    if(argc!=2)
    {
        fprintf(stderr,"Usage:%s portnumber\a\n",argv[0]);
        exit(1);
    }
    if((portnumber=atoi(argv[1]))<0)
    {
        fprintf(stderr,"Usage:%s portnumber\a\n",argv[0]);
        exit(1);
    }
    
    /* 服務器端開始建立socket描述符 */
    if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
    {
        fprintf(stderr,"Socket error:%s\n\a",strerror(errno));
        exit(1);
    }
    
    /* 服務器端填充 sockaddr結構 */
    bzero(&server_addr,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);
    
    /* 捆綁sockfd描述符 */
    if(bind(sockfd,(struct sockaddr*)(&server_addr),sizeof(struct sockaddr))==-1)
    {
        fprintf(stderr,"Bind error:%s\n\a",strerror(errno));
        exit(1);
    }
    
    /* 監聽sockfd描述符 */
    if(listen(sockfd,5)==-1)
    {
        fprintf(stderr,"Listen error:%s\n\a",strerror(errno));
        exit(1);
    }
    
    while(1)
    {
        /* 服務器阻塞,直到客戶程序建立連接 */
        sin_size=sizeof(struct sockaddr_in);
        if((new_fd=accept(sockfd,(struct sockaddr*)(&client_addr),&sin_size))==-1)
        {
            fprintf(stderr,"Accept error:%s\n\a",strerror(errno));
            exit(1);
        }
        fprintf(stderr,"Server get connection from %s\n",inet_ntoa(client_addr.sin_addr));

        /*接收消息，顯示相關信*/
        fprintf(stderr,"port:%d\n",portnumber);
        if((nbytes=read(new_fd,buffer,1024))==-1)
        {
            fprintf(stderr,"Read Error:%s\n",strerror(errno));
            exit(1);
        }
        buffer[nbytes]='\0' ;
        printf("I have received:%s\n",buffer);

        /* 這個通訊已經結束 */
        close(new_fd);
        /* 循環下一個 */
    }
    
    close(sockfd);
    exit(0);
}