#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <string.h>
#include <errno.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h> //信号头文件

#define SERVERIP "192.168.0.23"
#define SERVERPORT 12345
#define MAXBUFFER 256

int serverFd=-1, connfd=-1;
char *readBuf=NULL;
/*
*功能：SIGINT自定义处理函数，用于释放申请的内存空间
*/
void handInt(int signo)
{
    printf("捕捉到SIGINT信号,服务端被终止,善后处理中...\n");
    if (readBuf != NULL)
    {
        free(readBuf);
        readBuf = NULL;
    }
    close(serverFd);
    close(connfd);
    exit(-1);
}

int main(int argc, char** argv)
{
    int ret;
    readBuf=(char *)malloc(MAXBUFFER);
    socklen_t len;
    struct sockaddr_in serveraddr,clientaddr;   
    char ip[40]={0};
    serverFd=socket(AF_INET,SOCK_STREAM,0);//创建socket
    if(serverFd < 0)
    {
        printf("socket error:%s\n",strerror(errno));
        exit(-1);
    }
    bzero(&serveraddr,sizeof(serveraddr));
    serveraddr.sin_family=AF_INET;
    serveraddr.sin_port=htons(SERVERPORT);
    inet_pton(AF_INET,SERVERIP,&serveraddr.sin_addr);//将c语言字节序转换为网络字节序

    if (signal(SIGINT, handInt) == SIG_ERR)//注册信号处理函数
    {
        printf("signal error: %s", strerror(errno));
        free(readBuf);
        exit(-1);
    }
    ret=bind(serverFd,(struct sockaddr *)&serveraddr,sizeof(serveraddr));//绑定IP和端口
    if(ret!=0)
    {
        close(serverFd);
        printf("bind error:%s\n",strerror(errno));
        exit(-1);
    }
    ret=listen(serverFd,5);//监听
    if(ret!=0)
    {
       close(serverFd);
       printf("listen error:%s\n",strerror(errno));
       exit(-1);
    }
    len=sizeof(clientaddr);
    bzero(&clientaddr,sizeof(clientaddr));
    while (1)
    {
        connfd = accept(serverFd, (struct sockaddr *) &clientaddr, &len);//接受客户端的连接
        printf("%s 连接到服务器 \n",inet_ntop(AF_INET,&clientaddr.sin_addr,ip,sizeof(ip)));
        if (serverFd < 0)
        {
            printf("accept error : %s\n", strerror(errno));
            continue;
        }
        while((ret=read(connfd,readBuf,MAXBUFFER)))//读客户端发送的数据        
        {
            write(connfd,readBuf,MAXBUFFER);//写回客户端
            bzero(readBuf,MAXBUFFER);
        }
        if(ret==0)
        {
            printf("客户端关闭连接\n");        
        }else
        {
            printf("read error:%s\n",strerror(errno));
        }
        close(connfd);
    }
    free(readBuf);
    close(serverFd);
    return 0;
}