day37 1219
作业1：tftp
#include
//实现下载功能
int do_download(int cfd, struct sockaddr_in sin)
{
//定义变量存储下载请求包
char buf[516] = "";
//定义变量存储文件名
char fileName[40] = "";
printf("请输入文件名：");
scanf("%s", fileName);
getchar();
//组装请求包
short *p1 = (short *)buf;
*p1 = htons(1); //表明要下载
char *p2 = buf+2; //文件名段
strcpy(p2, fileName);
char *p4 = p2+strlen(p2)+1; //模式段
strcpy(p4, "octet");
int size = 4 + strlen(p2) + strlen(p4); //要发送数据的大小
//向服务器发送下载请求
if(sendto(cfd, buf, size, 0, (struct sockaddr*)&sin, sizeof(sin)) == -1)
{
perror("sendto error");
return -1;
}
printf("请求成功\n");
struct sockaddr_in newsin;
socklen_t socklen = sizeof(newsin);
int res = 0;
int fd = -1;
fd = open(fileName,O_WRONLY|O_CREAT|O_TRUNC,0664);
PERROR_INFO(fd);
//循环接收回复服务器发来的消息
while (1)
{
bzero(buf,sizeof(buf));
res = recvfrom(cfd,buf,sizeof(buf),0,(struct sockaddr *)&newsin,&socklen);
//printf("*p1 = %d\n",ntohs(*p1));
if (ntohs(*p1) == 3)
{
write(fd,buf+4,res-4);
buf[1] = 4;
if(sendto(cfd,buf,4,0,(struct sockaddr*)&newsin,sizeof(newsin)) == -1)
{
perror("sendto error");
return -1;
}
}
else if (buf[1] == 5)
{
printf("5 error\n");
return -1;
}
if (res < 516)
{
puts("file is clone over!!!");
close(fd);
break;
}
}
close(fd);
return 0;
}
int do_upload(int cfd, struct sockaddr_in sin)
{
//定义变量存储下载请求包
char buf[516] = "";
//定义变量存储文件名
char fileName[40] = "";
printf("请输入文件名：");
scanf("%s", fileName);
getchar();
//组装请求包
short *p1 = (short *)buf;
*p1 = htons(2); //表明要上传
char *p2 = buf+2; //文件名段
strcpy(p2, fileName);
char *p4 = p2+strlen(p2)+1; //模式段
strcpy(p4, "octet");
int size = 4 + strlen(p2) + strlen(p4); //要发送数据的大小
//向服务器发送下载请求
if(sendto(cfd, buf, size, 0, (struct sockaddr*)&sin, sizeof(sin)) == -1)
{
perror("sendto error");
return -1;
}
printf("请求成功\n");
///p5指向块编号的字节
///p1指向前两个字节
short *p5 = p1+1;
bzero(buf,sizeof(buf));
socklen_t socklen = sizeof(sin);
recvfrom(cfd,buf,sizeof(buf),0,(struct sockaddr*)&sin,&socklen);
printf("port = %d\n",ntohs(sin.sin_port));
printf("第0次:%d\n",ntohs(*p1));
///确认服务器接收到上传请求，发挥给我的ACK应答包前两个字节是4，然后是块编号是0
///下面收发数据块编号从1开始
if (ntohs(*p1) == 4 && ntohs(*p5) == 0)
{
printf("收到服务器应答包\n");
}
int fd = -1;
fd = open(fileName,O_RDONLY);
PERROR_INFO(fd);
int res = -1;
///定义块编号
int count = 1;
while (1)
{
bzero(buf,sizeof(buf));
res = read(fd,buf+4,512);
//两种方式，将前两个字节修改为3，表示这个包为数据包
//将块编号修改为count
*p5 = htons(count);
buf[1] = 3;
//发送数据包
sendto(cfd,buf,res+4,0,(struct sockaddr*)&sin,sizeof(sin));
//接收服务器返回的应答包
recvfrom(cfd,buf,4,0,(struct sockaddr*)&sin,&socklen);
printf("第%d次:p1 = %d,p5 = %d,res = %d\n",count,ntohs(*p1),ntohs(*p5),res);
//判断前两个字节是不是4，如果是的话，就是应答包，再判断块编号与发送过去的是否一致
if (ntohs(*p1) == 4&&ntohs(*p5) == count)
{
printf("收到%d应答包\n",count);
if (res < 512)
{
printf("发送结束\n");
break;
}
//当确认收到了应答包之后，块编号++，继续发送下一块
count++;
}
else
{
//如果服务器返回的应答包不对，则跳出循环
printf("error!!!!!!\n");
return 0;
}
}
close(fd);
return 0;
}
int main(int argc, const char *argv[])
{
if(argc != 2)
{
printf("input error\n");
printf("usage:./a.out ip\n");
return -1;
}
//1、创建套接字
int cfd = socket(AF_INET, SOCK_DGRAM, 0);
if(cfd == -1)
{
perror("socket error");
return -1;
}
//2、填充服务器地址信息结构体
struct sockaddr_in sin;
sin.sin_family = AF_INET;
sin.sin_port = htons(69);
sin.sin_addr.s_addr = inet_addr(argv[1]);
int mune = -1;
while(1)
{
system("clear"); //清屏
printf("\t\t======1、下载=======\n");
printf("\t\t======2、上传=======\n");
printf("\t\t======0、退出=======\n");
printf("请输入功能：");
scanf("%d", &mune);
getchar();
//多分支选择
switch(mune)
{
case 1:
{
do_download(cfd, sin);
}
break;
case 2:
{
do_upload(cfd,sin);
}
break;
case 0:
goto POS;
default:printf("输入功能有误，请重新输入\n");
}
//阻塞
printf("输入任意键，按回车清空:");
while(getchar() != '\n');
}
POS:
//关闭套接字
close(cfd);
return 0;
}
思维导图