网络编程 day3

TFTP协议
 

#include<my_head.h>
#define PORT 69
#define IP "192.168.125.220"
int do_download(int cfd,struct sockaddr_in sin);
int do_upload(int cfd,struct sockaddr_in sin);
int main(int argc, const char *argv[])
{
	int cfd =socket(AF_INET,SOCK_DGRAM,0);
	if(cfd<0)
	{
		ERR_MSG("socket");
		return -1;
	}
	printf("socket success sfd=%d\n",cfd);


	struct sockaddr_in sin;
	sin.sin_family=AF_INET;
	sin.sin_port=htons(PORT);
	sin.sin_addr.s_addr=inet_addr(IP);

	char choose;
	while(1)
	{
		printf("----------------------------------\n");
		printf("--------------1.下载--------------\n");
		printf("----------------------------------\n");
		printf("--------------2.上传--------------\n");
		printf("----------------------------------\n");
		printf("--------------3.退出--------------\n");
		printf("----------------------------------\n");
		printf("请输入：");
		choose=getchar();
		while(getchar()!=10);
		switch(choose)
		{
		case '1':
			do_download(cfd,sin);
			break;
		case '2':
			do_upload(cfd,sin);
			break;
		case'3':
			goto END;

		}
	}
END:
	close(cfd);
	return 0;
}
int do_download(int cfd,struct sockaddr_in sin)
{
	char name[20]="";
	printf("请输入文件名：");
	scanf("%s",name);
	getchar();

	//组下载协议
	char buf[516]="";
	unsigned short *p1=(unsigned short *)buf;
	*p1=htons(1);
	char * p2= (char *)(p1+1);
	strcpy(p2,name);
	char * p3=p2+strlen(p2)+1;
	strcpy(p3,"octet");

	//发送下载协议给服务器
	int size=2+strlen(p2)+1+strlen(p3)+1;
	if(sendto(cfd,buf,size,0,(struct sockaddr *)&sin,sizeof(sin))<0)
	{
		ERR_MSG("sendto");
		return -1;
	}
	//printf("sendto success\n");
	int fd=open(name,O_WRONLY|O_CREAT|O_TRUNC,0664);
	
	//创建新的结构体 接收服务器的随机端口和ip
	struct sockaddr_in newsin;
	socklen_t len=sizeof(newsin);
	while(1)
	{
		//接收数据包
		ssize_t res=0;
		res = recvfrom(cfd,buf,sizeof(buf),0,(struct sockaddr *)&newsin,&len);
	 	if(res<0)
		{
			ERR_MSG("recvfrom");
			return -1;
		}
		if(write(fd,buf+4,res-4)<0)
		{
			ERR_MSG("write");
			return -1;
		}

		//组ACK包
		char ackbuf[4]="";
		unsigned short *ps=(unsigned short *)ackbuf;
		*ps=htons(4);
		unsigned short *pl=(unsigned short *)(ackbuf+2);
		*pl=*((unsigned short *)(buf+2));

		//发送ACK包
		if(sendto(cfd,ackbuf,sizeof(ackbuf),0,(struct sockaddr *)&newsin,sizeof(newsin))<0)
		{
			ERR_MSG("sendto");
			return -1;
		}

		//数据小于512退出下载
		if(res-4<516)
		{
			printf("下载成功\n");
			break;
		}
	}
	close(fd);
	return 0;
}
int do_upload(int cfd,struct sockaddr_in sin)
{
	char name[20]="";
	printf("请输入文件名：");
	scanf("%s",name);
	getchar();

	//组上传协议
	char buf[516]="";
	unsigned short *p1=(unsigned short *)buf;
	*p1=htons(2);
	char * p2= (char *)(p1+1);
	strcpy(p2,name);
	char * p3=p2+strlen(p2)+1;
	strcpy(p3,"octet");

	//发送上传协议给服务器
	int size=2+strlen(p2)+1+strlen(p3)+1;
	if(sendto(cfd,buf,size,0,(struct sockaddr *)&sin,sizeof(sin))<0)
	{
		ERR_MSG("sendto");
		return -1;
	}
	printf("sendto success\n");

	//接收服务器的应答
	struct sockaddr_in newsin;
	socklen_t len= sizeof(newsin);
	recvfrom(cfd,buf,size,0,(struct sockaddr *)&newsin,&len);  //接收服务器的随机端口和ip
	printf("%d\n",ntohs(newsin.sin_port));

	//打开读文件
	int fd = open(name,O_RDONLY);

	short i=0;
	ssize_t res=0;
	while(1)
	{
		bzero(buf,sizeof(buf));
		//组数据包
		unsigned short * pl =(unsigned short *)buf;
		*pl=htons(3);
		unsigned short * ps=(unsigned short *)(buf+2);
		*ps=htons(++i);
		char * readbuf= buf+4;
		res = read(fd,readbuf,sizeof(buf)-4);
		if(res<0)
		{
			ERR_MSG("read");
			return -1;
		}

		//发送数据包
		if(sendto(cfd,buf,sizeof(buf),0,(struct sockaddr *)&newsin,len)<0)
		{
			ERR_MSG("sendto");
			return -1;
		}

		//接收服务器的应答 并判断是否正确 错误退出
		char ackbuf[4]="";

		if(recvfrom(cfd,ackbuf,sizeof(ackbuf),0,NULL,NULL)<0)
		{
			ERR_MSG("recvfrom");
			return -1;
		}
		//判断操作码是否为4 块编号是否为i
		if(*((unsigned short *)ackbuf)!=htons(4) || *((unsigned short *)(ackbuf+2))!=htons(i))
		{
			printf("接收应答错误\n");
			break;
		}

		//判断上传数据是否小于512
		if(res<512)
		{
			printf("上传完毕\n");
			break;
		}

	}
	close(fd);
	return 0;
}