网络编程day3 基于UDP的tftp下载上传

 tftp下载客户端代码

#include 
#include 
#include 
#include
#define PORT 69
#define IP "192.168.122.137"
#define NAME "5.png"
int main(int argc, const char *argv[])
{
	//创建报式套接字
	int cfd = socket(AF_INET,SOCK_DGRAM,0);
	if(cfd < 0)
	{
		ERR_MSG("socket");
		return -1;
	}
	printf("sfd = %d\n",cfd);
    //编辑下载请求
	char buf[517] = "";
	char *ptr = buf;
	unsigned short* p1 = (unsigned short*)buf;
	*p1 = htons(1);
	char *p2 = (char*)p1+2;
	strcpy(p2,NAME);
	char *p3 = p2 + strlen(p2)+1;
	strcpy(p3,"octet");
	size_t size = 2+strlen(p2)+1+strlen("octet")+1;
	ssize_t res = 0;
	//存储服务器地址和69端口
	struct sockaddr_in sin;
	socklen_t addrlen = sizeof(sin);
	sin.sin_family = AF_INET;
	sin.sin_port = htons(PORT);
	sin.sin_addr.s_addr = inet_addr(IP);
	//发送下载请求
	if(sendto(cfd,buf,size,0,(struct sockaddr*)&sin,addrlen)< 0 )
	{
		ERR_MSG("sendto");
		return -1;
	}
	int fd = open("./2.png",O_WRONLY|O_CREAT|O_TRUNC,0664);
	if(fd < 0)
	{
		ERR_MSG("open");
		return -1;
	}
	char* p4 =(char*)p1+4;
	int i = 1;
	while(i)
	{
		//接收数据包
		res = recvfrom(cfd,buf,517,0,\
				(struct sockaddr*)&sin,&addrlen);
		if(res < 0)
		{
			ERR_MSG("recvfrom");
			return -1;
		}
		write(fd,p4,512);
		//发送ACK
		*p1 = htons(4);
		size_t size_ACK = 4;
		if(sendto(cfd,buf,size_ACK,0,(struct sockaddr*)&sin,addrlen)< 0 )
		{
			ERR_MSG("sendto");
			return -1;
		}
		if(res < 516)
		{
			i = 0;
		}
	}	
	//关闭文件描述符
	close(cfd);
	return 0;
}

上传客户端代码

#include 
#include 
#include 
#include
#define PORT 69
#define IP "192.168.122.137"
#define NAME "1.png"
int main(int argc, const char *argv[])
{
	//创建报式套接字
	int cfd = socket(AF_INET,SOCK_DGRAM,0);
	if(cfd < 0)
	{
		ERR_MSG("socket");
		return -1;
	}
	printf("sfd = %d\n",cfd);

	char buf[516] = "";
	char *ptr = buf;
	unsigned short* p1 = (unsigned short*)buf;
	*p1 = htons(2);
	char *p2 = (char*)p1+2;
	strcpy(p2,NAME);
	char *p3 = p2 + strlen(p2)+1;
	strcpy(p3,"octet");
	size_t size = 2+strlen(p2)+1+strlen("octet")+1;
	ssize_t res = 0;
	//存储服务器地址和69端口
	struct sockaddr_in sin;
	socklen_t addrlen = sizeof(sin);
	sin.sin_family = AF_INET;
	sin.sin_port = htons(PORT);
	sin.sin_addr.s_addr = inet_addr(IP);
	//发送上传请求
	if(sendto(cfd,buf,size,0,(struct sockaddr*)&sin,addrlen)< 0 )
	{
		ERR_MSG("sendto");
		return -1;
	}
	int fd = open("./1.png",O_RDONLY);
	if(fd < 0)
	{
		ERR_MSG("open");
		return -1;
	}
	char* p4 =(char*)p1+4;
	//接收ACK
	recvfrom(cfd,buf,4,0,\
			(struct sockaddr*)&sin,&addrlen);
	int i = 1;
	int a = 1;
	while(i)
	{
		//发送数据包
		*p1 = htons(3);
		*((short*)p2) = htons(a);
		a++;
		res = read(fd,p4,512);
		if(res < 0)
		{
			ERR_MSG("recvfrom");
			return -1;
		}
		if(sendto(cfd,buf,sizeof(buf),0,(struct sockaddr*)&sin,addrlen)< 0 )
		{
			ERR_MSG("sendto");
			return -1;
		}
		//接收ACK
		recvfrom(cfd,buf,4,0,\
				(struct sockaddr*)&sin,&addrlen);
		if(res < 512)
		{
			i = 0;
		}
	}
	//关闭文件描述符
	close(cfd);
	return 0;
}

思维导图