day36:网编day3，TCP、UDP模型

下载：

#include 

#define ERR(s) do\
{\
	fprintf(stderr,"__%d__",__LINE__);\
	perror(s);\
}while(0)
#define PORT 69
#define IP "192.168.115.184"

int do_download(int cfd,struct sockaddr_in sin);
//int do_upload();
int main(int argc, const char *argv[])
{
	
	//创建报式套接字socket
	int cfd;
	if((cfd = socket(AF_INET,SOCK_DGRAM,0)) < 0)
	{
		ERR("socket");
		return -1;
	}
	printf("socket success\n");

	struct sockaddr_in sin;
	sin.sin_family = AF_INET;
	sin.sin_port = htons(PORT);
	sin.sin_addr.s_addr = inet_addr(IP);
	char choose = 0;
	while(1)
	{
		system("clear");
		printf("--------------------------------\n");
		printf("-------------1下载--------------\n");
		printf("-------------2上传--------------\n");
		printf("-------------3退出--------------\n");
		printf("--------------------------------\n");
		printf("请输入>>>");
		scanf("%c",&choose);
		while(getchar()!=10); 	//吸收垃圾字符
		switch(choose)
		{
			case '1':
				do_download(cfd,sin);
				break;
			case '2':
				//do_upload();
				break;
			case '3':
				goto END;
				break;
			default :
				printf("输入错误，请重新输入\n");
		}
		printf("请输入任意字符清屏\n");
		while(getchar()!=10);
	}
END:
	//关闭套接字
	close(cfd);
	return 0;
}

int do_download(int cfd,struct sockaddr_in sin)
{
	/*
	//组下载请求包
	char buf[516] = "";
	char f_n[20] = "";
	//操作码
	unsigned short *ptr1 = (unsigned short*)buf;
	*ptr1 = htons(1); 	//组操作码
	//文件名
	char *ptr2 = (char *)(ptr1+1);
	strcpy(ptr2,f_n);
	//模式
	char *ptr3 = ptr2 + strlen(f_n) + 1;
	strcpy(ptr3,"octet");
	
	int size = 2+strlen(ptr2)+1+strlen(ptr3)+1;
	*/
	char buf[516] = "";
	char f_n[20] = "";
	int num=1;
	printf("请输入文件名>>> ");
	//终端输入要下载的文件名
	fgets(f_n,sizeof(f_n),stdin);
	f_n[strlen(f_n)-1] = '\0';
	int fd;
	if((fd = open(f_n,O_WRONLY|O_CREAT|O_TRUNC,0664)) == -1)
	{
		ERR("open");
		return -1;
	}
	//用sprintf拼接
	int size = sprintf(buf,"%c%c%s%c%s%c",0,1,f_n,0,"octet",0);
	//发送下载请求sendto
	if(sendto(cfd,buf,size,0,(struct sockaddr*)&sin,sizeof(sin)) < 0 )
	{
		ERR("sendto askpackage");
		return -1;
	}
	printf("sendto askpackage success\n");
	ssize_t len = 0;
	struct sockaddr_in addrin;
	socklen_t addrlen=sizeof(addrin);
	while(1)
	{
		//清空buf
		bzero(buf,sizeof(buf));
		//接收数据recvfrom，接收地址信息
		if((len = recvfrom(cfd,buf,sizeof(buf),0,(struct sockaddr*)&addrin,&addrlen)) < 0)
		{
			ERR("recvfrom datapackage");
			return -1;
		}
		unsigned short ptr2=ntohs(*(unsigned short*)(buf+2));
		printf("%hu\n",ptr2);	
		//当操作码为5时
		if(5 == buf[1])
		{
			fprintf(stderr, "错误码：%d，错误信息：%s\n", ntohs(*(unsigned short*)(buf+2)), buf+4);			
			break;
		}
		//当操作码为3,并且块编号正确时
		else if(3 == buf[1] && num == ptr2)
		{
			printf("%d\n",fd);
			//跳过前四个字节，写入文件
		
			if(write(fd,buf+4,len-4)<0)
			{
				ERR("write");
				return -1;
			}
			
			//组ACK包
			buf[1] = 4;	
			//发送ACK包，sendto
			if(sendto(cfd,buf,4,0,(struct sockaddr*)&addrin,addrlen) < 0)
			{
				ERR("sendto ACKpackage");
				return -1;
			}
			num++;
			//判断数据是否小于512个字节，若小于则下载完成
			if(len < 516)
			{
				printf("download success\n");
				break;
			}
		}
	}
	close(fd);
	return 0;
}

思维导图：有道云笔记