4.16 网络编程

2.UDP TFTP

#include <myhead.h>
#define SER_IP "192.168.125.78"
#define SER_PORT 69
#define CLI_IP "192.168.125.176"
#define CLI_PORT 4399
//文件上传
void upload(int cfd,struct sockaddr_in sin)//服务器信息结构体传参
{
	//填充读写请求字符数组-->操作码+文件名+0+模式+0
	char path[128];
	printf("请输入要上传的文件路径:");
	fgets(path,sizeof(path),stdin);
	path[strlen(path)-1]=0;
	char data[516];
	short* code=(short*)data;
	*code=htons(2);
	char* pathname=data+2;
	strcpy(pathname,path);
	char* mode=pathname+strlen(pathname)+1;
	strcpy(mode,"octet");
	int size=4+strlen(pathname)+strlen(mode);
 
 
	//向服务器发送下载请求
	if(sendto(cfd,data,size,0,(struct sockaddr*)&sin,sizeof(sin))==-1)
	{
		perror("sendto error");
		return;
	}
	socklen_t socklen=sizeof(sin);//接受服务器信息结构体容器
	int fd=open(path,O_RDONLY);
	if(fd==-1)
	{
		perror("open error");
		return;
	}
	int hblock=1;//数据包块编码号从1开始
	while(1)
	{
		memset(data,0,516);
		//接收应答包
		if(recvfrom(cfd,data,516,0,(struct sockaddr*)&sin,&socklen)==-1)
		{
			perror("recvfrom error");
			return;
		}
		int res=read(fd,data+4,516-4);
		short *p1=(short*)data;
		*p1=htons(3);
		*(p1+1)=htons(hblock++);
		//发送数据包
		if(sendto(cfd,data,res+4,0,(struct sockaddr*)&sin,sizeof(sin))==-1)
		{
			perror("sendto error");
			return;
		}
		if(res==0)
		{
			printf("上传完毕\n");
			break;
		}
	}
	close(fd);
}
//文件下载
void download(int cfd,struct sockaddr_in sin)
{
	//填充读写请求字符数组-->操作码+文件名+0+模式+0
	char filename[32];
	printf("请输入要下载的文件名:");
	fgets(filename,sizeof(filename),stdin);
	filename[strlen(filename)-1]=0;
	char data[516]="";
	short *code=(short*)data;
	*code=htons(1);
	char* file=data+2;
	strcpy(file,filename);
	char* mode=file+strlen(file)+1;
	strcpy(mode,"octet");
	int size=4+strlen(file)+strlen(mode);
 
 
	if(sendto(cfd,data,size,0,(struct sockaddr*)&sin,sizeof(sin))==-1)
	{
		perror("sendto error");
		return;
	}
	socklen_t socklen=sizeof(sin);
	int fd=open(filename,O_CREAT|O_WRONLY,0664);
	while(1)
	{
		memset(data,0,516);
		//接收数据包
		int len=recvfrom(cfd,data,516,0,(struct sockaddr*)&sin,&socklen);
		if(len==-1)
		{
			perror("recvfrom error");
			return;
		}
		write(fd,data+4,len-4);
		if(len<516)
		{
			printf("下载完毕\n");
			break;
		}
		short *p1=(short*)data;
		*p1=htons(4);
		//发送应答包
		if(sendto(cfd,data,4,0,(struct sockaddr*)&sin,sizeof(sin))==-1)
		{
			perror("sendto perror");
			return;
		}
	}
	close(fd);
}
int main(int argc, const char *argv[])
{
	//创建客服端套接字
	int cfd=socket(AF_INET,SOCK_DGRAM,0);
	if(cfd==-1)
	{
		perror("socket error");
		return -1;
	}
	printf("socket success cfd=%d\n",cfd);
 
	//填充客户端信息结构体绑定
	struct sockaddr_in cin;
	cin.sin_family=AF_INET;
	cin.sin_port=htons(CLI_PORT);
	cin.sin_addr.s_addr=inet_addr(CLI_IP);
	if(bind(cfd,(struct sockaddr*)&cin,sizeof(cin))==-1)
	{
		perror("bind error");
		return -1;
	}
	printf("bind success\n");
 
	//填充服务器信息结构体
	struct sockaddr_in sin;
	sin.sin_family=AF_INET;
	sin.sin_port=htons(SER_PORT);
	sin.sin_addr.s_addr=inet_addr(SER_IP);
 
 
 
	int ch;
	while(1)
	{
		printf("请选择要操作的选项:\n");
		printf("1.上传\n");
		printf("2.下载\n");
		printf("3.退出\n");
		scanf("%d",&ch);
		while(getchar()!=10);
		switch(ch)
		{
		case 1:
			upload(cfd,sin);
			break;
		case 2:
			download(cfd,sin);
			break;
		case 3:
			return 1;
		default:
			printf("输入错误请重新输入\n");
			break;
		}
 
	}
 
	close(cfd);
	return 0;
}

思维导图