网络编程day3

tftp协议传输文件

#include <myhead.h>
#define SER_PORT 69
#define SER_IP "192.168.117.86"
#define CLI_PORT 6666
#define CLI_IP "192.168.117.79"
int main(int argc, const char *argv[])
{
	//创建套接字
	int cfd=socket(AF_INET,SOCK_DGRAM,0);
	if(cfd==-1)
	{
		perror("socket error");
		return -1;
	}
	printf("socket success\n");
	//绑定端口号和IP
	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");
	//发送端的地址信息结构体
	struct sockaddr_in sin;
	sin.sin_family=AF_INET;
	sin.sin_port=htons(SER_PORT);
	sin.sin_addr.s_addr=inet_addr(SER_IP);
	//收发文件
	char buf[256]="";
	//向服务器发送下载请求
	short *p1=(short*)buf;
	*p1=htons(1);
	char *p2=buf+2;
	char *fn=NULL;
	scanf("%s",fn);
	strcpy(p2,fn);
	char *p4=p2+strlen(p2)+1;
	strcpy(p4,"octet");
	int buf_size=4+strlen(p2)+strlen(p4);
	if(sendto(cfd,buf,buf_size,0,(struct sockaddr*)&sin,sizeof(sin)<0));
	{
		perror("sendto error");
		return -1;
	}
	printf("sendto success\n");	
	int fd=open("./download",O_WRONLY|O_CREAT|O_TRUNC,0664);
	if(fd<0)
	{
		perror("open error");
		return -1;
	}
	printf("open success\n");
	while(1)
	{
		bzero(buf,sizeof(buf));
		ssize_t res=recvfrom(cfd,buf,sizeof(buf),0,(struct sockaddr*)&sin,sizeof(sin));
		unsigned short *p1=(unsigned short *)buf;
		short *p2=(short *)(buf+2);
		char *p3=buf+4;
		if(p1==htons(3))
		{
			if(write(fd,p3,res-4)<0)
			{
				perror("write error");
				return -1;
			}
			printf("write success\n");
			char ack[4]="";
			short *a1=(short *)ack;
			*a1=htons(4);
			short *a2=p2;
			strcpy(a2,p2);
			if(sendto(cfd,ack,sizeof(ack),0,(struct sockaddr*)&sin,sizeof(sin))<0)
			{
				perror("send error");
				return -1;
			}
			printf("sendto success");
			if(res<516)
			{
				goto END;
				break;
			}
		}
		else
		{
			printf("%s\n",p3);
		}
	}
END:
	close(cfd);
	return 0;
}