tftpd
 

#include <myhead.h>
#define SER_IP "192.168.125.243"     //服务器IP地址
#define SER_PORT 69                //服务器端口号
#define CLI_IP "192.168.125.244"     //客户端IP地址
#define CLI_PORT 8889                //客户端端口号
int main(int argc, const char *argv[])
{
	//创建用于通信的套接字文件描述符
	int cfd = socket(AF_INET, SOCK_DGRAM, 0);
	if(cfd == -1)
	{
		perror("socket error");
		return -1;
	}
	printf("socket success sfd = %d\n", cfd);
	//绑定IP地址和端口号
	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");
	//服务端信息结构体
	struct sockaddr_in sin;
	sin.sin_family = AF_INET;
	sin.sin_port = htons(SER_PORT);
	sin.sin_addr.s_addr = inet_addr(SER_IP);
	//接收文件
	char data[516] = {0};
	short *p1=data;
	*p1=htons(1);
	char *p2=data+2;
	strcpy(p2,"5.png");
	char *p4=p2+strlen(p2)+1;
	strcpy(p4,"octet");
	int req_size=4+strlen(p2)+strlen(p4);
	sendto(cfd,data,req_size,0,(struct sockaddr*)&sin,sizeof(sin));
	int fd=open("./5.png",O_WRONLY|O_CREAT|O_TRUNC,0777);
	if(fd==-1)
	{
		perror("open err");
		return -1;
	}
	while(1)
	{
		bzero(data,sizeof(data));
		recv(cfd,data,sizeof(data),0);
		short *b=data+2;
		char ack[4]={0};
		short *q1=ack;
		*q1=htons(4);
		short *q2=ack+2;
		*q2=*b;
		sendto(cfd,ack,4,0,(struct sockaddr*)&sin,sizeof(sin));		
		write(fd,data,sizeof(data));
		int len=strlen(data);
		if(len<515)
			break;
	}
	close(fd);
	close(cfd);
	return 0;
}