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坚持每天一个小程序(TFTP下载和上传)

时间:2014-03-18 12:20:52      阅读:309      评论:0      收藏:0      [点我收藏+]

在写程序之前,我们应该首先了解TFT(Trivial File Transfer Protocol)P协议的过程:

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目前TFTP有三种传送模式:

  • l netascii型:一种修改的8bit ascii码
  • l octet型:即binary普通的二进制型
  • l mail型:过时,不再使用

具体每个包的格式在下面表格里列出:

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下面附上上传和下载源码(刚学没多久,写的不是很标准,其实上传代码和下载代码基本上是一样的,只不过一个是读一个是写):

下载代码:

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <fcntl.h>

int main(int argc, char *argv[])
{
if(argc != 3)
{
printf("please input server ip and filename:\n");
exit(-1);
}
//copy filename to array
char filename[50] = "";
strcpy(filename, argv[2]);
char server_ip[INET_ADDRSTRLEN] = "";
strcpy(server_ip, argv[1]);

// printf("%s\n", server_ip);
//create socket
int sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
if(sock_fd < 0)
{
perror("socket");
exit(-1);
}
//send tftp request
struct sockaddr_in server_addr;
bzero(&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(69);
inet_pton(AF_INET, server_ip, &server_addr.sin_addr);
char tftp_requst[1024] = "";
int len;
len = sprintf(tftp_requst, "%c%c%s%c%s%c%s%c", 0, 1, filename, 0, "octet", 0, "tsize", 0);
sendto(sock_fd, tftp_requst, len, 0, (struct sockaddr *)&server_addr, sizeof(server_addr));

unsigned char buf[1024] = "";
unsigned char cli_len = sizeof(server_addr);
unsigned short num = 0;
//open file and ready to write data down
int fd = open(filename, O_RDWR | O_CREAT, 0666);
if(fd < 0)
{
perror("open");
close(sock_fd);
exit(-1);
}
socklen_t server_len = sizeof(server_addr);
while(1)
{
len = recvfrom(sock_fd, buf, sizeof(buf), 0, (struct sockaddr *)&server_addr, &server_len);
unsigned short cmd = ntohs(*((unsigned short*)buf));
printf("cmd:%d\tlen:%d\tnum:%d\n", cmd, len, ntohs(*((unsigned short*)(buf + 2))));
switch(cmd)
{
case 3://SEND ACK AND RECIEVE DATA
{
if(num + 1 == ntohs(*(unsigned short *)(buf + 2)))
{
write(fd, buf + 4, len - 4);
num = ntohs(*(unsigned short *)(buf + 2));
}
buf[1] = 4;
sendto(sock_fd, buf, 4, 0, (struct sockaddr *)&server_addr, sizeof(server_addr));
break;
}
case 5://error information
{
close(fd);
close(sock_fd);
unlink(filename);
printf("err:%s\n", buf + 4);
exit(-1);
}
case 6://send ACK
{
int i = 2;
while(buf[i] != ‘\0‘)
{
i++;
}
i++;
int size = atoi(buf + i);
printf("size:%d\n", size);//show the size dest source
sendto(sock_fd, buf, 4, 0, (struct sockaddr *)&server_addr, sizeof(server_addr));
break;
}
}
if(len != 516 && cmd != 6)
{
break;
}
}
close(fd);
close(sock_fd);
return 0;
}

上传代码:

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>


int main(int argc, char *argv[])
{
if(argc != 3)
{
printf("please input the server ip and filename you want to upload:\n");
exit(-1);
}
//copy server ip
char serv_ip[50] = "";
strcpy(serv_ip, argv[1]);
//copy file name
char filename[50] = "";
strcpy(filename, argv[2]);

//create socket
int sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
if(sock_fd < 0)
{
perror("socket");
exit(-1);
}
//construct upload request
char send_buf[1024] = "";
int len = sprintf(send_buf, "%c%c%s%c%s%c", 0, 2, filename, 0, "octet", 0);

struct sockaddr_in serv_addr;
bzero(&serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(69);
inet_pton(AF_INET, serv_ip, &serv_addr.sin_addr.s_addr);
//send upload request
sendto(sock_fd, send_buf, len, 0, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
//open the file you want to upload
int fd;
if( (fd = open(filename, O_RDONLY)) < 0)
{
perror("open");
close(sock_fd);
exit(-1);
}
socklen_t serv_len = sizeof(struct sockaddr);
unsigned short num = 0;
while(1)
{
bzero(send_buf, sizeof(send_buf));
len = recvfrom(sock_fd, send_buf, sizeof(send_buf), 0, (struct sockaddr*)&serv_addr, &serv_len);
//output the command
unsigned short cmd = ntohs(*((unsigned short*)send_buf));
printf("request cmd:%d\t len:%d\tserial number:%d\n", cmd, len, ntohs(*(unsigned short*)(send_buf + 2)));
switch(cmd)
{
case 4://if it was an answer package
{
if(num++ == ntohs(*(unsigned short*)(send_buf + 2)))//if the answer num is equal to the send num
{
sprintf(send_buf, "%c%c%c%c", 0, 3, num / 256, num % 256);
len = read(fd, send_buf + 4, 512);
sendto(sock_fd, send_buf, len + 4, 0, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
if(len < 512)
{
printf("upload completed\n");
close(sock_fd);
close(fd);
exit(0);
}
}
break;
}
case 5://if it was a error package
{
printf("upload file failed!!!\n");
close(fd);
close(sock_fd);
printf("err:%s\n", send_buf + 4);
break;
}
}
}


return 0;
}

坚持每天一个小程序(TFTP下载和上传),布布扣,bubuko.com

坚持每天一个小程序(TFTP下载和上传)

原文:http://www.cnblogs.com/lsblogs/p/3603761.html

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