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:
目前TFTP有三种传送模式:
具体每个包的格式在下面表格里列出:
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
原文:http://www.cnblogs.com/lsblogs/p/3603761.html