86 lines
2.2 KiB
C
86 lines
2.2 KiB
C
|
#include <stdio.h>
|
|||
|
|
#include <arpa/inet.h>
|
|||
|
|
#include <sys/socket.h>
|
|||
|
|
#include <netinet/in.h>
|
|||
|
|
#include <unistd.h>
|
|||
|
|
#include <string.h>
|
|||
|
|
#include <fcntl.h>
|
|||
|
|
#include <sys/types.h>
|
|||
|
|
#include <sys/stat.h>
|
|||
|
|
|
|||
|
|
/**
|
|||
|
|
* ./a.out server_ip 下载的文件名
|
|||
|
|
* ./tftpc server_ip filename
|
|||
|
|
*/
|
|||
|
|
int main(int argc, char const *argv[])
|
|||
|
|
{
|
|||
|
|
if (argc < 3)
|
|||
|
|
{
|
|||
|
|
printf("format: %s server_ip filename\n", argv[0]);
|
|||
|
|
return -1;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
int sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
|
|||
|
|
if (sock_fd < 0)
|
|||
|
|
{
|
|||
|
|
perror("socket");
|
|||
|
|
return -1;
|
|||
|
|
}
|
|||
|
|
// 生成请求数据包
|
|||
|
|
char request[64];
|
|||
|
|
int request_size = sprintf(request, "%c%c%s%c%s%c", 0, 1, argv[2], 0, "octet", 0);
|
|||
|
|
|
|||
|
|
// 发送请求
|
|||
|
|
struct sockaddr_in server_addr;
|
|||
|
|
bzero(&server_addr, sizeof(server_addr));
|
|||
|
|
server_addr.sin_family = AF_INET;
|
|||
|
|
server_addr.sin_port = htons(69);
|
|||
|
|
server_addr.sin_addr.s_addr = inet_addr(argv[1]);
|
|||
|
|
|
|||
|
|
sendto(sock_fd, request, request_size, 0, (struct sockaddr *)&server_addr, sizeof(server_addr));
|
|||
|
|
|
|||
|
|
char buf[516] = "";
|
|||
|
|
struct sockaddr_in data_addr;
|
|||
|
|
socklen_t data_addr_len = sizeof(data_addr);
|
|||
|
|
bzero(&data_addr, data_addr_len);
|
|||
|
|
ssize_t len = recvfrom(sock_fd, buf, 516, 0, (struct sockaddr *)&data_addr, &data_addr_len);
|
|||
|
|
|
|||
|
|
// 验证接收的数据是否OK
|
|||
|
|
if (buf[1] == 3)
|
|||
|
|
{
|
|||
|
|
// 创建本地文件的描述符（打开或创建文件）
|
|||
|
|
int fd = open(argv[2], O_CREAT | O_WRONLY, 0666);
|
|||
|
|
|
|||
|
|
while (1)
|
|||
|
|
{
|
|||
|
|
// 收到的是数据包
|
|||
|
|
write(fd, buf + 4, len - 4);
|
|||
|
|
// 回ACK
|
|||
|
|
buf[1] = 4;
|
|||
|
|
sendto(sock_fd, buf, 4, 0, (struct sockaddr *)&data_addr, sizeof(data_addr));
|
|||
|
|
if (len < 516)
|
|||
|
|
{
|
|||
|
|
printf("数据接收完成\n");
|
|||
|
|
break;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
bzero(&data_addr, data_addr_len);
|
|||
|
|
bzero(buf, sizeof(buf));
|
|||
|
|
len = recvfrom(sock_fd, buf, 516, 0, (struct sockaddr *)&data_addr, &data_addr_len);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
close(fd);
|
|||
|
|
}
|
|||
|
|
else if (buf[1] == 5)
|
|||
|
|
{
|
|||
|
|
// 收到的错误信息包
|
|||
|
|
printf("error: %s\n", buf + 4);
|
|||
|
|
}
|
|||
|
|
else if (buf[1] == 6)
|
|||
|
|
{
|
|||
|
|
// 收到的OACK包，包含请求选项回传的值
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
close(sock_fd);
|
|||
|
|
return 0;
|
|||
|
|
}
|