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