2024.03.01作业

1. 基于UDP的TFTP文件传输

#include "test.h"#define SER_IP "192.168.1.104"
#define SER_PORT 69
#define IP "192.168.191.128"
#define PORT 9999enum mode
{TFTP_READ = 1,TFTP_WRITE = 2,TFTP_DATA = 3,TFTP_ACK = 4,TFTP_ERR = 5
};void get_filename(char* filename, int size)
{bzero(filename, size);printf("请输入文件名：");fgets(filename, size, stdin);filename[strlen(filename) - 1] = 0;
}void rw_request(char* pack, int pack_size, char* filename, int mode, int* packlen)
{bzero(pack, pack_size); short* p1 = (short*)pack;*p1 = htons(mode);char* p2 = (char*)(p1 + 1);strcpy(p2, filename);char* p4 = p2 + strlen(p2) + 1;strcpy(p4, "octet");*packlen = 4 + strlen(p2) + strlen(p4);
}void pack_data(char* pack, int num, char* rbuf, int len, int* packlen)
{bzero(pack, sizeof(pack)); short* p1 = (short*)pack;*p1 = htons(TFTP_DATA);short* p2 = p1 + 1;*p2 = htons(num);char* p4 = (char*)(p2 + 1);for (int i = 0; i < len; i++){*(p4 + i) = rbuf[i];}*packlen = 4 + len;
}void pack_ack(char* ack, int num)
{bzero(ack, 4);short* a = (short*)ack;*a = htons(TFTP_ACK);*(a + 1) = htons(num);
}void pack_errmsg(char* pack, char* msg, int* packlen)
{bzero(pack, sizeof(pack));short* p = (short*)pack;*p = htons(TFTP_ERR);*(p + 1) = htons(0);char* errmsg = (char*)(p + 2);strcpy(errmsg, msg);*packlen = 4 + strlen(errmsg);
}void client_recv(int sfd, struct sockaddr_in* sin, socklen_t* socklen)
{char filename[128];get_filename(filename, sizeof(filename));char pack[516] = "";int packlen = 0;rw_request(pack, sizeof(pack), filename, TFTP_READ, &packlen);sendto(sfd, pack, packlen, 0, (struct sockaddr*)sin, *socklen);int fd = -1;if ((fd = open(filename, O_WRONLY|O_CREAT|O_TRUNC, 0664)) == -1){perror("create file error");return;}char wbuf[512] = "";int block_num = 0;while (1){bzero(pack, sizeof(pack));packlen = recvfrom(sfd, pack, sizeof(pack), 0, (struct sockaddr*)sin, socklen);short* p = (short*)pack;short code = ntohs(*p);short num = ntohs(*(p + 1));if (3 == code && num == ++block_num){write(fd, pack + 4, packlen - 4);char ack[4];pack_ack(ack, block_num);sendto(sfd, ack, 4, 0, (struct sockaddr*)sin, *socklen);if (packlen < 512){printf("下载完成\n");close(fd);break;}}}
}void client_send(int sfd, struct sockaddr_in* sin, socklen_t* socklen)
{char filename[128];get_filename(filename, sizeof(filename));char pack[516] = "";int packlen = 0;rw_request(pack, sizeof(pack), filename, TFTP_WRITE, &packlen);sendto(sfd, pack, packlen, 0, (struct sockaddr*)sin, *socklen);int fd = -1;if ((fd = open(filename, O_RDONLY)) == -1){perror("open error");return;}char ack[4];char rbuf[512] = "";int len;while (1){recvfrom(sfd, ack, 4, 0, (struct sockaddr*)sin, socklen);short* a = (short*)ack;short code = ntohs(*a);short num = ntohs(*(a + 1));if (4 == code && (len = read(fd, rbuf, sizeof(rbuf))) > 0){pack_data(pack, num + 1, rbuf, len, &packlen);sendto(sfd, pack, packlen, 0, (struct sockaddr*)sin, *socklen);bzero(rbuf, sizeof(rbuf));}else{printf("上传成功\n");break;}}
}int main(int argc, char const *argv[])
{int sfd = -1;sfd = socket(AF_INET, SOCK_DGRAM, 0);if (-1 == sfd){perror("socket error");return -1;}printf("sfd = %d\n", sfd);int reuse = 1;if (setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) == -1){perror("setsockopt error");return -1;}printf("端口号快速重用成功\n");struct sockaddr_in sin;sin.sin_family = AF_INET;sin.sin_port = htons(SER_PORT);sin.sin_addr.s_addr = inet_addr(SER_IP);socklen_t socklen = sizeof(sin);printf("1.上传\n");printf("2.下载\n");printf("0.退出\n");printf("请输入：");int n;scanf("%d", &n);getchar();if (1 == n){client_send(sfd, &sin, &socklen);}else if (2 == n){client_recv(sfd, &sin, &socklen);}else{printf("输入错误\n");}close(sfd);return 0;
}