基于UDP的TFTP文件上传

#include <myhead.h>#define PORT 69
#define IP "192.168.125.59"int down(const char *);
int up(const char *);int main(int argc, const char *argv[])
{while(1){system("clear");//打印菜单puts("***************功能**************");puts("*************1. 下载*************");puts("*************2. 上传*************");puts("*************3. 退出*************");int choose = -1;char filename[128] = "";scanf("%d", &choose);switch(choose){case 1:{printf("输入文件名>>");scanf(" %[^\n]", filename);if(down(filename) == -1){return -1;}}break;case 2:{printf("输入文件名>>");scanf(" %[^\n]", filename);if(up(filename) == -1){return -1;}}break;case 3:return 0;default:puts("输入错误");}}return 0;
}int down(const char *filename){int cfd = socket(AF_INET, SOCK_DGRAM, 0);if(cfd == -1){perror("socket error");return -1;}char buf[516];bzero(buf, sizeof(buf));//设置为下载（读）操作buf[1] = 1;//将文件名加入协议包中strcpy(buf+2, filename);//模式char mod[6] = "octet";//将模式字符串加入协议包中strcpy(buf+2+strlen(filename)+1, mod);//统计协议包字节数总大小int size = 2+strlen(filename)+1+strlen(mod)+1;struct sockaddr_in sin;sin.sin_family = AF_INET;sin.sin_port = htons(PORT);sin.sin_addr.s_addr = inet_addr(IP);socklen_t socklen = sizeof(sin);if(sendto(cfd, buf, size, 0, (struct sockaddr *)&sin, sizeof(sin)) == -1){perror("sendto error");return -1;}puts("请求成功");int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0664);while(1){bzero(buf, sizeof(buf));int res = -1;if((res = recvfrom(cfd, buf, sizeof(buf), 0, (struct sockaddr *)&sin, &socklen)) == -1){perror("recvfrom error");return -1;}if(buf[1] == 3){if(res < 516){//若接收字节数小于516则将数据写入后结束下载write(fd, buf+4, res-4);buf[1] = 4;sendto(cfd, buf, 4, 0, (struct sockaddr *)&sin, sizeof(sin));break;}else{write(fd, buf+4, 512);buf[1] = 4;sendto(cfd, buf, 4, 0, (struct sockaddr *)&sin, sizeof(sin));}}else{printf("未知错误，错误码: %d\n", buf[3]);close(fd);close(cfd);return -1;}}close(fd);close(cfd);return 0;
}int up(const char *filename){int cfd = socket(AF_INET, SOCK_DGRAM, 0);if(cfd == -1){perror("socket error");return -1;}char buf[516];bzero(buf, sizeof(buf));//设置为上传（写）操作buf[1] = 2;//将文件名加入协议包中strcpy(buf+2, filename);//模式char mod[6] = "octet";//将模式字符串加入协议包中strcpy(buf+2+strlen(filename)+1, mod);//统计协议包字节数总大小int size = 2+strlen(filename)+1+strlen(mod)+1;struct sockaddr_in sin;sin.sin_family = AF_INET;sin.sin_port = htons(PORT);sin.sin_addr.s_addr = inet_addr(IP);socklen_t socklen = sizeof(sin);if(sendto(cfd, buf, size, 0, (struct sockaddr *)&sin, sizeof(sin)) == -1){perror("sendto error");return -1;}puts("请求成功");int fd = open(filename, O_RDONLY);//用于表示传输块的编号short block_num = 0;//用于操作ACK应答包的数据块的编号short * const p = (short *)(buf+2);int res = -1;while(1){recvfrom(cfd, buf, 4, 0, (struct sockaddr *)&sin, &socklen);//printf("num = %d, block_num = %d\n", buf[1], block_num);if(buf[1] == 4){//使用指针p提取数据时需要注意字节序的问题if(ntohs(*p) == 0 || block_num == ntohs(*p)){buf[1] = 3;res = read(fd, buf+4, 512);*p = htons(++block_num);size = res + 4;if(res == 0){break;}else{sendto(cfd, buf, size, 0, (struct sockaddr *)&sin, sizeof(sin));}}else{buf[1] = 3;sendto(cfd, buf, size, 0, (struct sockaddr *)&sin, sizeof(sin));}}else{printf("未知错误，错误码: %d\n", buf[3]);close(fd);close(cfd);return -1;}}close(fd);close(cfd);return 0;
}

思维导图