思维导图

tftp上传

#include <myhead.h>#define ERR_LOG(msg) do{\perror(msg);\printf("%d %s %s\n", __LINE__, __func__, __FILE__);\
}while(0)#define PORT   	 69 
#define N         516int do_upload(int sfd, struct sockaddr_in sin);int main(int argc, const char *argv[])
{if(argc < 2){printf("请输入IP\n");return -1;}//1.创建报式套接字int sfd = socket(AF_INET, SOCK_DGRAM, 0);if(sfd < 0){perror("socket");return -1;}//2.填充服务器ip和端口号struct sockaddr_in sin;sin.sin_family = AF_INET;sin.sin_port = htons(PORT);sin.sin_addr.s_addr = inet_addr(argv[1]);char choose;while(1){printf("######1.上传######\n");printf("######2.退出######\n");scanf("%c", &choose);while(getchar()!=10);switch(choose){case '1'://上传功能,tododo_upload(sfd, sin);break;case '2':goto END;break;default:printf("输入错误\n");}printf("请输入任意字符清屏:");while(getchar()!=10);        }//关闭文件描述符
END:close(sfd);return 0;
}//上传功能
int do_upload(int sfd, struct sockaddr_in sin)
{char filename[20] = "";printf("请输入要上传的文件名:");fgets(filename, 20, stdin);filename[strlen(filename)-1] = 0;//判断该文件是否存在int fd = open(filename, O_RDONLY);if(fd < 0){if(errno == ENOENT){printf(">>>文件不存在,请重新输入<<<\n");return -2;}else{ERR_LOG("open");return -1;}}//发送上传请求//上传协议char buf[N] = "";int size = sprintf(buf, "%c%c%s%c%s%c", 0, 2, filename, 0, "octet", 0);if(sendto(sfd, buf, size, 0, (struct sockaddr*)&sin, sizeof(sin))<0){ERR_LOG("sendto");return -1;}//循环接收发送数据包int recv_len;unsigned short num = 0;socklen_t addrlen = sizeof(sin);while(1){bzero(buf, N);recv_len = recvfrom(sfd, buf, sizeof(buf), 0, (struct sockaddr*)&sin, &addrlen);if(recv_len < 0){ERR_LOG("recvfrom");return -1;}//操作码的范围是1-5,因为是网络字节序//所以有效操作吗存储在高位,即buf[1]的位置.//服务器返回应答包if(4 == buf[1]){//判断当前数据包的编号是否等于应答包的编号//防止数据包在传送过程丢包或重复收包if(num == ntohs(*(unsigned short*)(buf+2))){//修改操作码为数据包buf[1] = 3;//填充块编号num++;*(unsigned short*)(buf+2) = htons(num);//读取数据//发送数据int res = read(fd, buf+4, N-4);if(res < 0){ERR_LOG("read");return -1;}else if(0 == res){printf("-----文件上传完毕-----\n");break;}//发送数据包//发送的数据包大小为,读取到的字节数(res)+操作码(2byte)+快编号(2byte)if(sendto(sfd, buf, res+4, 0, (struct sockaddr*)&sin, sizeof(sin)) <0){ERR_LOG("sendto");return -1;}}else{printf("-----文件上传失败,请检查网络环境-----\n");break;}}else if(5 == buf[1]){printf("-----ERROR:%s-----\n", buf+4);break;}}return 0;
}