如何基于c语言tftp服务器与客户端实现_华清远见

如何基于c语言tftp服务器与客户端实现本篇文章主要的内容就是教大家，如何基于c语言tftp服务器与客户端实现，是非常精彩的内容，希望对大家的学习之路有所帮助。

TFTP(Trivial File Transfer Protocol,简单文件传输协议)是TCP/IP协议族中的一个用来在客户机与服务器之间进行简单文件传输的协议，提供不复杂、开销不大的文件传输服务。

端口号为69。

开发环境：ubuntu所用知识点：c，socket, tcp/ip协议A)本实验主要实现tftp协议的服务器与客户端。

服务器实现功能有：1)接收处理客户端请求，上传下下载文件2)进行用户验证3)对传输数据进行加密解密处理4)生成日志文件客户端实现功能有：1)向服务器发出请求，上传或下载文件2)对传输数据加密解密3)对用户信息进行MD5加密B)相关代码实现：宏定下：#ifndef MAKEWORD#define MAKEWORD(l,h) ((unsigned short)(((unsigned char)(l))|(((unsigned short)(unsigned char)(h))<<8)))#endif#define WSA_MAJOR_VERSION 1#define WSA_MINOR_VERSION 1#define WSA_VERSION MAKEWORD(WSA_MAJOR_VERSION, WSA_MINOR_VERSION) #define TFTP_OCTET 1#define TFTP_WSTAT_FIRSTACK 0#define TFTP_WSTAT_NEXTACK 1#define TFTP_WSTAT_LASTACK 2#define TFTP_RRQ 1 //读请求#define TFTP_WRQ 2 //写请求#define TFTP_DATA 3 //数据#define TFTP_ACK 4 //ACK#define TFTP_ERROR 5 //Error#define MAX_RETRY 3 //最大重复次数#define TFTP_NOTEND_DATALEN 512+2+2 //数据块长度//错误种类#define Not_defined 0#define File_not_found 1#define Access_violation 2#define Disk_full 3#define Illegal_TFTP_operation 4#define Unknown_port 5#define File_already_exists 6#define No_such_user 7#define Time_out 8#define Read_file_Error 9#define Cannot_create_file 10#define passwd_or_user_error 11包的填充：#include "define.h"#include#includeint makeack(unsigned short num,char *buffer,int size );int makedata(unsigned short num,char *data,int datasize,char *buffer,int bufsize); int makeerr(unsigned short num,char *buffer);//ACK包填充int makeack(unsigned short num,char *buffer,int size ){int pos = 0;buffer[pos] = 0;pos++;buffer[pos] = TFTP_ACK; //操作码为04pos++;buffer[pos] = (char)(num>>8);//块号2个字节pos++;buffer[pos] = (char)num;pos++;return pos;}//Data包填充int makedata(unsigned short num,char *data,int datasize,char *buffer,int bufsize){int pos = 0;buffer[pos] = 0;pos++;buffer[pos] = TFTP_DATA; //操作码为03pos++;buffer[pos] = (char)(num>>8);//块号pos++;buffer[pos] = (char)num;pos++;memcpy(&buffer[pos],data,datasize);//填充数据pos = pos + datasize;return pos;}//ERROR包填充int makeerr(unsigned short num,char *buffer) {int pos=0;buffer[pos]=0;pos++;buffer[pos]=TFTP_ERROR; //操作码为05pos++;buffer[pos] = (char)(num>>8); //错误种类号pos++;buffer[pos] = (char)num;pos++;return pos;}日志log.c实现#includestatic char log[100]; //日志char datetime[20]; //记录时间变量int timeout=2,retran=3; //服务器参数void record(int a,struct sockaddr_in *sin,char *file){char tem[60];time_t t=time(0); //初始化日历时间strftime(datetime,sizeof(datetime),"%y/%m/%d %X",localtime(&t));//将时间格式化strcat(log,datetime);//将时间写入记录//将字符串格式化bzero(&tem,sizeof(tem));if(a==1)sprintf(tem," 收到来自 %s 上传文件 %s 的请求。

\n",inet_ntoa(sin->sin_addr),file); if(a==2)sprintf(tem," %s 上传文件 %s 完毕。

\n",inet_ntoa(sin->sin_addr),file);if(a==3)sprintf(tem," 收到来自 %s 下载文件 %s的请求。

\n",inet_ntoa(sin->sin_addr),file); if(a==4)sprintf(tem," %s 下载文件 %s 完毕。

\n",inet_ntoa(sin->sin_addr),file); if(a==5)sprintf(tem," 出现出错，操作中断。

\n",inet_ntoa(sin->sin_addr),file); //将具体信息写入记录strcat(log,tem);FILE *write;if((write=fopen("log.txt","a+"))==NULL)printf("打开记录文件失败\n");//将记录写入文件fwrite(&log,strlen(log),1,write);fclose(write);bzero(&log,sizeof(log));}加密解密实现#include#include#includeint decrypt(FILE *in,FILE *out);int encrypt(FILE *in,FILE *out);unsigned char atoh(char *hexstr);int encrypt(FILE *in,FILE *out){if(in == NULL || out == NULL){fprintf(stderr,"%s\n","file error!\n"); return -1;}unsigned char hex;while(fread(&hex,1,1,in)){hex = ~hex^0x98;fprintf(out,"%02X",hex);}return 0;}int decrypt(FILE *in,FILE *out){if(in == NULL || out == NULL){fprintf(stderr,"%s\n","file error!"); return -1;}unsigned char hexstr[3];unsigned char hex = 0;int i = 0;while(fread(hexstr,2,1,in)){hex = atoh(hexstr);hex = ~(hex ^ 0x98);fwrite(&hex,1,1,out);}return 0;}/* convert string to hex */unsigned char atoh(char *hexstr){int i;int hextodec[]={0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};char chtodec[] = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'}; unsigned char hexnum = 0;for(i = 0; i < sizeof(chtodec); ++i){if(hexstr[0] == chtodec[i]){hexnum += hextodec[i]*16;}}for(i = 0; i < sizeof(chtodec); ++i){if(hexstr[1] == chtodec[i]){hexnum += hextodec[i];}}return hexnum;}上传数据：//上传函数void upload(struct sockaddr_in sour_addr,char buffer[]) {char send_buffer[1024] = {0};char recv_buffer[1024] = {0};struct sockaddr_in dest_addr;struct timeval timeout = {10,0};int sour_len = 0;int ret = 0;int len = 0;int flen = 0;fd_set fdr;unsigned short lastdata = 0;unsigned short blocknum = 0;FILE *file;FILE *decrypt_file = NULL;char filename[256];//获取文件名strcpy(filename,buffer+2);dest_addr.sin_family = AF_INET;dest_addr.sin_port = sour_addr.sin_port;dest_addr.sin_addr.s_addr = inet_addr(desthost);////如果本地存在同名文件if((file=fopen(filename,"rb"))!=NULL){//发送一个error包,报告存在同名文件printf("***存在同名文件***");len = makeerr(File_already_exists,send_buffer);ret = sendto(sock,send_buffer,len,0,(struct sockaddr *)&dest_addr,sizeof(dest_addr)); record(5,&sour_addr,filename);return;}//建立文件if((file=fopen(filename,"w+b"))==NULL){//如果失败,发送error包printf("创建文件失败\n");len = makeerr(Cannot_create_file,send_buffer);ret = sendto(sock,send_buffer,len,0,(struct sockaddr *)&dest_addr,sizeof(dest_addr)); record(5,&sour_addr,filename);return;}//发送ACKlen = makeack(blocknum,send_buffer,sizeof(send_buffer));ret = sendto(sock,send_buffer,len,0,(struct sockaddr *)&dest_addr,sizeof(dest_addr)); blocknum++;while(1){FD_ZERO(&fdr);FD_SET(sock, &fdr);ret = select(sock+1, &fdr, NULL,NULL, &timeout);if(-1==ret){printf("Socket 错误\n");fclose(file);record(5,&sour_addr,filename);return;}else{if(0==ret){printf("超时\n");fclose(file);record(5,&sour_addr,filename);return;}else{if (FD_ISSET(sock,&fdr)){//接收数据包sour_len = sizeof(struct sockaddr);ret = recvfrom(sock,recv_buffer,sizeof(recv_buffer),0,(struct sockaddr*)&sour_addr,&sour_len);//如果是数据包if(TFTP_DATA==recv_buffer[1]){lastdata = MAKEWORD(recv_buffer[3],recv_buffer[2]); //块号//如果块号正确if(lastdata == blocknum){//发送ACK包len = makeack(blocknum,send_buffer,sizeof(send_buffer));sendto(sock,send_buffer,len,0,(struct sockaddr *)&dest_addr,sizeof(dest_addr)); blocknum++;if(blocknum > 65535)blocknum = 0;//最后一包if(ret < TFTP_NOTEND_DATALEN){//写入文件fwrite(&recv_buffer[4],1,ret-4,file);flen = flen + ret -4;#ifdef _DEBUG_printf("%s %s %d\n", __FILE__, __FUNCTION__, __LINE__); printf("*****传输结束,共收到 %d 字节*****\n",flen);#endifrewind(file);if((decrypt_file =fopen("decrypt_temp","wb+"))==NULL){ printf("decrypt file open error \n");return;}decrypt(file, decrypt_file);fclose(decrypt_file);rename("decrypt_temp", filename);fclose(file);record(2,&sour_addr,filename);return;}else{fwrite(&recv_buffer[4],1,512,file);flen = flen + 512;#ifdef _DEBUG_printf("%s %s %d\n", __FILE__, __FUNCTION__, __LINE__);printf("已收到 %d 字节\n",flen);#endif}}else{//重新发送ACK包printf("数据包块号错误.\n");sendto(sock,send_buffer,len,0,(struct sockaddr *)&dest_addr,sizeof(dest_addr)); }}}}}}}C)客户端与服务都配有工程管理器，可通过make 完成编译。