tftp_client.rar_client tftp_tftp client_tftp client_tftp_clien

/* 程序目的: 实现从TFTP服务器下载文件，或将文件上传至TFTP服务器 */ #include <stdio.h> #include <fcntl.h> #include <string.h> #include <unistd.h> #include <stdlib.h> #include <sys/time.h> #include <sys/stat.h> #include <sys/types.h> #include <arpa/inet.h> #include <sys/socket.h> #include <netinet/in.h> #define ASK 0x0 #define READ 0x01 #define WRITE 0x02 #define DATA 0x0 #define DATPACK 0x03 /*用户接口函数*/ int UsrInterface(int argc,char *argv[],struct sockaddr_in seraddr,char askmessage[]) { int length=0; char *model = "octet"; /*数据传输模式(二进制模式)*/ char operate[10] = ""; /*存放tftp协议的操作码*/ if(argc != 4) /*必须输入6个参数: ./tftp 192.168.220.61 read(write) filename*/ { printf("input error,please reference to example\n"); printf("form:\"./tftp 192.168.220.xxx read(write) filename blksize xxx\"\n"); exit(1); } if(argv[1]) /*第一个参数是服务器的IP地址*/ { seraddr.sin_addr.s_addr = inet_addr(argv[1]); } operate[0] = ASK; if( strcmp("read",argv[2]) == 0) //若第二个参数是read，表示从服务器下载文件 operate[1] = READ; if( strcmp("write",argv[2]) == 0) //若第二个参数是write，表示向服务器上传文件 operate[1] = WRITE; length = sprintf(askmessage,"%c%c%s%c%s%c",operate[0],operate[1],argv[3],0,model,0); //将读写请求命令打入数组中 return length; } /*创建套接字(UDP协议)*/ int creatsock(void) { int tftpfd; if((tftpfd=socket(AF_INET,SOCK_DGRAM, 0))<0) { perror("socket"); exit(1); } return tftpfd; } /*从服务器下载数据*/ void download(int fd,int tftpfd,char askmessage[],int length,struct sockaddr_in seraddr) { int len; unsigned char low = 1; unsigned char high = 0; unsigned char donwloaddata[516] = ""; socklen_t addrlen = sizeof(seraddr); //length表示发送请求命令的实际长度.实际命令有多长就发送多长，这里千万不能使用sizeof(askmessage) //若发送的请求命令中不包含选项，当客户端发送请求命令后，服务器直接发送数据，而不再发送OACK. sendto(tftpfd, askmessage, length,0,(struct sockaddr*)&seraddr, addrlen); do { memset(donwloaddata,0,sizeof(donwloaddata)); //从服务器接收数据(数据包括4个字节的操作码和512个字节的目标数据，共516个字节) len = recvfrom(tftpfd, donwloaddata, sizeof(donwloaddata), 0, (struct sockaddr*)&seraddr, &addrlen); if( (donwloaddata[2] == high) && (donwloaddata[3] == low) ) { printf("len=%d\n",len); //将接收到的数据写入文件内 //"donwloaddata+4"表示从数据缓存buffer的第4个字节开始写入文件(前4个字节是操作码，不能写入文件内) //"len-4"表示写入数据的长度，该长度应去除4个字节的操作码长度 write(fd,(donwloaddata+4),(len-4)); donwloaddata[1] = 4; //设置ACK包(数据包和应答包的操作码区别在于，第1个字节不同) //发送ACK包.缓存donwloaddata的前4个字节是ACK包，后面是从服务器上接收到的实际数据，因此只发送前4个字节即可 sendto(tftpfd, donwloaddata, 4,0,(struct sockaddr*)&seraddr, addrlen); low++; /*数据包发送成功，则包序号加1*/ if(low == 0) /*当低字节加到FF时，高字节加1*/ high++; } } while( (len == 516) || (donwloaddata[1] == 6) ); /*判断从服务器上下载的数据是否为516个字节以及是否出错*/ printf("download success\n"); } /*向服务器上传文件*/ void upload(int fd,int tftpfd,char askmessage[],int length,struct sockaddr_in seraddr,char *argv[]) { int readsize; unsigned char high = 0; unsigned char low = 1; unsigned char uploaddata[516] = ""; socklen_t addrlen = sizeof(seraddr); sendto(tftpfd, askmessage, length,0,(struct sockaddr*)&seraddr, addrlen); /*向服务器发送请求上传命令*/ recvfrom(tftpfd, uploaddata, 4, 0, (struct sockaddr*)&seraddr, &addrlen); /*收到服务器的ack*/ while(uploaddata[1] == 0x04) /*判断是否为服务器的ack*/ { memset(uploaddata,0,sizeof(uploaddata)); uploaddata[0] = 0; /*操作码第一个字节*/ uploaddata[1] = 3; /*操作码第二个字节，表明是要发送数据包*/ uploaddata[2] = high; /*包序号的高字节*/ uploaddata[3] = low; /*包序号的低字节*/ readsize = read(fd,uploaddata+4,512); /*每次从文件中读取512个字节，并从缓存的第4个字节开始存储(前面4个字节是操作码)*/ sendto(tftpfd, uploaddata, readsize+4,0,(struct sockaddr*)&seraddr, addrlen); /*向服务器发送数据包*/ memset(uploaddata,0,sizeof(uploaddata)); recvfrom(tftpfd, uploaddata, 4, 0, (struct sockaddr*)&seraddr, &addrlen); /*等待服务器的ack(只接收前4个字节)*/ if( (uploaddata[2] == high) && (uploaddata[3] == low) ) /*若发送的数据包序号等于服务器返回的包序号，表明服务器正常接收数据*/ { low++; /*服务器正常接收数据，则包序号加1*/ if(low == 0) /*当低字节加到FF时，高字节加1*/ high++; if(readsize < 512) /*当读取到文件的小于512时，退出.此时文件的最后一包数据已发送，服务器的ack已收到*/ break; } else /*若发送的数据包序号不等于服务器返回的包序号，则这一包数据重发*/ continue; } printf("upload success\n"); } int main(int argc,char *argv[]) { int tftpfd; int fd; int flag; int length = 0; char askmessage[100] = ""; struct sockaddr_in seraddr; seraddr.sin_family = AF_INET; seraddr.sin_port = htons(69); //TFTP服务器默认端口为69 seraddr.sin_addr.s_addr = inet_addr("192.168.220.61"); //服务器IP地址 tftpfd = creatsock(); length = UsrInterface(argc,argv,seraddr,askmessage); if( strcmp("read",argv[2]) == 0) { if((fd=open(argv[3],O_WRONLY|O_CREAT,0666)) < 0) perror("read open"); flag = 1; } if( strcmp("write",argv[2]) == 0) { if((fd=open(argv[3],O_RDONLY)) < 0) perror("write open"); flag = 2; } switch(flag) { case 1: download(fd,tftpfd,askmessage,length,seraddr); break; case 2: upload(fd,tftpfd,askmessage,length,seraddr,argv); break; default: printf("input error\n"); exit(1); break; } return 0; }