tftp client

#include
#include
#include
#include
#include
#include
#include
#include

 

int main()
{
 int sockfd;
 struct sockaddr_in server;
 char read_cmd[100]="";
 char buf[512]="";
 char up_buf[512]="";
 int count=0;
 int temp;
 char block_num[2]="";
 int addrlen = sizeof(server);
 int fd;
 char filename[100]="0";
 char filename_temp[100]="0";
 char up_temp[516]="";
 char ch;
 char code;
 bzero(&server, sizeof(struct sockaddr_in));
 server.sin_family = AF_INET;
 server.sin_port = htons(69);
 server.sin_addr.s_addr = inet_addr("192.168.220.37");

 printf("please input filename\n");
 scanf("%s",filename);
 strcpy(filename_temp,filename);
 printf("please input opreating code\n1 is download\n2 is upload\n");
 scanf("%s",&ch);
// sprintf(read_cmd,"%c%c%s%c%s%c",0,ch,filename,0,"octet",0);
 
 sockfd = socket(AF_INET, SOCK_DGRAM, 0);
 if(sockfd < 0)
 {
  perror("Invalid socket");
  exit(1);
 }
// sendto(sockfd, read_cmd, 18, 0, (struct sockaddr*)&server, sizeof(struct sockaddr));
 
 if(ch=='1')
 {
  sprintf(read_cmd,"%c%c%s%c%s%c",0,1,filename,0,"octet",0);
  sendto(sockfd, read_cmd, 18, 0, (struct sockaddr*)&server, sizeof(struct sockaddr));
  count=recvfrom(sockfd, buf, 512, 0, (struct sockaddr*)&server, &addrlen);
  printf("%d\n",count);
  if((buf[1]==5))
  {
   printf("FILE NOT FIND\n");
   printf("buf=%s\n",buf+4);
   exit(1);
  }
  if((fd = open(filename, O_RDWR|O_CREAT))<0) 
  { 
   printf("filename=%s\n",filename_temp);
   perror("open");
   exit(1);
  }

  while(count>=512)
  {
 
  write(fd,buf+4,strlen(buf+4));
  block_num[0]=buf[2];
  block_num[1]=buf[3];
  sendto(sockfd,block_num,2,0,(struct sockaddr*)&server,sizeof(struct sockaddr));
  memset(buf,0,512);
  count=recvfrom(sockfd, buf, 512, 0, (struct sockaddr*)&server, &addrlen);
  }
  write(fd,buf+4,strlen(buf+4));
  close(fd);
  return 0;
 }
 if(ch=='2')
 { 
  sprintf(read_cmd,"%c%c%s%c%s%c",0,2,filename,0,"octet",0);
 // sprintf(up_temp,"%c%c%c%c",0,3,0,1);
  printf("up_temp=%d\n",up_temp[1]);
  sendto(sockfd, read_cmd, 9+strlen(filename), 0, (struct sockaddr*)&server, sizeof(struct sockaddr));
  recvfrom(sockfd, buf, 512, 0, (struct sockaddr*)&server, &addrlen);
  if((buf[1]==5))
  {
   printf("FILE NOT FIND\n");
   printf("buf=%s\n",buf+4);
   exit(1);
  }
  if((fd = open(filename, O_RDWR))<0) 
  {  
   perror("open");
   exit(1);
  }

  count=read(fd,up_buf,512);
   code=1;
  while (count>0)
  {
   int i=0;
//   printf("up_buf=%s\n",up_buf);
//   strcat(up_temp,up_buf);
   sprintf(up_temp, "%c%c%c%c%s", 0,3,0,code,up_buf);
   sendto(sockfd,up_temp,516,0,(struct sockaddr*)&server,sizeof(struct sockaddr));
   recvfrom(sockfd, buf, 512, 0, (struct sockaddr*)&server, &addrlen);
   block_num[0]=buf[2];
   block_num[1]=buf[3];
     printf("buf[3]=%s\n",buf+3);
   count=read(fd,up_buf,512);
   code++;
     memset(buf,0,512);
   memset(up_temp,0,516);

  }

 

  
 }
}