base64dec.cpp

BASE64译码

#define N (1<<16)
#define TYPE (unsigned short)
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int pp(unsigned char *subs,unsigned char *s,int qd);
unsigned char tb[]="base64",tb1[]="BASE64";

main(int argc,char *argv[])
{
 int c=0,len=0,i,qd,js,FLAG=0,flag,filejs=1,sum,start,id_0,id_1;
 unsigned long mw=0;
 unsigned char str[N],word[256];
 char fname[]="000000000000";
 FILE *fp,*fpw,*fp1;

 if(argc<2) {
		  printf("Usage:%s infile temp_file\n",argv[0]);
		  exit(-1);
 }

 if( (fp= fopen(argv[1],"rb"))==NULL ){
		  printf("cant open file\n");
		  exit(-1);
 }


if ((fp1=fopen("base.b64","ab"))==NULL){
    printf(" cant open the windowfile ! \n");
	 exit (-1);
    }

 for(i=0;i < 256 ;i++)   word[i]=0x15;     /* 00010101 */
 for(i='A';i <= 'Z';i++) word[i]=(char)(c++)+'0';
 for(i='a';i <= 'z';i++) word[i]=(char)(c++)+'0';
 for(i='0';i <= '9';i++) word[i]=(char)(c++)+'0';
 word['+']=(char)(c++)+'0';
 word['/']=(char)(c++)+'0';


 for(flag=0,sum=0,qd=0,js=0;;){
		 if(sum-qd<N/2){
			   if( (c=getc(fp))==EOF ) break;
				str[TYPE(sum++)]=(unsigned char)c;
				continue;
		 }

       if((pp(tb,str,qd)==0)||(pp(tb1,str,qd)==0)){

          strcpy(fname,"base64.64");
          fname[9]=(char)filejs+'0';
          fname[10]='\0';
          printf("Create file : %s \n",fname);

          if ((fpw=fopen(fname,"wb"))==NULL) {
                printf("cant open the %s !!\n",fname);
                exit(-1);
              }

          filejs++;
          FLAG=1;id_0=qd;
       }

		 if (str[TYPE(qd)]==0x0d&&str[TYPE(qd+1)]==0x0a&&
			  str[TYPE(qd+2)]==0x0d&&str[TYPE(qd+3)]==0x0a){
				 start=1;mw=0;len=0;id_1=qd;  //id_1=qd+4;
		 }
		 if (FLAG==1&&start==1&&(id_1>id_0)){
				if (str[TYPE(qd)]!=0x0d&&str[TYPE(qd)]!=0x0a){
					  mw <<=6; mw |=word[ str[TYPE(qd)] ]; len +=6;
					  while(len >= 8){
							 fprintf(fpw,"%c",(mw >> (len-8)) & 0xff);
							 len -=8;
					  }
				}
				else{
				  if (str[TYPE(qd)]==0x0d&&str[TYPE(qd+1)]==0x0a&&
						str[TYPE(qd+2)]==0x0d&&str[TYPE(qd+3)]==0x0a)
				  js++;
				  if (js>=2) {js=0;FLAG=0;start=0;id_0=0;id_1=0;fclose(fpw);}
				}

		 }
		 else
			 fprintf(fp1,"%c",str[TYPE(qd)]);
		  qd++;
    
 }
 fclose(fp);
 fclose(fpw);
 return 0;
}

pp(unsigned char *subs,unsigned char *s,int qd)
{
  int  i;
  for(i=0;subs[i];i++,qd++)if(subs[i] != s[TYPE(qd)])return 1;
  return 0;
}