83 lines
2.9 KiB
C++
83 lines
2.9 KiB
C++
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#include "utils.h"
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#include <string.h>
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void base64_encode(const unsigned char *str, int str_len, unsigned char *res, int *res_len)
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{
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long len;
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int i,j;
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//定义base64编码表
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unsigned char base64_table[128]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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//计算经过base64编码后的字符串长度
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if(str_len % 3 == 0)
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len=str_len/3*4;
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else
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len=(str_len/3+1)*4;
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*res_len = len;
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res[len]='\0';
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//以3个8位字符为一组进行编码
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for(i=0,j=0;i<len-2;j+=3,i+=4)
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{
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res[i]=base64_table[str[j]>>2]; //取出第一个字符的前6位并找出对应的结果字符
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res[i+1]=base64_table[(str[j]&0x3)<<4 | (str[j+1]>>4)]; //将第一个字符的后位与第二个字符的前4位进行组合并找到对应的结果字符
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res[i+2]=base64_table[(str[j+1]&0xf)<<2 | (str[j+2]>>6)]; //将第二个字符的后4位与第三个字符的前2位组合并找出对应的结果字符
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res[i+3]=base64_table[str[j+2]&0x3f]; //取出第三个字符的后6位并找出结果字符
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}
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switch(str_len % 3)
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{
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case 1:
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res[i-2]='=';
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res[i-1]='=';
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break;
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case 2:
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res[i-1]='=';
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break;
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}
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}
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void base64_decode(const unsigned char *code, int code_len, unsigned char *res, int *res_len)
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{
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//根据base64表，以字符找到对应的十进制数据
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int table[]={0,0,0,0,0,0,0,0,0,0,0,0,
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0,0,0,0,0,0,0,0,0,0,0,0,
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0,0,0,0,0,0,0,0,0,0,0,0,
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0,0,0,0,0,0,0,62,0,0,0,
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63,52,53,54,55,56,57,58,
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59,60,61,0,0,0,0,0,0,0,0,
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1,2,3,4,5,6,7,8,9,10,11,12,
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13,14,15,16,17,18,19,20,21,
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22,23,24,25,0,0,0,0,0,0,26,
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27,28,29,30,31,32,33,34,35,
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36,37,38,39,40,41,42,43,44,
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45,46,47,48,49,50,51
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};
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long len;
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long str_len;
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int i,j;
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//计算解码后的字符串长度
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len = code_len;
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//判断编码后的字符串后是否有=
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if(strstr((char*)code,"=="))
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str_len=len/4*3-2;
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else if(strstr((char*)code,"="))
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str_len=len/4*3-1;
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else
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str_len=len/4*3;
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res[str_len]='\0';
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*res_len = str_len;
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//以4个字符为一位进行解码
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for(i=0,j=0;i < len-2;j+=3,i+=4)
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{
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res[j]=((unsigned char)table[code[i]])<<2 | (((unsigned char)table[code[i+1]])>>4); //取出第一个字符对应base64表的十进制数的前6位与第二个字符对应base64表的十进制数的后2位进行组合
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res[j+1]=(((unsigned char)table[code[i+1]])<<4) | (((unsigned char)table[code[i+2]])>>2); //取出第二个字符对应base64表的十进制数的后4位与第三个字符对应bas464表的十进制数的后4位进行组合
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res[j+2]=(((unsigned char)table[code[i+2]])<<6) | ((unsigned char)table[code[i+3]]); //取出第三个字符对应base64表的十进制数的后2位与第4个字符进行组合
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}
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}
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