base64编解码的两个函数(安全版本)
void base64_encode_s(const unsigned char *str, long inlen, std::string& outstr, long* lpBufLen) { long len; long str_len; //unsigned char *res; //std::shared_ptr<std::string> res; int i,j; //定义base64编码表 const unsigned char *base64_table = (const unsigned char *)("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"); //计算经过base64编码后的字符串长度 str_len= inlen; if(str_len % 3 == 0) len=str_len/3*4; else len=(str_len/3+1)*4; if (NULL != lpBufLen) { *lpBufLen = len; } //std::shared_ptr<std::string> res(new std::string(sizeof(unsigned char)*len+1)); //(unsigned char *)malloc(sizeof(unsigned char)*len+1); outstr.resize(sizeof(unsigned char)*len+1); outstr[len] = '\0'; //以3个8位字符为一组进行编码 for(i=0,j=0;i<len-2;j+=3,i+=4) { outstr[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 outstr[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 outstr[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 outstr[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 } switch(str_len % 3) { case 1: outstr[i-2]='='; outstr[i-1]='='; break; case 2: outstr[i-1]='='; break; } return; } void base64_decode_s(const unsigned char *code, std::string& outstr, long* lpBufLen) { //根据base64表,以字符找到对应的十进制数据 int table[]={0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,62,0,0,0, 63,52,53,54,55,56,57,58, 59,60,61,0,0,0,0,0,0,0,0, 1,2,3,4,5,6,7,8,9,10,11,12, 13,14,15,16,17,18,19,20,21, 22,23,24,25,0,0,0,0,0,0,26, 27,28,29,30,31,32,33,34,35, 36,37,38,39,40,41,42,43,44, 45,46,47,48,49,50,51 }; long len; long str_len; //unsigned char *res = NULL; int i,j; //计算解码后的字符串长度 len = strlen((const char*)code); //判断编码后的字符串后是否有= if(strstr((const char*)code,"==")) str_len=len/4*3-2; else if(strstr((const char*)code,"=")) str_len=len/4*3-1; else str_len=len/4*3; if (NULL != lpBufLen) { *lpBufLen = str_len; } //res = (unsigned char*)malloc(sizeof(unsigned char)*str_len+1); outstr.resize(sizeof(unsigned char)*len+1); //memset(outstr.,0, str_len+1); //res[str_len]='\0'; //以4个字符为一位进行解码 for(i=0,j=0;i < len-2;j+=3,i+=4) { outstr[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 outstr[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 outstr[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 } return; }