/**********************************************************************
*
* File name : base64.cpp / base64.c
* Function : base64 encoding and decoding of data or file.
* Created time : 2020-08-04
*
*********************************************************************/
#include <stdio.h>
#include <string.h>
//base64 编码转换表，共64个
static const char base64_encode_table[] = {
'A','B','C','D','E','F','G','H','I','J',
'K','L','M','N','O','P','Q','R','S','T',
'U','V','W','X','Y','Z','a','b','c','d',
'e','f','g','h','i','j','k','l','m','n',
'o','p','q','r','s','t','u','v','w','x',
'y','z','0','1','2','3','4','5','6','7',
'8','9','+','/'
};
//base64 解码表
static const unsigned char base64_decode_table[] = {
//每行16个
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, //1 - 16
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, //17 - 32
0,0,0,0,0,0,0,0,0,0,0,62,0,0,0,63, //33 - 48
52,53,54,55,56,57,58,59,60,61,0,0,0,0,0,0, //49 - 64
0,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14, //65 - 80
15,16,17,18,19,20,21,22,23,24,25,0,0,0,0,0, //81 - 96
0,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40, //97 - 112
41,42,43,44,45,46,47,48,49,50,51,0,0,0,0,0 //113 - 128
};
/**
* @brief base64_encode base64编码
* @param indata 需编码的数据
* @param inlen 需编码的数据大小
* @param outdata 编码后输出的数据
* @param outlen 编码后输出的数据大小
* @return int 0：成功 -1：无效参数
*/
int base64_encode(const char *indata, int inlen, char *outdata, int *outlen)
{
if(indata == NULL || inlen <= 0) {
return -1;
}
/*
//方法一：
int i, j;
char ch;
int add_len = (inlen % 3 == 0 ? 0 : 3 - inlen % 3); //原字符串需补齐的字符个数
int in_len = inlen + add_len; //源字符串补齐字符后的长度，为3的倍数
if(outdata != NULL) {
//编码，长度为调整之后的长度，3字节一组
for(i=0, j=0; i<in_len; i+=3, j+=4) {
//将indata第一个字符向右移动2bit（丢弃2bit）
ch = base64_encode_table[(unsigned char)indata[i] >> 2]; //对应base64转换表的字符
outdata[j] = ch; //赋值
//处理最后一组（最后3个字节）的数据
if(i == in_len - 3 && add_len != 0) {
if(add_len == 1) {
outdata[j + 1] = base64_encode_table[(((unsigned char)indata[i] & 0x03) << 4) | ((unsigned char)indata[i + 1] >> 4)];
outdata[j + 2] = base64_encode_table[((unsigned char)indata[i + 1] & 0x0f) << 2];
outdata[j + 3] = '=';
}
else if(add_len == 2) {
outdata[j + 1] = base64_encode_table[((unsigned char)indata[i] & 0x03) << 4];
outdata[j + 2] = '=';
outdata[j + 3] = '=';
}
}
//处理正常的3字节数据
else {
outdata[j + 1] = base64_encode_table[(((unsigned char)indata[i] & 0x03) << 4) | ((unsigned char)indata[i + 1] >> 4)];
outdata[j + 2] = base64_encode_table[(((unsigned char)indata[i + 1] & 0x0f) << 2) | ((unsigned char)indata[i + 2] >> 6)];
outdata[j + 3] = base64_encode_table[(unsigned char)indata[i + 2] & 0x3f];
}
}
}
if(outlen != NULL) {
*outlen = in_len * 4 / 3; //编码后的长度
}
*/
//方法二：
int i, j;
unsigned char num = inlen % 3;
if(outdata != NULL) {
//编码，3个字节一组，若数据总长度不是3的倍数，则跳过最后的 num 个字节数据
for(i=0, j=0; i<inlen - num; i+=3, j+=4) {
outdata[j] = base64_encode_table[(unsigned char)indata[i] >> 2];
outdata[j + 1] = base64_encode_table[(((unsigned char)indata[i] & 0x03) << 4) | ((unsigned char)indata[i + 1] >> 4)];
outdata[j + 2] = base64_encode_table[(((unsigned char)indata[i + 1] & 0x0f) << 2) | ((unsigned char)indata[i + 2] >> 6)];
outdata[j + 3] = base64_encode_table[(unsigned char)indata[i + 2] & 0x3f];
}
//继续处理最后的 num 个字节的数据
if(num == 1) { //余数为1，需补齐两个字节'='
outdata[j] = base64_encode_table[(unsigned char)indata[inlen - 1] >> 2];
outdata[j + 1] = base64_encode_table[((unsigned char)indata[inlen - 1] & 0x03) << 4];
outdata[j + 2] = '=';
outdata[j + 3] = '=';
}
else if(num == 2) { //余数为2，需补齐一个字节'='
outdata[j] = base64_encode_table[(unsigned char)indata[inlen - 2] >> 2];
outdata[j + 1] = base64_encode_table[(((unsigned char)indata[inlen - 2] & 0x03) << 4) | ((unsigned char)indata[inlen - 1] >> 4)];
outdata[j + 2] = base64_encode_table[((unsigned char)indata[inlen - 1] & 0x0f) << 2];
outdata[j + 3] = '=';
}
}
if(outlen != NULL) {
*outlen = (inlen + (num == 0 ? 0 : 3 - num)) * 4 / 3; //编码后的长度
}
return 0;
}
/**
* @brief base64_decode base64解码
* @param indata 需解码的数据
* @param inlen 需解码的数据大小
* @param outdata 解码后输出的数据
* @param outlen 解码后输出的数据大小
* @return int 0：成功 -1：无效参数
* 注意：解码的数据的大小必须大于4，且是4的倍数
*/
int base64_decode(const char *indata, int inlen, char *outdata, int *outlen)
{
if(indata == NULL || inlen <= 0 || (outdata == NULL && outlen == NULL)) {
return -1;
}
if(inlen < 4 ||inlen % 4 != 0) { //需要解码的数据长度不是4的倍数 //inlen < 4 ||
return -1;
}
int i, j;
//计算解码后的字符串长度
int len = inlen / 4 * 3;
if(indata[inlen - 1] == '=') {
len--;
}
if(indata[inlen - 2] == '=') {
len--;
}
if(outdata != NULL) {
for(i=0, j=0; i<inlen; i+=4, j+=3) {
outdata[j] = (base64_decode_table[(unsigned char)indata[i]] << 2) | (base64_decode_table[(unsigned char)indata[i + 1]] >> 4);
outdata[j + 1] = (base64_decode_table[(unsigned char)indata[i + 1]] << 4) | (base64_decode_table[(unsigned char)indata[i + 2]] >> 2);
outdata[j + 2] = (base64_decode_table[(unsigned char)indata[i + 2]] << 6) | (base64_decode_table[(unsigned char)indata[i + 3]]);
}
}
if(outlen != NULL) {
*outlen = len;
}
return 0;
}
/**
* @brief base64_encode_file base64编码文件
* @param src 需编码的文件路径
* @param dst 编码后输出的文件路径
* @return int 0：成功 -1：无效参数 -2：文件操作失败
*/
int base64_encode_file(const char *src, const char *dst)
{
if(src == NULL || dst == NULL) {
return -1;
}
FILE *src_fp, *dst_fp;
char rdata[128*3+3]; //存放读取到的文件数据，+3表示预留3个字节空间存放余下来的数据
size_t rmemb; //读文件数据返回值，读取到的块数
size_t nmemb = sizeof(rdata) - 3; //每次读取文件数据的块数，最好是3的倍数
char encode_data[(nmemb+(nmemb%3==0?0:3-nmemb%3))*4/3+1]; //存放编码后的数据
int encode_datalen; //编码后的数据大小
unsigned char num = 0, lastnum = 0;
src_fp = fopen(src, "rb");
if(NULL == src_fp) {
perror("open src file failed");
return -2;
}
dst_fp = fopen(dst, "wb");
if(NULL == dst_fp) {
fclose(src_fp);
perror("open dst file failed");
return -2;
}
while(1) {
//memset(rdata, 0, sizeof(rdata));
//memset(encode_data, 0, sizeof(encode_data));
encode_datalen = 0;
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