速速收藏！纯C实现的BASE64编解码~！
验证网站：https://www.toolhelper.cn/EncodeDecode/Base64HexEncodeDecode
头文件
/**
* \file base64.h
*
* \brief RFC 1521 base64 encoding/decoding
*/
#ifndef BASE64_H__
#define BASE64_H__
#ifdef __cplusplus
extern "C" {
#endif
/**
* \brief Encode a buffer into base64 format
*
* \param src source buffer
* \param slen amount of data to be encoded
* \param dst destination buffer
* \param dlen size of the destination buffer
* \param olen number of bytes written
*
* \return 0: successful
* -1: Output buffer too small.
*/
int base64_encode(const unsigned char *src, unsigned int slen, unsigned char *dst, unsigned int dlen, unsigned int *olen);
/**
* \brief Encode a buffer into base64 format
*
* \param src source buffer
* \param slen amount of data to be encoded
* \param dst destination buffer
* \param dlen size of the destination buffer
* \param olen number of bytes written
*
* \return 0: successful
* -1: Invalid character in input
* -2: Output buffer too small
*/
int base64_decode(const unsigned char *src, unsigned int slen, unsigned char* dst, unsigned int dlen, unsigned int *olen);
#ifdef __cplusplus
}
#endif
#endif /* base64.h */源文件
/**
* \file base64.c
*
* \brief RFC 1521 base64 encoding/decoding
*/
#include "base64.h"
#ifndef NULL
#define NULL ((void *)0)
#endif
static const unsigned char base64_enc_map[64] =
{ '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', '+', '/' };
static const unsigned char base64_dec_map[128] =
{ 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
62, 127, 127, 127, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 127, 127,
127, 64, 127, 127, 127, 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, 127, 127, 127, 127, 127,
127, 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, 127, 127, 127, 127, 127 };
#define BASE64_UNSIGNED_INT_MAX ( (unsigned int) -1 ) /* unsigned int_MAX is not standard */
/**
* \brief Encode a buffer into base64 format
*
* \param src source buffer
* \param slen amount of data to be encoded
* \param dst destination buffer
* \param dlen size of the destination buffer
* \param olen number of bytes written
*
* \return 0: successful
* -1: Output buffer too small.
*/
int base64_encode(const unsigned char *src, unsigned int slen, unsigned char *dst, unsigned int dlen, unsigned int *olen)
{
unsigned int i, n;
int C1, C2, C3;
unsigned char *p;
*olen = 0;
if (slen == 0)
{
*olen = 0;
return (0);
}
n = slen / 3 + (slen % 3 != 0);
if (n > ( BASE64_UNSIGNED_INT_MAX - 1) / 4)
{
*olen = BASE64_UNSIGNED_INT_MAX;
return -1;
}
n *= 4;
if ((dlen < n + 1) || ( NULL == dst))
{
*olen = n + 1;
return -1;
}
n = (slen / 3) * 3;
for (i = 0, p = dst; i < n; i += 3)
{
C1 = *src++;
C2 = *src++;
C3 = *src++;
*p++ = base64_enc_map[(C1 >> 2) & 0x3F];
*p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F];
*p++ = base64_enc_map[(((C2 & 15) << 2) + (C3 >> 6)) & 0x3F];
*p++ = base64_enc_map[C3 & 0x3F];
}
if (i < slen)
{
C1 = *src++;
C2 = ((i + 1) < slen) ? *src++ : 0;
*p++ = base64_enc_map[(C1 >> 2) & 0x3F];
*p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F];
if ((i + 1) < slen)
*p++ = base64_enc_map[((C2 & 15) << 2) & 0x3F];
else
*p++ = '=';
*p++ = '=';
}
*olen = p - dst;
*p = 0;
return (0);
}
/**
* \brief Encode a buffer into base64 format
*
* \param src source buffer
* \param slen amount of data to be encoded
* \param dst destination buffer
* \param dlen size of the destination buffer
* \param olen number of bytes written
*
* \return 0: successful
* -1: Invalid character in input
* -2: Output buffer too small
*/
int base64_decode(const unsigned char *src, unsigned int slen, unsigned char* dst, unsigned int dlen, unsigned int *olen)
{
unsigned int i, n;
unsigned int j, x;
unsigned char *p;
*olen = 0;
/* First pass: check for validity and get output length */
for (i = n = j = 0; i < slen; i++)
{
/* Skip spaces before checking for EOL */
x = 0;
while (i < slen && src[i] == ' ')
{
++i;
++x;
}
/* Spaces at end of buffer are OK */
if (i == slen)
break;
if ((slen - i) >= 2 && src[i] == '\r' && src[i + 1] == '\n')
continue;
if (src[i] == '\n')
continue;
/* Space inside a line is an error */
if (x != 0)
return -1;
if (src[i] == '=' && ++j > 2)
return -1;
if (src[i] > 127 || base64_dec_map[src[i]] == 127)
return -1;
if (base64_dec_map[src[i]] < 64 && j != 0)
return -1;
n++;
}
if (n == 0)
{
*olen = 0;
return (0);
}
/* The following expression is to calculate the following formula without
* risk of integer overflow in n:
* n = ( ( n * 6 ) + 7 ) >> 3;
*/
n = (6 * (n >> 3)) + ((6 * (n & 0x7) + 7) >> 3);
n -= j;
if (dst == NULL || dlen < n)
{
*olen = n;
return -2;
}
for (j = 3, n = x = 0, p = dst; i > 0; i--, src++)
{
if (*src == '\r' || *src == '\n' || *src == ' ')
continue;
j -= (base64_dec_map[*src] == 64);
x = (x << 6) | (base64_dec_map[*src] & 0x3F);
if (++n == 4)
{
n = 0;
if (j > 0)
*p++ = (unsigned char) (x >> 16);
if (j > 1)
*p++ = (unsigned char) (x >> 8);
if (j > 2)
*p++ = (unsigned char) (x);
}
}
*olen = p - dst;
return (0);
}
#if 0
#include <stdio.h>
#include <stdlib.h>
#include "base64.h"
/*
verify: https://www.toolhelper.cn/EncodeDecode/Base64HexEncodeDecode
testdata: 00 01 02 03 04 05 06 07 08 09
encode: AAECAwQFBgcICQ==
decode: 00 01 02 03 04 05 06 07 08 09
*/
int main(void)
{
int i;
unsigned char testdata[10];
printf("testdata: ");
for (i = 0; i < sizeof(testdata); i++)
{
testdata[i] = i;
printf("%02X ", testdata[i]);
}
printf("\n");
unsigned char encbuf[200];
unsigned char decbuf[200];
size_t enclen = 0, declen = 0;
base64_encode(testdata, sizeof(testdata), encbuf, sizeof(encbuf), &enclen);
printf("encode: %s\n", encbuf);
base64_decode(encbuf, enclen, decbuf, sizeof(decbuf), &declen);
printf("decode: ");
for (i = 0; i < declen; i++)
{
printf("%02X ", decbuf[i]);
}
printf("\n");
return EXIT_SUCCESS;
}
#endifends…
