/*** base64编码原理* 1. 源数据都是8位位宽的数据；* 2. 相当于分组码，将源数据分为3个一组，每一组共24bits，采用每6位对应一个编码码字，那么3*8bits = 4*6its,将3个数据映射成4个数据，由于编码的码字都是6位长度，换位10进制就是0-63，总共有64中可能性，这也是base64名字的来历；* 3. 6bits对应10进制数对应的码字如表；[ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/]*  转解码过程*  3 * 8 = 4 * 6; 3字节占24位, 4*6=24*  先将要编码的转成对应的ASCII值*  如编码: s 1 3*  对应ASCII值为: 115 49 51*  对应二进制为: 01110011 00110001 00110011*  将其6个分组分4组: 011100 110011 000100 110011*  而计算机是以8bit存储, 所以在每组的高位补两个0如下:*  00011100 00110011 00000100 00110011对应:28 51 4 51*  查找base64 转换表 对应 c z E z*  *  解码*  c z E z*  对应ASCII值为 99 122 69 122*  对应表base64_suffix_map的值为 28 51 4 51*  对应二进制值为 00011100 00110011 00000100 00110011*  依次去除每组的前两位, 再拼接成3字节*  即: 01110011 00110001 00110011*  对应的就是s 1 3*/

#ifndef __BASE64_H_
#define __BASE64_H_/********************************************************Func Name: base64_encode
Date Created: 2018-8-3Description: base64编码Input: plaintext_in：源文件length_in：源文件长度Output:     code_out：生成编码文件length_out：生成编码文件的长度Return: Caution: code_out内存由调用函数释放
*********************************************************/
int base64_encode(const char *plaintext_in, int length_in, char **code_out, int *length_out);/********************************************************Func Name: base64_decode
Date Created: 2018-8-3Description: base64解码Input:       code_in;编码后的文件length_in：编码后的文件长度Output: plaintext_out：源文件outlen：源文件长度Return: Caution: plaintext_out内存由调用函数释放
*********************************************************/
int base64_decode(char *code_in, int length_in, char **plaintext_out, int *outlen);/********************************************************Func Name: base64_encode_calculate
Date Created: 2018-8-2Description: 编码算法Input: plaintext_in：源文件length_in：源文件长度Output:     code_out：生成编码文件length_out：生成编码文件的长度Return: Caution: code_out内存由调用函数释放
*********************************************************/
int base64_encode_calculate(const char *plaintext_in, int length_in, char **code_out, int *length_out);/********************************************************Func Name: base64_decode_calculate
Date Created: 2018-8-3Description: 解码算法Input:       code_in;编码后的文件length_in：编码后的文件长度Output: plaintext_out：源文件outlen：源文件长度Return: Caution: plaintext_out内存由调用函数释放
*********************************************************/
int base64_decode_calculate(char *code_in, int length_in, char **plaintext_out, int *outlen);#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>#include "base64.h"
#include "ucharcode.h"#define SRC_CHAR_SIZE 3                //源码3个字节
#define BASE_CHAR_SIZE 4               //编码后4个字节
#define CHAR_SIZE 8                    //一个字节有8bits
#define BASE_DATA_SIZE 6               //base编码中6个bits是实际数据#define DEFAULT_CODE "UTF-8"/********************************************************Func Name: base64_encode_value
Date Created: 2018-8-2Description: 获取对应编码的值Input: value_in：需要编码的字符Output: Return: Caution:
*********************************************************/
char base64_encode_value(char value_in)
{static const char* encoding = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";if (value_in > 63) return '=';return encoding[(int)value_in];
}/********************************************************Func Name: base64_decode_value
Date Created: 2018-8-2Description: 获取对应解码的值Input: value_in：需要解码的字符Output: Return: Caution:
*********************************************************/
int base64_decode_value(char value_in)
{static const char decoding[] = {62,-1,-1,-1,63,52,53,54,55,56,57,58,59,60,61,-1,-1,-1,-2,-1,-1,-1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,-1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51};static const char decoding_size = sizeof(decoding);//+ 的ascll值是43value_in -= 43;if (value_in < 0 || value_in >= decoding_size) return -1;return decoding[(int)value_in];
}/********************************************************Func Name: base64_encode
Date Created: 2018-8-3Description: base64编码Input: plaintext_in：源文件length_in：源文件长度Output:     code_out：生成编码文件length_out：生成编码文件的长度Return: Caution: code_out内存由调用函数释放
*********************************************************/
int base64_encode(const char *plaintext_in, int length_in, char **code_out, int *length_out)
{int iRet = 0;char * pcCode = NULL;char *pcOut = NULL;//因为utf8一个汉字用3个字节表示，gdk用两个字节表示，所以2倍的长度应该是够用的int iOutLen = length_in * 2;int iLeftNum = iOutLen;//参数校验if (NULL == plaintext_in || 0 == length_in || NULL == code_out || NULL == length_out){return -1;}//编码格式判断iRet = getStringCode(plaintext_in, length_in, &pcCode);if(0 != iRet){return -2;}if (0 == strcmp(pcCode,DEFAULT_CODE)){iRet = base64_encode_calculate(plaintext_in, length_in, code_out, length_out);return iRet;}//如果不是UTF-8编码 需要转码pcOut = (char *)malloc(iOutLen);if (NULL == pcOut){return -3;}memset(pcOut, 0, iOutLen);iRet = transcodeToUTF8((char *)plaintext_in, length_in, pcOut, &iLeftNum, pcCode);if (0 != iRet){//释放资源if (pcOut){free(pcOut);pcOut = NULL;}return -4;}//释放编码资源if (pcCode){free(pcCode);pcCode = NULL;}iRet = base64_encode_calculate(pcOut, iOutLen - iLeftNum, code_out, length_out);//释放资源if (pcOut){free(pcOut);pcOut = NULL;}return iRet;}/********************************************************Func Name: base64_encode_calculate
Date Created: 2018-8-2Description: 编码算法Input: plaintext_in：源文件length_in：源文件长度Output:     code_out：生成编码文件length_out：生成编码文件的长度Return: Caution: code_out内存由调用函数释放
*********************************************************/
int base64_encode_calculate(const char *plaintext_in, int length_in, char **code_out, int *length_out)
{int iPadLen = 0;                 //需要补齐的字节数int iBaseLen = 0;                //base64编码后的字节数int i = 0;char *pcOut = NULL;char gPadChar[BASE_CHAR_SIZE] = {0};char * pcOutIndex = NULL;if (NULL == plaintext_in || 0 == length_in || NULL == code_out || NULL == length_out){return -1;}if (0 != length_in % SRC_CHAR_SIZE){//3 - length_in%3 源码需要添加的字节数iPadLen = SRC_CHAR_SIZE - length_in % SRC_CHAR_SIZE;}//计算base编码后实际长度 +1 最后一个字符是'/0'iBaseLen = (length_in + iPadLen)* CHAR_SIZE / BASE_DATA_SIZE + 1;pcOut = (char *)malloc(sizeof(char) * iBaseLen);if (NULL == pcOut){return -2;}memset(pcOut, 0, sizeof(char) * iBaseLen);pcOutIndex = pcOut;for (i = 0; i < length_in; i += SRC_CHAR_SIZE){if (i == (length_in + iPadLen -3) && 0 != iPadLen){if (1 == iPadLen){//末尾实际上有两个字节的数据，将这两个字节的数据进行编码//第一个字节处理gPadChar[0] = base64_encode_value(*(plaintext_in+i) >> 2 & 0x3f);//第二个字节处理gPadChar[1] = base64_encode_value((*(plaintext_in+i) << 6 >> 2 & 0x30) + (*(plaintext_in+i+1) >> 4 & 0xf));//第二个字节最后4bits处理,不足的补0gPadChar[2] = base64_encode_value((*(plaintext_in+i+1) << 4 >> 2 & 0x3c));//没有字节的以'='代替 因为base编码只有6bit真实数据，所以不会和源数据中的"="重复gPadChar[3] = '=';}else if (2 == iPadLen){//末尾实际上有一个字节的数据，将这一个字节的数据进行编码//第一个字节处理gPadChar[0] = base64_encode_value(*(plaintext_in+i) >> 2 & 0x3f);//第一个字节最后2bits处理gPadChar[1] = base64_encode_value((*(plaintext_in+i) << 6 >> 2 & 0x30));gPadChar[2] = '=';gPadChar[3] = '=';}}else{//第一个字节处理  0x3f前两位清零//取第一个字节的前6bitsgPadChar[0] =base64_encode_value(*(plaintext_in+i) >> 2 & 0x3f);//第二个字节处理//*(pcIndex+i) << 6 >> 2 & 0x30 取第一个字节的后2bits 无效数据清零//*(pcIndex+i+1) >> 4 & 0xf 取第二个字节的前4bits 无效数据清零gPadChar[1] = base64_encode_value((*(plaintext_in+i) << 6 >> 2 & 0x30) + (*(plaintext_in+i+1) >> 4 & 0xf));//第二个字节和第三个字节处理//*(pcIndex+i+1) << 4 >> 2 & 0x3c 取第二个字节的后4bits数据 无效数据清零//(*(pcIndex+i+2) >> 6 & 0x3 取第三个字节的前2bits数据 无效数据清零gPadChar[2] = base64_encode_value((*(plaintext_in+i+1) << 4 >> 2 & 0x3c) + (*(plaintext_in+i+2) >> 6 & 0x3));//第三个字节处理//*(pcIndex+i+2) & 0x3f  清除第三个字节的前2bits数据gPadChar[3] = base64_encode_value(*(plaintext_in+i+2) & 0x3f);}//并非字符串操作，不能使用strcat
        memcpy(pcOutIndex, gPadChar, BASE_CHAR_SIZE);pcOutIndex += BASE_CHAR_SIZE;memset(gPadChar, 0, BASE_CHAR_SIZE);}pcOut[iBaseLen-1] = 0;*length_out = iBaseLen;*code_out = pcOut;return 0;
}/********************************************************Func Name: base64_decode
Date Created: 2018-8-3Description: base64解码Input:       code_in;编码后的文件length_in：编码后的文件长度Output: plaintext_out：源文件outlen：源文件长度Return: Caution: plaintext_out内存由调用函数释放
*********************************************************/
int base64_decode(char *code_in, int length_in, char **plaintext_out, int *outlen)
{int iRet = base64_decode_calculate(code_in, length_in, plaintext_out, outlen);return iRet;
}/********************************************************Func Name: base64_decode_calculate
Date Created: 2018-8-3Description: 解码算法Input:       code_in;编码后的文件length_in：编码后的文件长度Output: plaintext_out：源文件outlen：源文件长度Return: Caution: plaintext_out内存由调用函数释放
*********************************************************/
int base64_decode_calculate(char *code_in, int length_in, char **plaintext_out, int *outlen)
{int i = 0, j = 0;int iPadNum = 0;char *pcSrc = code_in;char * pcIndex = NULL;int iSrcLen = 0;char *pcOut = NULL;if (NULL == code_in || NULL == plaintext_out || NULL == outlen){return -1;}while(1){pcIndex = strchr(pcSrc, '=');if (NULL == pcIndex){break;}iPadNum++;pcIndex += 1;pcSrc = pcIndex;}//计算源文件的字符个数iSrcLen = length_in/4*3 - iPadNum;//末尾增加\0pcOut = (char *)malloc(sizeof(char)*iSrcLen + 1);if (NULL == pcOut){return -2;}memset(pcOut, 0, sizeof(char)*iSrcLen + 1);for (i = 0, j = 0; i < length_in; i += 4){if ((i == length_in-4) && iPadNum > 0){if (1 == iPadNum){//实际上有两个字符 只能用3个base字符表示//字符1pcOut[j] = (base64_decode_value(code_in[i]) << 2) + (base64_decode_value(code_in[i+1]) << 2 >> 6 & 0x3);//字符2pcOut[j+1] = (base64_decode_value(code_in[i+1]) << 4) + (base64_decode_value(code_in[i+2]) << 2 >> 4 & 0xf);j += 2;}else if (2 == iPadNum){//实际上有1个字符数据 只能用2个base字符表示pcOut[j] = (base64_decode_value(code_in[i])<<2) + (base64_decode_value(code_in[i+1]) << 2 >> 6 &0x3);j ++;}}else{//字符1pcOut[j] = (base64_decode_value(code_in[i])<<2) + (base64_decode_value(code_in[i+1]) << 2 >> 6 &0x3);//字符2pcOut[j+1] = (base64_decode_value(code_in[i+1]) << 4) + (base64_decode_value(code_in[i+2]) << 2 >> 4 & 0xf);//字符3pcOut[j+2] = (base64_decode_value(code_in[i+2]) << 6) + (base64_decode_value(code_in[i+3]) & 0x3f);j += 3;}}pcOut[iSrcLen] = '\0';*plaintext_out = pcOut;*outlen = iSrcLen;return 0;
}

#ifndef __UNCHARCODE_H_
#define __UNCHARCODE_H_/********************************************************Func Name: getStringCode
Date Created: 2018-8-3Description: 获取字符串编码Input: pcSrc：源编码数据iLenIn：源编码长度pcCode：结果存放内存地址Output:         Return: error codeCaution: pcDest内存需要由调用函数释放
*********************************************************/
int getStringCode(const char *pcSrc, int iLenIn, char **pcCode);/********************************************************Func Name: transcodeToUTF8
Date Created: 2018-8-3Description: 转码UTF8Input: pcSrc：源编码数据lenIn：源编码长度pcDest：结果存放内存地址（INOUT）lenOut：剩余内存单位个数（INOUT）pcCodeType：源编码类型Output:         Return: error codeCaution: pcDest内存需要由调用函数分配
*********************************************************/
int transcodeToUTF8(char *pcSrc, int lenIn, char *pcDest, int *lenOut,const char *pcCodeType);/********************************************************Func Name: transcodeToGBK
Date Created: 2018-8-3Description: 转码GBKInput: pcSrc：源编码数据lenIn：源编码长度pcDest：结果存放内存地址（INOUT）lenOut：剩余内存单位个数（INOUT）pcCodeType：源编码类型Output:         Return: error codeCaution: pcDest内存需要由调用函数分配
*********************************************************/
int transcodeToGBK(char *pcSrc, int lenIn, char *pcDest, int *lenOut,const char *pcCodeType);#endif

#include <stdlib.h>
#include <string.h>
#include <iconv.h>#include "ucharcode.h"
#include "uchardet.h"/********************************************************Func Name: transcodeToUTF8
Date Created: 2018-8-3Description: 转码UTF8Input: pcSrc：源编码数据lenIn：源编码长度pcDest：结果存放内存地址（INOUT）lenOut：剩余内存单位个数（INOUT）pcCodeType：源编码类型Output:         Return: error codeCaution: pcDest内存需要由调用函数分配
*********************************************************/
int fromcodeToCode(char *pcSrc, int lenIn, char *pcDest, int *lenOut, const char *pcFromCode, const char *pcToCode)
{int iRet = 0;//由于iconv()函数会修改指针，所以要保存源指针char *pcStart = pcSrc;char *pcOut = pcDest;iconv_t cd = (iconv_t)-1;size_t inbytesleft = (size_t)lenIn;if (NULL == pcSrc || 0 >= lenIn || NULL == pcDest || NULL == lenOut || NULL == pcFromCode || NULL == pcToCode){return -1;}cd = iconv_open(pcToCode, pcFromCode);if ((iconv_t)-1 == cd){return -2;}/* *@param cd iconv_open()产生的句柄*@param pcStart 需要转换的字符串*@param inbytesleft 存放还有多少字符没有转换*@param pcOut 存放转换后的字符串*@param outlen 存放转换后,pcOut剩余的空间*/iRet = iconv(cd, &pcStart, &inbytesleft, &pcOut, (size_t *)lenOut);if (iRet < 0){return -3;}iconv_close(cd);return iRet;
}/********************************************************Func Name: transcodeToUTF8
Date Created: 2018-8-3Description: 转码UTF8Input: pcSrc：源编码数据lenIn：源编码长度pcDest：结果存放内存地址（INOUT）lenOut：剩余内存单位个数（INOUT）pcCodeType：源编码类型Output:         Return: error codeCaution: pcDest内存需要由调用函数分配
*********************************************************/
int transcodeToUTF8(char *pcSrc, int lenIn, char *pcDest, int *lenOut,const char *pcCodeType)
{int iRet = 0;const char * targetCode = "UTF8";if (NULL == pcSrc || 0 >= lenIn || NULL == pcDest || NULL == lenOut || NULL == pcCodeType){return -1;}iRet = fromcodeToCode(pcSrc, lenIn, pcDest, lenOut, pcCodeType, targetCode);return iRet;
}/********************************************************Func Name: transcodeToGBK
Date Created: 2018-8-3Description: 转码GBKInput: pcSrc：源编码数据lenIn：源编码长度pcDest：结果存放内存地址（INOUT）lenOut：剩余内存单位个数（INOUT）pcCodeType：源编码类型Output:         Return: error codeCaution: pcDest内存需要由调用函数分配
*********************************************************/
int transcodeToGBK(char *pcSrc, int lenIn, char *pcDest, int *lenOut, char *pcCodeType)
{int iRet = 0;const char * targetCode = "GBK";if (NULL == pcSrc || 0 >= lenIn || NULL == pcDest || NULL == lenOut || NULL == pcCodeType){return -1;}iRet = fromcodeToCode(pcSrc, lenIn, pcDest, lenOut, pcCodeType, targetCode);return iRet;
}/********************************************************Func Name: getStringCode
Date Created: 2018-8-3Description: 获取字符串编码Input: pcSrc：源编码数据iLenIn：源编码长度pcCode：结果存放内存地址Output:         Return: error codeCaution: pcDest内存需要由调用函数释放
*********************************************************/
int getStringCode(const char *pcSrc, int iLenIn, char **pcCode)
{uchardet_t ud;int iErrorCode = 0;char *pcBuf = NULL;const char *pcDest = NULL;if (NULL == pcSrc || 0 == iLenIn || NULL == pcCode){return -1;}ud = uchardet_new();//如果样本字符不够，那么有可能导致分析失败iErrorCode = uchardet_handle_data(ud, pcSrc, iLenIn);if (0 != iErrorCode){return -2;}uchardet_data_end(ud);pcDest = uchardet_get_charset(ud);//+1 多留一个字符'\0'pcBuf = (char *)malloc(strlen(pcDest)+1);if (NULL == pcBuf){return -3;}memset(pcBuf, 0, strlen(pcDest)+1);strcpy(pcBuf,pcDest);*pcCode = pcBuf;uchardet_delete(ud);return 0;
}

#include <iostream>
#include <cstring>#include "base64.h"using namespace std;/* 测试小程序 */void test()
{int len = 0;int iRet= 0;char *pcOut = NULL;const char* s = "我是中国人";char * pcBuf = NULL;int lastLen = 0;//base64编码iRet = base64_encode((char *)s, strlen(s), &pcOut, &len);if (0 != iRet){cout << "base64_encode() error ." << endl;}cout << "result = " << pcOut << endl;//base64解码iRet = base64_decode(pcOut, len, &pcBuf, &lastLen);if (0 != iRet){cout << "base64_decode() error ." << endl;}cout << "end len = " << lastLen << "  result = " << pcBuf << endl;if (pcOut){free(pcOut);pcOut = NULL;}if (pcBuf){free(pcBuf);pcBuf = NULL;}
}int main()
{test();getchar();return 0;
}