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Base64 encoding and decoding functions.

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This commit is contained in:
Guus Sliepen 2011-07-03 22:13:58 +02:00
parent c385d11533
commit 1d92dd62a7
2 changed files with 71 additions and 0 deletions
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68
src/utils.c
View file

@ -24,6 +24,7 @@
#include "utils.h"
static const char hexadecimals[] = "0123456789ABCDEF";
static const char base64imals[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static int charhex2bin(char c) {
if(isdigit(c))
@ -32,6 +33,14 @@ static int charhex2bin(char c) {
return toupper(c) - 'A' + 10;
}
static int charb64decode(char c) {
if(c > 'a')
return c - 'a' + 26;
else if(c > 'A')
return c - 'A';
else
return c - '0';
}
void hex2bin(char *src, char *dst, int length) {
int i;
@ -47,6 +56,65 @@ void bin2hex(char *src, char *dst, int length) {
}
}
int b64decode(const char *src, char *dst, int length) {
uint32_t triplet = 0;
unsigned char *udst;
for(int i = 0; i < length; i++) {
triplet |= charb64decode(src[i]) << (6 * (i % 4));
if((i % 4) == 3) {
udst[0] = triplet & 0xff; triplet >>= 8;
udst[1] = triplet & 0xff; triplet >>= 8;
udst[2] = triplet;
triplet = 0;
udst += 3;
}
}
if((length % 4) == 3) {
udst[0] = triplet & 0xff; triplet >>= 8;
udst[1] = triplet & 0xff;
return length / 4 * 3 + 2;
} else if((length % 4) == 2) {
udst[0] = triplet & 0xff;
return length / 4 * 3 + 1;
} else {
return length / 4 * 3;
}
}
int b64encode(const char *src, char *dst, int length) {
uint32_t triplet;
const unsigned char *usrc = src;
int origlen = length;
while(length > 0) {
if(length >= 3) {
triplet = usrc[0] | usrc[1] << 8 | usrc[2] << 16;
dst[0] = base64imals[triplet & 63]; triplet >>= 6;
dst[1] = base64imals[triplet & 63]; triplet >>= 6;
dst[2] = base64imals[triplet & 63]; triplet >>= 6;
dst[3] = base64imals[triplet];
dst += 4; usrc += 3; length -= 3;
} else if(length >=2) {
triplet = usrc[0] | usrc[1] << 8;
dst[0] = base64imals[triplet & 63]; triplet >>= 6;
dst[1] = base64imals[triplet & 63]; triplet >>= 6;
dst[2] = base64imals[triplet];
dst[3] = 0;
return origlen / 3 * 4 + 3;
} else {
triplet = usrc[0];
dst[0] = base64imals[triplet & 63]; triplet >>= 6;
dst[1] = base64imals[triplet];
dst[2] = 0;
return origlen / 3 * 4 + 2;
}
}
*dst = 0;
return origlen / 4 * 3;
}
#if defined(HAVE_MINGW) || defined(HAVE_CYGWIN)
#ifdef HAVE_CYGWIN
#include <w32api/windows.h>

3
src/utils.h
View file

@ -24,6 +24,9 @@
extern void hex2bin(char *src, char *dst, int length);
extern void bin2hex(char *src, char *dst, int length);
extern int b64encode(const char *src, char *dst, int length);
extern int b64decode(const char *src, char *dst, int length);
#ifdef HAVE_MINGW
extern const char *winerror(int);
#define strerror(x) ((x)>0?strerror(x):winerror(GetLastError()))