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/*
* Argyll Color Correction System
*
* Very simple & concise base64 encoder/decoder
*
*/
/*
* Author: Graeme W. Gill
*
* Copyright 2014, Graeme W. Gill
* All rights reserved.
*
* This material is licenced under the GNU GENERAL PUBLIC LICENSE Version 2 or later :-
* see the License2.txt file for licencing details.
*/
#include <stdio.h>
# define DLL_LOCAL
#include "base64.h"
static int enc(int val) {
val &= 0x3f;
if (val <= 25)
return ('A' + val);
if (val <= 51)
return ('a' + val - 26);
if (val <= 61)
return ('0' + val - 52);
if (val == 62)
return '+';
return '/';
}
/* Encode slen bytes into nul terminated string. */
/* if dlen is !NULL, then set it to resulting string length excluding nul */
/* We assume that the destination buffer is long enough at EBASE64LEN */
void DLL_LOCAL ebase64(int *dlen, char *dst, unsigned char *src, int slen) {
unsigned char buf[3];
int i, j;
/* Do this 3 characters at a time */
for (j = i = 0; i < slen; i += 3) {
int ib;
/* Grab 3 bytes or zero pad, and count bits */
buf[0] = src[i]; ib = 8;
buf[1] = (i+1) < slen ? (ib += 8, src[i+1]) : 0;
buf[2] = (i+2) < slen ? (ib += 8, src[i+2]) : 0;
/* Output up to 4 encoded characters */
dst[j] = enc(buf[0] >> 2), j++;
if (ib > 6) {
dst[j] = enc(buf[0] << 4 | buf[1] >> 4), j++;
if (ib > 12) {
dst[j] = enc(buf[1] << 2 | buf[2] >> 6), j++;
if (ib > 18)
dst[j] = enc(buf[2]), j++;
}
}
}
if (dlen != NULL)
*dlen = j;
dst[j++] = '\000';
}
/* Return binary value corresponding to encoded character, */
/* -1 for invalid character, -2 if nul terminator */
/* (We're assuming ASCII encoding) */
static int dec(int val) {
val &= 0xff;
if (val == 0)
return -2;
if (val == '+')
return 62;
if (val == '/')
return 63;
if (val < '0')
return -1;
if (val <= '9')
return val - '0' + 52;
if (val < 'A')
return -1;
if (val <= 'Z')
return val - 'A';
if (val < 'a')
return -1;
if (val <= 'z')
return val - 'a' + 26;
return -1;
}
/* Decode nul terminated string into bytes, ignoring illegal characters. */
/* if dlen is !NULL, then set it to resulting byte length */
/* We assume that the destination buffer is long enough at DBASE64LEN */
void DLL_LOCAL dbase64(int *dlen, unsigned char *dst, char *src) {
int buf[4];
int j;
/* Do this 4 characters at a time */
for (j = 0;;) {
int v, ib;
/* Grab 4 characters skipping illegals, and count bits */
while ((buf[0] = dec(*src++)) == -1)
;
if (buf[0] == -2)
break;
ib = 6;
while ((buf[1] = dec(*src++)) == -1)
;
if (buf[1] != -2) {
ib += 6;
while ((buf[2] = dec(*src++)) == -1)
;
if (buf[2] != -2) {
ib += 6;
while ((buf[3] = dec(*src++)) == -1)
;
if (buf[3] != -2)
ib += 6;
else
buf[3] = 0;
} else
buf[2] = 0;
} else
buf[1] = 0;
/* Output up to 3 decoded bytes */
dst[j] = buf[0] << 2 | buf[1] >> 4, j++;
if (ib > 12) {
dst[j] = buf[1] << 4 | buf[2] >> 2, j++;
if (ib > 18) {
dst[j] = buf[2] << 6 | buf[3], j++;
continue; /* We didn't run out */
}
}
break; /* Must be done if didn't continue */
}
if (dlen != NULL)
*dlen = j;
}
#ifdef STANDALONE_TEST
/* test base64 code */
#include <numlib.h>
#define MAXLEN 30
int main() {
unsigned char src[MAXLEN], check[MAXLEN];
char dst[EBASE64LEN(MAXLEN) + 1];
int n, slen, dlen, chlen, i, j;
printf("Testing base64 encode/decode:\n");
for (n = 0; n < 10000000; n++) {
/* Create a random binary */
slen = i_rand(0, MAXLEN);
for (i = 0; i < slen; i++)
src[i] = i_rand(0, 255);
/* Encode it */
ebase64(&dlen, dst, src, slen);
if (dlen != EBASE64LEN(slen)) {
error("%d: Wrong encoded length, src %d, is %d should be %d\n",n,slen,dlen,EBASE64LEN(slen));
}
/* Decode it */
dbase64(&chlen, check, dst);
if (chlen != DBASE64LEN(dlen)) {
error("%d: Wrong decoded length, enc %d, is %d should be %d\n",n,dlen,chlen,DBASE64LEN(dlen));
}
/* Check characters match */
for (i = 0; i < slen; i++) {
if (src[i] != check[i]) {
for (j = 0; j < slen; j++) {
printf("%02X ",src[j]);
if ((j % 3) == 2)
printf(" ");
}
printf("\n");
for (j = 0; j < dlen; j++) {
printf("%c ",dst[j]);
if ((j % 4) == 3)
printf(" ");
}
printf("\n");
for (j = 0; j < slen; j++) {
printf("%02X ",check[j]);
if ((j % 3) == 2)
printf(" ");
}
printf("\n\n");
printf("src len %d, dst len %d\n",slen, dlen);
error("%d: Verify error at byte %d, is 0x%x should be 0x%x\n",n,i,check[i],src[i]);
}
}
if ((n % 10000) == 0)
printf("done %d tests\n",n);
}
printf("Testing %d conversions base64 complete\n",n);
}
#endif /* STANDALONE_TEST */
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