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/*
* Part of DNS zone file validator `validns`.
*
* Copyright 2011-2014 Anton Berezin <tobez@tobez.org>
* Modified BSD license.
* (See LICENSE file in the distribution.)
*
*/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <ctype.h>
#include "base64.h"
/*
* Very straightforward, ugly, unoptimized,
* not much in the way of error handling.
* But it works.
*/
int
decode_base64(void *dest, char *src, size_t dstsize)
{
size_t processed = 0;
int full_bytes = 0;
unsigned char *dst = dest;
while (*src) {
int v;
if (*src >= 'A' && *src <= 'Z')
v = *src - 'A';
else if (*src >= 'a' && *src <= 'z')
v = 26 + *src - 'a';
else if (*src >= '0' && *src <= '9')
v = 52 + *src - '0';
else if (*src == '+')
v = 62;
else if (*src == '/')
v = 63;
else if (isspace(*src) || *src == '=') {
src++;
continue;
} else {
/* any junk chars means input is corrupted */
errno = EINVAL;
return -1;
}
src++;
if (processed % 4 == 0) {
if (dstsize <= 0) {
errno = EINVAL;
return -1;
}
dst[0] &= 0x03;
dst[0] |= (v << 2) & 0xFC;
processed++;
} else if (processed % 4 == 1) {
if (dstsize < 1) {
errno = EINVAL;
return -1;
}
dst[0] &= 0xFC;
dst[0] |= (v >> 4) & 0x03;
if (dstsize >= 2) {
dst[1] &= 0x0F;
dst[1] |= (v << 4) & 0xF0;
}
processed++;
full_bytes++;
} else if (processed % 4 == 2) {
if (dstsize < 2) {
errno = EINVAL;
return -1;
}
dst[1] &= 0xF0;
dst[1] |= (v >> 2) & 0x0F;
if (dstsize >= 3) {
dst[2] &= 0x3F;
dst[2] |= (v << 6) & 0xC0;
}
processed++;
full_bytes++;
} else {
if (dstsize <= 2) {
errno = EINVAL;
return -1;
}
dst[2] &= 0xC0;
dst[2] |= v & 0x3F;
processed++;
dst += 3;
dstsize -= 3;
full_bytes++;
}
}
return full_bytes;
}
#ifdef TEST_PROGRAM
static int ok_string_test(int testnum, char *src, char *expect)
{
unsigned char dstbuf[512];
int r, r0, i;
int expect_sz = strlen(expect);
if (expect_sz >= 512) {
printf("test %d: NOT OK: internal *test* error, buffer too small for proper testing, FIXME\n", testnum);
return 1;
}
memset(dstbuf, 0xAA, 512);
r = decode_base64(dstbuf, src, expect_sz);
if (r != expect_sz) {
printf("test %d: NOT OK: expect size %d, got %d\n", testnum, expect_sz, r);
return 1;
} else if (memcmp(dstbuf, expect, r) != 0) {
printf("test %d: NOT OK: unexpected buffer content\n", testnum);
return 1;
}
if (dstbuf[expect_sz] != 0xAA) {
printf("test %d: NOT OK: corrupts memory with \"just enough\" bufsize\n", testnum);
return 1;
}
memset(dstbuf, 0xAA, 512);
for (i = 0; i < expect_sz; i++) {
r0 = decode_base64(dstbuf, src, i);
if (r0 > 0) {
printf("test %d: NOT OK: buffer size %d should not be enough\n", testnum, i);
return 1;
}
if (dstbuf[i] != 0xAA) {
printf("test %d: NOT OK: corrupts memory with bufsize %d\n", testnum, i);
return 1;
}
}
printf("test %d: ok\n", testnum);
return 0;
}
static int expect_junk_error(int testnum, char *src)
{
char *buf[20];
int r;
r = decode_base64(buf, src, 20);
if (r != -1) {
printf("test %d: NOT OK: junk input not recognized\n", testnum);
return 1;
}
printf("test %d: ok\n", testnum);
return 0;
}
int main(void)
{
int ret = 0;
/* from http://en.wikipedia.org/wiki/Base64 */
ret |= ok_string_test(1, "bGVhc3VyZS4=", "leasure.");
ret |= ok_string_test(2, "bGVhc3VyZS4", "leasure.");
ret |= ok_string_test(3, "ZWFzdXJlLg==", "easure.");
ret |= ok_string_test(4, "ZWFzdXJlLg=", "easure.");
ret |= ok_string_test(5, "ZWFzdXJlLg", "easure.");
ret |= ok_string_test(6, "YXN1cmUu", "asure.");
ret |= ok_string_test(7, "c3VyZS4=", "sure.");
ret |= ok_string_test(8, "c3VyZS4", "sure.");
ret |= ok_string_test(9, "TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dCBieSB0aGlz\n"
"IHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2Yg\n"
"dGhlIG1pbmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGlu\n"
"dWVkIGFuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleGNlZWRzIHRo\n"
"ZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4=",
"Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.");
/* from http://tools.ietf.org/html/rfc4648#section-10 */
ret |= ok_string_test(10, "", "");
ret |= ok_string_test(11, "Zg==", "f");
ret |= ok_string_test(12, "Zg=", "f");
ret |= ok_string_test(13, "Zg", "f");
ret |= ok_string_test(14, "Zm8=", "fo");
ret |= ok_string_test(15, "Zm8", "fo");
ret |= ok_string_test(16, "Zm9v", "foo");
ret |= ok_string_test(17, "Zm9vYg==", "foob");
ret |= ok_string_test(18, "Zm9vYg=", "foob");
ret |= ok_string_test(19, "Zm9vYg", "foob");
ret |= ok_string_test(20, "Zm9vYmE=", "fooba");
ret |= ok_string_test(21, "Zm9vYmE", "fooba");
ret |= ok_string_test(22, "Zm9vYmFy", "foobar");
ret |= expect_junk_error(23, "?Zm9vYmFy");
ret |= expect_junk_error(24, "Z%m9vYmFy");
ret |= expect_junk_error(25, "Zm&9vYmFy");
ret |= expect_junk_error(26, "Zm9-vYmFy");
ret |= expect_junk_error(27, "Zm9v*YmFy");
ret |= expect_junk_error(28, "Zm9vY#mFy");
ret |= expect_junk_error(29, "Zm9vYm\x01Fy");
ret |= expect_junk_error(30, "Zm9vYmF!y");
ret |= expect_junk_error(31, "Zm9vYmFy.");
return ret;
}
#endif
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