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/* See LICENSE file for copyright and license details. */
#include "common.h"
#ifndef TEST
ssize_t
librecrypt_decode(void *out_buffer, size_t size, const char *ascii, size_t len,
const unsigned char lut[restrict static 256], char pad, int strict_pad)
{
const unsigned char *str = (const unsigned char *)ascii;
unsigned char *data = out_buffer;
unsigned char a, b, c, d;
size_t n = 0u;
/* For as many multiple of 4 input characters as available,
* it can be coded into multiples of 3 bytes (or less if
* padding is used), however we need to check that the output
* buffer is large enough. Even if `size` is 0, we need read
* all characters to ensure that they only use the valid
* characters in the encoding alphabet or that padding is
* used correct — we want to validate the string, and we do
* not support padding in the middle (it is technically
* doable, but there is no reason it would ever be used) */
for(; len >= 4u; str += 4u) {
len -= 4u;
a = lut[str[0u]];
b = lut[str[1u]];
if ((a | b) == 0xFFu)
goto einval;
if (n < size)
data[n] = (unsigned char)((a << 2) | (b >> 4));
n++;
c = lut[str[2u]];
if (c == 0xFFu) {
if (len || !pad || str[2u] != pad || str[3u] != pad)
goto einval;
break;
}
if (n < size)
data[n] = (unsigned char)((b << 4u) | (c >> 2u));
n++;
d = lut[str[3u]];
if (d == 0xFFu) {
if (len || !pad || str[3u] != pad)
goto einval;
break;
}
if (n < size)
data[n] = (unsigned char)((c << 6) | (d >> 0));
n++;
}
/* If the number of input characters was not a multiple of
* four, the string is invalid if padding was required
* (`strict_pad` is ignored if `pad` is the NUL byte) */
if (len && pad && strict_pad)
goto einval;
/* Decode the remainder of the input, which shouldn't
* contain any padding since it is less than 4 bytes,
* and padding is done to multiples of 4 bytes */
switch (len) {
case 0u:
/* 0 characters left over, there was nothing left, and we are done */
goto out;
case 1u:
/* 1 character left over, this is invalid as at least 2 base-64
* characters is required to encode at least 1 byte */
goto einval;
default:
/* 2 or 3 characters left over */
a = lut[str[0u]];
b = lut[str[1u]];
if ((a | b) == 0xFFu)
goto einval;
if (n < size)
data[n] = (unsigned char)((a << 2) | (b >> 4));
n++;
if (len == 2u)
break;
c = lut[str[2u]];
if (c == 0xFFu) {
if (!pad)
goto einval;
if (str[2u] != pad)
goto einval;
break;
}
if (n < size)
data[n] = (unsigned char)((b << 4u) | (c >> 2u));
n++;
break;
}
out:
return (ssize_t)n;
einval:
errno = EINVAL;
return -1;
}
#else
static const unsigned char lut[256u] = {
XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, 62, XX, XX, XX, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, XX, XX, XX, XX, XX, XX,
XX, 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, XX, XX, XX, XX, XX,
XX, 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, XX, XX, XX, XX, XX,
XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX,
XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX, XX
};
#define CHECK(BINARY, ASCII, PAD)\
check((BINARY), sizeof(BINARY) - 1u, (ASCII PAD), sizeof(ASCII) - 1u, sizeof(ASCII PAD) - 1u)
static int check_good_padding = 1;
static void
check(const char *binary, size_t binary_len, const char *ascii, size_t unpadded_len, size_t padded_len)
{
char buf[16u];
size_t i, j;
/* Internal test check */
assert(binary_len <= sizeof(buf));
/* Internal test check */
if (check_good_padding) {
assert(padded_len % 4u == 0u);
assert(padded_len / 4u == (unpadded_len + 3u) / 4u);
}
assert(padded_len >= unpadded_len);
/* Test no output and without padding */
EXPECT(librecrypt_decode(NULL, 0u, ascii, unpadded_len, lut, '\0', 0) == (ssize_t)binary_len);
EXPECT(librecrypt_decode(NULL, 0u, ascii, unpadded_len, lut, '\0', 1) == (ssize_t)binary_len);
EXPECT(librecrypt_decode(NULL, 0u, ascii, unpadded_len, lut, '=', 0) == (ssize_t)binary_len);
if (padded_len == unpadded_len) {
EXPECT(librecrypt_decode(NULL, 0u, ascii, unpadded_len, lut, '=', 1) == (ssize_t)binary_len);
} else {
/* illegal combination: padding missing but required */
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, ascii, unpadded_len, lut, '=', 1) == -1);
EXPECT(errno == EINVAL);
}
/* Test no output and with padding */
if (padded_len != unpadded_len) {
/* illegal combinations: padding present no padding character defined (padded with illegal characters) */
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, ascii, padded_len, lut, '\0', 0) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, ascii, padded_len, lut, '\0', 1) == -1);
EXPECT(errno == EINVAL);
}
EXPECT(librecrypt_decode(NULL, 0u, ascii, padded_len, lut, '=', 0) == (ssize_t)binary_len);
if (check_good_padding)
EXPECT(librecrypt_decode(NULL, 0u, ascii, padded_len, lut, '=', 1) == (ssize_t)binary_len);
/* Test output, with and without truncation */
for (i = 0u; i < sizeof(buf); i++) {
memset(buf, 99, sizeof(buf));
EXPECT(librecrypt_decode(buf, i, ascii, unpadded_len, lut, '\0', 0) == (ssize_t)binary_len);
j = MIN(i, binary_len);
EXPECT(!memcmp(buf, binary, j));
for (; j < sizeof(buf); j++)
EXPECT(buf[j] == 99);
memset(buf, 99, sizeof(buf));
EXPECT(librecrypt_decode(buf, i, ascii, unpadded_len, lut, '\0', 1) == (ssize_t)binary_len);
j = MIN(i, binary_len);
EXPECT(!memcmp(buf, binary, j));
for (; j < sizeof(buf); j++)
EXPECT(buf[j] == 99);
memset(buf, 99, sizeof(buf));
EXPECT(librecrypt_decode(buf, i, ascii, unpadded_len, lut, '=', 0) == (ssize_t)binary_len);
j = MIN(i, binary_len);
EXPECT(!memcmp(buf, binary, j));
for (; j < sizeof(buf); j++)
EXPECT(buf[j] == 99);
if (padded_len == unpadded_len) {
memset(buf, 99, sizeof(buf));
EXPECT(librecrypt_decode(buf, i, ascii, unpadded_len, lut, '=', 1) == (ssize_t)binary_len);
j = MIN(i, binary_len);
EXPECT(!memcmp(buf, binary, j));
for (; j < sizeof(buf); j++)
EXPECT(buf[j] == 99);
} else {
errno = 0;
EXPECT(librecrypt_decode(buf, i, ascii, unpadded_len, lut, '=', 1) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(buf, i, ascii, padded_len, lut, '\0', 0) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(buf, i, ascii, padded_len, lut, '\0', 1) == -1);
EXPECT(errno == EINVAL);
}
memset(buf, 99, sizeof(buf));
EXPECT(librecrypt_decode(buf, i, ascii, padded_len, lut, '=', 0) == (ssize_t)binary_len);
j = MIN(i, binary_len);
EXPECT(!memcmp(buf, binary, j));
for (; j < sizeof(buf); j++)
EXPECT(buf[j] == 99);
if (check_good_padding) {
memset(buf, 99, sizeof(buf));
EXPECT(librecrypt_decode(buf, i, ascii, padded_len, lut, '=', 1) == (ssize_t)binary_len);
j = MIN(i, binary_len);
EXPECT(!memcmp(buf, binary, j));
for (; j < sizeof(buf); j++)
EXPECT(buf[j] == 99);
}
}
}
int
main(void)
{
int i;
SET_UP_ALARM();
INIT_RESOURCE_TEST();
/* Normal test cases */
check_good_padding = 1;
CHECK("", "", "");
CHECK("\x00", "AA", "==");
CHECK("\x00\x00", "AAA", "=");
CHECK("\x00\x00\x00", "AAAA", "");
CHECK("12345678", "MTIzNDU2Nzg", "=");
CHECK("testtest", "dGVzdHRlc3Q", "=");
CHECK("zy[]y21 !", "enlbXXkyMSAh", "");
CHECK("{~|~}~~~\x7f\x7f", "e358fn1+fn5/fw", "==");
/* Bad but acceptable case */
check_good_padding = 0;
CHECK("\x00", "AA", "=");
/* Test illegal characters, and 1 non-value character with
* 3 pad characeters (illegal since at least 2 base-64
* characters are needed to encode at least 1 byte) */
check_good_padding = 1;
for (i = 0; i <= 1; i++) {
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "AA=*", 4u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "AA*=", 4u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "AA**", 4u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "A===", 4u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "A", 1u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "====", 4u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "A*==", 4u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "*A==", 4u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "A*", 2u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "*A", 2u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "=", 1u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "==", 2u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "=A", 2u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "AA*", 3u, lut, '=', i) == -1);
EXPECT(errno == EINVAL);
errno = 0;
EXPECT(librecrypt_decode(NULL, 0u, "AA*", 3u, lut, '\0', i) == -1);
EXPECT(errno == EINVAL);
}
STOP_RESOURCE_TEST();
return 0;
}
#endif
|
