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(rr13): handle zero length bit strings

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git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@6880 ec53bebd-3082-4978-b11e-865c3cabbd6b
This commit is contained in:
Johan Danielsson
1999-08-27 09:03:41 +00:00
parent 92c4c345c6
commit 5196926ac0
1 changed files with 32 additions and 28 deletions
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60
lib/krb5/n-fold.c
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@@ -40,37 +40,41 @@ rr13(unsigned char *buf, size_t len)
unsigned char *tmp; unsigned char *tmp;
int bytes = (len + 7) / 8; int bytes = (len + 7) / 8;
int i; int i;
const int bits = 13 % len; if(len == 0)
const int lbit = len % 8; return;
{
const int bits = 13 % len;
const int lbit = len % 8;
tmp = malloc(bytes); tmp = malloc(bytes);
memcpy(tmp, buf, bytes); memcpy(tmp, buf, bytes);
if(lbit) { if(lbit) {
/* pad final byte with inital bits */ /* pad final byte with inital bits */
tmp[bytes - 1] &= 0xff << (8 - lbit); tmp[bytes - 1] &= 0xff << (8 - lbit);
for(i = lbit; i < 8; i += len) for(i = lbit; i < 8; i += len)
tmp[bytes - 1] |= buf[0] >> i; tmp[bytes - 1] |= buf[0] >> i;
} }
for(i = 0; i < bytes; i++) { for(i = 0; i < bytes; i++) {
int bb; int bb;
int b1, s1, b2, s2; int b1, s1, b2, s2;
/* calculate first bit position of this byte */ /* calculate first bit position of this byte */
bb = 8 * i - bits; bb = 8 * i - bits;
while(bb < 0) while(bb < 0)
bb += len; bb += len;
/* byte offset and shift count */ /* byte offset and shift count */
b1 = bb / 8; b1 = bb / 8;
s1 = bb % 8; s1 = bb % 8;
if(bb + 8 > bytes * 8) if(bb + 8 > bytes * 8)
/* watch for wraparound */ /* watch for wraparound */
s2 = (len + 8 - s1) % 8; s2 = (len + 8 - s1) % 8;
else else
s2 = 8 - s1; s2 = 8 - s1;
b2 = (b1 + 1) % bytes; b2 = (b1 + 1) % bytes;
buf[i] = (tmp[b1] << s1) | (tmp[b2] >> s2); buf[i] = (tmp[b1] << s1) | (tmp[b2] >> s2);
}
free(tmp);
} }
free(tmp);
} }
/* Add `b' to `a', both beeing one's complement numbers. */ /* Add `b' to `a', both beeing one's complement numbers. */