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From 49d2c8c6bcf8c926e52c7f510033b6adc31355f5 Mon Sep 17 00:00:00 2001
From: Szabolcs Nagy <nsz@port70.net>
Date: Thu, 4 Sep 2014 18:29:16 +0200
Subject: [PATCH] fix dn_expand empty name handling and offsets to 0
Empty name was rejected in dn_expand since commit
56b57f37a46dab432247bf29d96fcb11fbd02a6d
which is a regression as reported by Natanael Copa.
Furthermore if an offset pointer in a compressed name
pointed to a terminating 0 byte (instead of a label)
the returned name was not null terminated.
---
src/network/dn_expand.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/src/network/dn_expand.c b/src/network/dn_expand.c
index 849df19..d9b3393 100644
--- a/src/network/dn_expand.c
+++ b/src/network/dn_expand.c
@@ -4,11 +4,13 @@
int __dn_expand(const unsigned char *base, const unsigned char *end, const unsigned char *src, char *dest, int space)
{
const unsigned char *p = src;
- char *dend = dest + (space > 254 ? 254 : space);
+ char *dend, *dbegin = dest;
int len = -1, i, j;
- if (p==end || !*p) return -1;
+ if (p==end || space <= 0) return -1;
+ dend = dest + (space > 254 ? 254 : space);
/* detect reference loop using an iteration counter */
for (i=0; i < end-base; i+=2) {
+ /* loop invariants: p<end, dest<dend */
if (*p & 0xc0) {
if (p+1==end) return -1;
j = ((p[0] & 0x3f) << 8) | p[1];
@@ -16,11 +18,12 @@ int __dn_expand(const unsigned char *base, const unsigned char *end, const unsig
if (j >= end-base) return -1;
p = base+j;
} else if (*p) {
- j = *p+1;
- if (j>=end-p || j>dend-dest) return -1;
- while (--j) *dest++ = *++p;
- *dest++ = *++p ? '.' : 0;
+ if (dest != dbegin) *dest++ = '.';
+ j = *p++;
+ if (j >= end-p || j >= dend-dest) return -1;
+ while (j--) *dest++ = *p++;
} else {
+ *dest = 0;
if (len < 0) len = p+1-src;
return len;
}
--
2.3.3
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