From: Peter van Dijk <peter.van.dijk@netherlabs.nl>
Date: Fri, 21 Sep 2012 13:44:20 +0000 (+0000)
Subject: make extract_bits slightly more robust; document limitations (thanks Maik)
X-Git-Tag: auth-3.2-rc1~166
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=79fe6bef998382979c7cd14dc6da250dae29955b;p=thirdparty%2Fpdns.git

make extract_bits slightly more robust; document limitations (thanks Maik)

git-svn-id: svn://svn.powerdns.com/pdns/trunk/pdns@2716 d19b8d6e-7fed-0310-83ef-9ca221ded41b
---

diff --git a/pdns/base32.cc b/pdns/base32.cc
index d20926d698..5c96cc2ff1 100644
--- a/pdns/base32.cc
+++ b/pdns/base32.cc
@@ -8,6 +8,7 @@
 #include "namespaces.hh"
 
 /* based on freebsd:src/contrib/opie/libopie/btoe.c extract: get bit ranges from a char* */
+/* NOTE: length should not exceed 8; all callers inside PowerDNS only pass length=5 though */
 unsigned char extract_bits(const char *s, int start, int length)
 {
   uint16_t x;
@@ -19,6 +20,8 @@ unsigned char extract_bits(const char *s, int start, int length)
   cl = s[start / 8];
   if(start / 8 < (start + length-1)/8)
     cc = s[start / 8 + 1];
+  else
+    cc = 0;
 
   x = (uint16_t) (cl << 8 | cc);
   x = x >> (16 - (length + (start % 8)));