Package: libc6
Version: 2.3.6.ds1-13
Severity: important
getaddrinfo() does not prefer IPv6 addresses, even though it should
according to RFC 3484. I have debugged the issue and it all boils down
to match_prefix() in sysdeps/posix/getaddrinfo.c. The prefix test runs
like this:
while (bits > 8)
{
if (*mask != *val)
break;
++mask;
++val;
bits -= 8;
}
if (bits < 8)
{
if ((*mask & (0xff00 >> bits)) == (*val & (0xff00 >> bits)))
/* Match! */
break;
}
Of course, for prefix lengths which are a multiple of 8 the loop ends
prematurely and the subsequent test returns 8, so there is never a match
for these lengths. Since the prefix for IPv4 addresses is 96 bits long
(see default_precedence), IPv4 addresses get the default priority (40)
and not the correct one (10). I was able to fix this by changing the
condition to:
while (bits >= 8)
Since match_prefix() is used for labels as well, this bug probably also
breaks RFC 3484 rule 5 (Prefer matching label).
-- System Information:
Debian Release: 4.0
APT prefers stable
APT policy: (500, 'stable')
Architecture: i386 (i686)
Shell: /bin/sh linked to /bin/bash
Kernel: Linux 2.6.20.3
Locale: LANG=cs_CZ.UTF-8, LC_CTYPE=cs_CZ.UTF-8 (charmap=UTF-8)
Versions of packages libc6 depends on:
ii tzdata 2007b-1 Time Zone and Daylight Saving Time
libc6 recommends no packages.
-- no debconf information
--
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
