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Correctly detect PLAT prefixes containing embedded WKAs

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The previous code would fail to detect PLAT prefix if ipv4only.arpa resolved to
an address such as 2001:db8:c000:aa::c000:aa. It would get confused as to
whether the prefix was 2001:db8::/32 (incorrect) or 2001:db8:c000:aa::/96
(correct).

Bug reported by Kasper Dupont - thanks!
This commit is contained in:
Tore Anderson
2018-12-14 23:48:32 +01:00
parent c228c2bb64
commit b8f583a4e0
1 changed files with 5 additions and 9 deletions
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14
clatd
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@@ -219,9 +219,9 @@ sub sysctl {
#
# Look for either of the WKAs for ipv4only.arpa (192.0.0.170 and .171) in an
# IPv6 address at all of the locations RFC 6052 says it can occur. If it's
# present at any of those locations (but no more than once), return the
# inferred translation prefix.
# IPv6 address at all of the locations RFC 6052 says it can occur, starting at
# the longest prefix length. If it's present at any of those locations, return
# the inferred translation prefix.
#
sub find_rfc7050_wka {
my $AAAA = shift;
@@ -248,7 +248,7 @@ sub find_rfc7050_wka {
my $discovered_pfx_len;
for my $len (keys(%rfc6052table)) {
outer: for my $len (sort {$b <=> $a} keys(%rfc6052table)) {
d2("Looking for Well-Known Addresses at prefix length /$len");
my $maskedip = $ip->intip();
my $mask = Net::IP->new($rfc6052table{"$len"}{"mask"}, 6);
@@ -269,13 +269,9 @@ sub find_rfc7050_wka {
}
if($maskedip == $wkaint->intip) {
if($discovered_pfx_len) {
w("Found WKA at two locations in ", $ip->sort,
"(/$discovered_pfx_len and /$len) - ignoring");
return;
}
d2("Found it!");
$discovered_pfx_len = $len;
last outer;
} else {
d2("Didn't find it");
}