attempts to bind to wrong interface for CNAME-to-A-only MX when ipv6 available
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
sendmail (Ubuntu) |
Fix Released
|
Undecided
|
Unassigned | ||
Precise |
Fix Released
|
Undecided
|
Unassigned | ||
Saucy |
Fix Released
|
Undecided
|
Unassigned |
Bug Description
When sendmail is configured with both IPv4 and IPv6 interfaces, it can fail to deliver to any hosts that have a CNAME as an MX record that resolves only to an A record with no AAAA record.
An existing example of this is here:
http://
IMPACT: if ipv6 is routable, sendmail suddenly cannot deliver email to a subset of servers with slightly misconfigured MX records.
TEST CASE:
- bring up routable ipv6 interface
- install and configure sendmail-bin
- Run "date | sendmail -v -Am -d61.14 -d16.14 <email address hidden>"
- observe failure "makeconnection: cannot bind [IPv6:nnnnn....]: Address family not supported by protocol"
REGRESSION POTENTIAL: low. This is an upstream patch backported specifically for this version of sendmail. Proper operation is trivially verifiable.
Working with upstream, the cause of the bug was tracked down, and the following patch solves the issue.