Reported by eagle on 14 Dec 2008 10:15 UTC
A long-standing problem with innd is that it stores the DNS lookup results for everything in incoming.conf when it starts up and then never rechecks DNS. Most sites periodically reload incoming.conf to work around this, but it still breaks the DNS requirement to honor TTL.
Unfortunately, there's no way to do asynchronous DNS lookups using the getaddrinfo() interface, which is required to support /etc/hosts and other non-DNS sources of IP information, and we can't do the blocking calls since they can block for a long time.
That leaves, as a solution, doing DNS resolution in a child process and then asynchronously filling in the results. This will require putting incoming connections to sleep until the DNS resolution finishes, and then waking them up to do permission checking.
Reported by eagle on 14 Dec 2008 10:15 UTC
A long-standing problem with innd is that it stores the DNS lookup results for everything in incoming.conf when it starts up and then never rechecks DNS. Most sites periodically reload incoming.conf to work around this, but it still breaks the DNS requirement to honor TTL.
Unfortunately, there's no way to do asynchronous DNS lookups using the getaddrinfo() interface, which is required to support /etc/hosts and other non-DNS sources of IP information, and we can't do the blocking calls since they can block for a long time.
That leaves, as a solution, doing DNS resolution in a child process and then asynchronously filling in the results. This will require putting incoming connections to sleep until the DNS resolution finishes, and then waking them up to do permission checking.