I finally manged to crank out a new release of mod_epp. So, what’s new?
Last November Gavin Brown sent me a bug report regarding the handling of large answers. I provided a quick fix back then but did no official release.
While debugging that issue, I noticed that mod_epp didn’t generate the greeting on newer apaches. Tracing that, I found that the kernel didn’t return from accept on connection open, but on the first data reception. First I suspected the epoll interface, but some more intensive debugging found a more mundane reason: setsockopt is used to set:
TCP_DEFER_ACCEPTAllows a listener to be awakened only when data arrives on the socket. Takes an integer value (seconds), this can bound the maximum number of attempts TCP will make to complete the connection.
Some more googling found the answer: you need to use the AcceptFilter directive to disable this optimization for the EPP socket.
This is not really documented, thus this bug report.