OpenBSD does not support TCP_KEEPALIVE or a timeout with SO_KEEPALIVE

[reyk]

Hi,

using net2 on OpenBSD, I've stumbled over this:

 24878 arca-broker CALL  setsockopt(23,SOL_SOCKET,SO_KEEPALIVE,0x1f005a366034,4)
 24878 arca-broker RET   setsockopt 0
 24878 arca-broker CALL  setsockopt(23,6<unknown>,8,0x1f005a366034,4)
 24878 arca-broker RET   setsockopt -1 errno 1 Operation not permitted
 24878 arca-broker CALL  close(23)

The first setsockopt() call is enabling SO_KEEPALIVE, which is OK and supported, the second setsockopt() call is trying to set the timeout with IPPROTO_TCP (6) and TCP_KEEPALIVE (mapped to SO_KEEPALIVE == 8).

Using SO_KEEPALIVE/TCP_KEEPALIVE on a IPPROTO_TCP level is not supported on OpenBSD. OpenBSD only supports global sysctl settings for setting the keepalive intervals:

net.inet.tcp.keepinittime=150
net.inet.tcp.keepidle=14400
net.inet.tcp.keepintvl=150
net.inet.tcp.always_keepalive=0

This mapping is invalid on OpenBSD...:
https://github.com/rust-lang-nursery/net2-rs/blob/a3d51b36da8dfbc62e0df2219662537e110aeb59/src/ext.rs#L661

...as it is used here:
https://github.com/rust-lang-nursery/net2-rs/blob/master/src/ext.rs#L735-L736

...and here:
https://github.com/rust-lang-nursery/net2-rs/blob/master/src/ext.rs#L748-L749

[matm]

Thanks @reyk for this explanation.

On another topic, the echo web framework I try to use on my OpenBSD box is also concerned, I now understand why.

Looks like this is a recurring issue that can be found here and there on the web, like in aerogo/aero#10.

[reyk]

I think I've sent a proper bug report but never got any response 😿

I guess we have to come up with a pull request instead.

[jhatala]

@reyk, I stumbled upon the same problem as you had, and I was delighted to find that you had documented it in this ticket. According to my testing the patch in #99 fixes the problem.