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ipv6only listen option #17664
Description
Currently, listening on the :: address will attempt to bind on IPv4 and IPv6, whatever is available. This works most of the time but a issue arises on Linux with the ipv6.disable=1 kernel option set (which can be default on certain NAS devices). With it, listening on :: results in a EAFNOSUPPORT error. To work around and still get a IPv4 socket, one would have to apply one of these workarounds:
- Listen on
::, catch theEAFNOSUPPORTerror and listen again on0.0.0.0on error. - Listen on
::and0.0.0.0and ignore both theEAFNOSUPPORT(can happen on::) andEADDRINUSE(happens on the latter call when dual-stack actually works) errors.
To resolve above ugly error handling, I suggest exposing the existing UV_{TCP,UDP}_IPV6ONLY flags on server#listen and socket#bind via a new boolean option ipv6only. With the option set, one can listen on :: and 0.0.0.0 without any unexpected errors happening.
Related: nginx also features the ipv6only option, which has been enabled by default since v1.3.4.
Activity
imZack commentedon Dec 23, 2017
+1, we should have something like
net.createServer({ ipv6only: true })#9390 (comment)silverwind commentedon Dec 23, 2017
Putting it on
createServerseems wrong to me, it's a flag specific to the listen action, so should be on listen/bind.cjihrig commentedon Jul 20, 2018
This makes sense on the net side, but do we need this on the dgram side? On my machine at least, I seem unable to bind a
'udp6'socket on an IPv4 address, and vice versa.silverwind commentedon Jul 20, 2018
Yes, seems that's not possible, I get a "bind EINVAL" when attempting this, so it seems for UDP, the bound address family is dictated by the type of socket and the issue only applies to
net.[-]ipv6only listen/bind option[/-][+]ipv6only listen option[/+]net,dgram: add ipv6Only option for net and dgram
net,dgram: add ipv6Only option for net and dgram
net,dgram: add ipv6Only option for net and dgram
net,dgram: add ipv6Only option for net and dgram
net,dgram: add ipv6Only option for net and dgram