[zeromq-dev] zmq_forwarder fails when my machine is not on the internet

[Martin Lucina]

Hi Mike,

> I am running zmq_forwarder for a pub/sub situation.  My config file is below:

> [...]

> when my machine is connected to the internet it runs no problem.  when I am
> offline, it terminates immediately with this as output:
> 
> terminate called after throwing an instance of 'zmq::error_t'
>   what():  Invalid argument
> Aborted

I know about this and have reported the issue to the bug tracker.

There is a problem at least on Linux when the host only has a loopback
address configured, getaddrinfo() will not resolve anything. AFAICT this is
due to the AI_ADDRCONFIG flag being used when resolving names/addresses.

> Any thoughts?

AI_ADDRCONFIG can probably go while we're ignoring IPv6, but this does look
like a getaddrinfo() bug to me, since the POSIX wording is:

       "If the AI_ADDRCONFIG flag is specified, IPv4 addresses shall be
       returned only if an  IPv4  address is configured on the local
       system,    and IPv6 addresses shall be returned only if an IPv6
       address is configured on the local
       system."

Since when does 127.0.0.1 not count as "an IPv4 address"...?

-mato