pgwire cannot bind to IPV4 "all-addresses"

[knz]

Without any arguments, pgwire listens only on [::]:15432 (ipv6 all-addresses).

With --pgaddr 0.0.0.0:15432 (ipv4 all-ddresses), the configuration is ignored and it starts listening on [::]:15432 as well.

Only with an explicit ipv4 address (eg. --pgaddr x.y.z.w:15432) does the desired behavior appear.

I think this is rather new as I did not have this problem last week.

There are two bugs in here:

1. --pgaddr 0.0.0.0:15432 should really listen on ipv4
2. by default (no argument) pgwire should probably listen on both ipv4 and ipv6 or the current behavior should be clearly outlined in the doc.

[tamird]

cc @mberhault

[knz]

(Via @tamird) might be related to #3757

[knz]

Ok after some more investigation this issue is not reallyn related to the argument --pgaddr but more to the general behavior of net.Listen when provided these values as input. What is the general way in Go to specify the "any" binding for ipv4?

[knz]

Found while investigating #4036

[maddyblue]

https://groups.google.com/forum/#!msg/golang-nuts/F5HE7Eqb6iM/q_um2VqT5vAJ has some good info on this.

[maddyblue]

@knz can you replicate this on a Mac? I dived in a bit and it seems like Go thinks it's a ipv4 address. Linux may be doing some auto ipv6 magic.

[bdarnell]

I'm not sure exactly how the system calls are exposed via go, but I've run into this in the past. In short, linux likes to bind to both ipv4 and ipv6 together whenever it can, while BSD and OSX require them to be bound separately. To handle things in a sane and cross-platform way you have to pass extra socket options on linux to make it act more like BSD. This seems like something Go should handle for us instead of something we do at our level.

[knz]

The issue was found and was affecting a Linux system.
The issue has gone away after upgrading to 4fc0779.
Closing this issue for now, if found again on BSD/OSX another issue could be opened too.

[tamird]

This was (unintentionally) fixes in #4161.