--listen and --host options do not support IPv6 addresses

[eserte]

If using an IPv6 address in --listen or --host (any, because every IPv6 address contains at least one colon), then starman fails like this:

$ starman --host '[::]'            
2023/09/29-13:59:09 Starman::Server (type Net::Server::PreFork) starting! pid(931201)
Missing port in hashref passed in port argument.

$ starman --listen '[::]:5000'            
2023/09/29-13:59:13 Starman::Server (type Net::Server::PreFork) starting! pid(931207)
Missing port in hashref passed in port argument.

(depending on the used address different error messages like

2023/09/29-14:09:47 Could not determine host from "[fe00"
  at line 56 in file /opt/perl-5.30.3/lib/site_perl/5.30.3/Net/Server/Proto.pm

may happen)

Problem is the usage of split in

Starman/lib/Starman/Server.pm

Line 77 in 1fb6f66

my($h, $p, $opt) = split /:/, $listen, 3;

A proper solution would implement something similar like IO::Socket::IP->split_addr.
However, a solution would also need to support the "...:$option" (i.e. "...:ssl") notation.

An informal patch exists in eserte@6ffcd59
However I do not propose to apply this patch, as it would require an additional dependency.

[miyagawa]

the patch looks reasonable and the additional dep for IO::Socket::IP sounds fine to me. Not sure what else you need to support ipv6 though.

[eserte]

About testing starman with IPv6: assuming your /etc/hosts already contains an entry like this one

::1     ip6-localhost ip6-loopback

then you can already test IPv6 using a hostname, not an address. This looks good:

$ starman --listen 'ip6-localhost:5000' app.psgi
...
Resolved [ip6-localhost]:5000 to [::1]:5000, IPv6
Binding to TCP port 5000 on host ::1 with IPv6
...

netstat sees only a IPv6 bind, no tcp (without "6") entry:

$ sudo netstat -tulpen | grep starman
tcp6       0      0 ::1:5000                :::*                    LISTEN      1000       15945944   1757861/starman mas 

Accessing using the IPv4 localhost address does not work, as expected:

$ curl 'http://127.0.0.1:5000'    
curl: (7) Failed to connect to 127.0.0.1 port 5000: Connection refused

IPv6 works, both with address and hostname:

$ curl 'http://ip6-localhost:5000'
... response ...
$ curl 'http://[::1]:5000'
... response ...

strace also shows that IPv6 is in use:

connect(5, {sa_family=AF_INET6, sin6_port=htons(5000), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_scope_id=0}, 28) = -1 EINPROGRESS (Operation now in progress)
getpeername(5, {sa_family=AF_INET6, sin6_port=htons(5000), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_scope_id=0}, [128->28]) = 0
getsockname(5, {sa_family=AF_INET6, sin6_port=htons(55814), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_scope_id=0}, [128->28]) = 0

[eserte]

Patching Starman::Server is not enough, also https://github.com/plack/Plack/blob/ae1fb1d2fc603f11bdd2fb162438a103007d12ac/lib/Plack/Runner.pm#L93-L115 needs proper IPv6 handling.

[miyagawa]

Yeah, what about requiring square bracket for ipv6 addresses like you do in URI?