Format unresolvable specific socket addresses correctly

It seems that IO::Socket::IP::sockhostname() formats unresolvable
addresses. However, IPv6 numerical addresses must be properly
delimited by brackets:

$ perl -Ilib -MHTTP::Daemon -e '$d=HTTP::Daemon->new(LocalAddr=>q{::2}) or die; print $d->url, qq{\n}'
http://::2:52153/

And a zone seperator must be URI-quoted:

$ perl -Ilib -MHTTP::Daemon -e '$d=HTTP::Daemon->new(LocalAddr=>q{fe80::250:54ff:fe00:f15%ens3}) or die; print $d->url, qq{\n}'
http://fe80::250:54ff:fe00:f15%ens3:57797/

This patch fixes these two formatting issues.

Signed-off-by: Petr Písař <ppisar@redhat.com>

Author: ppisar

Changes

@@ -1,6 +1,8 @@
 Revision history for HTTP-Daemon
 
 {{$NEXT}}
+  - Delimit IPv6 numeric address with brackets and URI-quote an IPv6 zone
+    separator in url() method output
   - Handle undef and empty LocalAddr value in new() constructor as an
     unspecified address (GH#24, RT#123069)
 

lib/HTTP/Daemon.pm

@@ -62,6 +62,20 @@ sub url {
     }
     else {
         my $host = $self->sockhostname;
+
+        # sockhostname() seems to return a stringified IP address if not
+        # resolvable. Then quote it for a port separator and an IPv6 zone
+        # separator. But be paranoid for a case when it already contains
+        # a bracket.
+        if (defined $host and $host =~ /:/) {
+            if ($host =~ /[\[\]]/) {
+                $host = undef;
+            }
+            else {
+                $host =~ s/%/%25/g;
+                $host = '[' . $host . ']';
+            }
+        }
         if (!defined $host) {
             my $family = sockaddr_family($self->sockname);
             if ($family && $family == AF_INET6) {