Signed-off-by: Manuel Franceschini <livewire@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

This patch enables IPv6 name resolution by using socket.getaddrinfo
instead of socket.gethostbyname_ex.

It renames the HostInfo class to Hostname and unifies its use throughout
the code. This is achieved by using static calls where no object is
needed and removes some obsolete code.

For now, we just resolve to IPv4 addresses, but this will change once it
is needed.

Signed-off-by: Manuel Franceschini <livewire@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>

In light of the upcoming IPv6 support, this patch enables the rpc.Client
to always use a node's address to connect to it. This is necessary as we
do not want to rely on name resolution to connect to the correct IP
address on a dual-stack machine.

Signed-off-by: Manuel Franceschini <livewire@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>

Instead of using our custom HTTP client, using PycURL's multi
interface allows us to get rid of the HTTP client threadpool.
The majority of the code is still in the ganeti.http.client
module.

A simple per-thread HTTP client pool gives cURL a chance to
cache and retain as much information as possible (e.g. SSL certs).
Unused HTTP clients (e.g. due to removed nodes) are deleted after
25 requests going through the pool.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>