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>

Use RFC 5737 IP addresses and RFC 2606 domain names in all
unittests, docs, qa and docstrings.

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

This patch moves network utility functions to a dedicated module.

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

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

This also updates a comment in the unittest for utils.py. We unittest
the new function for two things: correct reporting on real case (for
localhost), and correct reporting with a mocked-out TcpPing that returns
false.

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

Certificates and keys generated using these functions will be used for
inter-cluster instance moves. As per design, the private key should never
leave the node.

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