solookup() was only compatible with TCP. Having the socket list in
argument, it is now compatible with UDP too.

Some optimization code is factorized inside the function (the function
look at the last returned result before browsing the complete socket
list).

This prepares for IPv6 support.
Signed-off-by: NGuillaume Subiron <maethor@subiron.org>
Signed-off-by: NSamuel Thibault <samuel.thibault@ens-lyon.org>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>