vty: add bind command for telnet vty line

Add VTY command
    line vty
     bind A.B.C.D

The command merely stores the configured IP-address, which can then be used by
the calling main program to set the telnet port of the VTY line. (Commits in
openbsc and osmo-iuh will follow up on this.)

Add function vty_get_bind_addr() to publish the address in the vty.h API.

Add static vty_bind_addr to store.

For allocation/freeing reasons, a NULL address defaults to 127.0.0.1.

BTW, I decided against allowing keywords 'any' and 'localhost' in place of an
actual IP address to make sure a written config is always identical to the
parsed config.
2 files changed