config.py 文件源码

def __str__(self):
        if self.fqdn is None:
            #
            # If the SSH config contains AddressFamily, use that when
            # determining  the local host's FQDN. Using socket.getfqdn() from
            # the standard library is the most general solution, but can
            # result in noticeable delays on some platforms when IPv6 is
            # misconfigured or not available, as it calls getaddrinfo with no
            # address family specified, so both IPv4 and IPv6 are checked.
            #

            # Handle specific option
            fqdn = None
            address_family = self.config.get('addressfamily', 'any').lower()
            if address_family != 'any':
                try:
                    family = socket.AF_INET if address_family == 'inet' \
                        else socket.AF_INET6
                    results = socket.getaddrinfo(
                        self.host,
                        None,
                        family,
                        socket.SOCK_DGRAM,
                        socket.IPPROTO_IP,
                        socket.AI_CANONNAME
                    )
                    for res in results:
                        af, socktype, proto, canonname, sa = res
                        if canonname and '.' in canonname:
                            fqdn = canonname
                            break
                # giaerror -> socket.getaddrinfo() can't resolve self.host
                # (which is from socket.gethostname()). Fall back to the
                # getfqdn() call below.
                except socket.gaierror:
                    pass
            # Handle 'any' / unspecified
            if fqdn is None:
                fqdn = socket.getfqdn()
            # Cache
            self.fqdn = fqdn
        return self.fqdn