helpers.py 文件源码

def check_host(host, allow_localhost=config.ALLOW_CONNECT_LOCALHOST):
    """Check if a given host is a valid DNS name or IPv4 address"""

    try:
        ipaddr = socket.gethostbyname(host)
    except UnicodeEncodeError:
        raise MistError('Please provide a valid DNS name')
    except socket.gaierror:
        raise MistError("Not a valid IP address or resolvable DNS name: '%s'."
                        % host)

    if host != ipaddr:
        msg = "Host '%s' resolves to '%s' which" % (host, ipaddr)
    else:
        msg = "Host '%s'" % host

    if not netaddr.valid_ipv4(ipaddr):
        raise MistError(msg + " is not a valid IPv4 address.")

    forbidden_subnets = {
        '0.0.0.0/8': "used for broadcast messages to the current network",
        '100.64.0.0/10': ("used for communications between a service provider "
                          "and its subscribers when using a "
                          "Carrier-grade NAT"),
        '169.254.0.0/16': ("used for link-local addresses between two hosts "
                           "on a single link when no IP address is otherwise "
                           "specified"),
        '192.0.0.0/24': ("used for the IANA IPv4 Special Purpose Address "
                         "Registry"),
        '192.0.2.0/24': ("assigned as 'TEST-NET' for use solely in "
                         "documentation and example source code"),
        '192.88.99.0/24': "used by 6to4 anycast relays",
        '198.18.0.0/15': ("used for testing of inter-network communications "
                          "between two separate subnets"),
        '198.51.100.0/24': ("assigned as 'TEST-NET-2' for use solely in "
                            "documentation and example source code"),
        '203.0.113.0/24': ("assigned as 'TEST-NET-3' for use solely in "
                           "documentation and example source code"),
        '224.0.0.0/4': "reserved for multicast assignments",
        '240.0.0.0/4': "reserved for future use",
        '255.255.255.255/32': ("reserved for the 'limited broadcast' "
                               "destination address"),
    }

    if not allow_localhost:
        forbidden_subnets['127.0.0.0/8'] = ("used for loopback addresses "
                                            "to the local host")

    cidr = netaddr.smallest_matching_cidr(ipaddr, forbidden_subnets.keys())
    if cidr:
        raise MistError("%s is not allowed. It belongs to '%s' "
                        "which is %s." % (msg, cidr,
                                          forbidden_subnets[str(cidr)]))