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gns3-server/gns3server/utils/hostname.py

60 lines
1.9 KiB
Python

#!/usr/bin/env python
#
# Copyright (C) 2022 GNS3 Technologies Inc.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import re
def is_ios_hostname_valid(hostname: str) -> bool:
"""
Check if an IOS hostname is valid
IOS hostname must start with a letter, end with a letter or digit, and
have as interior characters only letters, digits, and hyphens.
They must be 63 characters or fewer (ARPANET rules).
"""
if re.search(r"""^(?!-|[0-9])[a-zA-Z0-9-]{1,63}(?<!-)$""", hostname):
return True
return False
def is_rfc1123_hostname_valid(hostname: str) -> bool:
"""
Check if a hostname is valid according to RFC 1123
Each element of the hostname must be from 1 to 63 characters long
and the entire hostname, including the dots, can be at most 253
characters long. Valid characters for hostnames are ASCII
letters from a to z, the digits from 0 to 9, and the hyphen (-).
A hostname may not start with a hyphen.
"""
if hostname[-1] == ".":
hostname = hostname[:-1] # strip exactly one dot from the right, if present
if len(hostname) > 253:
return False
labels = hostname.split(".")
# the TLD must be not all-numeric
if re.match(r"[0-9]+$", labels[-1]):
return False
allowed = re.compile(r"(?!-)[a-zA-Z0-9-]{1,63}(?<!-)$")
return all(allowed.match(label) for label in labels)