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gns3-server/gns3server/utils/hostname.py

113 lines
3.3 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}(?<!-)$""", hostname):
return True
return False
def to_ios_hostname(name):
"""
Convert name to an IOS hostname
"""
# Replace invalid characters with hyphens
name = re.sub(r'[^a-zA-Z0-9-]', '-', name)
# Ensure the hostname starts with a letter
if not re.search(r'^[a-zA-Z]', name):
name = 'a' + name
# Ensure the hostname ends with a letter or digit
if not re.search(r'[a-zA-Z0-9]$', name):
name = name.rstrip('-') + '0'
# Truncate the hostname to 63 characters
name = name[:63]
return name
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)
def to_rfc1123_hostname(name: str) -> str:
"""
Convert name to RFC 1123 hostname
"""
# Replace invalid characters with hyphens
name = re.sub(r'[^a-zA-Z0-9-.]', '-', name)
# Remove trailing dot if it exists
name = name.rstrip('.')
# Ensure each label is not longer than 63 characters
labels = name.split('.')
labels = [label[:63] for label in labels]
# Remove leading and trailing hyphens from each label if they exist
labels = [label.strip('-') for label in labels]
# Check if the TLD is all-numeric and if so, replace it with "invalid"
if re.match(r"[0-9]+$", labels[-1]):
labels[-1] = 'invalid'
# Join the labels back together
name = '.'.join(labels)
# Ensure the total length is not longer than 253 characters
name = name[:253]
return name