# Copyright 2019 VyOS maintainers and contributors <maintainers@vyos.io> # # This library is free software; you can redistribute it and/or # modify it under the terms of the GNU Lesser General Public # License as published by the Free Software Foundation; either # version 2.1 of the License, or (at your option) any later version. # # This library 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 # Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public # License along with this library. If not, see <http://www.gnu.org/licenses/>. import sys import os import re import fileinput from vyos.util import cmd, DEVNULL def check_and_add_host_key(host_name): """ Filter host keys and prompt for adding key to known_hosts file, if needed. """ known_hosts = '{}/.ssh/known_hosts'.format(os.getenv('HOME')) if not os.path.exists(known_hosts): mode = 0o600 os.mknod(known_hosts, 0o600) keyscan_cmd = 'ssh-keyscan -t rsa {} 2>/dev/null'.format(host_name) try: host_key = cmd(keyscan_cmd, shell=True, stderr=DEVNULL) except OSError: sys.exit("Can not get RSA host key") # libssh2 (jessie; stretch) does not recognize ec host keys, and curl # will fail with error 51 if present in known_hosts file; limit to rsa. usable_keys = False offending_keys = [] for line in fileinput.input(known_hosts, inplace=True): if host_name in line and 'ssh-rsa' in line: if line.split()[-1] != host_key.split()[-1]: offending_keys.append(line) continue else: usable_keys = True if host_name in line and not 'ssh-rsa' in line: continue sys.stdout.write(line) if usable_keys: return if offending_keys: print("Host key has changed!") print("If you trust the host key fingerprint below, continue.") fingerprint_cmd = 'ssh-keygen -lf /dev/stdin <<< "{}"'.format(host_key) try: fingerprint = cmd(fingerprint_cmd, shell=True, stderr=DEVNULL) except OSError: sys.exit("Can not get RSA host key fingerprint.") print("RSA host key fingerprint is {}".format(fingerprint.split()[1])) response = input("Do you trust this host? [y]/n ") if not response or response == 'y': with open(known_hosts, 'a+') as f: print("Adding {} to the list of known" " hosts.".format(host_name)) f.write(host_key) else: sys.exit("Host not trusted") def get_remote_config(remote_file): """ Invoke curl to download remote (config) file. Args: remote file URI: scp://<user>[:<passwd>]@<host>/<file> sftp://<user>[:<passwd>]@<host>/<file> http://<host>/<file> https://<host>/<file> ftp://<user>[:<passwd>]@<host>/<file> tftp://<host>/<file> """ request = dict.fromkeys(['protocol', 'host', 'file', 'user', 'passwd']) protocols = ['scp', 'sftp', 'http', 'https', 'ftp', 'tftp'] or_protocols = '|'.join(protocols) request_match = re.match(r'(' + or_protocols + r')://(.*?)(/.*)', remote_file) if request_match: (request['protocol'], request['host'], request['file']) = request_match.groups() else: print("Malformed URI") sys.exit(1) user_match = re.search(r'(.*)@(.*)', request['host']) if user_match: request['user'] = user_match.groups()[0] request['host'] = user_match.groups()[1] passwd_match = re.search(r'(.*):(.*)', request['user']) if passwd_match: # Deprectated in RFC 3986, but maintain for backward compatability. request['user'] = passwd_match.groups()[0] request['passwd'] = passwd_match.groups()[1] remote_file = '{0}://{1}{2}'.format(request['protocol'], request['host'], request['file']) if request['protocol'] in ('scp', 'sftp'): check_and_add_host_key(request['host']) redirect_opt = '' if request['protocol'] in ('http', 'https'): redirect_opt = '-L' # Try header first, and look for 'OK' or 'Moved' codes: curl_cmd = 'curl {0} -q -I {1}'.format(redirect_opt, remote_file) try: curl_output = cmd(curl_cmd, shell=True) except OSError: sys.exit(1) return_vals = re.findall(r'^HTTP\/\d+\.?\d\s+(\d+)\s+(.*)$', curl_output, re.MULTILINE) for val in return_vals: if int(val[0]) not in [200, 301, 302]: print('HTTP error: {0} {1}'.format(*val)) sys.exit(1) if request['user'] and not request['passwd']: curl_cmd = 'curl -# -u {0} {1}'.format(request['user'], remote_file) else: curl_cmd = 'curl {0} -# {1}'.format(redirect_opt, remote_file) try: return cmd(curl_cmd, shell=True, stderr=None) except OSError: return None