# Copyright 2020 VyOS maintainers and contributors # # 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 . r""" A Library for interracting with the FRR daemon suite. It supports simple configuration manipulation and loading using the official tools supplied with FRR (vtysh and frr-reload) All configuration management and manipulation is done using strings and regex. Example Usage ##### # Reading configuration from frr: ``` >>> original_config = get_configuration() >>> repr(original_config) '!\nfrr version 7.3.1\nfrr defaults traditional\nhostname debian\n...... ``` # Modify a configuration section: ``` >>> new_bgp_section = 'router bgp 65000\n neighbor 192.0.2.1 remote-as 65000\n' >>> modified_config = replace_section(original_config, new_bgp_section, replace_re=r'router bgp \d+') >>> repr(modified_config) '............router bgp 65000\n neighbor 192.0.2.1 remote-as 65000\n...........' ``` Remove a configuration section: ``` >>> modified_config = remove_section(original_config, r'router ospf') ``` Test the new configuration: ``` >>> try: >>> mark_configuration(modified configuration) >>> except ConfigurationNotValid as e: >>> print('resulting configuration is not valid') >>> sys.exit(1) ``` Apply the new configuration: ``` >>> try: >>> replace_configuration(modified_config) >>> except CommitError as e: >>> print('Exception while commiting the supplied configuration') >>> print(e) >>> exit(1) ``` """ import tempfile import re from vyos import util import logging from logging.handlers import SysLogHandler import os LOG = logging.getLogger(__name__) DEBUG = os.path.exists('/tmp/vyos.frr.debug') if DEBUG: LOG.setLevel(logging.DEBUG) ch = SysLogHandler(address='/dev/log') ch2 = logging.StreamHandler() LOG.addHandler(ch) LOG.addHandler(ch2) _frr_daemons = ['zebra', 'bgpd', 'fabricd', 'isisd', 'ospf6d', 'ospfd', 'pbrd', 'pimd', 'ripd', 'ripngd', 'sharpd', 'staticd', 'vrrpd', 'ldpd'] path_vtysh = '/usr/bin/vtysh' path_frr_reload = '/usr/lib/frr/frr-reload.py' class FrrError(Exception): pass class ConfigurationNotValid(FrrError): """ The configuratioin supplied to vtysh is not valid """ pass class CommitError(FrrError): """ Commiting the supplied configuration failed to commit by a unknown reason see commit error and/or run mark_configuration on the specified configuration to se error generated used by: reload_configuration() """ pass class ConfigSectionNotFound(FrrError): """ Removal of configuration failed because it is not existing in the supplied configuration """ pass def get_configuration(daemon=None, marked=False): """ Get current running FRR configuration daemon: Collect only configuration for the specified FRR daemon, supplying daemon=None retrieves the complete configuration marked: Mark the configuration with "end" tags return: string containing the running configuration from frr """ if daemon and daemon not in _frr_daemons: raise ValueError(f'The specified daemon type is not supported {repr(daemon)}') cmd = f"{path_vtysh} -c 'show run'" if daemon: cmd += f' -d {daemon}' output, code = util.popen(cmd, stderr=util.STDOUT) if code: raise OSError(code, output) config = output.replace('\r', '') # Remove first header lines from FRR config config = config.split("\n", 3)[-1] # Mark the configuration with end tags if marked: config = mark_configuration(config) return config def mark_configuration(config): """ Add end marks and Test the configuration for syntax faults If the configuration is valid a marked version of the configuration is returned, or else it failes with a ConfigurationNotValid Exception config: The configuration string to mark/test return: The marked configuration from FRR """ output, code = util.popen(f"{path_vtysh} -m -f -", stderr=util.STDOUT, input=config) if code == 2: raise ConfigurationNotValid(str(output)) elif code: raise OSError(code, output) config = output.replace('\r', '') return config def reload_configuration(config, daemon=None): """ Execute frr-reload with the new configuration This will try to reapply the supplied configuration inside FRR. The configuration needs to be a complete configuration from the integrated config or from a daemon. config: The configuration to apply daemon: Apply the conigutaion to the specified FRR daemon, supplying daemon=None applies to the integrated configuration return: None """ if daemon and daemon not in _frr_daemons: raise ValueError(f'The specified daemon type is not supported {repr(daemon)}') f = tempfile.NamedTemporaryFile('w') f.write(config) f.flush() LOG.debug(f'reload_configuration: Reloading config using temporary file: {f.name}') cmd = f'{path_frr_reload} --reload' if daemon: cmd += f' --daemon {daemon}' if DEBUG: cmd += f' --debug --stdout' cmd += f' {f.name}' LOG.debug(f'reload_configuration: Executing command against frr-reload: "{cmd}"') output, code = util.popen(cmd, stderr=util.STDOUT) f.close() for i, e in enumerate(output.split('\n')): LOG.debug(f'frr-reload output: {i:3} {e}') if code == 1: raise CommitError(f'Configuration FRR failed while commiting code, please enabling debugging to examine logs') elif code: raise OSError(code, output) return output def execute(command): """ Run commands inside vtysh command: str containing commands to execute inside a vtysh session """ if not isinstance(command, str): raise ValueError(f'command needs to be a string: {repr(command)}') cmd = f"{path_vtysh} -c '{command}'" output, code = util.popen(cmd, stderr=util.STDOUT) if code: raise OSError(code, output) config = output.replace('\r', '') return config def configure(lines, daemon=False): """ run commands inside config mode vtysh lines: list or str conaining commands to execute inside a configure session only one command executed on each configure() Executing commands inside a subcontext uses the list to describe the context ex: ['router bgp 6500', 'neighbor 192.0.2.1 remote-as 65000'] return: None """ if isinstance(lines, str): lines = [lines] elif not isinstance(lines, list): raise ValueError('lines needs to be string or list of commands') if daemon and daemon not in _frr_daemons: raise ValueError(f'The specified daemon type is not supported {repr(daemon)}') cmd = f'{path_vtysh}' if daemon: cmd += f' -d {daemon}' cmd += " -c 'configure terminal'" for x in lines: cmd += f" -c '{x}'" output, code = util.popen(cmd, stderr=util.STDOUT) if code == 1: raise ConfigurationNotValid(f'Configuration FRR failed: {repr(output)}') elif code: raise OSError(code, output) config = output.replace('\r', '') return config def _replace_section(config, replacement, replace_re, before_re): r"""Replace a section of FRR config config: full original configuration replacement: replacement configuration section replace_re: The regex to replace example: ^router bgp \d+$.?*^!$ this will replace everything between ^router bgp X$ and ^!$ before_re: When replace_re is not existant, the config will be added before this tag example: ^line vty$ return: modified configuration as a text file """ # DEPRECATED, this is replaced by a new implementation # Check if block is configured, remove the existing instance else add a new one if re.findall(replace_re, config, flags=re.MULTILINE | re.DOTALL): # Section is in the configration, replace it return re.sub(replace_re, replacement, config, count=1, flags=re.MULTILINE | re.DOTALL) if before_re: if not re.findall(before_re, config, flags=re.MULTILINE | re.DOTALL): raise ConfigSectionNotFound(f"Config section {before_re} not found in config") # If no section is in the configuration, add it before the line vty line return re.sub(before_re, rf'{replacement}\n\g<1>', config, count=1, flags=re.MULTILINE | re.DOTALL) raise ConfigSectionNotFound(f"Config section {replacement} not found in config") def replace_section(config, replacement, from_re, to_re=r'!', before_re=r'line vty'): r"""Replace a section of FRR config config: full original configuration replacement: replacement configuration section from_re: Regex for the start of section matching example: 'router bgp \d+' to_re: Regex for stop of section matching default: '!' example: '!' or 'end' before_re: When from_re/to_re does not return a match, the config will be added before this tag default: ^line vty$ startline and endline tags will be automatically added to the resulting from_re/to_re and before_re regex'es """ # DEPRECATED, this is replaced by a new implementation return _replace_section(config, replacement, replace_re=rf'^{from_re}$.*?^{to_re}$', before_re=rf'^({before_re})$') def remove_section(config, from_re, to_re='!'): # DEPRECATED, this is replaced by a new implementation return _replace_section(config, '', replace_re=rf'^{from_re}$.*?^{to_re}$', before_re=None) def _find_first_block(config, start_pattern, stop_pattern, start_at=0): '''Find start and stop line numbers for a config block config: (list) A list conaining the configuration that is searched start_pattern: (raw-str) The pattern searched for a a start of block tag stop_pattern: (raw-str) The pattern searched for to signify the end of the block start_at: (int) The index to start searching at in the Returns: None: No complete block could be found set(int, int): A complete block found between the line numbers returned in the set The object is searched from the start for the regex until the first match is found. On a successful match it continues the search for the regex until it is found. After a successful run a set is returned containing the start and stop line numbers. ''' LOG.debug(f'_find_first_block: find start={repr(start_pattern)} stop={repr(stop_pattern)} start_at={start_at}') _start = None for i, element in enumerate(config[start_at:], start=start_at): # LOG.debug(f'_find_first_block: running line {i:3} "{element}"') if not _start: if not re.match(start_pattern, element): LOG.debug(f'_find_first_block: no match {i:3} "{element}"') continue _start = i LOG.debug(f'_find_first_block: Found start {i:3} "{element}"') continue if not re.match(stop_pattern, element): LOG.debug(f'_find_first_block: no match {i:3} "{element}"') continue LOG.debug(f'_find_first_block: Found stop {i:3} "{element}"') return (_start, i) LOG.debug('_find_first_block: exit start={repr(start_pattern)} stop={repr(stop_pattern)} start_at={start_at}') return None def _find_first_element(config, pattern, start_at=0): '''Find the first element that matches the current pattern in config config: (list) A list containing the configuration that is searched start_pattern: (raw-str) The pattern searched for start_at: (int) The index to start searching at in the return: Line index of the line containing the searched pattern TODO: for now it returns -1 on a no-match because 0 also returns as False TODO: that means that we can not use False matching to tell if its ''' LOG.debug(f'_find_first_element: find start="{pattern}" start_at={start_at}') for i, element in enumerate(config[start_at:], start=0): if re.match(pattern + '$', element): LOG.debug(f'_find_first_element: Found stop {i:3} "{element}"') return i LOG.debug(f'_find_first_element: no match {i:3} "{element}"') LOG.debug(f'_find_first_element: Did not find any match, exiting') return -1 def _find_elements(config, pattern, start_at=0): '''Find all instances of pattern and return a list containing all element indexes config: (list) A list containing the configuration that is searched start_pattern: (raw-str) The pattern searched for start_at: (int) The index to start searching at in the return: A list of line indexes containing the searched pattern TODO: refactor this to return a generator instead ''' return [i for i, element in enumerate(config[start_at:], start=0) if re.match(pattern + '$', element)] class FRRConfig: '''Main FRR Configuration manipulation object Using this object the user could load, manipulate and commit the configuration to FRR ''' def __init__(self, config=[]): self.imported_config = '' if isinstance(config, list): self.config = config.copy() self.original_config = config.copy() elif isinstance(config, str): self.config = config.split('\n') self.original_config = self.config.copy() else: raise ValueError( 'The config element needs to be a string or list type object') if config: LOG.debug(f'__init__: frr library initiated with initial config') for i, e in enumerate(self.config): LOG.debug(f'__init__: initial {i:3} {e}') def load_configuration(self, daemon=None): '''Load the running configuration from FRR into the config object daemon: str with name of the FRR Daemon to load configuration from or None to load the consolidated config Using this overwrites the current loaded config objects and replaces the original loaded config ''' self.imported_config = get_configuration(daemon=daemon) if daemon: LOG.debug(f'load_configuration: Configuration loaded from FRR daemon {daemon}') else: LOG.debug(f'load_configuration: Configuration loaded from FRR integrated config') self.original_config = self.imported_config.split('\n') self.config = self.original_config.copy() for i, e in enumerate(self.imported_config.split('\n')): LOG.debug(f'load_configuration: loaded {i:3} {e}') return def test_configuration(self): '''Test the current configuration against FRR This will exception if FRR failes to load the current configuration object ''' LOG.debug('test_configation: Testing configuration') mark_configuration('\n'.join(self.config)) def commit_configuration(self, daemon=None): '''Commit the current configuration to FRR daemon: str with name of the FRR daemon to commit to or None to use the consolidated config ''' LOG.debug('commit_configuration: Commiting configuration') for i, e in enumerate(self.config): LOG.debug(f'commit_configuration: new_config {i:3} {e}') reload_configuration('\n'.join(self.config), daemon=daemon) def modify_section(self, start_pattern, replacement=[], stop_pattern=r'\S+', remove_stop_mark=False, count=0): if isinstance(replacement, str): replacement = replacement.split('\n') elif not isinstance(replacement, list): return ValueError("The replacement element needs to be a string or list type object") LOG.debug(f'modify_section: starting search for {repr(start_pattern)} until {repr(stop_pattern)}') _count = 0 _next_start = 0 while True: if count and count <= _count: # Break out of the loop after specified amount of matches LOG.debug(f'modify_section: reached limit ({_count}), exiting loop at line {_next_start}') break # While searching, always assume that the user wants to search for the exact pattern he entered # To be more specific the user needs a override, eg. a "pattern.*" _w = _find_first_block( self.config, start_pattern+'$', stop_pattern, start_at=_next_start) if not _w: # Reached the end, no more elements to remove LOG.debug(f'modify_section: No more config sections found, exiting') break start_element, end_element = _w LOG.debug(f'modify_section: found match between {start_element} and {end_element}') for i, e in enumerate(self.config[start_element:end_element+1 if remove_stop_mark else end_element], start=start_element): LOG.debug(f'modify_section: remove {i:3} {e}') del self.config[start_element:end_element + 1 if remove_stop_mark else end_element] if replacement: # Append the replacement config at the current position for i, e in enumerate(replacement, start=start_element): LOG.debug(f'modify_section: add {i:3} {e}') self.config[start_element:start_element] = replacement _count += 1 _next_start = start_element + len(replacement) return _count def add_before(self, before_pattern, addition): '''Add config block before this element in the configuration''' if isinstance(addition, str): addition = addition.split('\n') elif not isinstance(addition, list): return ValueError("The replacement element needs to be a string or list type object") start = _find_first_element(self.config, before_pattern) if start < 0: return False for i, e in enumerate(addition, start=start): LOG.debug(f'add_before: add {i:3} {e}') self.config[start:start] = addition return True def __str__(self): return '\n'.join(self.config) def __repr__(self): return f'frr({repr(str(self))})'