T5474: establish common file name pattern for XML conf mode commands

We will use _ as CLI level divider. The XML definition filename and also
the Python helper should match the CLI node.

Example:
set interfaces ethernet -> interfaces_ethernet.xml.in
set interfaces bond -> interfaces_bond.xml.in
set service dhcp-server -> service_dhcp-server-xml.in

1 files changed, 269 insertions, 0 deletions

diff --git a/src/conf_mode/service_snmp.py b/src/conf_mode/service_snmp.py
new file mode 100755
index 000000000..6565ffd60
--- /dev/null
+++ b/src/conf_mode/service_snmp.py
@@ -0,0 +1,269 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2018-2023 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# 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 os
+
+from sys import exit
+
+from vyos.base import Warning
+from vyos.config import Config
+from vyos.configdict import dict_merge
+from vyos.configverify import verify_vrf
+from vyos.snmpv3_hashgen import plaintext_to_md5
+from vyos.snmpv3_hashgen import plaintext_to_sha1
+from vyos.snmpv3_hashgen import random
+from vyos.template import render
+from vyos.utils.process import call
+from vyos.utils.permission import chmod_755
+from vyos.utils.dict import dict_search
+from vyos.utils.network import is_addr_assigned
+from vyos.version import get_version_data
+from vyos import ConfigError
+from vyos import airbag
+airbag.enable()
+
+config_file_client  = r'/etc/snmp/snmp.conf'
+config_file_daemon  = r'/etc/snmp/snmpd.conf'
+config_file_access  = r'/usr/share/snmp/snmpd.conf'
+config_file_user    = r'/var/lib/snmp/snmpd.conf'
+systemd_override    = r'/run/systemd/system/snmpd.service.d/override.conf'
+systemd_service     = 'snmpd.service'
+
+def get_config(config=None):
+    if config:
+        conf = config
+    else:
+        conf = Config()
+    base = ['service', 'snmp']
+
+    snmp = conf.get_config_dict(base, key_mangling=('-', '_'),
+                                get_first_key=True, no_tag_node_value_mangle=True)
+    if not conf.exists(base):
+        snmp.update({'deleted' : ''})
+
+    if conf.exists(['service', 'lldp', 'snmp']):
+        snmp.update({'lldp_snmp' : ''})
+
+    if 'deleted' in snmp:
+        return snmp
+
+    version_data = get_version_data()
+    snmp['version'] = version_data['version']
+
+    # create an internal snmpv3 user of the form 'vyosxxxxxxxxxxxxxxxx'
+    snmp['vyos_user'] = 'vyos' + random(8)
+    snmp['vyos_user_pass'] = random(16)
+
+    # We have gathered the dict representation of the CLI, but there are default
+    # options which we need to update into the dictionary retrived.
+    snmp = conf.merge_defaults(snmp, recursive=True)
+
+    if 'listen_address' in snmp:
+        # Always listen on localhost if an explicit address has been configured
+        # This is a safety measure to not end up with invalid listen addresses
+        # that are not configured on this system. See https://vyos.dev/T850
+        if '127.0.0.1' not in snmp['listen_address']:
+            tmp = {'127.0.0.1': {'port': '161'}}
+            snmp['listen_address'] = dict_merge(tmp, snmp['listen_address'])
+
+        if '::1' not in snmp['listen_address']:
+            tmp = {'::1': {'port': '161'}}
+            snmp['listen_address'] = dict_merge(tmp, snmp['listen_address'])
+
+    return snmp
+
+def verify(snmp):
+    if 'deleted' in snmp:
+        return None
+
+    if {'deleted', 'lldp_snmp'} <= set(snmp):
+        raise ConfigError('Can not delete SNMP service, as LLDP still uses SNMP!')
+
+    ### check if the configured script actually exist
+    if 'script_extensions' in snmp and 'extension_name' in snmp['script_extensions']:
+        for extension, extension_opt in snmp['script_extensions']['extension_name'].items():
+            if 'script' not in extension_opt:
+                raise ConfigError(f'Script extension "{extension}" requires an actual script to be configured!')
+
+            tmp = extension_opt['script']
+            if not os.path.isfile(tmp):
+                Warning(f'script "{tmp}" does not exist!')
+            else:
+                chmod_755(extension_opt['script'])
+
+    if 'listen_address' in snmp:
+        for address in snmp['listen_address']:
+            # We only wan't to configure addresses that exist on the system.
+            # Hint the user if they don't exist
+            if 'vrf' in snmp:
+                vrf_name = snmp['vrf']
+                if not is_addr_assigned(address, vrf_name) and address not in ['::1','127.0.0.1']:
+                    raise ConfigError(f'SNMP listen address "{address}" not configured in vrf "{vrf_name}"!')
+            elif not is_addr_assigned(address):
+                raise ConfigError(f'SNMP listen address "{address}" not configured in default vrf!')
+
+    if 'trap_target' in snmp:
+        for trap, trap_config in snmp['trap_target'].items():
+            if 'community' not in trap_config:
+                raise ConfigError(f'Trap target "{trap}" requires a community to be set!')
+
+    if 'oid_enable' in snmp:
+        Warning(f'Custom OIDs are enabled and may lead to system instability and high resource consumption')
+
+
+    verify_vrf(snmp)
+
+    # bail out early if SNMP v3 is not configured
+    if 'v3' not in snmp:
+        return None
+
+    if 'user' in snmp['v3']:
+        for user, user_config in snmp['v3']['user'].items():
+            if 'group' not in user_config:
+                raise ConfigError(f'Group membership required for user "{user}"!')
+
+            if 'plaintext_password' not in user_config['auth'] and 'encrypted_password' not in user_config['auth']:
+                raise ConfigError(f'Must specify authentication encrypted-password or plaintext-password for user "{user}"!')
+
+            if 'plaintext_password' not in user_config['privacy'] and 'encrypted_password' not in user_config['privacy']:
+                raise ConfigError(f'Must specify privacy encrypted-password or plaintext-password for user "{user}"!')
+
+    if 'group' in snmp['v3']:
+        for group, group_config in snmp['v3']['group'].items():
+            if 'seclevel' not in group_config:
+                raise ConfigError(f'Must configure "seclevel" for group "{group}"!')
+            if 'view' not in group_config:
+                raise ConfigError(f'Must configure "view" for group "{group}"!')
+
+            # Check if 'view' exists
+            view = group_config['view']
+            if 'view' not in snmp['v3'] or view not in snmp['v3']['view']:
+                raise ConfigError(f'You must create view "{view}" first!')
+
+    if 'view' in snmp['v3']:
+        for view, view_config in snmp['v3']['view'].items():
+            if 'oid' not in view_config:
+                raise ConfigError(f'Must configure an "oid" for view "{view}"!')
+
+    if 'trap_target' in snmp['v3']:
+        for trap, trap_config in snmp['v3']['trap_target'].items():
+            if 'plaintext_password' not in trap_config['auth'] and 'encrypted_password' not in trap_config['auth']:
+                raise ConfigError(f'Must specify one of authentication encrypted-password or plaintext-password for trap "{trap}"!')
+
+            if {'plaintext_password', 'encrypted_password'} <= set(trap_config['auth']):
+                raise ConfigError(f'Can not specify both authentication encrypted-password and plaintext-password for trap "{trap}"!')
+
+            if 'plaintext_password' not in trap_config['privacy'] and 'encrypted_password' not in trap_config['privacy']:
+                raise ConfigError(f'Must specify one of privacy encrypted-password or plaintext-password for trap "{trap}"!')
+
+            if {'plaintext_password', 'encrypted_password'} <= set(trap_config['privacy']):
+                raise ConfigError(f'Can not specify both privacy encrypted-password and plaintext-password for trap "{trap}"!')
+
+            if 'type' not in trap_config:
+                raise ConfigError('SNMP v3 trap "type" must be specified!')
+
+    return None
+
+def generate(snmp):
+    # As we are manipulating the snmpd user database we have to stop it first!
+    # This is even save if service is going to be removed
+    call(f'systemctl stop {systemd_service}')
+    # Clean config files
+    config_files = [config_file_client, config_file_daemon,
+                    config_file_access, config_file_user, systemd_override]
+    for file in config_files:
+        if os.path.isfile(file):
+            os.unlink(file)
+
+    if 'deleted' in snmp:
+        return None
+
+    if 'v3' in snmp:
+        # net-snmp is now regenerating the configuration file in the background
+        # thus we need to re-open and re-read the file as the content changed.
+        # After that we can no read the encrypted password from the config and
+        # replace the CLI plaintext password with its encrypted version.
+        os.environ['vyos_libexec_dir'] = '/usr/libexec/vyos'
+
+        if 'user' in snmp['v3']:
+            for user, user_config in snmp['v3']['user'].items():
+                if dict_search('auth.type', user_config)  == 'sha':
+                    hash = plaintext_to_sha1
+                else:
+                    hash = plaintext_to_md5
+
+                if dict_search('auth.plaintext_password', user_config) is not None:
+                    tmp = hash(dict_search('auth.plaintext_password', user_config),
+                        dict_search('v3.engineid', snmp))
+
+                    snmp['v3']['user'][user]['auth']['encrypted_password'] = tmp
+                    del snmp['v3']['user'][user]['auth']['plaintext_password']
+
+                    call(f'/opt/vyatta/sbin/my_set service snmp v3 user "{user}" auth encrypted-password "{tmp}" > /dev/null')
+                    call(f'/opt/vyatta/sbin/my_delete service snmp v3 user "{user}" auth plaintext-password > /dev/null')
+
+                if dict_search('privacy.plaintext_password', user_config) is not None:
+                    tmp = hash(dict_search('privacy.plaintext_password', user_config),
+                        dict_search('v3.engineid', snmp))
+
+                    snmp['v3']['user'][user]['privacy']['encrypted_password'] = tmp
+                    del snmp['v3']['user'][user]['privacy']['plaintext_password']
+
+                    call(f'/opt/vyatta/sbin/my_set service snmp v3 user "{user}" privacy encrypted-password "{tmp}" > /dev/null')
+                    call(f'/opt/vyatta/sbin/my_delete service snmp v3 user "{user}" privacy plaintext-password > /dev/null')
+
+    # Write client config file
+    render(config_file_client, 'snmp/etc.snmp.conf.j2', snmp)
+    # Write server config file
+    render(config_file_daemon, 'snmp/etc.snmpd.conf.j2', snmp)
+    # Write access rights config file
+    render(config_file_access, 'snmp/usr.snmpd.conf.j2', snmp)
+    # Write access rights config file
+    render(config_file_user, 'snmp/var.snmpd.conf.j2', snmp)
+    # Write daemon configuration file
+    render(systemd_override, 'snmp/override.conf.j2', snmp)
+
+    return None
+
+def apply(snmp):
+    # Always reload systemd manager configuration
+    call('systemctl daemon-reload')
+
+    if 'deleted' in snmp:
+        return None
+
+    # start SNMP daemon
+    call(f'systemctl restart {systemd_service}')
+
+    # Enable AgentX in FRR
+    # This should be done for each daemon individually because common command
+    # works only if all the daemons started with SNMP support
+    # Following daemons from FRR 9.0/stable have SNMP module compiled in VyOS
+    frr_daemons_list = ['zebra', 'bgpd', 'ospf6d', 'ospfd', 'ripd', 'isisd', 'ldpd']
+    for frr_daemon in frr_daemons_list:
+        call(f'vtysh -c "configure terminal" -d {frr_daemon} -c "agentx" >/dev/null')
+
+    return None
+
+if __name__ == '__main__':
+    try:
+        c = get_config()
+        verify(c)
+        generate(c)
+        apply(c)
+    except ConfigError as e:
+        print(e)
+        exit(1)