T4758: Rewrite show DHCP(v6) server leases to vyos.opmode format

Rewrite op-mode DHCP and DHCPv6 leases to vyos.opmode format
Abbility to show 'raw' format

show dhcp server leases
show dhcpv6 server leases

3 files changed, 282 insertions, 2 deletions

diff --git a/data/op-mode-standardized.json b/data/op-mode-standardized.json
index 9500d3aa7..03b85b50f 100644
--- a/data/op-mode-standardized.json
+++ b/data/op-mode-standardized.json
@@ -3,6 +3,8 @@
 "conntrack.py",
 "container.py",
 "cpu.py",
+"dhcp.py",
+"log.py",
 "memory.py",
 "nat.py",
 "neighbor.py",
diff --git a/op-mode-definitions/dhcp.xml.in b/op-mode-definitions/dhcp.xml.in
index 241cca0ce..ce4026ff4 100644
--- a/op-mode-definitions/dhcp.xml.in
+++ b/op-mode-definitions/dhcp.xml.in
@@ -16,7 +16,7 @@
                 <properties>
                   <help>Show DHCP server leases</help>
                 </properties>
-                <command>sudo ${vyos_op_scripts_dir}/show_dhcp.py --leases</command>
+                <command>sudo ${vyos_op_scripts_dir}/dhcp.py show_server_leases --family inet</command>
                 <children>
                   <tagNode name="pool">
                     <properties>
@@ -82,7 +82,7 @@
                 <properties>
                   <help>Show DHCPv6 server leases</help>
                 </properties>
-                <command>sudo ${vyos_op_scripts_dir}/show_dhcpv6.py --leases</command>
+                <command>sudo ${vyos_op_scripts_dir}/dhcp.py show_server_leases --family inet6</command>
                 <children>
                   <tagNode name="pool">
                     <properties>
diff --git a/src/op_mode/dhcp.py b/src/op_mode/dhcp.py
new file mode 100755
index 000000000..07e9b7d6c
--- /dev/null
+++ b/src/op_mode/dhcp.py
@@ -0,0 +1,278 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2022 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 sys
+from ipaddress import ip_address
+import typing
+
+from datetime import datetime
+from sys import exit
+from tabulate import tabulate
+from isc_dhcp_leases import IscDhcpLeases
+
+from vyos.base import Warning
+from vyos.configquery import ConfigTreeQuery
+
+from vyos.util import cmd
+from vyos.util import dict_search
+from vyos.util import is_systemd_service_running
+
+import vyos.opmode
+
+
+config = ConfigTreeQuery()
+pool_key = "shared-networkname"
+
+
+def _in_pool(lease, pool):
+    if pool_key in lease.sets:
+        if lease.sets[pool_key] == pool:
+            return True
+    return False
+
+
+def _utc_to_local(utc_dt):
+    return datetime.fromtimestamp((datetime.fromtimestamp(utc_dt) - datetime(1970, 1, 1)).total_seconds())
+
+
+def _format_hex_string(in_str):
+    out_str = ""
+    # if input is divisible by 2, add : every 2 chars
+    if len(in_str) > 0 and len(in_str) % 2 == 0:
+        out_str = ':'.join(a+b for a,b in zip(in_str[::2], in_str[1::2]))
+    else:
+        out_str = in_str
+
+    return out_str
+
+
+def _find_list_of_dict_index(lst, key='ip', value='') -> int:
+    """
+    Find the index entry of list of dict matching the dict value
+    Exampe:
+        % lst = [{'ip': '192.0.2.1'}, {'ip': '192.0.2.2'}]
+        % _find_list_of_dict_index(lst, key='ip', value='192.0.2.2')
+        % 1
+    """
+    idx = next((index for (index, d) in enumerate(lst) if d[key] == value), None)
+    return idx
+
+
+def _get_raw_server_leases(family, pool=None) -> list:
+    """
+    Get DHCP server leases
+    :return list
+    """
+    lease_file = '/config/dhcpdv6.leases' if family == 'inet6' else '/config/dhcpd.leases'
+    data = []
+    leases = IscDhcpLeases(lease_file).get()
+    if pool is not None:
+        if config.exists(f'service dhcp-server shared-network-name {pool}'):
+            leases = list(filter(lambda x: _in_pool(x, pool), leases))
+    for lease in leases:
+        data_lease = {}
+        data_lease['ip'] = lease.ip
+        data_lease['state'] = lease.binding_state
+        data_lease['pool'] = lease.sets.get('shared-networkname', '')
+        data_lease['end'] = lease.end.timestamp()
+
+        if family == 'inet':
+            data_lease['hardware'] = lease.ethernet
+            data_lease['start'] = lease.start.timestamp()
+            data_lease['hostname'] = lease.hostname
+
+        if family == 'inet6':
+            data_lease['last_communication'] = lease.last_communication.timestamp()
+            data_lease['iaid_duid'] = _format_hex_string(lease.host_identifier_string)
+            lease_types_long = {'na': 'non-temporary', 'ta': 'temporary', 'pd': 'prefix delegation'}
+            data_lease['type'] = lease_types_long[lease.type]
+
+        data_lease['remaining'] = lease.end - datetime.utcnow()
+
+        if data_lease['remaining'].days >= 0:
+            # substraction gives us a timedelta object which can't be formatted with strftime
+            # so we use str(), split gets rid of the microseconds
+            data_lease['remaining'] = str(data_lease["remaining"]).split('.')[0]
+        else:
+            data_lease['remaining'] = ''
+
+        # Do not add old leases
+        if data_lease['remaining'] != '':
+            data.append(data_lease)
+
+        # deduplicate
+        checked = []
+        for entry in data:
+            addr = entry.get('ip')
+            if addr not in checked:
+                checked.append(addr)
+            else:
+                idx = _find_list_of_dict_index(data, key='ip', value=addr)
+                data.pop(idx)
+
+    return data
+
+
+def _get_formatted_server_leases(raw_data, family):
+    data_entries = []
+    if family == 'inet':
+        for lease in raw_data:
+            ipaddr = lease.get('ip')
+            hw_addr = lease.get('hardware')
+            state = lease.get('state')
+            start = lease.get('start')
+            start =  _utc_to_local(start).strftime('%Y/%m/%d %H:%M:%S')
+            end = lease.get('end')
+            end =  _utc_to_local(end).strftime('%Y/%m/%d %H:%M:%S')
+            remain = lease.get('remaining')
+            pool = lease.get('pool')
+            hostname = lease.get('hostname')
+            data_entries.append([ipaddr, hw_addr, state, start, end, remain, pool, hostname])
+
+        headers = ['IP Address', 'Hardware address', 'State', 'Lease start', 'Lease expiration', 'Remaining', 'Pool',
+                   'Hostname']
+
+    if family == 'inet6':
+        for lease in raw_data:
+            ipaddr = lease.get('ip')
+            state = lease.get('state')
+            start = lease.get('last_communication')
+            start =  _utc_to_local(start).strftime('%Y/%m/%d %H:%M:%S')
+            end = lease.get('end')
+            end =  _utc_to_local(end).strftime('%Y/%m/%d %H:%M:%S')
+            remain = lease.get('remaining')
+            lease_type = lease.get('type')
+            pool = lease.get('pool')
+            host_identifier = lease.get('iaid_duid')
+            data_entries.append([ipaddr, state, start, end, remain, lease_type, pool, host_identifier])
+
+        headers = ['IPv6 address', 'State', 'Last communication', 'Lease expiration', 'Remaining', 'Type', 'Pool',
+                   'IAID_DUID']
+
+    output = tabulate(data_entries, headers, numalign='left')
+    return output
+
+
+def _get_dhcp_pools(family='inet') -> list:
+    v = 'v6' if family == 'inet6' else ''
+    pools = config.list_nodes(f'service dhcp{v}-server shared-network-name')
+    return pools
+
+
+def _get_pool_size(pool, family='inet'):
+    v = 'v6' if family == 'inet6' else ''
+    base = f'service dhcp{v}-server shared-network-name {pool}'
+    size = 0
+    subnets = config.list_nodes(f'{base} subnet')
+    for subnet in subnets:
+        if family == 'inet6':
+            ranges = config.list_nodes(f'{base} subnet {subnet} address-range start')
+        else:
+            ranges = config.list_nodes(f'{base} subnet {subnet} range')
+        for range in ranges:
+            if family == 'inet6':
+                start = config.list_nodes(f'{base} subnet {subnet} address-range start')[0]
+                stop = config.value(f'{base} subnet {subnet} address-range start {start} stop')
+            else:
+                start = config.value(f'{base} subnet {subnet} range {range} start')
+                stop = config.value(f'{base} subnet {subnet} range {range} stop')
+            # Add +1 because both range boundaries are inclusive
+            size += int(ip_address(stop)) - int(ip_address(start)) + 1
+    return size
+
+
+def _get_raw_pool_statistics(family='inet', pool=None):
+    if pool is None:
+        pool = _get_dhcp_pools(family=family)
+    else:
+        pool = [pool]
+
+    v = 'v6' if family == 'inet6' else ''
+    stats = []
+    for p in pool:
+        subnet = config.list_nodes(f'service dhcp{v}-server shared-network-name {p} subnet')
+        size = _get_pool_size(family=family, pool=p)
+        leases = len(_get_raw_server_leases(family=family, pool=p))
+        use_percentage = round(leases / size * 100) if size != 0 else 0
+        pool_stats = {'pool': p, 'size': size, 'leases': leases,
+                      'available': (size - leases), 'use_percentage': use_percentage, 'subnet': subnet}
+        stats.append(pool_stats)
+    return stats
+
+
+def _get_formatted_pool_statistics(pool_data, family='inet'):
+    data_entries = []
+    for entry in pool_data:
+        pool = entry.get('pool')
+        size = entry.get('size')
+        leases = entry.get('leases')
+        available = entry.get('available')
+        use_percentage = entry.get('use_percentage')
+        use_percentage = f'{use_percentage}%'
+        data_entries.append([pool, size, leases, available, use_percentage])
+
+    headers = ['Pool', 'Size','Leases', 'Available', 'Usage']
+    output = tabulate(data_entries, headers, numalign='left')
+    return output
+
+
+def _verify(func):
+    """Decorator checks if DHCP(v6) config exists"""
+    from functools import wraps
+
+    @wraps(func)
+    def _wrapper(*args, **kwargs):
+        config = ConfigTreeQuery()
+        family = kwargs.get('family')
+        v = 'v6' if family == 'inet6' else ''
+        unconf_message = f'DHCP{v} server is not configured'
+        # Check if config does not exist
+        if not config.exists(f'service dhcp{v}-server'):
+            raise vyos.opmode.UnconfiguredSubsystem(unconf_message)
+        return func(*args, **kwargs)
+    return _wrapper
+
+
+@_verify
+def show_pool_statistics(raw: bool, family: str, pool: typing.Optional[str]):
+    pool_data = _get_raw_pool_statistics(family=family, pool=pool)
+    if raw:
+        return pool_data
+    else:
+        return _get_formatted_pool_statistics(pool_data, family=family)
+
+
+@_verify
+def show_server_leases(raw: bool, family: str):
+    # if dhcp server is down, inactive leases may still be shown as active, so warn the user.
+    if not is_systemd_service_running('isc-dhcp-server.service'):
+        Warning('DHCP server is configured but not started. Data may be stale.')
+
+    leases = _get_raw_server_leases(family)
+    if raw:
+        return leases
+    else:
+        return _get_formatted_server_leases(leases, family)
+
+
+if __name__ == '__main__':
+    try:
+        res = vyos.opmode.run(sys.modules[__name__])
+        if res:
+            print(res)
+    except (ValueError, vyos.opmode.Error) as e:
+        print(e)
+        sys.exit(1)