openvpn: T1548: add 'show openvpn' command

vyos@vyos:~$ show openvpn site-to-site
OpenVPN status on vtun1

Client CN   Remote Host  Local Host          TX bytes  RX bytes  Connected Since
---------   -----------  ----------          --------  --------  ---------------
None (PSK)  N/A          172.18.201.10:1195  3.3 KiB   3.3 KiB   N/A

vyos@vyos:~$ show openvpn server
OpenVPN status on vtun10

Client CN   Remote Host          Local Host          TX bytes  RX bytes  Connected Since
---------   -----------          ----------          --------  --------  ---------------
client1     172.18.202.10:58644  172.18.201.10:1194  63.6 KiB  63.4 KiB  Mon Aug 26 11:47:56 2019
client3     172.18.204.10:52641  172.18.201.10:1194  63.1 KiB  62.7 KiB  Mon Aug 26 11:47:58 2019

OpenVPN status on vtun11

Client CN   Remote Host          Local Host          TX bytes  RX bytes  Connected Since
---------   -----------          ----------          --------  --------  ---------------
client2     172.18.203.10:39472  172.18.201.10:1200  61.2 KiB  61.5 KiB  Mon Aug 26 11:50:30 2019

1 files changed, 170 insertions, 0 deletions

diff --git a/src/op_mode/show_openvpn.py b/src/op_mode/show_openvpn.py
new file mode 100755
index 000000000..ee3729fc3
--- /dev/null
+++ b/src/op_mode/show_openvpn.py
@@ -0,0 +1,170 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2018 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 jinja2
+import argparse
+
+from vyos.config import Config
+
+outp_tmpl = """
+{% if clients %}
+OpenVPN status on {{ intf }}
+
+Client CN       Remote Host           Local Host           TX bytes    RX bytes   Connected Since
+---------       -----------           ----------           --------    --------   ---------------
+{%- for c in clients %}
+{{ "%-15s"|format(c.name) }} {{ "%-21s"|format(c.remote) }} {{ "%-15s"|format(local) }}   {{ "%-9s"|format(c.tx_bytes) }}   {{ "%-9s"|format(c.tx_bytes) }}  {{ c.online_since }}
+{%- endfor %}
+{% endif %}
+"""
+
+def bytes2HR(size):
+    # we need to operate in integers
+    size = int(size)
+
+    suff = ['B', 'KB', 'MB', 'GB', 'TB']
+    suffIdx = 0
+
+    while size > 1024:
+        # incr. suffix index
+        suffIdx += 1
+        # divide
+        size = size/1024.0
+
+    output="{0:.1f} {1}".format(size, suff[suffIdx])
+    return output
+
+def get_status(mode, interface):
+    status_file = '/opt/vyatta/etc/openvpn/status/{}.status'.format(interface)
+    # this is an empirical value - I assume we have no more then 999999
+    # current OpenVPN connections
+    routing_table_line = 999999
+
+    data = {
+        'mode': mode,
+        'intf': interface,
+        'local': '',
+        'date': '',
+        'clients': [],
+    }
+
+    with open(status_file, 'r') as f:
+        lines = f.readlines()
+        for line_no, line in enumerate(lines):
+            # remove trailing newline character first
+            line = line.rstrip('\n')
+
+            # check first line header
+            if line_no == 0:
+                if mode == 'server':
+                    if not line == 'OpenVPN CLIENT LIST':
+                        raise NameError('Expected "OpenVPN CLIENT LIST"')
+                else:
+                    if not line == 'OpenVPN STATISTICS':
+                        raise NameError('Expected "OpenVPN STATISTICS"')
+
+                continue
+
+            # second line informs us when the status file has been last updated
+            if line_no == 1:
+                data['date'] = line.lstrip('Updated,').rstrip('\n')
+                continue
+
+            if mode == 'server':
+                # followed by line3 giving output information and the actual output data
+                #
+                # Common Name,Real Address,Bytes Received,Bytes Sent,Connected Since
+                # client1,172.18.202.10:55904,2880587,2882653,Fri Aug 23 16:25:48 2019
+                # client3,172.18.204.10:41328,2850832,2869729,Fri Aug 23 16:25:43 2019
+                # client2,172.18.203.10:48987,2856153,2871022,Fri Aug 23 16:25:45 2019
+                if (line_no >= 3) and (line_no < routing_table_line):
+                    # indicator that there are no more clients and we will continue with the
+                    # routing table
+                    if line == 'ROUTING TABLE':
+                        routing_table_line = line_no
+                        continue
+
+                    client = {
+                        'name': line.split(',')[0],
+                        'remote': line.split(',')[1],
+                        'rx_bytes': bytes2HR(line.split(',')[2]),
+                        'tx_bytes': bytes2HR(line.split(',')[3]),
+                        'online_since': line.split(',')[4]
+                    }
+
+                    data['clients'].append(client)
+                    continue
+            else:
+                if line_no == 2:
+                    client = {
+                        'name': 'N/A',
+                        'rx_bytes': bytes2HR(line.split(',')[1]),
+                        'tx_bytes': '',
+                        'online_since': 'N/A'
+                    }
+                    continue
+
+                if line_no == 3:
+                    client['tx_bytes'] = bytes2HR(line.split(',')[1])
+                    data['clients'].append(client)
+                    break
+
+    return data
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-m', '--mode', help='OpenVPN operation mode (server, client, site-2-site)', required=True)
+
+    args = parser.parse_args()
+
+    # Do nothing if service is not configured
+    config = Config()
+    if len(config.list_effective_nodes('interfaces openvpn')) == 0:
+        print("No OpenVPN interfaces configured")
+        sys.exit(0)
+
+    # search all OpenVPN interfaces and add those with a matching mode to our
+    # interfaces list
+    interfaces = []
+    for intf in config.list_effective_nodes('interfaces openvpn'):
+        # get interface type (server, client, site-to-site)
+        mode = config.return_effective_value('interfaces openvpn {} mode'.format(intf))
+        if args.mode == mode:
+            interfaces.append(intf)
+
+    for intf in interfaces:
+        data = get_status(args.mode, intf)
+        local_host = config.return_effective_value('interfaces openvpn {} local-host'.format(intf))
+        local_port = config.return_effective_value('interfaces openvpn {} local-port'.format(intf))
+        data['local'] = local_host + ':' + local_port
+
+        if args.mode in ['client', 'site-to-site']:
+            for client in data['clients']:
+                if config.exists_effective('interfaces openvpn {} shared-secret-key-file'.format(intf)):
+                    client['name'] = "None (PSK)"
+
+                remote_host = config.return_effective_values('interfaces openvpn {} remote-host'.format(intf))
+                remote_port = config.return_effective_value('interfaces openvpn {} remote-port'.format(intf))
+                if len(remote_host) >= 1:
+                    client['remote'] = str(remote_host[0]) + ':' + remote_port
+                else:
+                    client['remote'] = 'N/A'
+
+
+        tmpl = jinja2.Template(outp_tmpl)
+        print(tmpl.render(data))
+