ifconfig: T2057: break down DHCP

1 files changed, 266 insertions, 0 deletions

diff --git a/python/vyos/ifconfig/dhcp.py b/python/vyos/ifconfig/dhcp.py
new file mode 100644
index 000000000..8d3653433
--- /dev/null
+++ b/python/vyos/ifconfig/dhcp.py
@@ -0,0 +1,266 @@
+# Copyright 2020 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 os
+import jinja2
+
+from vyos.ifconfig.control import Control
+
+template_v4 = """
+# generated by ifconfig.py
+option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;
+timeout 60;
+retry 300;
+
+interface "{{ intf }}" {
+    send host-name "{{ hostname }}";
+    {% if client_id -%}
+    send dhcp-client-identifier "{{ client_id }}";
+    {% endif -%}
+    {% if vendor_class_id -%}
+    send vendor-class-identifier "{{ vendor_class_id }}";
+    {% endif -%}
+    request subnet-mask, broadcast-address, routers, domain-name-servers,
+        rfc3442-classless-static-routes, domain-name, interface-mtu;
+    require subnet-mask;
+}
+
+"""
+
+template_v6 = """
+# generated by ifconfig.py
+interface "{{ intf }}" {
+    request routers, domain-name-servers, domain-name;
+}
+
+"""
+
+class DHCP (Control):
+    client_base = r'/var/lib/dhcp/dhclient_'
+
+    def __init__ (self, ifname):
+        # per interface DHCP config files
+        self._dhcp = {
+            4: {
+                'ifname': ifname,
+                'conf': self.client_base + ifname + '.conf',
+                'pid':  self.client_base + ifname + '.pid',
+                'lease': self.client_base + ifname + '.leases',
+                'options': {
+                    'intf': ifname,
+                    'hostname': '',
+                    'client_id': '',
+                    'vendor_class_id': ''
+                },
+            },
+            6: {
+                'ifname': ifname,
+                'conf': self.client_base + ifname + '.v6conf',
+                'pid':  self.client_base + ifname + '.v6pid',
+                'lease': self.client_base + ifname + '.v6leases',
+                'accept_ra': f'/proc/sys/net/ipv6/conf/{ifname}/accept_ra',
+                'options': {
+                    'intf': ifname,
+                    'dhcpv6_prm_only': False,
+                    'dhcpv6_temporary': False
+                },
+            },
+        }
+
+    def get_dhcp_options(self):
+        """
+        Return dictionary with supported DHCP options.
+
+        Dictionary should be altered and send back via set_dhcp_options()
+        so those options are applied when DHCP is run.
+        """
+        return self._dhcp[4]['options']
+
+    def set_dhcp_options(self, options):
+        """
+        Store new DHCP options used by next run of DHCP client.
+        """
+        self._dhcp[4]['options'] = options
+
+    def get_dhcpv6_options(self):
+        """
+        Return dictionary with supported DHCPv6 options.
+
+        Dictionary should be altered and send back via set_dhcp_options()
+        so those options are applied when DHCP is run.
+        """
+        return self._dhcp[6]['options']
+
+    def set_dhcpv6_options(self, options):
+        """
+        Store new DHCP options used by next run of DHCP client.
+        """
+        self._dhcp[6]['options'] = options
+
+    # replace dhcpv4/v6 with systemd.networkd?
+    def _set_dhcp(self):
+        """
+        Configure interface as DHCP client. The dhclient binary is automatically
+        started in background!
+
+        Example:
+
+        >>> from vyos.ifconfig import Interface
+        >>> j = Interface('eth0')
+        >>> j.set_dhcp()
+        """
+
+        dhcp = self.get_dhcp_options()
+        if not dhcp['hostname']:
+            # read configured system hostname.
+            # maybe change to vyos hostd client ???
+            with open('/etc/hostname', 'r') as f:
+                dhcp['hostname'] = f.read().rstrip('\n')
+
+        # render DHCP configuration
+        tmpl = jinja2.Template(template_v4)
+        dhcp_text = tmpl.render(dhcp)
+        with open(self._dhcp[4]['conf'], 'w') as f:
+            f.write(dhcp_text)
+
+        cmd = 'start-stop-daemon'
+        cmd += ' --start'
+        cmd += ' --oknodo'
+        cmd += ' --quiet'
+        cmd += ' --pidfile {pid}'
+        cmd += ' --exec /sbin/dhclient'
+        cmd += ' --'
+        # now pass arguments to dhclient binary
+        cmd += ' -4 -nw -cf {conf} -pf {pid} -lf {lease} {ifname}'
+        return self._cmd(cmd.format(**self._dhcp[4]))
+
+    def _del_dhcp(self):
+        """
+        De-configure interface as DHCP clinet. All auto generated files like
+        pid, config and lease will be removed.
+
+        Example:
+
+        >>> from vyos.ifconfig import Interface
+        >>> j = Interface('eth0')
+        >>> j.del_dhcp()
+        """
+        if not os.path.isfile(self._dhcp[4]['pid']):
+            self._debug_msg('No DHCP client PID found')
+            return None
+
+		# with open(self._dhcp[4]['pid'], 'r') as f:
+		# 	pid = int(f.read())
+
+        # stop dhclient, we need to call dhclient and tell it should release the
+        # aquired IP address. tcpdump tells me:
+        # 172.16.35.103.68 > 172.16.35.254.67: [bad udp cksum 0xa0cb -> 0xb943!] BOOTP/DHCP, Request from 00:50:56:9d:11:df, length 300, xid 0x620e6946, Flags [none] (0x0000)
+        #  Client-IP 172.16.35.103
+        #  Client-Ethernet-Address 00:50:56:9d:11:df
+        #  Vendor-rfc1048 Extensions
+        #    Magic Cookie 0x63825363
+        #    DHCP-Message Option 53, length 1: Release
+        #    Server-ID Option 54, length 4: 172.16.35.254
+        #    Hostname Option 12, length 10: "vyos"
+        #
+        cmd = '/sbin/dhclient -cf {conf} -pf {pid} -lf {lease} -r {ifname}'
+        self._cmd(cmd.format(**self._dhcp[4]))
+
+        # cleanup old config files
+        for name in ('conf', 'pid', 'lease'):
+            if os.path.isfile(self._dhcp[4][name]):
+                os.remove(self._dhcp[4][name])
+
+    def _set_dhcpv6(self):
+        """
+        Configure interface as DHCPv6 client. The dhclient binary is automatically
+        started in background!
+
+        Example:
+
+        >>> from vyos.ifconfig import Interface
+        >>> j = Interface('eth0')
+        >>> j.set_dhcpv6()
+        """
+        dhcpv6 = self.get_dhcpv6_options()
+
+        # better save then sorry .. should be checked in interface script
+        # but if you missed it we are safe!
+        if dhcpv6['dhcpv6_prm_only'] and dhcpv6['dhcpv6_temporary']:
+            raise Exception(
+                'DHCPv6 temporary and parameters-only options are mutually exclusive!')
+
+        # render DHCP configuration
+        tmpl = jinja2.Template(template_v6)
+        dhcpv6_text = tmpl.render(dhcpv6)
+        with open(self._dhcp[6]['conf'], 'w') as f:
+            f.write(dhcpv6_text)
+
+        # no longer accept router announcements on this interface
+        self._write_sysfs(self._dhcp[6]['accept_ra'], 0)
+
+        # assemble command-line to start DHCPv6 client (dhclient)
+        cmd = 'start-stop-daemon'
+        cmd += ' --start'
+        cmd += ' --oknodo'
+        cmd += ' --quiet'
+        cmd += ' --pidfile {pid}'
+        cmd += ' --exec /sbin/dhclient'
+        cmd += ' --'
+        # now pass arguments to dhclient binary
+        cmd += ' -6 -nw -cf {conf} -pf {pid} -lf {lease}'
+        # add optional arguments
+        if dhcpv6['dhcpv6_prm_only']:
+            cmd += ' -S'
+        if dhcpv6['dhcpv6_temporary']:
+            cmd += ' -T'
+        cmd += ' {ifname}'
+
+        return self._cmd(cmd.format(**self._dhcp[6]))
+
+    def _del_dhcpv6(self):
+        """
+        De-configure interface as DHCPv6 clinet. All auto generated files like
+        pid, config and lease will be removed.
+
+        Example:
+
+        >>> from vyos.ifconfig import Interface
+        >>> j = Interface('eth0')
+        >>> j.del_dhcpv6()
+        """
+        if not os.path.isfile(self._dhcp[6]['pid']):
+            self._debug_msg('No DHCPv6 client PID found')
+            return None
+
+		# with open(self._dhcp[6]['pid'], 'r') as f:
+		# 	pid = int(f.read())
+
+        # stop dhclient
+        cmd = 'start-stop-daemon'
+        cmd += ' --start'
+        cmd += ' --oknodo'
+        cmd += ' --quiet'
+        cmd += ' --pidfile {pid}'
+        self._cmd(cmd.format(**self._dhcp[6]))
+
+        # accept router announcements on this interface
+        self._write_sysfs(self._dhcp[6]['accept_ra'], 1)
+
+        # cleanup old config files
+        for name in ('conf', 'pid', 'lease'):
+            if os.path.isfile(self._dhcp[6][name]):
+                os.remove(self._dhcp[6][name])
+