Merge pull request #5499 from c-po/wwan-improvements

wwan: T9350: possible dead interface after boot, disconnect does not stick

1 files changed, 180 insertions, 0 deletions

diff --git a/python/vyos/utils/wwan.py b/python/vyos/utils/wwan.py
new file mode 100644
index 000000000..d8da34bfa
--- /dev/null
+++ b/python/vyos/utils/wwan.py
@@ -0,0 +1,180 @@
+# Copyright (C) VyOS Inc.
+#
+# 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/>.
+
+"""ModemManager helpers shared between the WWAN conf_mode script and
+vyos-netlinkd.
+
+Both dial the very same modem with the very same parameters - conf_mode when
+the CLI config is applied, vyos-netlinkd when a session has to be re-
+established after it was lost. Keeping the option string and the mmcli
+invocations in one place means a re-dial can never drift from what conf_mode
+would have done.
+"""
+
+import os
+
+from time import sleep
+
+from vyos.utils.dict import dict_search
+from vyos.utils.process import call
+from vyos.utils.process import cmdl
+from vyos.utils.process import DEVNULL
+from vyos.utils.process import is_systemd_service_active
+
+service_name = 'ModemManager.service'
+
+# Bounded wait for a modem to become dialable. Neither the service being up
+# nor the modem being listed is enough: it is exported on the bus as soon as
+# it is created and reports state 'unknown' until probing finishes, and a dial
+# in that window is refused. An HP lt4132 needed 33s of that, two 10s MBIM
+# timeouts of it, so the budget is generous - it is only ever spent on a modem
+# that is not answering.
+modem_wait_timeout = 60
+modem_wait_poll = 0.250
+
+# Markers for WWAN interfaces the operator has taken down with op-mode
+# "disconnect interface wwanN". vyos-netlinkd re-dials every configured
+# interface that has lost its session, which would otherwise bring the
+# interface back up within one reconcile interval and make the disconnect look
+# like it never happened. Kept in /run - a manual disconnect is not meant to
+# survive a reboot, and a commit re-asserts the configured state too.
+admin_disconnect_dir = '/run/vyos-wwan'
+
+def modem_index(ifname: str) -> str:
+    """ Return the ModemManager modem index backing an interface, wwan0 -> 0 """
+    if not ifname.startswith('wwan'):
+        raise ValueError(f'Specified interface "{ifname}" is not a WWAN interface')
+    return ifname[len('wwan'):]
+
+def modem_state(index: str) -> str:
+    """ ModemManager state of a modem, empty if it cannot be read yet """
+    try:
+        tmp = cmdl(['mmcli', '--output-keyvalue', '--modem', index])
+    except OSError:
+        # up but not yet answering on the bus, or no such modem
+        return ''
+
+    for line in tmp.splitlines():
+        key, _, value = line.partition(':')
+        if key.strip() == 'modem.generic.state':
+            return value.strip()
+    return ''
+
+def start_modem_manager(ifname: str) -> None:
+    """ ModemManager is required to dial WWAN connections - a single instance
+    serves all modems. Start it if it is not running yet, then wait until the
+    modem behind ifname will accept a dial.
+
+    Waiting on the service, or on the modem merely being listed, is not
+    enough - both are true long before probing finishes, and dialling then
+    leaves the interface without a session until something re-dials it. """
+    if not is_systemd_service_active(service_name):
+        cmdl(['systemctl', 'start', service_name])
+
+    index = modem_index(ifname)
+    counter = int(modem_wait_timeout / modem_wait_poll)
+    while counter > 0:
+        counter -= 1
+        # 'unknown' and 'initializing' are both reported while the modem is
+        # still being brought up. Every other state means it is done, including
+        # 'failed' - waiting out the budget would not improve that, and the dial
+        # reports it far better than a timeout here could
+        if modem_state(index) not in ('', 'unknown', 'initializing'):
+            break
+        sleep(modem_wait_poll)
+
+    return None
+
+def connect_options(config: dict) -> str:
+    """ Build the mmcli --simple-connect option string for a WWAN interface.
+
+    config is an interface configuration dict as returned by
+    get_interface_dict() in conf_mode or op_mode_config_dict() in an op-mode
+    context - both are key-mangled the same way, so both are accepted here.
+    """
+    ip_type = 'ipv4'
+    slaac = dict_search('ipv6.address.autoconf', config) != None
+    if 'address' in config:
+        if 'dhcp' in config['address'] and ('dhcpv6' in config['address'] or slaac):
+            ip_type = 'ipv4v6'
+        elif 'dhcpv6' in config['address'] or slaac:
+            ip_type = 'ipv6'
+        elif 'dhcp' in config['address']:
+            ip_type = 'ipv4'
+
+    options = f'ip-type={ip_type},apn=' + config['apn']
+    if 'authentication' in config:
+        options += ',user={username},password={password}'.format(**config['authentication'])
+
+    return options
+
+def _admin_disconnect_marker(ifname: str) -> str:
+    return os.path.join(admin_disconnect_dir, f'{ifname}.disconnected')
+
+def set_admin_disconnected(ifname: str) -> None:
+    """ Mark a WWAN interface as administratively disconnected, so it is left
+    alone by the re-dial pass in vyos-netlinkd """
+    # rejects anything that is not a WWAN interface, so a bogus name can never
+    # end up creating a file here
+    modem_index(ifname)
+    os.makedirs(admin_disconnect_dir, exist_ok=True)
+    with open(_admin_disconnect_marker(ifname), 'w'):
+        pass
+
+def clear_admin_disconnected(ifname: str) -> None:
+    """ Take a WWAN interface out of the administratively disconnected state """
+    modem_index(ifname)
+    try:
+        os.unlink(_admin_disconnect_marker(ifname))
+    except FileNotFoundError:
+        pass
+
+def is_admin_disconnected(ifname: str) -> bool:
+    """ True if a WWAN interface was taken down with op-mode "disconnect" and
+    has not been connected again since """
+    return os.path.exists(_admin_disconnect_marker(ifname))
+
+def modem_disconnect(ifname: str, quiet: bool = False) -> None:
+    """ Disconnect every bearer of the modem backing ifname. The number of
+    bearers a modem can hold is limited, so we always disconnect before we
+    dial again. """
+    call(f'mmcli --modem {modem_index(ifname)} --simple-disconnect',
+         stdout=DEVNULL if quiet else None,
+         stderr=DEVNULL if quiet else None)
+
+def modem_connect(ifname: str, options: str) -> bool:
+    """ Dial the modem backing ifname, returns True if the modem connected """
+    modem = modem_index(ifname)
+
+    # Some networks only ever admit a single combined IPv4+IPv6 PDN context per
+    # APN and reject a standalone IPv6 "Start Network" request outright (QMI
+    # CallEndReason ip-version-mismatch) once an IPv4 session already exists for
+    # that APN. ModemManager's --simple-connect with ip-type=ipv4v6 opens two
+    # separate WDS sessions (one per family) rather than negotiating both
+    # together, which is what a normal handset attach does and why this is
+    # invisible on most other devices.
+    #
+    # Pre-negotiating the attach-time PDN type upfront avoids the rejection; the
+    # resulting bearer only sets up what the *next* --simple-connect is allowed
+    # to request and can't be connected directly, so a failure here isn't fatal
+    # - unsupported modems simply proceed to --simple-connect exactly as before.
+    if options.partition('ip-type=')[2].partition(',')[0] in ('ipv6', 'ipv4v6'):
+        # best effort by definition, so do not report the rejection a modem
+        # without attach configuration support answers with on every dial
+        call(f'mmcli --modem {modem} --3gpp-set-initial-eps-bearer-settings="{options}"',
+             stdout=DEVNULL, stderr=DEVNULL)
+
+    command = f'mmcli --modem {modem} --simple-connect="{options}"'
+    return call(command, stdout=DEVNULL) == 0