wwan: T9350: properly disconnect "disconnect interface wwanN"

Two things kept an operator disconnect from taking effect.

vyos-netlinkd re-dials every configured WWAN interface that has lost its
session. It cannot tell a session lost to RF signal loss from one that was
taken down on purpose, so the disconnect was undone on the next reconcile
pass, at most 30 seconds later:

  $ disconnect interface wwan0
  08:53:33 t+10s state=registered
  08:53:43 t+20s state=registered
  08:53:53 t+30s state=connected     <- re-dialled
  08:54:03 t+40s state=connected

  vyos-netlinkd: WWAN interface wwan0 is not connected, re-dialling...
  vyos-netlinkd: Re-dialled WWAN interface wwan0

Record the intent instead of inferring it from the session state. op-mode
"disconnect" drops a marker in /run/vyos-wwan, which _reconcile_wwan() honours
and "connect" removes again. conf_mode removes it too, so a commit keeps
re-asserting the configured state - the marker only survives for as long as
nobody says otherwise, and never across a reboot.

3 files changed, 39 insertions, 3 deletions

diff --git a/src/conf_mode/interfaces_wwan.py b/src/conf_mode/interfaces_wwan.py
index 7e02d9d7a..dd5a1e8c3 100755
--- a/src/conf_mode/interfaces_wwan.py
+++ b/src/conf_mode/interfaces_wwan.py
@@ -30,6 +30,7 @@ from vyos.configverify import verify_mtu_ipv6
 from vyos.ifconfig import WWANIf
 from vyos.utils.network import is_wwan_connected
 from vyos.utils.process import cmdl
+from vyos.utils.wwan import clear_admin_disconnected
 from vyos.utils.wwan import connect_options
 from vyos.utils.wwan import modem_connect
 from vyos.utils.wwan import modem_disconnect
@@ -117,6 +118,11 @@ def generate(wwan):
     return None
 
 def apply(wwan):
+    # A commit re-asserts the configured state, so it also takes the interface
+    # out of the administratively disconnected state that op-mode "disconnect
+    # interface wwanN" put it in.
+    clear_admin_disconnected(wwan['ifname'])
+
     # ModemManager is required to dial WWAN connections - one instance is
     # required to serve all modems. Activate ModemManager on first invocation
     # of any WWAN interface.
diff --git a/src/op_mode/connect_disconnect.py b/src/op_mode/connect_disconnect.py
index 17cf9d7e0..9b43e4fd2 100755
--- a/src/op_mode/connect_disconnect.py
+++ b/src/op_mode/connect_disconnect.py
@@ -19,10 +19,13 @@ import argparse
 
 from psutil import process_iter
 
+from vyos.ifconfig import WWANIf
 from vyos.utils.process import call
 from vyos.utils.commit import commit_in_progress
 from vyos.utils.network import is_wwan_connected
-from vyos.utils.process import DEVNULL
+from vyos.utils.wwan import clear_admin_disconnected
+from vyos.utils.wwan import modem_disconnect
+from vyos.utils.wwan import set_admin_disconnected
 
 def check_ppp_interface(interface):
     if not os.path.isfile(f'/etc/ppp/peers/{interface}'):
@@ -52,6 +55,9 @@ def connect(interface):
             print(f'Interface {interface}: connecting...')
             call(f'systemctl restart ppp@{interface}.service')
     elif interface.startswith('wwan'):
+        # Take the interface out of the administratively disconnected state, so
+        # vyos-netlinkd re-dials it again should the session be lost later on
+        clear_admin_disconnected(interface)
         if is_wwan_connected(interface):
             print(f'Interface {interface}: already connected!')
         else:
@@ -72,11 +78,27 @@ def disconnect(interface):
             print(f'Interface {interface}: disconnecting...')
             call(f'systemctl stop ppp@{interface}.service')
     elif interface.startswith('wwan'):
+        # Keep the interface down until it is connected again. vyos-netlinkd
+        # re-dials every configured WWAN interface that lost its session, and
+        # would otherwise undo this disconnect on its next reconcile pass. The
+        # marker is set even when the session is already down, so a disconnect
+        # issued while the modem happens to be searching for a network is not
+        # silently ignored.
+        set_admin_disconnected(interface)
         if not is_wwan_connected(interface):
             print(f'Interface {interface}: connection is already down')
         else:
-            modem = interface.lstrip('wwan')
-            call(f'mmcli --modem {modem} --simple-disconnect', stdout=DEVNULL)
+            print(f'Interface {interface}: disconnecting...')
+            modem_disconnect(interface, quiet=True)
+
+        # Dropping the bearer does not touch the netdev - a cdc_mbim/qmi_wwan
+        # interface stays IFF_UP with carrier and an operstate of "unknown"
+        # once ModemManager is done, so it would keep reporting u/u and hold
+        # on to the address the DHCP client got for the session that just
+        # ended. Tear it down the same way conf_mode does for "disable".
+        w = WWANIf(interface)
+        if w.exists(interface):
+            w.remove()
     else:
         print(f'Unknown interface {interface}, cannot disconnect. Aborting!')
 
diff --git a/src/services/vyos-netlinkd b/src/services/vyos-netlinkd
index 5cce1ceff..4c91561d2 100755
--- a/src/services/vyos-netlinkd
+++ b/src/services/vyos-netlinkd
@@ -43,6 +43,7 @@ from vyos.utils.process import cmdl
 from vyos.utils.process import is_systemd_service_active
 from vyos.utils.process import stop_systemd_unit
 from vyos.utils.wwan import connect_options
+from vyos.utils.wwan import is_admin_disconnected
 from vyos.utils.wwan import modem_connect
 from vyos.utils.wwan import modem_disconnect
 from vyos.utils.wwan import start_modem_manager
@@ -370,6 +371,13 @@ def _reconcile_wwan() -> None:
             _wwan_clear_backoff(ifname)
             continue
 
+        # Do not undo an explicit op-mode "disconnect interface wwanN" - the
+        # session stays down until it is connected again or the configuration
+        # is re-applied by a commit.
+        if is_admin_disconnected(ifname):
+            _wwan_clear_backoff(ifname)
+            continue
+
         if is_wwan_connected(ifname):
             _wwan_clear_backoff(ifname)
             continue