Merge pull request #5503 from c-po/T9354

op-mode: T9354: replace "reset connection" with "reconnect interface"

3 files changed, 95 insertions, 2 deletions

diff --git a/src/op_mode/connect_disconnect.py b/src/op_mode/connect_disconnect.py
index 17cf9d7e0..e30f512a0 100755
--- a/src/op_mode/connect_disconnect.py
+++ b/src/op_mode/connect_disconnect.py
@@ -15,15 +15,22 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import os
+import re
 import argparse
 
+from argparse import SUPPRESS
 from psutil import process_iter
 
 from vyos.utils.process import call
+from vyos.utils.process import rc_cmd
 from vyos.utils.commit import commit_in_progress
 from vyos.utils.network import is_wwan_connected
 from vyos.utils.process import DEVNULL
 
+# Dialer interfaces we support - also sanitizes the name before it becomes
+# part of a systemd-run(1) command line
+dialer_interface_re = r'(pppoe|sstpc|wwan)\d+'
+
 def check_ppp_interface(interface):
     if not os.path.isfile(f'/etc/ppp/peers/{interface}'):
         print(f'Interface {interface} does not exist!')
@@ -80,6 +87,51 @@ def disconnect(interface):
     else:
         print(f'Unknown interface {interface}, cannot disconnect. Aborting!')
 
+def reconnect(interface):
+    """ Reconnect dialer interface """
+
+    if interface.startswith('pppoe') or interface.startswith('sstpc'):
+        check_ppp_interface(interface)
+        # Restarting the service hangs up and dials again in one operation,
+        # leaving no window in which we could be interrupted with the link down
+        print(f'Interface {interface}: reconnecting...')
+        call(f'systemctl restart ppp@{interface}.service')
+    elif interface.startswith('wwan'):
+        # The modem must be disconnected before it can be dialed again
+        disconnect(interface)
+        connect(interface)
+    else:
+        print(f'Unknown interface {interface}, cannot reconnect. Aborting!')
+
+def reconnect_detached(interface):
+    """ Reconnect dialer interface from a transient systemd unit.
+
+    A reconnect is usually issued via the very interface being reconnected.
+    Once the link drops, the calling session dies and this process would be
+    killed by SIGHUP - or SIGPIPE on the next write to the dead terminal -
+    before the interface is dialed again, leaving the system unreachable. """
+
+    if not re.fullmatch(dialer_interface_re, interface):
+        print(f'Unknown interface {interface}, cannot reconnect. Aborting!')
+        exit(1)
+
+    unit = f'vyos-reconnect-{interface}'
+    command = (
+        f'systemd-run --quiet --collect --unit={unit} '
+        f'{os.path.abspath(__file__)} --reconnect --detached '
+        f'--interface {interface}'
+    )
+
+    rc, output = rc_cmd(command)
+    if rc != 0:
+        print(f'Interface {interface}: cannot reconnect: {output}')
+        exit(1)
+
+    print(
+        f'Interface {interface}: reconnecting in the background, this session '
+        f'may be disconnected. Progress is logged to journal unit {unit}.'
+    )
+
 def main():
     parser = argparse.ArgumentParser()
     group = parser.add_mutually_exclusive_group()
@@ -87,6 +139,8 @@ def main():
     group.add_argument("--disconnect", help="Take down connection-oriented network interface", action="store_true")
     group.add_argument("--reconnect", help="Reconnect connection-oriented network interface", action="store_true")
     parser.add_argument("--interface", help="Interface name", action="store", required=True)
+    # Set only when we re-launch ourself detached from the calling session
+    parser.add_argument('--detached', action='store_true', help=SUPPRESS)
     args = parser.parse_args()
 
     # Disallow connecting interfaces while their configuration might be changing
@@ -100,8 +154,10 @@ def main():
     elif args.disconnect:
         disconnect(args.interface)
     elif args.reconnect:
-        disconnect(args.interface)
-        connect(args.interface)
+        if args.detached:
+            reconnect(args.interface)
+        else:
+            reconnect_detached(args.interface)
     else:
         parser.print_help()
 
diff --git a/src/services/api/rest/models.py b/src/services/api/rest/models.py
index 8321ad2e3..8762c3bff 100644
--- a/src/services/api/rest/models.py
+++ b/src/services/api/rest/models.py
@@ -291,6 +291,20 @@ class ResetModel(ApiModel):
         }
 
 
+class ReconnectModel(ApiModel):
+    op: StrictStr
+    path: List[StrictStr]
+
+    class Config:
+        json_schema_extra = {
+            'example': {
+                'key': 'id_key',
+                'op': 'reconnect',
+                'path': ['op', 'mode', 'path'],
+            }
+        }
+
+
 class PoweroffModel(ApiModel):
     op: StrictStr
     path: List[StrictStr]
diff --git a/src/services/api/rest/routers.py b/src/services/api/rest/routers.py
index 1808e5a5b..c2aa033bc 100644
--- a/src/services/api/rest/routers.py
+++ b/src/services/api/rest/routers.py
@@ -74,6 +74,7 @@ from .models import GenerateModel
 from .models import ShowModel
 from .models import RebootModel
 from .models import ResetModel
+from .models import ReconnectModel
 from .models import RenewModel
 from .models import ImportPkiModel
 from .models import PingModel
@@ -934,6 +935,28 @@ def reset_op(data: ResetModel):
     return success(res)
 
 
+@router.post('/reconnect')
+def reconnect_op(data: ReconnectModel):
+    state = SessionState()
+    session = state.session
+
+    op = data.op
+    path = data.path
+
+    try:
+        if op == 'reconnect':
+            res = session.reconnect(path)
+        else:
+            return error(400, f"'{op}' is not a valid operation")
+    except ConfigSessionError as e:
+        return error(400, str(e))
+    except Exception:
+        LOG.critical(traceback.format_exc())
+        return error(500, 'An internal error occurred. Check the logs for details.')
+
+    return success(res)
+
+
 @router.post('/import-pki')
 def import_pki(data: ImportPkiModel):
     # pylint: disable=consider-using-with