T2719: prototype of an op mode command runner

based on type hints and introspection

5 files changed, 153 insertions, 28 deletions

diff --git a/op-mode-definitions/ipv6-route.xml.in b/op-mode-definitions/ipv6-route.xml.in
index 4f8792f9f..50f34dd56 100644
--- a/op-mode-definitions/ipv6-route.xml.in
+++ b/op-mode-definitions/ipv6-route.xml.in
@@ -20,7 +20,7 @@
             <properties>
               <help>Show IPv6 neighbor (NDP) table</help>
             </properties>
-            <command>${vyos_op_scripts_dir}/show_neigh.py --family inet6</command>
+            <command>${vyos_op_scripts_dir}/neighbor.py --family inet6</command>
             <children>
               <tagNode name="interface">
                 <properties>
@@ -29,7 +29,7 @@
                     <script>${vyos_completion_dir}/list_interfaces.py -b</script>
                   </completionHelp>
                 </properties>
-                <command>${vyos_op_scripts_dir}/show_neigh.py --family inet6 --interface "$5"</command>
+                <command>${vyos_op_scripts_dir}/neighbor.py --family inet6 --interface "$5"</command>
               </tagNode>
               <tagNode name="state">
                 <properties>
@@ -38,7 +38,7 @@
                     <list>reachable stale failed permanent</list>
                   </completionHelp>
                 </properties>
-                <command>${vyos_op_scripts_dir}/show_neigh.py --family inet6 --state "$5"</command>
+                <command>${vyos_op_scripts_dir}/neighbor.py --family inet6 --state "$5"</command>
               </tagNode>
             </children>
           </node>
diff --git a/op-mode-definitions/show-arp.xml.in b/op-mode-definitions/show-arp.xml.in
index 58cc6e45e..11ac6a252 100644
--- a/op-mode-definitions/show-arp.xml.in
+++ b/op-mode-definitions/show-arp.xml.in
@@ -6,7 +6,7 @@
         <properties>
           <help>Show Address Resolution Protocol (ARP) information</help>
         </properties>
-        <command>${vyos_op_scripts_dir}/show_neigh.py --family inet</command>
+        <command>${vyos_op_scripts_dir}/neighbor.py --family inet</command>
         <children>
           <tagNode name="interface">
             <properties>
@@ -15,7 +15,7 @@
                 <script>${vyos_completion_dir}/list_interfaces.py -b</script>
               </completionHelp>
             </properties>
-            <command>${vyos_op_scripts_dir}/show_neigh.py --family inet --interface "$4"</command>
+            <command>${vyos_op_scripts_dir}/neighbor.py --family inet --interface "$4"</command>
           </tagNode>
         </children>
       </node>
diff --git a/op-mode-definitions/show-ip.xml.in b/op-mode-definitions/show-ip.xml.in
index d342ac192..1903aca05 100644
--- a/op-mode-definitions/show-ip.xml.in
+++ b/op-mode-definitions/show-ip.xml.in
@@ -11,7 +11,7 @@
             <properties>
               <help>Show IPv4 neighbor (ARP) table</help>
             </properties>
-            <command>${vyos_op_scripts_dir}/show_neigh.py --family inet</command>
+            <command>${vyos_op_scripts_dir}/neighbor.py --family inet</command>
             <children>
               <tagNode name="interface">
                 <properties>
@@ -20,7 +20,7 @@
                     <script>${vyos_completion_dir}/list_interfaces.py -b</script>
                   </completionHelp>
                 </properties>
-                <command>${vyos_op_scripts_dir}/show_neigh.py --family inet --interface "$5"</command>
+                <command>${vyos_op_scripts_dir}/neighbor.py --family inet --interface "$5"</command>
               </tagNode>
               <tagNode name="state">
                 <properties>
@@ -29,7 +29,7 @@
                     <list>reachable stale failed permanent</list>
                   </completionHelp>
                 </properties>
-                <command>${vyos_op_scripts_dir}/show_neigh.py --family inet --state "$5"</command>
+                <command>${vyos_op_scripts_dir}/neighbor.py --family inet --state "$5"</command>
               </tagNode>
             </children>
           </node>
diff --git a/python/vyos/opmode.py b/python/vyos/opmode.py
new file mode 100644
index 000000000..c0812c7fd
--- /dev/null
+++ b/python/vyos/opmode.py
@@ -0,0 +1,123 @@
+# Copyright 2022 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 typing
+
+
+def _is_op_mode_function_name(name):
+    from re import match
+
+    if match(r"^(show|clear|reset|restart)", name):
+        return True
+    else:
+        return False
+
+def _is_show(name):
+    from re import match
+
+    if match(r"^show", name):
+        return True
+    else:
+        return False
+
+def _get_op_mode_functions(module):
+    from inspect import getmembers, isfunction
+
+    # Get all functions in that module
+    funcs = getmembers(module, isfunction)
+
+    # getmembers returns (name, func) tuples
+    funcs = list(filter(lambda ft: _is_op_mode_function_name(ft[0]), funcs))
+
+    funcs_dict = {}
+    for (name, thunk) in funcs:
+        funcs_dict[name] = thunk
+
+    return funcs_dict
+
+def _is_optional_type(t):
+    # Optional[t] is internally an alias for Union[t, NoneType]
+    # and there's no easy way to get union members it seems
+    if (type(t) == typing._UnionGenericAlias):
+        if (len(t.__args__) == 2):
+            if t.__args__[1] == type(None):
+                return True
+
+    return False
+
+def _get_arg_type(t):
+    """ Returns the type itself if it's a primitive type,
+        or the "real" type of typing.Optional
+
+       Doesn't work with anything else at the moment!
+    """
+    if _is_optional_type(t):
+        t.__args__[0]
+    else:
+        return t
+
+def run(module):
+    from argparse import ArgumentParser
+
+    functions = _get_op_mode_functions(module)
+
+    parser = ArgumentParser()
+    subparsers = parser.add_subparsers(dest="subcommand")
+
+    for function_name in functions:
+        subparser = subparsers.add_parser(function_name, help=functions[function_name].__doc__)
+
+        type_hints = typing.get_type_hints(functions[function_name])
+        for opt in type_hints:
+            th = type_hints[opt]
+
+            # Show commands require an option to choose between raw JSON and human-readable
+            # formatted output.
+            # For interactive use, they default to formatted output.
+            if (function_name == "show") and (opt == "raw"):
+                subparser.add_argument(f"--raw",  action='store_true')
+            elif _is_optional_type(th):
+                subparser.add_argument(f"--{opt}", type=_get_arg_type(th), default=None)
+            else:
+                subparser.add_argument(f"--{opt}", type=_get_arg_type(th), required=True)
+
+    # Get options as a dict rather than a namespace,
+    # so that we can modify it and pack for passing to functions
+    args = vars(parser.parse_args())
+
+    func = functions[args["subcommand"]]
+
+    # Remove the subcommand from the arguments,
+    # it would cause an extra argument error when we pass the dict to a function
+    del args["subcommand"]
+
+    if "raw" not in args:
+        args["raw"] = False
+
+    if function_name == "show":
+        # Show commands are slightly special:
+        # they may return human-formatted output
+        # or a raw dict that we need to serialize in JSON for printing
+        res = func(**args)
+        if not args["raw"]:
+            return res
+        else:
+            from json import dumps
+            return dumps(res, indent=4)
+    else:
+        # Other functions should not return anything,
+        # although they may print their own warnings or status messages
+        func(**args)
+
diff --git a/src/op_mode/show_neigh.py b/src/op_mode/neighbor.py
index d874bd544..b50e75d91 100755
--- a/src/op_mode/show_neigh.py
+++ b/src/op_mode/neighbor.py
@@ -28,29 +28,32 @@
 # ]
 
 import sys
+import typing
 
+import opmode
 
-def get_raw_data(family, device=None, state=None):
+
+def get_raw_data(family, interface=None, state=None):
     from json import loads
     from vyos.util import cmd
 
-    if device:
-        device = f"dev {device}"
+    if interface:
+        interface = f"dev {interface}"
     else:
-        device = ""
+        interface = ""
 
     if state:
         state = f"nud {state}"
     else:
         state = ""
 
-    neigh_cmd = f"ip --family {family} --json neighbor list {device} {state}"
+    neigh_cmd = f"ip --family {family} --json neighbor list {interface} {state}"
 
     data = loads(cmd(neigh_cmd))
 
     return data
 
-def get_formatted_output(family, device=None, state=None):
+def format_neighbors(neighs, interface=None):
     from tabulate import tabulate
 
     def entry_to_list(e, intf=None):
@@ -68,35 +71,34 @@ def get_formatted_output(family, device=None, state=None):
         # Device field is absent from outputs of `ip neigh list dev ...`
         if "dev" in e:
             dev = e["dev"]
-        elif device:
-            dev = device
+        elif interface:
+            dev = interface
         else:
             raise ValueError("interface is not defined")
 
         return [dst, dev, lladdr, state]
 
-    neighs = get_raw_data(family, device=device, state=state)
     neighs = map(entry_to_list, neighs)
 
     headers = ["Address", "Interface", "Link layer address",  "State"]
     return tabulate(neighs, headers)
 
-if __name__ == '__main__':
-    from argparse import ArgumentParser
+def show(raw: bool, family: str, interface: typing.Optional[str], state: typing.Optional[str]):
+    """ Display neighbor table contents """
+    data = get_raw_data(family, interface, state=state)
 
-    parser = ArgumentParser()
-    parser.add_argument("-f", "--family", type=str, default="inet", help="Address family")
-    parser.add_argument("-i", "--interface", type=str, help="Network interface")
-    parser.add_argument("-s", "--state", type=str, help="Neighbor table entry state")
+    if raw:
+        return data
+    else:
+        return format_neighbors(data, interface)
 
-    args = parser.parse_args()
 
-    if args.state:
-        if args.state not in ["reachable", "failed", "stale", "permanent"]:
-            raise ValueError(f"""Incorrect state "{args.state}"! Must be one of: reachable, stale, failed, permanent""")
+if __name__ == '__main__':
+    from argparse import ArgumentParser
 
     try:
-        print(get_formatted_output(args.family, device=args.interface, state=args.state))
+        print(opmode.run(sys.modules[__name__]))
     except ValueError as e:
         print(e)
         sys.exit(1)
+