tunnel: T3364: rename encapsulation mode "gre-bridge" to "gretap"

The following list shows the mapping of VyOS tunnel encapsulation modes to the
corresponding Linux modes.

VyOS        Linux
gre         gre
gre-bridge  gretap
ipip        ipip
ipip6       ipip6
ip6ip6      ip6ip6
ip6gre      ip6gre
sit         sit

Besides gre-bridge this is pretty consistent. As bridge interfaces are also
called tap interfaces gre-bridge will be renamed to gretap to make the
post-processing much easier.

This means (in detail) that there are no more child classes of _Tunnel and
there will be now one geneirc TunnelIf class handling all sorts of encapsulation.

2 files changed, 75 insertions, 29 deletions

diff --git a/src/conf_mode/interfaces-tunnel.py b/src/conf_mode/interfaces-tunnel.py
index ae28f5101..2d2f29f94 100755
--- a/src/conf_mode/interfaces-tunnel.py
+++ b/src/conf_mode/interfaces-tunnel.py
@@ -31,21 +31,25 @@ from vyos.configverify import verify_mtu_ipv6
 from vyos.configverify import verify_vrf
 from vyos.configverify import verify_tunnel
 from vyos.ifconfig import Interface
-from vyos.ifconfig import GREIf
-from vyos.ifconfig import GRETapIf
-from vyos.ifconfig import IPIPIf
-from vyos.ifconfig import IP6GREIf
-from vyos.ifconfig import IPIP6If
-from vyos.ifconfig import IP6IP6If
-from vyos.ifconfig import SitIf
-from vyos.ifconfig import Sit6RDIf
+from vyos.ifconfig import TunnelIf
 from vyos.template import is_ipv4
 from vyos.template import is_ipv6
+from vyos.util import cmd
 from vyos.util import dict_search
 from vyos import ConfigError
 from vyos import airbag
 airbag.enable()
 
+def get_tunnel_encapsulation(interface):
+    """ Returns the used encapsulation protocol for given interface.
+        If interface does not exist, None is returned.
+    """
+    if not os.path.exists(f'/sys/class/net/{interface}'):
+        return None
+    from json import loads
+    tmp = loads(cmd(f'ip -d -j link show {interface}'))[0]
+    return tmp['linkinfo']['info_kind']
+
 def get_config(config=None):
     """
     Retrive CLI config as dictionary. Dictionary can never be empty, as at least
@@ -79,8 +83,8 @@ def verify(tunnel):
         return None
 
     if 'encapsulation' not in tunnel:
-        raise ConfigError('Must configure the tunnel encapsulation for '\
-                          '{ifname}!'.format(**tunnel))
+        error = 'Must configure encapsulation for "{ifname}"!'
+        raise ConfigError(error.format(**tunnel))
 
     verify_mtu_ipv6(tunnel)
     verify_address(tunnel)
@@ -103,29 +107,20 @@ def generate(tunnel):
     return None
 
 def apply(tunnel):
-    if 'deleted' in tunnel or 'encapsulation_changed' in tunnel:
-        if tunnel['ifname'] in interfaces():
-            tmp = Interface(tunnel['ifname'])
+    interface = tunnel['ifname']
+    # If a gretap tunnel is already existing we can not "simply" change local or
+    # remote addresses. This returns "Operation not supported" by the Kernel.
+    # There is no other solution to destroy and recreate the tunnel.
+    encap = get_tunnel_encapsulation(interface)
+
+    if 'deleted' in tunnel or 'encapsulation_changed' in tunnel or encap == 'gretap':
+        if interface in interfaces():
+            tmp = Interface(interface)
             tmp.remove()
         if 'deleted' in tunnel:
             return None
 
-    dispatch = {
-        'gre': GREIf,
-        'gre-bridge': GRETapIf,
-        'ipip': IPIPIf,
-        'ipip6': IPIP6If,
-        'ip6ip6': IP6IP6If,
-        'ip6gre': IP6GREIf,
-        'sit': SitIf,
-    }
-
-    # We need to re-map the tunnel encapsulation proto to a valid interface class
-    encap = tunnel['encapsulation']
-    klass = dispatch[encap]
-
-    tun = klass(**tunnel)
-    tun.change_options()
+    tun = TunnelIf(**tunnel)
     tun.update(tunnel)
 
     return None
diff --git a/src/migration-scripts/interfaces/19-to-20 b/src/migration-scripts/interfaces/19-to-20
new file mode 100755
index 000000000..be42cdd61
--- /dev/null
+++ b/src/migration-scripts/interfaces/19-to-20
@@ -0,0 +1,51 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2021 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from sys import argv
+from sys import exit
+from vyos.configtree import ConfigTree
+
+if __name__ == '__main__':
+    if (len(argv) < 1):
+        print("Must specify file name!")
+        exit(1)
+
+    file_name = argv[1]
+    with open(file_name, 'r') as f:
+        config_file = f.read()
+
+    config = ConfigTree(config_file)
+    base = ['interfaces', 'tunnel']
+
+    if not config.exists(base):
+        # Nothing to do
+        exit(0)
+
+    #
+    # Migrate "interface tunnel <tunX> encapsulation gre-bridge" to gretap
+    for interface in config.list_nodes(base):
+        path = base + [interface, 'encapsulation']
+        if config.exists(path):
+            tmp = config.return_value(path)
+            if tmp == 'gre-bridge':
+                config.set(path, value='gretap')
+
+    try:
+        with open(file_name, 'w') as f:
+            f.write(config.to_string())
+    except OSError as e:
+        print("Failed to save the modified config: {}".format(e))
+        exit(1)