T849: move BGP peer-group node to ipv4 address family

To have a consitent IPv4/IPv6 CLI a lot of BGP neighbor nodes have been
migrated. The IPv4 peer-group has been forgotten, leaving a non consistent CLI.

Previously:
-----------

neighbor 2001:DB8:FFFF::1 {
     address-family {
         ipv6-unicast {
             peer-group iBGP
         }
     }
     peer-group iBGP
}

Now:
----

neighbor 2001:DB8:FFFF::1 {
     address-family {
         ipv6-unicast {
             peer-group iBGP
         }
     }
     address-family {
         ipv4-unicast {
             peer-group iBGP
         }
     }
}

1 files changed, 75 insertions, 0 deletions

diff --git a/src/migration-scripts/quagga/3-to-4 b/src/migration-scripts/quagga/3-to-4
new file mode 100755
index 000000000..b8ba8351b
--- /dev/null
+++ b/src/migration-scripts/quagga/3-to-4
@@ -0,0 +1,75 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2019 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/>.
+#
+#
+
+import sys
+from vyos.configtree import ConfigTree
+
+if (len(sys.argv) < 1):
+    print("Must specify file name!")
+    sys.exit(1)
+
+file_name = sys.argv[1]
+
+with open(file_name, 'r') as f:
+    config_file = f.read()
+
+config = ConfigTree(config_file)
+
+def migrate_neighbor(config, neighbor_path, neighbor):
+    if config.exists(neighbor_path):
+        neighbors = config.list_nodes(neighbor_path)
+        for neighbor in neighbors:
+            # Move peer-group
+            if config.exists(neighbor_path + [neighbor, 'peer-group']):
+                peer_group = config.return_value(neighbor_path + [neighbor, 'peer-group'])
+                config.set(neighbor_path + [neighbor] + af_path + ['peer-group'], value=peer_group)
+                config.delete(neighbor_path + [neighbor, 'peer-group'])
+
+if not config.exists(['protocols', 'bgp']):
+    # Nothing to do
+    sys.exit(0)
+else:
+    # Just to avoid writing it so many times
+    af_path = ['address-family', 'ipv4-unicast']
+
+    # Check if BGP is actually configured and obtain the ASN
+    asn_list = config.list_nodes(['protocols', 'bgp'])
+    if asn_list:
+        # There's always just one BGP node, if any
+        asn = asn_list[0]
+        bgp_path = ['protocols', 'bgp', asn]
+    else:
+        # There's actually no BGP, just its empty shell
+        sys.exit(0)
+
+    ## Move global IPv4-specific BGP options to "address-family ipv4-unicast"
+
+    ## Migrate neighbor options
+    neighbor_path = ['protocols', 'bgp', asn, 'neighbor']
+    if config.exists(neighbor_path):
+        neighbors = config.list_nodes(neighbor_path)
+        for neighbor in neighbors:
+            migrate_neighbor(config, neighbor_path, neighbor)
+
+    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))
+        sys.exit(1)