From 05aa22dcb4ce54e3fb9909eddaa2aca3a6ac206e Mon Sep 17 00:00:00 2001
From: Christian Poessinger <christian@poessinger.com>
Date: Sun, 7 Nov 2021 19:54:09 +0100
Subject: protocols: static: T3680: do not delete DHCP received routes

An ISC DHCP hook script is used to install the received default route into FRR
by simple calls to vtysh. By moving to frr-reload.py the DHCP default route
was deleted as it was not found in the running config.

This commit checks all interfaces if DHCP is enabled and if so - will dynamically
add the route to the generated FRR configuration.
---
 data/templates/frr/staticd.frr.tmpl |  9 +++++++++
 python/vyos/configdict.py           | 35 +++++++++++++++++++++++++++++++++++
 src/conf_mode/protocols_static.py   |  5 +++++
 3 files changed, 49 insertions(+)

diff --git a/data/templates/frr/staticd.frr.tmpl b/data/templates/frr/staticd.frr.tmpl
index db59a44c2..bfe959c1d 100644
--- a/data/templates/frr/staticd.frr.tmpl
+++ b/data/templates/frr/staticd.frr.tmpl
@@ -15,6 +15,15 @@ vrf {{ vrf }}
 {{ static_routes(ip_prefix, prefix, prefix_config) }}
 {%-   endfor -%}
 {% endif %}
+{# IPv4 default routes from DHCP interfaces #}
+{% if dhcp is defined and dhcp is not none %}
+{%   for interface in dhcp %}
+{%     set next_hop = interface | get_dhcp_router %}
+{%     if next_hop is defined and next_hop is not none %}
+{{ ip_prefix }} route 0.0.0.0/0 {{ next_hop }} {{ interface }} tag 210 210
+{%     endif %}
+{%   endfor %}
+{% endif %}
 {# IPv6 routing #}
 {% if route6 is defined and route6 is not none %}
 {%   for prefix, prefix_config in route6.items() %}
diff --git a/python/vyos/configdict.py b/python/vyos/configdict.py
index e8a87bc38..998c10bb5 100644
--- a/python/vyos/configdict.py
+++ b/python/vyos/configdict.py
@@ -316,6 +316,41 @@ def is_source_interface(conf, interface, intftype=None):
     old_level = conf.set_level(old_level)
     return ret_val
 
+def get_dhcp_interfaces(conf, vrf=None):
+    """ Common helper functions to retrieve all interfaces from current CLI
+    sessions that have DHCP configured. """
+    dhcp_interfaces = []
+    dict = conf.get_config_dict(['interfaces'], get_first_key=True)
+    if not dict:
+        return dhcp_interfaces
+
+def check_dhcp(config, ifname):
+    out = []
+    if 'address' in config and 'dhcp' in config['address']:
+        if 'vrf' in config and vrf is config['vrf']:
+            out.append(ifname)
+        else:
+            out.append(ifname)
+    return out
+
+    for section, interface in dict.items():
+        for ifname, ifconfig in interface.items():
+            tmp = check_dhcp(ifconfig, ifname)
+            dhcp_interfaces.extend(tmp)
+            # check per VLAN interfaces
+            for vif, vif_config in ifconfig.get('vif', {}).items():
+                tmp = check_dhcp(vif_config, f'{ifname}.{vif}')
+                dhcp_interfaces.extend(tmp)
+            # check QinQ VLAN interfaces
+            for vif_s, vif_s_config in ifconfig.get('vif-s', {}).items():
+                tmp = check_dhcp(vif_s_config, f'{ifname}.{vif_s}')
+                dhcp_interfaces.extend(tmp)
+                for vif_c, vif_c_config in vif_s_config.get('vif-c', {}).items():
+                    tmp = check_dhcp(vif_c_config, f'{ifname}.{vif_s}.{vif_c}')
+                    dhcp_interfaces.extend(tmp)
+
+    return dhcp_interfaces
+
 def get_interface_dict(config, base, ifname=''):
     """
     Common utility function to retrieve and mangle the interfaces configuration
diff --git a/src/conf_mode/protocols_static.py b/src/conf_mode/protocols_static.py
index 597fcc443..f010141e9 100755
--- a/src/conf_mode/protocols_static.py
+++ b/src/conf_mode/protocols_static.py
@@ -21,6 +21,7 @@ from sys import argv
 
 from vyos.config import Config
 from vyos.configdict import dict_merge
+from vyos.configdict import get_dhcp_interfaces
 from vyos.configverify import verify_common_route_maps
 from vyos.configverify import verify_vrf
 from vyos.template import render_to_string
@@ -56,6 +57,10 @@ def get_config(config=None):
     # Merge policy dict into "regular" config dict
     static = dict_merge(tmp, static)
 
+    # T3680 - get a list of all interfaces currently configured to use DHCP
+    tmp = get_dhcp_interfaces(conf, vrf)
+    if tmp: static['dhcp'] = tmp
+
     return static
 
 def verify(static):
-- 
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