From 57dfa999f77d84a184960d3c2095c6c1d28c8a4e Mon Sep 17 00:00:00 2001
From: Thomas Haller <thaller@redhat.com>
Date: Tue, 21 Jun 2022 10:31:02 +0200
Subject: [PATCH] dhcp/nettools: accept missing "subnet mask" (option 1) in
 DHCP lease

Do the same as dhclient plugin in nm_dhcp_utils_ip4_config_from_options().

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/1037
---
 src/core/dhcp/nm-dhcp-nettools.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/src/core/dhcp/nm-dhcp-nettools.c b/src/core/dhcp/nm-dhcp-nettools.c
index 224f96d37..0a25f90d2 100644
--- a/src/core/dhcp/nm-dhcp-nettools.c
+++ b/src/core/dhcp/nm-dhcp-nettools.c
@@ -237,20 +237,26 @@ lease_parse_address(NDhcp4ClientLease *lease,
     }
 
     r = _client_lease_query(lease, NM_DHCP_OPTION_DHCP4_SUBNET_MASK, &l_data, &l_data_len);
-    if (r != 0
-        || !nm_dhcp_lease_data_parse_in_addr(l_data,
-                                             l_data_len,
-                                             &a_netmask,
-                                             iface,
-                                             NM_DHCP_OPTION_DHCP4_SUBNET_MASK)) {
-        nm_utils_error_set_literal(error,
-                                   NM_UTILS_ERROR_UNKNOWN,
-                                   "could not get netmask from lease");
-        return FALSE;
+    if (r == N_DHCP4_E_UNSET) {
+        /* Some DHCP servers may not set the subnet-mask (issue#1037).
+         * Do the same as the dhclient plugin and use a default. */
+        a_plen    = _nm_utils_ip4_get_default_prefix(a_address.s_addr);
+        a_netmask = _nm_utils_ip4_prefix_to_netmask(a_plen);
+    } else {
+        if (r != 0
+            || !nm_dhcp_lease_data_parse_in_addr(l_data,
+                                                 l_data_len,
+                                                 &a_netmask,
+                                                 iface,
+                                                 NM_DHCP_OPTION_DHCP4_SUBNET_MASK)) {
+            nm_utils_error_set_literal(error,
+                                       NM_UTILS_ERROR_UNKNOWN,
+                                       "could not get netmask from lease");
+            return FALSE;
+        }
+        a_plen = _nm_utils_ip4_netmask_to_prefix(a_netmask);
     }
 
-    a_plen = _nm_utils_ip4_netmask_to_prefix(a_netmask);
-
     nm_dhcp_option_add_option_in_addr(options,
                                       AF_INET,
                                       NM_DHCP_OPTION_DHCP4_NM_IP_ADDRESS,