From 43b27ab2c4735e35d84e6f5c90b8a79e23c05587 Mon Sep 17 00:00:00 2001
From: Thomas Haller <thaller@redhat.com>
Date: Thu, 9 Jun 2022 10:00:47 +0200
Subject: [PATCH 1/1] platform: workaround for preserving IPv6 address order
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/ ## 1021
---
src/libnm-platform/nm-platform.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/src/libnm-platform/nm-platform.c b/src/libnm-platform/nm-platform.c
index f264ed7a45b2..45534dd96a46 100644
--- a/src/libnm-platform/nm-platform.c
+++ b/src/libnm-platform/nm-platform.c
@@ -3978,11 +3978,26 @@ nm_platform_ip_address_sync(NMPlatform *self,
/* @plat_addresses for IPv6 must be sorted in decreasing priority order (highest priority addresses first).
* IPv4 are probably unsorted or sorted with lowest priority first, but their order doesn't matter because
* we check the "secondary" flag. */
- plat_addresses = nm_platform_lookup_clone(
- self,
- nmp_lookup_init_object(&lookup, NMP_OBJECT_TYPE_IP_ADDRESS(IS_IPv4), ifindex),
- NULL,
- NULL);
+ if (IS_IPv4) {
+ plat_addresses = nm_platform_lookup_clone(
+ self,
+ nmp_lookup_init_object(&lookup, NMP_OBJECT_TYPE_IP_ADDRESS(IS_IPv4), ifindex),
+ NULL,
+ NULL);
+ } else {
+ /* HACK: early 1.36 versions had a bug of not actually reordering the IPv6 addresses.
+ * This was fixed by commit cd4601802de5 ('platform: fix address order in
+ * nm_platform_ip_address_sync()').
+ *
+ * However, also in 1.36, the actually implemented order of IPv6 addresses is not
+ * the one we want ([1]). So disable the fix again, to not reorder IPv6 addresses.
+ *
+ * The effect is, that DHCPv6 addresses end up being preferred over SLAAC, because
+ * they get added later during activation. Of course, if any address gets added
+ * even later (like a new router appearing), then the order will be wrong again.
+ *
+ * [1] https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/1021 */
+ }
if (nm_g_ptr_array_len(plat_addresses) > 0) {
/* Delete addresses that interfere with our intended order. */
--
2.36.1