From 53c6d506cf1a3fbc8df0e298cf6b988c808fdbe5 Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Mon, 31 Mar 2025 23:15:28 +0100
Subject: [PATCH] dhcp6c subscribe to ppp ifindex

when the peer bounces ppp, s6 will restart the ppp process but not
restart the dependent services (because the service isn't considered
to have gone down)

so the dependent services need to notice when the outputs from ppp
have changed
---
 modules/dhcp6c/acquire-delegated-prefix.fnl |  1 +
 modules/dhcp6c/acquire-wan-address.fnl      |  1 +
 modules/dhcp6c/client.nix                   | 30 ++++++++++++++-------
 3 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/modules/dhcp6c/acquire-delegated-prefix.fnl b/modules/dhcp6c/acquire-delegated-prefix.fnl
index f0744df..8ff7892 100644
--- a/modules/dhcp6c/acquire-delegated-prefix.fnl
+++ b/modules/dhcp6c/acquire-delegated-prefix.fnl
@@ -25,6 +25,7 @@
 (fn run []
   (let [[state-directory lan-device] arg
         dir (svc.open state-directory)]
+    (update-prefixes lan-device [] (or (dir:output "prefix") []) system)
     (accumulate [addresses []
                  v (dir:events)]
       (update-prefixes lan-device addresses (or (v:output "prefix") []) system))))
diff --git a/modules/dhcp6c/acquire-wan-address.fnl b/modules/dhcp6c/acquire-wan-address.fnl
index de6edaf..b2c7e73 100644
--- a/modules/dhcp6c/acquire-wan-address.fnl
+++ b/modules/dhcp6c/acquire-wan-address.fnl
@@ -25,6 +25,7 @@
 (fn run []
   (let [[state-directory wan-device] arg
         dir (svc.open state-directory)]
+    (update-addresses wan-device [] (or (dir:output "address") []) system)
     (accumulate [addresses []
                  v (dir:events)]
       (update-addresses wan-device addresses (or (v:output "address") []) system))))
diff --git a/modules/dhcp6c/client.nix b/modules/dhcp6c/client.nix
index 77314f6..a2031f7 100644
--- a/modules/dhcp6c/client.nix
+++ b/modules/dhcp6c/client.nix
@@ -2,19 +2,29 @@
   liminix,
   odhcp6c,
   odhcp-script,
+  svc
 }:
 { interface }:
 let
   inherit (liminix.services) longrun;
+  inherit (liminix) outputRef;
   name = "dhcp6c.${interface.name}";
-in
-longrun {
-  inherit name;
-  notification-fd = 10;
-  run = ''
-    export SERVICE_STATE=$SERVICE_OUTPUTS/${name}
-    ${odhcp6c}/bin/odhcp6c -s ${odhcp-script} -e -v -p /run/${name}.pid -P0 $(output ${interface} ifname)
-    )
-  '';
-  dependencies = [ interface ];
+  service =
+    longrun {
+      inherit name;
+      notification-fd = 10;
+      run = ''
+        export SERVICE_STATE=$SERVICE_OUTPUTS/${name}
+        ifname=$(output ${interface} ifname)
+        test -n "$ifname" && ${odhcp6c}/bin/odhcp6c -s ${odhcp-script} -e -v -p /run/${name}.pid -P0 $ifname
+        )
+      '';
+      dependencies = [ interface ];
+    };
+in svc.secrets.subscriber.build {
+  # if the ppp service gets restarted, the interface may be different and
+  # we will have to restart dhcp on the new one
+  watch = [ (outputRef interface "ifindex") ];
+  action = "restart";
+  inherit service;
 }