From a960d64a87849d312b32d9432ffb722672c14878 Mon Sep 17 00:00:00 2001
From: Pim van Pelt <pim@ipng.nl>
Date: Tue, 5 Mar 2024 22:59:15 +0100
Subject: [PATCH] Add the ability to skip address sync on unnumbered interfaces

---
 lcpng.c           | 20 ++++++++++++++++++++
 lcpng.h           |  1 +
 lcpng_if_cli.c    | 31 +++++++++++++++++++++++++++++++
 lcpng_if_sync.c   | 17 ++++++++++++++++-
 lcpng_interface.c |  4 ++++
 lcpng_interface.h |  6 ++++++
 6 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/lcpng.c b/lcpng.c
index 3b102b5..7e8d617 100644
--- a/lcpng.c
+++ b/lcpng.c
@@ -95,6 +95,26 @@ lcp_sync (void)
   return lcpm->lcp_sync;
 }
 
+void
+lcp_set_sync_unnumbered (u8 is_sync)
+{
+  lcp_main_t *lcpm = &lcp_main;
+
+  lcpm->lcp_sync_unnumbered = (is_sync != 0);
+
+  // If we set to 'on', do a one-off sync of LCP interfaces
+  if (is_sync)
+    lcp_itf_pair_sync_state_all ();
+}
+
+int
+lcp_sync_unnumbered (void)
+{
+  lcp_main_t *lcpm = &lcp_main;
+
+  return lcpm->lcp_sync_unnumbered;
+}
+
 void
 lcp_set_auto_subint (u8 is_auto)
 {
diff --git a/lcpng.h b/lcpng.h
index cf51411..2447433 100644
--- a/lcpng.h
+++ b/lcpng.h
@@ -26,6 +26,7 @@ typedef struct lcp_main_s
   int default_ns_fd;
   u8 lcp_auto_subint; /* Automatically create/delete LCP sub-interfaces */
   u8 lcp_sync;	      /* Automatically sync VPP changes to LCP */
+  u8 lcp_sync_unnumbered; /* Automatically sync unnumbered interfaces to LCP */
   /* Set when Unit testing */
   u8 test_mode;
 } lcp_main_t;
diff --git a/lcpng_if_cli.c b/lcpng_if_cli.c
index beab982..22e44ab 100644
--- a/lcpng_if_cli.c
+++ b/lcpng_if_cli.c
@@ -142,6 +142,37 @@ VLIB_CLI_COMMAND (lcp_sync_command, static) = {
   .function = lcp_sync_command_fn,
 };
 
+static clib_error_t *
+lcp_sync_unnumbered_command_fn (vlib_main_t *vm, unformat_input_t *input,
+				vlib_cli_command_t *cmd)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (line_input, "on") || unformat (line_input, "enable"))
+	lcp_set_sync_unnumbered (1);
+      else if (unformat (line_input, "off") ||
+	       unformat (line_input, "disable"))
+	lcp_set_sync_unnumbered (0);
+      else
+	return clib_error_return (0, "unknown input `%U'",
+				  format_unformat_error, line_input);
+    }
+
+  unformat_free (line_input);
+  return 0;
+}
+
+VLIB_CLI_COMMAND (lcp_sync_unnumbered_command, static) = {
+  .path = "lcp lcp-sync-unnumbered",
+  .short_help = "lcp lcp-sync-unnumbered [on|enable|off|disable]",
+  .function = lcp_sync_unnumbered_command_fn,
+};
+
 static clib_error_t *
 lcp_auto_subint_command_fn (vlib_main_t *vm, unformat_input_t *input,
 			    vlib_cli_command_t *cmd)
diff --git a/lcpng_if_sync.c b/lcpng_if_sync.c
index 43bbb0a..1c82db6 100644
--- a/lcpng_if_sync.c
+++ b/lcpng_if_sync.c
@@ -109,7 +109,22 @@ lcp_itf_pair_sync_state (lcp_itf_pair_t *lip)
   /* Linux will remove IPv6 addresses on children when the parent state
    * goes down, so we ensure all IPv4/IPv6 addresses are synced.
    */
-  lcp_itf_set_interface_addr (lip);
+  if (sw->flags & VNET_SW_INTERFACE_FLAG_UNNUMBERED)
+    {
+      if (lcp_sync_unnumbered ())
+	{
+	  lcp_itf_set_interface_addr (lip);
+	}
+      else
+	{
+	  LCP_IF_NOTICE ("sync_state: not syncing addresses on unnumbered %U",
+			 format_lcp_itf_pair, lip);
+	}
+    }
+  else
+    {
+      lcp_itf_set_interface_addr (lip);
+    }
 
   if (vif_ns_fd != -1)
     close (vif_ns_fd);
diff --git a/lcpng_interface.c b/lcpng_interface.c
index 4e61f08..ac6f6d7 100644
--- a/lcpng_interface.c
+++ b/lcpng_interface.c
@@ -133,6 +133,8 @@ lcp_itf_pair_show (u32 phy_sw_if_index)
   vlib_cli_output (vm, "lcp lcp-auto-subint %s\n",
 		   lcp_auto_subint () ? "on" : "off");
   vlib_cli_output (vm, "lcp lcp-sync %s\n", lcp_sync () ? "on" : "off");
+  vlib_cli_output (vm, "lcp lcp-sync-unnumbered %s\n",
+		   lcp_sync_unnumbered () ? "on" : "off");
 
   if (phy_sw_if_index == ~0)
     {
@@ -1233,6 +1235,8 @@ lcp_itf_pair_init (vlib_main_t *vm)
   tcp_punt_unknown (vm, 0, 1);
   tcp_punt_unknown (vm, 1, 1);
 
+  lcp_main.lcp_sync_unnumbered = 1;
+
   return NULL;
 }
 
diff --git a/lcpng_interface.h b/lcpng_interface.h
index 9a6d64d..caf43e1 100644
--- a/lcpng_interface.h
+++ b/lcpng_interface.h
@@ -166,6 +166,12 @@ int lcp_auto_subint (void);
 void lcp_set_sync (u8 is_auto);
 int lcp_sync (void);
 
+/**
+ * sync address of unnumbered interfaces from VPP into LCP
+ */
+void lcp_set_sync_unnumbered (u8 is_sync);
+int lcp_sync_unnumbered (void);
+
 typedef void (*lcp_itf_pair_add_cb_t) (lcp_itf_pair_t *);
 typedef void (*lcp_itf_pair_del_cb_t) (lcp_itf_pair_t *);