[PATCH 3.3] Proto: Allow channel start() to refuse DOWN->START

[Zhang Maiyun via Bird-users]

From: Zhang Maiyun <m...@maiyun.me>

Signed-off-by: Zhang Maiyun <m...@maiyun.me>
---
 nest/proto.c    | 27 ++++++++++++++++++++-------
 proto/bgp/bgp.c |  2 +-
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/nest/proto.c b/nest/proto.c
index 4472fe6f..2edbe142 100644
--- a/nest/proto.c
+++ b/nest/proto.c
@@ -1086,7 +1086,7 @@ channel_setup_in_table(struct channel *c)
 }
 
 
-static void
+static int
 channel_do_start(struct channel *c)
 {
   c->proto->active_channels++;
@@ -1094,9 +1094,12 @@ channel_do_start(struct channel *c)
   if ((c->in_keep & RIK_PREFILTER) == RIK_PREFILTER)
     channel_setup_in_table(c);
 
-  CALL(c->class->start, c);
+  if (c->class->start)
+    if (c->class->start(c) != 0)
+      return -1;
 
   channel_start_import(c);
+  return 0;
 }
 
 static void
@@ -1176,7 +1179,11 @@ channel_set_state(struct channel *c, uint state)
     ASSERT(cs == CS_DOWN || cs == CS_PAUSE);
 
     if (cs == CS_DOWN)
-      channel_do_start(c);
+      if (channel_do_start(c) != 0) {
+        // Reject the channel start and return to down state
+        c->channel_state = CS_DOWN;
+        c->last_state_change = current_time();
+      }
 
     break;
 
@@ -1184,12 +1191,18 @@ channel_set_state(struct channel *c, uint state)
     ASSERT(cs == CS_DOWN || cs == CS_START || cs == CS_PAUSE);
 
     if (cs == CS_DOWN)
-      channel_do_start(c);
+      if (channel_do_start(c) != 0) {
+        // Reject the channel start and return to down state
+        c->channel_state = CS_DOWN;
+        c->last_state_change = current_time();
+      }
 
-    if (!c->gr_wait && c->proto->rt_notify)
-      channel_start_export(c);
+    if (c->channel_state != CS_DOWN) {
+      if (!c->gr_wait && c->proto->rt_notify)
+        channel_start_export(c);
 
-    channel_do_up(c);
+      channel_do_up(c);
+    }
     break;
 
   case CS_PAUSE:
diff --git a/proto/bgp/bgp.c b/proto/bgp/bgp.c
index 8d04a05d..1923a80d 100644
--- a/proto/bgp/bgp.c
+++ b/proto/bgp/bgp.c
@@ -3257,7 +3257,7 @@ bgp_channel_start(struct channel *C)
   if (ipa_zero(c->next_hop_addr))
   {
     log(L_WARN "%s: Missing next hop address", p->p.name);
-    return 0;
+    return -1;
   }
 
   /* Set link-local address for IPv6 single-hop BGP */
-- 
2.54.0