From fcd95d60216a6a081f5b9f00a5d82b53a9b53549 Mon Sep 17 00:00:00 2001
From: Lauri Gustafsson <lauri.gustafsson@iki.fi>
Date: Mon, 16 Dec 2024 11:45:09 +0200
Subject: [PATCH] server: Integrate Message::SetMajority to
 Message::Coordinator (v0.11.0)

---
 Cargo.lock                             |  2 +-
 server-node/Cargo.toml                 |  2 +-
 server-node/src/server.rs              | 12 +++++++-----
 server-node/src/server/peer/message.rs |  5 +++--
 4 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index f621678..7dfb524 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -305,7 +305,7 @@ dependencies = [
 
 [[package]]
 name = "server-node"
-version = "0.10.0"
+version = "0.11.0"
 dependencies = [
  "ciborium",
  "protocol",
diff --git a/server-node/Cargo.toml b/server-node/Cargo.toml
index 4dfd01c..e4fb3de 100644
--- a/server-node/Cargo.toml
+++ b/server-node/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "server-node"
-version = "0.10.0"
+version = "0.11.0"
 edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
diff --git a/server-node/src/server.rs b/server-node/src/server.rs
index 06d6dbd..91d83db 100644
--- a/server-node/src/server.rs
+++ b/server-node/src/server.rs
@@ -235,8 +235,7 @@ impl Server {
         self.handle_majority(majority);
 
         for peer in self.peers.values() {
-            peer.send_message(Message::Coordinator);
-            peer.send_message(Message::SetMajority(self.majority));
+            peer.send_message(Message::Coordinator { majority });
         }
 
         #[allow(
@@ -330,6 +329,9 @@ impl Server {
             self.become_coordinator();
         }
 
+        // If coordinator was lost, we need to hold an election again.
+        // It's possible, that during this election, the majority-bit is incorrect.
+        // This is acceptable, because DHCP clients should never use conflicting addresses.
         if Some(peer_id) == self.coordinator_id {
             self.start_election();
         }
@@ -440,10 +442,9 @@ impl Server {
             Message::Heartbeat => console::debug!("Received heartbeat from {sender_id}"),
             Message::Election => self.handle_election(sender_id),
             Message::Okay => self.handle_okay(sender_id),
-            Message::Coordinator => self.handle_coordinator(sender_id),
+            Message::Coordinator { majority } => self.handle_coordinator(sender_id, majority),
             Message::Lease(lease) => self.handle_add_lease(lease),
             Message::SetPool(update) => self.handle_set_pool(update),
-            Message::SetMajority(majority) => self.handle_majority(majority),
             Message::Join(..) | Message::JoinAck { .. } => {
                 console::warning!("Server received unexpected {message:?} from peer {sender_id}");
             }
@@ -473,10 +474,11 @@ impl Server {
         }
     }
 
-    fn handle_coordinator(&mut self, sender_id: peer::Id) {
+    fn handle_coordinator(&mut self, sender_id: peer::Id, majority: bool) {
         console::log!("Recognizing {sender_id} as Coordinator");
         self.coordinator_id = Some(sender_id);
         self.election_state = ElectionState::Follower;
+        self.handle_majority(majority);
         if sender_id < self.config.id {
             self.start_election();
         }
diff --git a/server-node/src/server/peer/message.rs b/server-node/src/server/peer/message.rs
index 78ebd69..9ffc653 100644
--- a/server-node/src/server/peer/message.rs
+++ b/server-node/src/server/peer/message.rs
@@ -25,10 +25,11 @@ pub enum Message {
     Heartbeat,
     Election,
     Okay,
-    Coordinator,
+    Coordinator {
+        majority: bool,
+    },
     Lease(Lease),
     SetPool(Ipv4Range),
-    SetMajority(bool),
 }
 
 impl RecvCbor<Message> for TcpStream {}