From 26234bec9ca3ca4084597939bc9c7bdf2db0edc0 Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Tue, 29 Oct 2024 12:35:06 +0100
Subject: [PATCH] refuse proposals with a round number that is too high

---
 mysticeti/validator.nim                    | 2 ++
 tests/mysticeti/validator/testMultiple.nim | 9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/mysticeti/validator.nim b/mysticeti/validator.nim
index 85a5d8a..c9e6f84 100644
--- a/mysticeti/validator.nim
+++ b/mysticeti/validator.nim
@@ -89,6 +89,8 @@ func check*(validator: Validator, signed: SignedBlock): auto =
     return BlockCheck.invalid("block is not signed by a committee member")
   if member != signed.blck.author:
     return BlockCheck.invalid("block is not signed by its author")
+  if signed.blck.round > validator.round:
+    return BlockCheck.invalid("block has a round number that is too high")
   for parent in signed.blck.parents:
     if parent.round >= signed.blck.round:
       return BlockCheck.invalid("block has a parent from an invalid round")
diff --git a/tests/mysticeti/validator/testMultiple.nim b/tests/mysticeti/validator/testMultiple.nim
index 9ea8572..b186dcd 100644
--- a/tests/mysticeti/validator/testMultiple.nim
+++ b/tests/mysticeti/validator/testMultiple.nim
@@ -114,6 +114,7 @@ suite "Multiple Validators":
 
   test "refuses proposals without >2/3 parents from the previous round":
     let parents = exchangeProposals().mapIt(it.blck.id)
+    nextRound()
     let blck = Block.new(
       CommitteeMember(0),
       round = 1,
@@ -142,6 +143,14 @@ suite "Multiple Validators":
     check checked.verdict == BlockVerdict.incomplete
     check checked.missing == @[parents[0].blck.id]
 
+  test "refuses proposals with a round number that is too high":
+    discard exchangeProposals()
+    validators[0].nextRound()
+    let proposal = validators[0].propose(seq[Transaction].example)
+    let checked = validators[1].check(proposal)
+    check checked.verdict == BlockVerdict.invalid
+    check checked.reason == "block has a round number that is too high"
+
   test "skips blocks that are ignored by >2f validators":
     # first round: other validators do not receive proposal from first validator
     let proposals = exchangeProposals {