From 19999ea51751f461c2d5c0f9a8405f33dfac0c28 Mon Sep 17 00:00:00 2001
From: Ethan Buchman <ethan@coinculture.info>
Date: Thu, 22 Jun 2017 20:32:22 -0400
Subject: [PATCH] ibc: UpdateChain fix blockid

---
 plugins/ibc/ibc.go | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/plugins/ibc/ibc.go b/plugins/ibc/ibc.go
index eb8a27f1b0..3a9b0f8c6e 100644
--- a/plugins/ibc/ibc.go
+++ b/plugins/ibc/ibc.go
@@ -570,7 +570,17 @@ func verifyCommit(chainState BlockchainState, header *tm.Header, commit *tm.Comm
 	chainID := chainState.ChainID
 	vals := chainState.Validators
 	valSet := tm.NewValidatorSet(vals)
-	blockID := commit.Precommits[0].BlockID // XXX: incorrect
+
+	var blockID tm.BlockID
+	for _, pc := range commit.Precommits {
+		// XXX: incorrect. we want the one for +2/3, not just the first one
+		if pc != nil {
+			blockID = pc.BlockID
+		}
+	}
+	if blockID.IsZero() {
+		return errors.New("All precommits are nil!")
+	}
 
 	// NOTE: Currently this only works with the exact same validator set.
 	// Not this, but perhaps "ValidatorSet.VerifyCommitAny" should expose